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Khan W, Wang YH, Chaurasiya ND, Nanayakkara NPD, Bandara Herath HM, Harrison KA, Dale G, Stanford DA, Dahl EP, McChesney JD, Gul W, ElSohly MA, Jollow D, Tekwani BL, Walker LA. Comparative metabolism and tolerability of racemic primaquine and its enantiomers in human volunteers during 7-day administration. Front Pharmacol 2023; 13:1104735. [PMID: 36726785 PMCID: PMC9885159 DOI: 10.3389/fphar.2022.1104735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 12/30/2022] [Indexed: 01/18/2023] Open
Abstract
Primaquine (PQ) is an 8-aminoquinoline antimalarial, active against dormant Plasmodium vivax hypnozoites and P. falciparum mature gametocytes. PQ is currently used for P. vivax radical cure and prevention of malaria transmission. PQ is a racemic drug and since the metabolism and pharmacology of PQ's enantiomers have been shown to be divergent, the objectives of this study were to evaluate the comparative tolerability and metabolism of PQ with respect to its two enantiomers in human volunteers in a 7 days' treatment schedule. Fifteen subjects with normal glucose-6-phosphate dehydrogenase (G6PDn) completed four arms, receiving each of the treatments, once daily for 7 days, in a crossover fashion, with a 7-14 days washout period in between: R-(-) enantiomer (RPQ) 22.5 mg; S-(+) enantiomer (SPQ) 22.5 mg; racemic PQ (RSPQ) 45 mg, and placebo. Volunteers were monitored for any adverse events (AEs) during the study period. PQ and metabolites were quantified in plasma and red blood cells (RBCs) by UHPLC-UV-MS/MS. Plasma PQ was significantly higher in SPQ treatment group than for RPQ. Carboxy-primaquine, a major plasma metabolite, was much higher in the RPQ treated group than SPQ; primaquine carbamoyl glucuronide, another major plasma metabolite, was derived only from SPQ. The ortho-quinone metabolites were also detected and showed differences for the two enantiomers in a similar pattern to the parent drugs. Both enantiomers and racemic PQ were well tolerated in G6PDn subjects with the 7 days regimen; three subjects showed mild AEs which did not require any intervention or discontinuation of the drug. The most consistent changes in G6PDn subjects were a gradual increase in methemoglobin and bilirubin, but these were not clinically important. However, the bilirubin increase suggests mild progressive damage to a small fraction of red cells. PQ enantiomers were also individually administered to two G6PD deficient (G6PDd) subjects, one heterozygous female and one hemizygous male. These G6PDd subjects showed similar results with the two enantiomers, but the responses in the hemizygous male were more pronounced. These studies suggest that although the metabolism profiles of individual PQ enantiomers are markedly different, they did not show significant differences in the safety and tolerability in G6PDn subjects.
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Affiliation(s)
- Washim Khan
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Yan-Hong Wang
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Narayan D. Chaurasiya
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research Institute, Birmingham, AL, United States
| | - N. P. Dhammika Nanayakkara
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - H. M. Bandara Herath
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Kerri A. Harrison
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Gray Dale
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Donald A. Stanford
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Eric P. Dahl
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | | | - Waseem Gul
- ElSohly Laboratories Inc., Oxford, MS, United States
| | - Mahmoud A. ElSohly
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States,ElSohly Laboratories Inc., Oxford, MS, United States,Pharmaceutics and Drug Delivery, School of Pharmacy, The University of Mississippi, University, MS, United States
| | - David Jollow
- Professor Emeritus, Department Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC, United States
| | - Babu L. Tekwani
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research Institute, Birmingham, AL, United States,*Correspondence: Babu L. Tekwani, ; Larry A. Walker,
| | - Larry A. Walker
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States,*Correspondence: Babu L. Tekwani, ; Larry A. Walker,
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2
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Khan W, Wang YH, Dhammika Nanayakkara N, Bandara Herath H, Chaurasiya ND, Tekwani BL, ElSohly MA, McChesney JD, Khan IA, Walker LA. Quantitative analysis of primaquine and its metabolites in human urine using liquid chromatography coupled with tandem mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2022; 1213:123517. [DOI: 10.1016/j.jchromb.2022.123517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022]
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Birrell GW, Van Breda K, Barber B, Webster R, McCarthy JS, Shanks GD, Edstein MD. Quantification of Tafenoquine and 5,6-Orthoquinone Tafenoquine by UHPLC-MS/MS in Blood, Plasma, and Urine, and Application to a Pharmacokinetic Study. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238186. [PMID: 36500278 PMCID: PMC9737280 DOI: 10.3390/molecules27238186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/15/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022]
Abstract
Analytical methods for the quantification of the new 8-aminoquinoline antimalarial tafenoquine (TQ) in human blood, plasma and urine, and the 5,6-orthoquinone tafenoquine metabolite (5,6-OQTQ) in human plasma and urine have been validated. The procedure involved acetonitrile extraction of samples followed by ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Chromatography was performed using a Waters Atlantis T3 column with a gradient of 0.1% formic acid and acetonitrile at a flow rate of 0.5 mL per minute for blood and plasma. Urine analysis was the same but with methanol containing 0.1% formic acid replacing acetonitrile mobile phase. The calibration range for TQ and 5,6-OQTQ in plasma was 1 to 1200 ng/mL, and in urine was 10 to 1000 ng/mL. Blood calibration range for TQ was 1 to 1200 ng/mL. Blood could not be validated for 5,6-OQTQ due to significant signal suppression. The inter-assay precision (coefficient of variation %) was 9.9% for TQ at 1 ng/mL in blood (n = 14) and 8.2% for TQ and 7.1% for 5,6-OQTQ at 1 ng/mL in plasma (n = 14). For urine, the inter-assay precision was 8.2% for TQ and 6.4% for 5,6-OQTQ at 10 ng/mL (n = 14). TQ and 5,6-OQTQ are stable in blood, plasma and urine for at least three months at both -80 °C and -20 °C. Once validated, the analytical methods were applied to samples collected from healthy volunteers who were experimentally infected with Plasmodium falciparum to evaluate the blood stage antimalarial activity of TQ and to determine the therapeutic dose estimates for TQ, the full details of which will be published elsewhere. In this study, the measurement of TQ and 5,6-OQTQ concentrations in samples from one of the four cohorts of participants is reported. Interestingly, TQ urine concentrations were proportional to parasite recrudescence times post dosing To our knowledge, this is the first description of a fully validated method for the measurement of TQ and 5,6-OQTQ quantification in urine.
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Affiliation(s)
- Geoffrey W. Birrell
- Drug Evaluation, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane 4051, Australia
- Correspondence:
| | - Karin Van Breda
- Drug Evaluation, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane 4051, Australia
| | - Bridget Barber
- Clinical Malaria Group, QIMR Berghofer Medical Research Institute, Brisbane 4006, Australia
| | - Rebecca Webster
- Clinical Malaria Group, QIMR Berghofer Medical Research Institute, Brisbane 4006, Australia
| | - James S. McCarthy
- Clinical Malaria Group, QIMR Berghofer Medical Research Institute, Brisbane 4006, Australia
- Department of Infectious Diseases, University of Melbourne, Melbourne 3010, Australia
| | - G. Dennis Shanks
- Drug Evaluation, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane 4051, Australia
| | - Michael D. Edstein
- Drug Evaluation, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane 4051, Australia
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Khan W, Wang YH, Chaurasiya ND, Nanayakkara NPD, Herath HMB, Harrison KA, Dale G, Stanford DA, Dahl EP, McChesney JD, Gul W, ElSohly MA, Khan SI, Fasinu PS, Khan IA, Tekwani BL, Walker LA. Comparative single dose pharmacokinetics and metabolism of racemic primaquine and its enantiomers in human volunteers. Drug Metab Pharmacokinet 2022; 45:100463. [PMID: 35709685 PMCID: PMC9789533 DOI: 10.1016/j.dmpk.2022.100463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/14/2022] [Accepted: 04/25/2022] [Indexed: 12/26/2022]
Abstract
Primaquine (PQ) is a racemic drug used in treatment of malaria for six decades. Recent studies suggest that the two enantiomers of PQ are differentially metabolized in animals, and this results in different pharmacological and toxicological profiles. The current study characterizes the pharmacokinetic (PK) properties, metabolism and tolerability of the individual enantiomers of PQ in healthy human volunteers with normal glucose-6-phosphate dehydrogenase (G6PD) activity. Two cohorts (at two dose levels), each with 18 subjects, participated in three study arms in a crossover fashion: a single dose of the (-)-R enantiomer (RPQ), a single dose of the (+)-S enantiomer (SPQ), and a single dose of racemic PQ (RSPQ). PQ and its key metabolites carboxyprimaquine (cPQ) and PQ-N-carbamoyl glucuronide (PQ-N-CG) were analyzed. Clear differences were observed in PK and metabolism of the two enantiomers. Relative PQ exposure was higher with SPQ as compared to RPQ. PQ maximum plasma concentration (Cmax) and area under the plasma concentration-time curve were higher for SPQ, while the apparent volume of distribution and total body clearance were higher for RPQ. Metabolism of the two enantiomers showed dramatic differences: plasma PQ-N-CG was derived solely from SPQ, while RPQ was much more efficiently converted to cPQ than was SPQ. Cmax of cPQ and PQ-N-CG were 10 and 2 times higher, respectively, than the parent drugs. The study demonstrates that the PK properties of PQ enantiomers show clear differences, and metabolism is highly enantioselective. Such differences in metabolism suggest potentially distinct toxicity profiles in multi-dose regimens, especially in G6PD-deficient subjects.
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Affiliation(s)
- Washim Khan
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Yan-Hong Wang
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Narayan D. Chaurasiya
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research Institute, Birmingham, AL, 35205, USA
| | - NP Dhammika Nanayakkara
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - HM Bandara Herath
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Kerri A. Harrison
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Gray Dale
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Donald A. Stanford
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Eric P. Dahl
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | | | - Waseem Gul
- ElSohly Laboratories, Inc., Oxford, MS, 38655, USA
| | - Mahmoud A. ElSohly
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA,Pharmaceutics and Drug Delivery, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA,ElSohly Laboratories, Inc., Oxford, MS, 38655, USA
| | - Shabana I. Khan
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Pius S. Fasinu
- Department of Pharmacology & Toxicology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Ikhlas A. Khan
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA,Departments of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Babu L. Tekwani
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research Institute, Birmingham, AL, 35205, USA,Corresponding author. (B.L. Tekwani)
| | - Larry A. Walker
- National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA,Corresponding author. (L.A. Walker)
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5
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Hanpithakpong W, Day NPJ, White NJ, Tarning J. Simultaneous and enantiospecific quantification of primaquine and carboxyprimaquine in human plasma using liquid chromatography-tandem mass spectrometry. Malar J 2022; 21:169. [PMID: 35659684 PMCID: PMC9166498 DOI: 10.1186/s12936-022-04191-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/19/2022] [Indexed: 11/20/2022] Open
Abstract
Background The enantiomers of the 8-aminoquinoline anti-malarial primaquine have different pharmacological properties. Development of an analytical method for simultaneous quantification of the enantiomers of primaquine and its metabolite, carboxyprimaquine, will support clinical pharmacometric assessments. Methods A simple and sensitive method consisting of liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) was developed for simultaneous and enantiospecific determination of primaquine and its metabolite, carboxyprimaquine, in human plasma. Stable isotopes were used as internal standards to compensate for potential interference and matrix effects. Plasma samples (100 µL) were precipitated with 1% formic acid in acetonitrile followed by phospholipid removal solid phase extraction. Primaquine and carboxyprimaquine enantiomers were separated on a Chiralcel OD-3R (150 mm × 4.6 mm; I.D. 3 μm) column using a LC gradient mode. For separation of racemic primaquine and carboxyprimaquine, the LC method was modified and validated using a reverse phase column (Hypersil Gold 100 mm × 4.6 mm; I.D. 3 µm) and a mobile phase composed of 10 mM ammonium acetate buffer, pH 3.5 and acetonitrile in the isocratic mode. Method validation was performed according to regulatory guidelines. Results The calibration range was set to 0.571–260 ng/mL and 2.44–2,500 ng/mL for primaquine and carboxyprimaquine enantiomers, respectively, resulting in a correlation coefficient (r2) ≥ 0.0998 for all calibration curves. The intra- and inter-day assay precisions were < 10% and the accuracy was between 94.7 to 103% for all enantiomers of primaquine and carboxyprimaquine. The enantiospecific method was also modified and validated to quantify racemic primaquine and carboxyprimaquine, reducing the total run time from 30 to 8 min. The inter-, intra-day assay precision of the racemic quantification method was < 15%. The absolute recoveries of primaquine and carboxyprimaquine were between 70 and 80%. Stability was demonstrated for up to 2 years in − 80 °C. Both the enantiomeric and racemic LC–MS/MS methods were successfully implemented in pharmacokinetic studies in healthy volunteers. Conclusions Simple, sensitive and accurate LC–MS/MS methods for the quantification of enantiomeric and racemic primaquine and carboxyprimaquine in human plasma were validated successfully and implemented in clinical routine drug analysis.
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Affiliation(s)
- Warunee Hanpithakpong
- Department of Clinical Pharmacology, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nicholas P J Day
- Department of Clinical Pharmacology, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Nicholas J White
- Department of Clinical Pharmacology, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Joel Tarning
- Department of Clinical Pharmacology, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
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6
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Chan ER, Mehlotra RK, Pirani KA, Ratsimbasoa AC, Williams SM, Gaedigk A, Zimmerman PA. CYP2D6 gene resequencing in the Malagasy, a population at the crossroads between Asia and Africa: a pilot study. Pharmacogenomics 2022; 23:315-325. [PMID: 35230160 PMCID: PMC8965795 DOI: 10.2217/pgs-2021-0146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Background: Plasmodium vivax malaria is endemic in Madagascar, where populations have genetic inheritance from Southeast Asia and East Africa. Primaquine, a drug of choice for vivax malaria, is metabolized principally via CYP2D6. CYP2D6 variation was characterized by locus-specific gene sequencing and was compared with TaqMan™ genotype data. Materials & methods: Long-range PCR amplicons were generated from 96 Malagasy samples and subjected to next-generation sequencing. Results: The authors observed high concordance between TaqMan™-based CYP2D6 genotype calls and the base calls from sequencing. In addition, there are new variants and haplotypes present in the Malagasy. Conclusion: Sequencing unique admixed populations provides more detailed and accurate insights regarding CYP2D6 variability, which may help optimize primaquine treatment across human genetic diversity.
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Affiliation(s)
- E Ricky Chan
- Cleveland Institute for Computational Biology, Case Western Reserve University, Cleveland, OH 44106, USA.,Population & Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Rajeev K Mehlotra
- Center for Global Health & Diseases, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Karim A Pirani
- Division of Clinical Pharmacology, Toxicology & Therapeutic Innovation, Children's Mercy Kansas City, Kansas City, MO 64108, USA
| | - Arsene C Ratsimbasoa
- University of Fianarantsoa, Fianarantsoa, Madagascar.,CNARP (Centre National d'Application de Recherche Pharmaceutique), Antananarivo, Madagascar
| | - Scott M Williams
- Cleveland Institute for Computational Biology, Case Western Reserve University, Cleveland, OH 44106, USA.,Population & Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Andrea Gaedigk
- Division of Clinical Pharmacology, Toxicology & Therapeutic Innovation, Children's Mercy Kansas City, Kansas City, MO 64108, USA
| | - Peter A Zimmerman
- Center for Global Health & Diseases, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Fasinu PS, Chaurasiya ND, Dhammika Nanayakkara NP, Wang Y, Bandara Herath HMT, Avula B, McChesney JD, Jollow D, Walker LA, Tekwani BL. Comparative pharmacokinetics and tissue distribution of primaquine enantiomers in mice. Malar J 2022; 21:33. [PMID: 35123453 PMCID: PMC8817607 DOI: 10.1186/s12936-022-04054-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/18/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Primaquine (PQ) has been used for the radical cure of relapsing Plasmodium vivax malaria for more than 60 years. PQ is also recommended for prophylaxis and prevention of transmission of Plasmodium falciparum. However, clinical utility of PQ has been limited due to toxicity in individuals with genetic deficiencies in glucose 6-phosphate dehydrogenase (G6PD). PQ is currently approved for clinical use as a racemic mixture. Recent studies in animals as well as humans have established differential pharmacological and toxicological properties of the two enantiomers of PQ. This has been attributed to differential metabolism and pharmacokinetics of individual PQ enantiomers. The aim of the current study is to evaluate the comparative pharmacokinetics (PK), tissue distribution and metabolic profiles of the individual enantiomers in mice.
Methods
Two groups of 21 male Albino ND4 Swiss mice were dosed orally with 45 mg/kg of S-(+)-PQ and R-(−)PQ respectively. Each of the enantiomers was comprised of a 50:50 mixture of 12C- and 13C- stable isotope labelled species (at 6 carbons on the benzene ring of the quinoline core). Three mice were euthanized from each group at different time points (at 0, 0.5, 1, 2, 4, 8, 24 h) and blood was collected by terminal cardiac bleed. Liver, spleen, lungs, kidneys and brain were removed, extracted and analysed using UPLC/MS. The metabolites were profiled by tandem mass (MS/MS) fragmentation profile and fragments with 12C–13C twin peaks. Non-compartmental analysis was performed using the Phoenix WinNonLin PK software module.
Results
The plasma AUC0-last (µg h/mL) (1.6 vs. 0.6), T1/2 (h) (1.9 vs. 0.45), and Tmax (h) (1 vs. 0.5) were greater for SPQ as compared to RPQ. Generally, the concentration of SPQ was higher in all tissues. At Tmax, (0.5–1 h in all tissues), the level of SPQ was 3 times that of RPQ in the liver. Measured Cmax of SPQ and RPQ in the liver were about 100 and 40 times the Cmax values in plasma, respectively. Similar observations were recorded in other tissues where the concentration of SPQ was higher compared to RPQ (2× in the spleen, 6× in the kidneys, and 49× in the lungs) than in the plasma. CPQ, the major metabolite, was preferentially generated from RPQ, with higher levels in all tissues (> 10× in the liver, and 3.5× in the plasma) than from SPQ. The PQ-o-quinone was preferentially formed from the SPQ (> 4× compared to RPQ), with higher concentrations in the liver.
Conclusion
These studies show that in mice, PQ enantiomers are differentially biodistributed and metabolized, which may contribute to differential pharmacologic and toxicity profiles of PQ enantiomers. The findings on higher levels of PQ-o-quinone in liver and RBCs compared to plasma and preferential generation of this metabolite from SPQ are consistent with the higher anti-malarial efficacy of SPQ observed in the mouse causal prophylaxis test, and higher haemolytic toxicity in the humanized mouse model of G6PD deficiency. Potential relevance of these findings to clinical use of racemic PQ and other 8-aminoquinolines vis-à-vis need for further clinical evaluation of individual enantiomers are discussed.
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8
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Chaurasiya ND, Liu H, Doerksen RJ, Nanayakkara NPD, Walker LA, Tekwani BL. Enantioselective Interactions of Anti-Infective 8-Aminoquinoline Therapeutics with Human Monoamine Oxidases A and B. Pharmaceuticals (Basel) 2021; 14:ph14050398. [PMID: 33922294 PMCID: PMC8146505 DOI: 10.3390/ph14050398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/09/2021] [Accepted: 04/17/2021] [Indexed: 11/25/2022] Open
Abstract
8-Aminoquinolines (8-AQs) are an important class of anti-infective therapeutics. The monoamine oxidases (MAOs) play a key role in metabolism of 8-AQs. A major role for MAO-A in metabolism of primaquine (PQ), the prototypical 8-AQ antimalarial, has been demonstrated. These investigations were further extended to characterize the enantioselective interactions of PQ and NPC1161 (8-[(4-amino-1-methylbutyl) amino]-5-[3, 4-dichlorophenoxy]-6-methoxy-4-methylquinoline) with human MAO-A and -B. NPC1161B, the (R)-(−) enantiomer with outstanding potential for malaria radical cure, treatment of visceral leishmaniasis and pneumocystis pneumonia infections is poised for clinical development. PQ showed moderate inhibition of human MAO-A and -B. Racemic PQ and (R)-(−)-PQ both showed marginally greater (1.2- and 1.6-fold, respectively) inhibition of MAO-A as compared to MAO-B. However, (S)-(+)-PQ showed a reverse selectivity with greater inhibition of MAO-B than MAO-A. Racemic NPC1161 was a strong inhibitor of MAOs with 3.7-fold selectivity against MAO-B compared to MAO-A. The (S)-(+) enantiomer (NPC1161A) was a better inhibitor of MAO-A and -B compared to the (R)-(−) enantiomer (NPC1161B), with more than 10-fold selectivity for inhibition of MAO-B over MAO-A. The enantioselective interaction of NPC1161 and strong binding of NPC1161A with MAO-B was further confirmed by enzyme-inhibitor binding and computational docking analyses. Differential interactions of PQ and NPC1161 enantiomers with human MAOs may contribute to the enantioselective pharmacodynamics and toxicity of anti-infective 8-AQs therapeutics.
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Affiliation(s)
- Narayan D. Chaurasiya
- Division of Drug Discovery, Department of Infectious Diseases, Southern Research, Birmingham, AL 35205, USA
- Correspondence: (N.D.C.); (B.L.T.); Tel.: +11-205-581-2026 (N.D.C.); +1-1-205-581-2205 (B.L.T.)
| | - Haining Liu
- Department of Bio-Molecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA; (H.L.); (R.J.D.)
| | - Robert J. Doerksen
- Department of Bio-Molecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA; (H.L.); (R.J.D.)
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, Oxford, MS 38677, USA; (N.P.D.N.); (L.A.W.)
| | - N. P. Dhammika Nanayakkara
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, Oxford, MS 38677, USA; (N.P.D.N.); (L.A.W.)
| | - Larry A. Walker
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, Oxford, MS 38677, USA; (N.P.D.N.); (L.A.W.)
| | - Babu L. Tekwani
- Division of Drug Discovery, Department of Infectious Diseases, Southern Research, Birmingham, AL 35205, USA
- Correspondence: (N.D.C.); (B.L.T.); Tel.: +11-205-581-2026 (N.D.C.); +1-1-205-581-2205 (B.L.T.)
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9
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Mehlotra RK, Gaedigk A, Howes RE, Rakotomanga TA, Ratsimbasoa AC, Zimmerman PA. CYP2D6 Genetic Variation and Its Implication for Vivax Malaria Treatment in Madagascar. Front Pharmacol 2021; 12:654054. [PMID: 33959023 PMCID: PMC8093859 DOI: 10.3389/fphar.2021.654054] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 03/01/2021] [Indexed: 12/19/2022] Open
Abstract
Plasmodium vivax is one of the five human malaria parasite species, which has a wide geographical distribution and can cause severe disease and fatal outcomes. It has the ability to relapse from dormant liver stages (hypnozoites), weeks to months after clearance of the acute blood-stage infection. An 8-aminoquinoline drug primaquine (PQ) can clear the hypnozoites, and thus can be used as an anti-relapse therapeutic agent. Recently, a number of studies have found that its efficacy is compromised by polymorphisms in the cytochrome P450 2D6 (CYP2D6) gene; decreased or absence of CYP2D6 activity contributes to PQ therapeutic failure. The present study sought to characterize CYP2D6 genetic variation in Madagascar, where populations originated from admixture between Asian and African populations, vivax malaria is endemic, and PQ can be deployed soon to achieve national malaria elimination. In a total of 211 samples collected from two health districts, CYP2D6 decreased function alleles CYP2D6*10, *17, *29, *36+*10, and *41 were observed at frequencies of 3.55-17.06%. In addition, nonfunctional alleles were observed, the most common of which were CYP2D6*4 (2.13%), *5 (1.66%), and the *4x2 gene duplication (1.42%). Given these frequencies, 34.6% of the individuals were predicted to be intermediate metabolizers (IM) with an enzyme activity score (AS) ≤ 1.0; both the IM phenotype and AS ≤ 1.0 have been found to be associated with PQ therapeutic failure. Furthermore, the allele and genotype frequency distributions add to the archaeological and genomic evidence of Malagasy populations constituting a unique, Asian-African admixed origin. The results from this exploratory study provide fresh insights about genomic characteristics that could affect the metabolism of PQ into its active state, and may enable optimization of PQ treatment across human genetic diversity, which is critical for achieving P. vivax elimination.
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Affiliation(s)
- Rajeev K Mehlotra
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Andrea Gaedigk
- Division of Clinical Pharmacology, Toxicology & Therapeutic Innovation, Children's Mercy Kansas City, Kanas City, MO, United States
| | - Rosalind E Howes
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom.,Foundation for Innovative New Diagnostics, Geneva, Switzerland
| | - Tovonahary A Rakotomanga
- The National Malaria Control Program, Ministry of Health, Antananarivo, Madagascar.,University of Fianarantsoa, Fianarantsoa, Madagascar
| | - Arsene C Ratsimbasoa
- The National Malaria Control Program, Ministry of Health, Antananarivo, Madagascar.,University of Fianarantsoa, Fianarantsoa, Madagascar
| | - Peter A Zimmerman
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, OH, United States
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10
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Khan W, Wang YH, Nanayakkara NPD, Herath HMTB, Catchings Z, Khan S, Fasinu PS, ElSohly MA, McChesney JD, Khan IA, Chaurasiya ND, Tekwani BL, Walker LA. Quantitative determination of primaquine-5,6-ortho-quinone and carboxyprimaquine-5,6-ortho-quinone in human erythrocytes by UHPLC-MS/MS. J Chromatogr B Analyt Technol Biomed Life Sci 2020; 1163:122510. [PMID: 33387859 DOI: 10.1016/j.jchromb.2020.122510] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 12/08/2020] [Accepted: 12/15/2020] [Indexed: 01/28/2023]
Abstract
The antimalarial drug primaquine (PQ) causes methemoglobinemia and hemolysis in individuals with a genetic deficiency of glucose 6-phosphate dehydrogenase. Reactive oxygen species (ROS) generated by redox cycling of the metabolite primaquine-5,6-orthoquinone (POQ) in erythrocytes has been attributed to be responsible for the toxicity of PQ. Carboxyprimaquine (CPQ), the major human plasma metabolite of PQ, can also form the analogous carboxyprimaquine-5,6-orthoquinone (CPOQ) metabolite, which can also generate ROS in erythrocytes by redox cycling, thus contributing to the hematotoxicity of this drug. In order to study these pathways and characterize such effects in vivo, methods are needed for characterization and quantification of POQ and CPOQ in human erythrocytes. The purpose of this work was to develop a validated method for the quantitative determination of CPOQ and POQ metabolites in human erythrocytes, suitable for clinical studies of PQ metabolism. Several liquid-liquid extraction methods using different organic solvents had been investigated. The solvent mixture of water-methanol-acetonitrile (9:9:5, v/v) was shown to yield the best results for the two analytes. Chromatographic analysis of POQ and CPOQ in human erythrocytes was achieved on a high strength silica (HSS) column and gradient elution (water and acetonitrile, both containing 0.1% formic acid) by ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). Quantitative estimation of POQ and CPOQ was executed by monitoring ion pairs of m/z 260.23 > 175.03 and m/z 275.19 > 175.04, respectively. The method, which was validated for precision, accuracy, selectivity, and linearity, was successfully applied for the quantitative determination of POQ and CPOQ, the key metabolites of PQ in human erythrocytes in PQ clinical study.
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Affiliation(s)
- Washim Khan
- National Center for Natural Products Research, The University of Mississippi, University, MS 38677, USA
| | - Yan-Hong Wang
- National Center for Natural Products Research, The University of Mississippi, University, MS 38677, USA.
| | - N P Dhammika Nanayakkara
- National Center for Natural Products Research, The University of Mississippi, University, MS 38677, USA
| | - H M T Bandara Herath
- National Center for Natural Products Research, The University of Mississippi, University, MS 38677, USA
| | - Zachara Catchings
- National Center for Natural Products Research, The University of Mississippi, University, MS 38677, USA
| | - Shabana Khan
- National Center for Natural Products Research, The University of Mississippi, University, MS 38677, USA
| | - Pius S Fasinu
- Department of Pharmaceutical Sciences, Campbell University, Buies Creek, NC 27506, USA
| | - Mahmoud A ElSohly
- National Center for Natural Products Research, The University of Mississippi, University, MS 38677, USA; ElSohly Laboratories, Inc., Oxford, MS 38655, USA
| | | | - Ikhlas A Khan
- National Center for Natural Products Research, The University of Mississippi, University, MS 38677, USA; Department of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS 38677, USA
| | - Narayan D Chaurasiya
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research Institute, Birmingham, AL 35205, USA
| | - Babu L Tekwani
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research Institute, Birmingham, AL 35205, USA
| | - Larry A Walker
- National Center for Natural Products Research, The University of Mississippi, University, MS 38677, USA.
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11
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Chamnanphon M, Gaedigk A, Puangpetch A, Pasomsub E, Chantratita W, Longley RJ, Sattabongkot J, Chariyavilaskul P, Sukasem C. Pharmacogene Variation in Thai Plasmodium vivax Relapse Patients Treated with a Combination of Primaquine and Chloroquine. PHARMACOGENOMICS & PERSONALIZED MEDICINE 2020; 13:1-12. [PMID: 32021383 PMCID: PMC6966953 DOI: 10.2147/pgpm.s201007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 12/03/2019] [Indexed: 01/16/2023]
Abstract
Purpose Pharmacogenes have an influence on biotransformation pathway and clinical outcome of primaquine and chloroquine which are often prescribed to treat Plasmodium vivax infection. Genetic variation may impact enzyme activity and/or transporter function and thereby contribute to relapse. The aim of the study was to assess allele, genotype frequencies and the association between pharmacogenes variation and primaquine response in Thai patients infected with Plasmodium vivax. Patients and Methods Fifty-one patients were genotyped for 74 variants in 18 genes by Sequenom MassARRAY® and Taqman® SNP Real-Time PCR. Results SNP frequencies were not significantly different between relapse (n=4) and non-relapse (n=47) patients. However, the CYP2C19 c.681G>A, the frequency of the A-allele that defines the non-functional CYP2C19*2 haplotype was significantly higher compared to the G-allele (OR=5.14, p=0.021). Patients heterozygous for ABCG2 c.421C>A had a higher odds ratio (OR=8.75, p=0.071) and the frequency of the G-allele of UGT2B7 c.372G>A was higher compared to the A-allele (OR=3.75, p=0.081). CYP2C19, ABCG2 and UGT2B7 emerged as potential high priority genes. Conclusion Decreased activity of CYP2C19, ABCG2 and UGT2B7 in combination with CYP2D6 intermediate or poor metabolizer status may expose patients to a higher risk of Plasmodium vivax relapse. Further investigations are warranted to substantiate these findings.
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Affiliation(s)
- Monpat Chamnanphon
- Clinical Pharmacokinetics and Pharmacogenomics Research Unit, Department of Pharmacology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| | - Andrea Gaedigk
- Division of Clinical Pharmacology, Toxicology & Therapeutic Innovation, Children's Mercy Kansas City, and School of Medicine, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Apichaya Puangpetch
- Division of Pharmacogenomics and Personalized Medicine, Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.,Laboratory for Pharmacogenomics, Somdech Phra Debaratana Medical Center (SDMC), Ramathibodi Hospital, Bangkok, Thailand
| | - Ekawat Pasomsub
- Division of Virology, Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Wasun Chantratita
- Center of Genomics Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Rhea J Longley
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Pajaree Chariyavilaskul
- Clinical Pharmacokinetics and Pharmacogenomics Research Unit, Department of Pharmacology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| | - Chonlaphat Sukasem
- Division of Pharmacogenomics and Personalized Medicine, Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.,Laboratory for Pharmacogenomics, Somdech Phra Debaratana Medical Center (SDMC), Ramathibodi Hospital, Bangkok, Thailand
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12
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Chairat K, Jittamala P, Hanboonkunupakarn B, Pukrittayakamee S, Hanpithakpong W, Blessborn D, White NJ, Day NPJ, Tarning J. Enantiospecific pharmacokinetics and drug-drug interactions of primaquine and blood-stage antimalarial drugs. J Antimicrob Chemother 2019; 73:3102-3113. [PMID: 30085149 PMCID: PMC6198747 DOI: 10.1093/jac/dky297] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/26/2018] [Indexed: 01/08/2023] Open
Abstract
Objectives Characterization of the pharmacokinetic properties of the enantiomers of primaquine and carboxyprimaquine following administration of racemic primaquine given alone and in combination with commonly used antimalarial drugs. Methods Enantiomeric pharmacokinetics were evaluated in 49 healthy adult volunteers enrolled in three randomized cross-over studies in which a single dose of primaquine was given alone and then, after a suitable washout period, in combination with chloroquine, dihydroartemisinin/piperaquine or pyronaridine/artesunate. Non-linear mixed-effects modelling was used to characterize pharmacokinetics and assess the impact of drug-drug interactions. Results The volume of distribution of racemic primaquine was decreased by a median (95% CI) of 22.0% (2.24%-39.9%), 24.0% (15.0%-31.5%) and 25.7% (20.3%-31.1%) when co-administered with chloroquine, dihydroartemisinin/piperaquine and pyronaridine/artesunate, respectively. The oral clearance of primaquine was decreased by a median of 19.1% (14.5%-22.8%) when co-administered with pyronaridine/artesunate. These interactions were enantiospecific with a relatively higher effect on (+)-S-primaquine than on (-)-R-primaquine. No drug-drug interaction effects were seen on the pharmacokinetics of either carboxyprimaquine enantiomer. Conclusions Population pharmacokinetic models characterizing the enantiospecific properties of primaquine were developed successfully. Exposure to primaquine, particularly to the (+)-S-primaquine but not the carboxy metabolites, increased by up to 30% when co-administered with commonly used antimalarial drugs. A better mechanistic understanding of primaquine metabolism is required for assessment of its efficacy and haematological toxicity in humans.
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Affiliation(s)
- Kalayanee Chairat
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Podjanee Jittamala
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Borimas Hanboonkunupakarn
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Sasithon Pukrittayakamee
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Warunee Hanpithakpong
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Daniel Blessborn
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Nicholas P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Joel Tarning
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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13
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Camarda G, Jirawatcharadech P, Priestley RS, Saif A, March S, Wong MHL, Leung S, Miller AB, Baker DA, Alano P, Paine MJI, Bhatia SN, O'Neill PM, Ward SA, Biagini GA. Antimalarial activity of primaquine operates via a two-step biochemical relay. Nat Commun 2019; 10:3226. [PMID: 31324806 PMCID: PMC6642103 DOI: 10.1038/s41467-019-11239-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 07/02/2019] [Indexed: 12/29/2022] Open
Abstract
Primaquine (PQ) is an essential antimalarial drug but despite being developed over 70 years ago, its mode of action is unclear. Here, we demonstrate that hydroxylated-PQ metabolites (OH-PQm) are responsible for efficacy against liver and sexual transmission stages of Plasmodium falciparum. The antimalarial activity of PQ against liver stages depends on host CYP2D6 status, whilst OH-PQm display direct, CYP2D6-independent, activity. PQ requires hepatic metabolism to exert activity against gametocyte stages. OH-PQm exert modest antimalarial efficacy against parasite gametocytes; however, potency is enhanced ca.1000 fold in the presence of cytochrome P450 NADPH:oxidoreductase (CPR) from the liver and bone marrow. Enhancement of OH-PQm efficacy is due to the direct reduction of quinoneimine metabolites by CPR with the concomitant and excessive generation of H2O2, leading to parasite killing. This detailed understanding of the mechanism paves the way to rationally re-designed 8-aminoquinolines with improved pharmacological profiles. Primaquine (PQ) is a widely used anti-malaria drug, but its mechanism of action is unclear. Here, Camarda et al. show that PQ’s activity against liver and sexual Plasmodium stages depends on generation of hydroxylated-PQ metabolites (OH-PQm), which, undergoing further reactions, results in production of H2O2.
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Affiliation(s)
- Grazia Camarda
- Centre for Drugs and Diagnostics Research, Tropical Disease Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Piyaporn Jirawatcharadech
- Centre for Drugs and Diagnostics Research, Tropical Disease Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Richard S Priestley
- Centre for Drugs and Diagnostics Research, Tropical Disease Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.,ARUK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ, UK
| | - Ahmed Saif
- Centre for Drugs and Diagnostics Research, Tropical Disease Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.,Clinical Laboratory sciences Department, College of Applied Medical Sciences, Najran University, Najran, 61441, Saudi Arabia
| | - Sandra March
- Health Sciences and Technology/Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Michael H L Wong
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Suet Leung
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Alex B Miller
- Health Sciences and Technology/Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - David A Baker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Pietro Alano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, 00161, Italy
| | - Mark J I Paine
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Sangeeta N Bhatia
- Health Sciences and Technology/Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Paul M O'Neill
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Stephen A Ward
- Centre for Drugs and Diagnostics Research, Tropical Disease Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Giancarlo A Biagini
- Centre for Drugs and Diagnostics Research, Tropical Disease Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.
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14
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Stegmaier K, Blinn CM, Bechtel DF, Greth C, Auerbach H, Müller CS, Jakob V, Reijerse EJ, Netz DJA, Schünemann V, Pierik AJ. Apd1 and Aim32 Are Prototypes of Bishistidinyl-Coordinated Non-Rieske [2Fe–2S] Proteins. J Am Chem Soc 2019; 141:5753-5765. [DOI: 10.1021/jacs.8b13274] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | | | | | | | | | | | | | - Edward J. Reijerse
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D45470 Mülheim an der Ruhr, Germany
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15
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Fasinu PS, Nanayakkara NPD, Wang YH, Chaurasiya ND, Herath HMB, McChesney JD, Avula B, Khan I, Tekwani BL, Walker LA. Formation primaquine-5,6-orthoquinone, the putative active and toxic metabolite of primaquine via direct oxidation in human erythrocytes. Malar J 2019; 18:30. [PMID: 30700282 PMCID: PMC6352325 DOI: 10.1186/s12936-019-2658-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 01/17/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND The activity and haemolytic toxicity associated with primaquine has been linked to its reactive metabolites. The reactive metabolites are thought to be primarily formed through the action of cytochrome P450-mediated pathways. Human erythrocytes generally are not considered a significant contributor to drug biotransformation. As erythrocytes are the target of primaquine toxicity, the ability of erythrocytes to mediate the formation of reactive oxidative primaquine metabolites in the absence of hepatic enzymes, was evaluated. METHODS Primaquine and its enantiomers were incubated separately with human red blood cells and haemoglobin. Post-incubation analysis was performed with UPLC-MS/MS to identify products of biotransformation. RESULTS The major metabolite detected was identified as primaquine-5,6-orthoquinone, reflecting the pathway yielding putative active and haematotoxic metabolites of primaquine, which was formed by oxidative demethylation of 5-hydroxyprimaquine. Incubation of primaquine with haemoglobin in a cell-free system yielded similar results. It appears that the observed biotransformation is due to non-enzymatic processes, perhaps due to reactive oxygen species (ROS) present in erythrocytes or in the haemoglobin incubates. CONCLUSION This study presents new evidence that primaquine-5,6-orthoquinone, the metabolite of primaquine reflecting the oxidative biotransformation pathway, is generated in erythrocytes, probably by non-enzymatic means, and may not require transport from the liver or other tissues.
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Affiliation(s)
- Pius S Fasinu
- The National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA. .,Department of Pharmaceutical Sciences, Campbell University, Buies Creek, NC, 27501, USA.
| | - N P Dhammika Nanayakkara
- The National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Yan-Hong Wang
- The National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Narayan D Chaurasiya
- The National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - H M Bandara Herath
- The National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | | | - Bharathi Avula
- The National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA
| | - Ikhlas Khan
- The National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA.,Department of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Babu L Tekwani
- The National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA.,Department of Infectious Diseases, Southern Research Institute, Birmingham, AL, USA
| | - Larry A Walker
- The National Center for Natural Products Research, The University of Mississippi, University, MS, 38677, USA. .,Department of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.
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16
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Avula B, Tekwani BL, Chaurasiya ND, Fasinu P, Dhammika Nanayakkara NP, Bhandara Herath HMT, Wang YH, Bae JY, Khan SI, Elsohly MA, McChesney JD, Zimmerman PA, Khan IA, Walker LA. Metabolism of primaquine in normal human volunteers: investigation of phase I and phase II metabolites from plasma and urine using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Malar J 2018; 17:294. [PMID: 30103751 PMCID: PMC6090659 DOI: 10.1186/s12936-018-2433-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 07/30/2018] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Primaquine (PQ), an 8-aminoquinoline, is the only drug approved by the United States Food and Drug Administration for radical cure and prevention of relapse in Plasmodium vivax infections. Knowledge of the metabolism of PQ is critical for understanding the therapeutic efficacy and hemolytic toxicity of this drug. Recent in vitro studies with primary human hepatocytes have been useful for developing the ultra high-performance liquid chromatography coupled with high-resolution mass spectrometric (UHPLC-QToF-MS) methods for simultaneous determination of PQ and its metabolites generated through phase I and phase II pathways for drug metabolism. METHODS These methods were further optimized and applied for phenotyping PQ metabolites from plasma and urine from healthy human volunteers treated with single 45 mg dose of PQ. Identity of the metabolites was predicted by MetaboLynx using LC-MS/MS fragmentation patterns. Selected metabolites were confirmed with appropriate standards. RESULTS Besides PQ and carboxy PQ (cPQ), the major plasma metabolite, thirty-four additional metabolites were identified in human plasma and urine. Based on these metabolites, PQ is viewed as metabolized in humans via three pathways. Pathway 1 involves direct glucuronide/glucose/carbamate/acetate conjugation of PQ. Pathway 2 involves hydroxylation (likely cytochrome P450-mediated) at different positions on the quinoline ring, with mono-, di-, or even tri-hydroxylations possible, and subsequent glucuronide conjugation of the hydroxylated metabolites. Pathway 3 involves the monoamine oxidase catalyzed oxidative deamination of PQ resulting in formation of PQ-aldehyde, PQ alcohol and cPQ, which are further metabolized through additional phase I hydroxylations and/or phase II glucuronide conjugations. CONCLUSION This approach and these findings augment our understanding and provide comprehensive view of pathways for PQ metabolism in humans. These will advance the clinical studies of PQ metabolism in different populations for different therapeutic regimens and an understanding of the role these play in PQ efficacy and safety outcomes, and their possible relation to metabolizing enzyme polymorphisms.
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Affiliation(s)
- Bharathi Avula
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Babu L Tekwani
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.
| | - Narayan D Chaurasiya
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Pius Fasinu
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - N P Dhammika Nanayakkara
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - H M T Bhandara Herath
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Yan-Hong Wang
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Ji-Yeong Bae
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Shabana I Khan
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Mahmoud A Elsohly
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | | | - Peter A Zimmerman
- Center for Global Health & Diseases, Case Western Reserve University Cleveland, Ohio, 44106, USA
| | - Ikhlas A Khan
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Larry A Walker
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
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17
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Pewkliang Y, Rungin S, Lerdpanyangam K, Duangmanee A, Kanjanasirirat P, Suthivanich P, Sa-Ngiamsuntorn K, Borwornpinyo S, Sattabongkot J, Patrapuvich R, Hongeng S. A novel immortalized hepatocyte-like cell line (imHC) supports in vitro liver stage development of the human malarial parasite Plasmodium vivax. Malar J 2018; 17:50. [PMID: 29370800 PMCID: PMC5785895 DOI: 10.1186/s12936-018-2198-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 01/19/2018] [Indexed: 12/31/2022] Open
Abstract
Background Eradication of malaria is difficult because of the ability of hypnozoite, the dormant liver-stage form of Plasmodium vivax, to cause relapse in patients. Research efforts to better understand the biology of P. vivax hypnozoite and design relapse prevention strategies have been hampered by the lack of a robust and reliable model for in vitro culture of liver-stage parasites. Although the HC-04 hepatoma cell line is used for culturing liver-stage forms of Plasmodium, these cells proliferate unrestrictedly and detach from the culture dish after several days, which limits their usefulness in a long-term hypnozoite assay. Methods A novel immortalized hepatocyte-like cell line (imHC) was evaluated for the capability to support P. vivax sporozoite infection. First, expression of basic hepatocyte markers and all major malaria sporozoite-associated host receptors in imHC was investigated. Next, in vitro hepatocyte infectivity and intracellular development of sporozoites in imHC were determined using an indirect immunofluorescence assay. Cytochrome P450 isotype activity was also measured to determine the ability of imHC to metabolize drugs. Finally, the anti-liver-stage agent primaquine was used to test this model for a drug sensitivity assay. Results imHCs maintained major hepatic functions and expressed the essential factors CD81, SR-BI and EphA2, which are required for host entry and development of the parasite in the liver. imHCs could be maintained long-term in a monolayer without overgrowth and thus served as a good, supportive substrate for the invasion and growth of P. vivax liver stages, including hypnozoites. The observed high drug metabolism activity and potent responses in liver-stage parasites to primaquine highlight the potential use of this imHC model for antimalarial drug screening. Conclusions imHCs, which maintain a hepatocyte phenotype and drug-metabolizing enzyme expression, constitute an alternative host for in vitro Plasmodium liver-stage studies, particularly those addressing the biology of P. vivax hypnozoite. They potentially offer a novel, robust model for screening drugs against liver-stage parasites. Electronic supplementary material The online version of this article (10.1186/s12936-018-2198-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yongyut Pewkliang
- Excellent Center for Drug Discovery (ECDD), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Siriwan Rungin
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Siriraj Initiative in System Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Kaewta Lerdpanyangam
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Apisak Duangmanee
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Phongthon Kanjanasirirat
- Excellent Center for Drug Discovery (ECDD), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Phichaya Suthivanich
- Excellent Center for Drug Discovery (ECDD), Faculty of Science, Mahidol University, Bangkok, Thailand
| | | | - Suparerk Borwornpinyo
- Excellent Center for Drug Discovery (ECDD), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Rapatbhorn Patrapuvich
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Center for Emerging and Neglected Infectious Diseases, Mahidol University, Bangkok, Thailand. .,Drug Research Unit for Malaria, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Suradej Hongeng
- Excellent Center for Drug Discovery (ECDD), Faculty of Science, Mahidol University, Bangkok, Thailand. .,Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
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Chu CS, Bancone G, Moore KA, Win HH, Thitipanawan N, Po C, Chowwiwat N, Raksapraidee R, Wilairisak P, Phyo AP, Keereecharoen L, Proux S, Charunwatthana P, Nosten F, White NJ. Haemolysis in G6PD Heterozygous Females Treated with Primaquine for Plasmodium vivax Malaria: A Nested Cohort in a Trial of Radical Curative Regimens. PLoS Med 2017; 14:e1002224. [PMID: 28170391 PMCID: PMC5295665 DOI: 10.1371/journal.pmed.1002224] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 12/15/2016] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Radical cure of Plasmodium vivax malaria with 8-aminoquinolines (primaquine or tafenoquine) is complicated by haemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. G6PD heterozygous females, because of individual variation in the pattern of X-chromosome inactivation (Lyonisation) in erythroid cells, may have low G6PD activity in the majority of their erythrocytes, yet are usually reported as G6PD "normal" by current phenotypic screening tests. Their haemolytic risk when treated with 8-aminoquinolines has not been well characterized. METHODS AND FINDINGS In a cohort study nested within a randomised clinical trial that compared different treatment regimens for P. vivax malaria, patients with a normal standard NADPH fluorescent spot test result (≳30%-40% of normal G6PD activity) were randomised to receive 3 d of chloroquine or dihydroartemisinin-piperaquine in combination with primaquine, either the standard high dose of 0.5 mg base/kg/day for 14 d or a higher dose of 1 mg base/kg/d for 7 d. Patterns of haemolysis were compared between G6PD wild-type and G6PD heterozygous female participants. Between 21 February 2012 and 04 July 2014, 241 female participants were enrolled, of whom 34 were heterozygous for the G6PD Mahidol variant. Haemolysis was substantially greater and a larger proportion of participants reached the threshold of clinically significant haemolysis (fractional haematocrit reduction >25%) in G6PD heterozygotes taking the higher (7 d) primaquine dose (9/17 [53%]) compared with G6PD heterozygotes taking the standard high (14 d) dose (2/16 [13%]; p = 0.022). In heterozygotes, the mean fractional haematocrit reductions were correspondingly greater with the higher primaquine dose (7-d regimen): -20.4% (95% CI -26.0% to -14.8%) (nadir on day 5) compared with the standard high (14 d) dose: -13.1% (95% CI -17.6% to -8.6%) (nadir day 6). Two heterozygotes taking the higher (7 d) primaquine dose required blood transfusion. In wild-type participants, mean haematocrit reductions were clinically insignificant and similar with both doses: -5.8 (95% CI -7.2% to -4.4%) (nadir day 3) compared with -5.5% (95% CI -7.4% to -3.7%) (nadir day 4), respectively. Limitations to this nested cohort study are that the primary objective of the trial was designed to measure efficacy and not haemolysis in relation to G6PD genotype and that the heterozygote groups were small. CONCLUSION Higher daily doses of primaquine have the potential to cause clinically significant haemolysis in G6PD heterozygous females who are reported as phenotypically normal with current point of care tests. TRIAL REGISTRATION ClinicalTrials.gov NCT01640574.
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Affiliation(s)
- Cindy S. Chu
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - Germana Bancone
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Kerryn A. Moore
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Htun Htun Win
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Niramon Thitipanawan
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Christina Po
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Nongnud Chowwiwat
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Rattanaporn Raksapraidee
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Pornpimon Wilairisak
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Aung Pyae Phyo
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Lily Keereecharoen
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Stéphane Proux
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Prakaykaew Charunwatthana
- Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - François Nosten
- Shoklo Malaria Research Unit, Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas J. White
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Mahidol–Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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Fasinu PS, Tekwani BL, Avula B, Chaurasiya ND, Nanayakkara NPD, Wang YH, Khan IA, Walker LA. Pathway-specific inhibition of primaquine metabolism by chloroquine/quinine. Malar J 2016; 15:466. [PMID: 27618912 PMCID: PMC5020452 DOI: 10.1186/s12936-016-1509-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/27/2016] [Indexed: 12/29/2022] Open
Abstract
Background There has been some evidence to suggest that the addition of chloroquine (CQ) or quinine (QN) to 8-aminoquinoline (8-AQ) treatment regimens may increase the therapeutic efficacy of the 8-AQ and simultaneously mitigate against its haemolytic toxicity. However, both CQ and QN are considered effective, although perhaps moderate inhibitors of CYP2D6, an enzyme now regarded as necessary for primaquine (PQ) pharmacologic activity. An understanding of the influence of CQ and QN on the metabolism of PQ may shed light on the potential mechanisms of the beneficial interaction. Methods Differential metabolism of PQ enantiomers by recombinant human CYP2D6, monoamine oxidase A (MAO), and cryopreserved human hepatocytes in the presence/absence of CQ and QN. Results Both CQ and QN significantly inhibited the activity of CYP2D6. PQ depletion by MAO and human hepatocytes was not affected significantly by the presence of CQ and QN. CYP2D6-mediated hydroxylation was largely suppressed by both CQ and QN. The formation of the primary deaminated metabolites, including carboxyprimaquine (CPQ) and cyclized side chain derivative from the aldehyde (m/z 241), was not sensitive to the presence of CQ and QN. However, the appearance of the glucuronides of CPQ and PQ alcohol were significantly suppressed. CQ and QN also inhibited the appearance of the m/z 257 metabolite with a similar pattern, suggesting that it may be derived from the CPQ conjugate. The apparent quinone-imine of CPQ (m/z 289) was only partially suppressed by both QN and CQ, but with a differential pattern of inhibition for the two drugs. The m/z 274 (quinone-imine of a ring-hydroxylated PQ metabolite) and m/z 422 (an apparent glucose conjugate of PQ) metabolites in hepatocytes were strongly suppressed by both QN and CQ, perhaps a reflection of the 2D6 inhibition by these drugs. The formation of the carbamoyl glucuronide of PQ (m/z 480) was not affected by CQ/QN. Conclusion The metabolite-specific interactions in the current studies seem at variance with earlier reports of the dependence of PQ on CYP2D6 metabolism, and enhanced PQ anti-malarial activity/reduced toxicity in the presence of CQ/QN. These results suggest a complex picture in which CQ/QN may shift metabolite pathway balances towards a profile that retains efficacy, while reducing the formation or availability of toxic metabolites to erythrocytes. Alternatively, these drugs may alter transport or distribution of PQ metabolites in a fashion that reduces toxicity while maintaining efficacy against the parasite.
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Affiliation(s)
- Pius S Fasinu
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.
| | - Babu L Tekwani
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Departments of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Bharathi Avula
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Narayan D Chaurasiya
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - N P Dhammika Nanayakkara
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Yan-Hong Wang
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Ikhlas A Khan
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Departments of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Larry A Walker
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Departments of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
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20
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Abstract
Introduction: Relapses are important contributors to illness and morbidity in Plasmodium vivax and P. ovale infections. Relapse prevention (radical cure) with primaquine is required for optimal management, control and ultimately elimination of Plasmodium vivax malaria. A review was conducted with publications in English, French, Portuguese and Spanish using the search terms ‘P. vivax’ and ‘relapse’. Areas covered: Hypnozoites causing relapses may be activated weeks or months after initial infection. Incidence and temporal patterns of relapse varies geographically. Relapses derive from parasites either genetically similar or different from the primary infection indicating that some derive from previous infections. Malaria illness itself may activate relapse. Primaquine is the only widely available treatment for radical cure. However, it is often not given because of uncertainty over the risks of primaquine induced haemolysis when G6PD deficiency testing is unavailable. Recommended dosing of primaquine for radical cure in East Asia and Oceania is 0.5 mg base/kg/day and elsewhere is 0.25 mg base/kg/day. Alternative treatments are under investigation. Expert commentary: Geographic heterogeneity in relapse patterns and chloroquine susceptibility of P. vivax, and G6PD deficiency epidemiology mean that radical treatment should be given much more than it is today. G6PD testing should be made widely available so primaquine can be given more safely.
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Affiliation(s)
- Cindy S Chu
- a Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine , Mahidol University , Mae Sot , Thailand.,b Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine , Mahidol University , Bangkok , Thailand
| | - Nicholas J White
- b Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine , Mahidol University , Bangkok , Thailand.,c Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine , University of Oxford , Oxford , UK
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21
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Jin X, Potter B, Luong TL, Nelson J, Vuong C, Potter C, Xie L, Zhang J, Zhang P, Sousa J, Li Q, Pybus BS, Kreishman-Deitrick M, Hickman M, Smith PL, Paris R, Reichard G, Marcsisin SR. Pre-clinical evaluation of CYP 2D6 dependent drug-drug interactions between primaquine and SSRI/SNRI antidepressants. Malar J 2016; 15:280. [PMID: 27188854 PMCID: PMC4869338 DOI: 10.1186/s12936-016-1329-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 05/05/2016] [Indexed: 12/21/2022] Open
Abstract
Background The liver-stage anti-malarial activity of primaquine and other 8-aminoquinoline molecules has been linked to bio-activation through CYP 2D6 metabolism. Factors such as CYP 2D6 poor metabolizer status and/or co-administration of drugs that inhibit/interact with CYP 2D6 could alter the pharmacological properties of primaquine. Methods In the present study, the inhibitory potential of the selective serotonin reuptake inhibitor (SSRI) and serotonin norepinephrine reuptake inhibitor (SNRI) classes of antidepressants for CYP 2D6-mediated primaquine metabolism was assessed using in vitro drug metabolism and in vivo pharmacological assays. Results The SSRI/SNRI classes of drug displayed a range of inhibitory activities on CYP 2D6-mediated metabolism of primaquine in vitro (IC50 1–94 μM). Fluoxetine and paroxetine were the most potent inhibitors (IC50 ~1 µM) of CYP 2D6-mediated primaquine metabolism, while desvenlafaxine was the least potent (IC50 ~94 µM). The most potent CYP 2D6 inhibitor, fluoxetine, was chosen to investigate the potential pharmacological consequences of co-administration with primaquine in vivo. The pharmacokinetics of a CYP 2D6-dependent primaquine metabolite were altered upon co-administration with fluoxetine. Additionally, in a mouse malaria model, co-administration of fluoxetine with primaquine reduced primaquine anti-malarial efficacy. Conclusions These results are the first from controlled pre-clinical experiments that indicate that primaquine pharmacological properties can be modulated upon co-incubation/administration with drugs that are known to interact with CYP 2D6. These results highlight the potential for CYP 2D6-mediated drug–drug interactions with primaquine and indicate that the SSRI/SNRI antidepressants could be used as probe molecules to address the primaquine-CYP 2D6 DDI link in clinical studies. Additionally, CYP 2D6-mediated drug–drug interactions can be considered when examining the possible causes of human primaquine therapy failures. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1329-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiannu Jin
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Brittney Potter
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Thu-Lan Luong
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Jennifer Nelson
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Chau Vuong
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Corttney Potter
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Lisa Xie
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Jing Zhang
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Ping Zhang
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Jason Sousa
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Qigui Li
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Brandon S Pybus
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Mara Kreishman-Deitrick
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Mark Hickman
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Philip L Smith
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Robert Paris
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Gregory Reichard
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Sean R Marcsisin
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA.
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22
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Fasinu PS, Avula B, Tekwani BL, Nanayakkara NPD, Wang YH, Bandara Herath HMT, McChesney JD, Reichard GA, Marcsisin SR, Elsohly MA, Khan SI, Khan IA, Walker LA. Differential kinetic profiles and metabolism of primaquine enantiomers by human hepatocytes. Malar J 2016; 15:224. [PMID: 27093859 PMCID: PMC4837544 DOI: 10.1186/s12936-016-1270-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 04/01/2016] [Indexed: 01/02/2023] Open
Abstract
Background The clinical utility of primaquine (PQ), used as a racemic mixture of two enantiomers, is limited due to metabolism-linked hemolytic toxicity in individuals with genetic deficiency in glucose-6-phosphate dehydrogenase. The current study investigated differential metabolism of PQ enantiomers in light of the suggestions that toxicity and efficacy might be largely enantioselective. Methods Stable isotope 13C-labelled primaquine and its two enantiomers (+)-PQ, (−)-PQ were separately incubated with cryopreserved human hepatocytes. Time-tracked substrate depletion and metabolite production were monitored via UHPLC–MS/MS. Results The initial half-life of 217 and 65 min; elimination rate constants (λ) of 0.19 and 0.64 h−1; intrinsic clearance (Clint) of 2.55 and 8.49 (µL/min)/million cells, which when up-scaled yielded Clint of 6.49 and 21.6 (mL/min)/kg body mass was obtained respectively for (+)- and (−)-PQ. The extrapolation of in vitro intrinsic clearance to in vivo human hepatic blood clearance, performed using the well-stirred liver model, showed that the rate of hepatic clearance of (+)-PQ was only 45 % that of (−)-PQ. Two major primary routes of metabolism were observed—oxidative deamination of the terminal amine and hydroxylations on the quinoline moiety of PQ. The major deaminated metabolite, carboxyprimaquine (CPQ) was preferentially generated from the (−)-PQ. Other deaminated metabolites including PQ terminal alcohol (m/z 261), a cyclized side chain derivative from the aldehyde (m/z 241), cyclized carboxylic acid derivative (m/z 257), a quinone-imine product of hydroxylated CPQ (m/z 289), CPQ glucuronide (m/z 451) and the glucuronide of PQ alcohol (m/z 437) were all preferentially generated from the (−)-PQ. The major quinoline oxidation product (m/z 274) was preferentially generated from (+)-PQ. In addition to the products of the two metabolic pathways, two other major metabolites were observed: a prominent glycosylated conjugate of PQ on the terminal amine (m/z 422), peaking by 30 min and preferentially generated by (+)-PQ; and the carbamoyl glucuronide of PQ (m/z 480) exclusively generated from (+)-PQ. Conclusion Metabolism of PQ showed enantioselectivity. These findings may provide important information in establishing clinical differences in PQ enantiomers.
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Affiliation(s)
- Pius S Fasinu
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Bharathi Avula
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Babu L Tekwani
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Department of BioMolecular Sciences School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - N P Dhammika Nanayakkara
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Yan-Hong Wang
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - H M T Bandara Herath
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | | | - Gregory A Reichard
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Sean R Marcsisin
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Mahmoud A Elsohly
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Departments of Pharmaceutical Sciences and Drug Delivery, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,ElSohly Laboratories, Inc., 5 Industrial Park Dr, Oxford, MS, 38655, USA
| | - Shabana I Khan
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Department of BioMolecular Sciences School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Ikhlas A Khan
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Department of BioMolecular Sciences School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Larry A Walker
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA. .,Department of BioMolecular Sciences School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.
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23
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Marcsisin SR, Reichard G, Pybus BS. Primaquine pharmacology in the context of CYP 2D6 pharmacogenomics: Current state of the art. Pharmacol Ther 2016; 161:1-10. [PMID: 27016470 DOI: 10.1016/j.pharmthera.2016.03.011] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Primaquine is the only antimalarial drug available to clinicians for the treatment of relapsing forms of malaria. Primaquine development and usage dates back to the 1940s and has been administered to millions of individuals to treat and eliminate malaria infections. Primaquine therapy is not without disadvantages, however, as it can cause life threatening hemolysis in humans with glucose-6-phosphate dehydrogenase (G6PD) deficiency. In addition, the efficacy of primaquine against relapsing malaria was recently linked to CYP 2D6 mediated activation to an active metabolite, the structure of which has escaped definitive identification for over 75years. CYP 2D6 is highly polymorphic among various human populations adding further complexity to a comprehensive understanding of primaquine pharmacology. This review aims to discuss primaquine pharmacology in the context of state of the art understanding of CYP 2D6 mediated 8-aminoquinoline metabolic activation, and shed light on the current knowledge gaps of 8-aminoquinoline mechanistic understanding against relapsing malaria.
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Affiliation(s)
- Sean R Marcsisin
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD 20910, USA.
| | - Gregory Reichard
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD 20910, USA
| | - Brandon S Pybus
- Department of Pathology, Dwight D. Eisenhower Army Medical Center, FT. Gordon, GA 30905, USA
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Campo B, Vandal O, Wesche DL, Burrows JN. Killing the hypnozoite--drug discovery approaches to prevent relapse in Plasmodium vivax. Pathog Glob Health 2015; 109:107-22. [PMID: 25891812 PMCID: PMC4455353 DOI: 10.1179/2047773215y.0000000013] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The eradication of malaria will only be possible if effective, well-tolerated medicines kill hypnozoites in vivax and ovale malaria, and thus prevent relapses in patients. Despite progress in the 8-aminoquinoline series, with tafenoquine in Phase III showing clear benefits over primaquine, the drug discovery challenge to identify hypnozoiticidal or hypnozoite-activating compounds has been hampered by the dearth of biological tools and assays, which in turn has been limited by the immense scientific and logistical challenges associated with accessing relevant human tissue and sporozoites. This review summarises the existing drug discovery series and approaches concerning the goal to block relapse.
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Affiliation(s)
- Brice Campo
- Medicines for Malaria Venture, Geneva, Switzerland
| | - Omar Vandal
- The Bill and Melinda Gates Foundation, Seattle, WA, USA
| | - David L. Wesche
- The Bill and Melinda Gates Foundation, Seattle, WA, USA
- Great Lakes Drug Development/Certara, Princeton, NJ, USA
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Differential CYP 2D6 metabolism alters primaquine pharmacokinetics. Antimicrob Agents Chemother 2015; 59:2380-7. [PMID: 25645856 DOI: 10.1128/aac.00015-15] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Primaquine (PQ) metabolism by the cytochrome P450 (CYP) 2D family of enzymes is required for antimalarial activity in both humans (2D6) and mice (2D). Human CYP 2D6 is highly polymorphic, and decreased CYP 2D6 enzyme activity has been linked to decreased PQ antimalarial activity. Despite the importance of CYP 2D metabolism in PQ efficacy, the exact role that these enzymes play in PQ metabolism and pharmacokinetics has not been extensively studied in vivo. In this study, a series of PQ pharmacokinetic experiments were conducted in mice with differential CYP 2D metabolism characteristics, including wild-type (WT), CYP 2D knockout (KO), and humanized CYP 2D6 (KO/knock-in [KO/KI]) mice. Plasma and liver pharmacokinetic profiles from a single PQ dose (20 mg/kg of body weight) differed significantly among the strains for PQ and carboxy-PQ. Additionally, due to the suspected role of phenolic metabolites in PQ efficacy, these were probed using reference standards. Levels of phenolic metabolites were highest in mice capable of metabolizing CYP 2D6 substrates (WT and KO/KI 2D6 mice). PQ phenolic metabolites were present in different quantities in the two strains, illustrating species-specific differences in PQ metabolism between the human and mouse enzymes. Taking the data together, this report furthers understanding of PQ pharmacokinetics in the context of differential CYP 2D metabolism and has important implications for PQ administration in humans with different levels of CYP 2D6 enzyme activity.
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Tekwani BL, Avula B, Sahu R, Chaurasiya ND, Khan SI, Jain S, Fasinu PS, Herath HMTB, Stanford D, Nanayakkara NPD, McChesney JD, Yates TW, ElSohly MA, Khan IA, Walker LA. Enantioselective pharmacokinetics of primaquine in healthy human volunteers. Drug Metab Dispos 2015; 43:571-7. [PMID: 25637634 DOI: 10.1124/dmd.114.061127] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Primaquine (PQ), a racemic drug, is the only treatment available for radical cure of relapsing Plasmodium vivax malaria and blocking transmission of P. falciparum malaria. Recent studies have shown differential pharmacologic and toxicologic profiles of individual PQ enantiomers in rodent, dog, and primate animal models. This study was conducted in six healthy adult human volunteers to determine the plasma pharmacokinetic profile of enantiomers of PQ and carboxyprimaquine (cPQ), the major plasma metabolite. The individuals were orally administered PQ diphosphate, equivalent to 45-mg base, 30 minutes after a normal breakfast. Blood samples were collected at different time intervals, and plasma samples were analyzed for enantiomers of PQ and cPQ. Plasma PQ concentrations were low and variable for both parent enantiomers and peaked around 2-4 hours. Peak (-)-(R)-PQ concentrations ranged from 121 ng/ml to 221 ng/ml, and peak (+)-(S)-PQ concentrations ranged from 168 ng/ml to 299 ng/ml. The cPQ concentrations were much higher and were surprisingly consistent from subject to subject. Essentially all the cPQ detected in plasma was (-)-cPQ. The peak concentrations of (-)-cPQ were observed at 8 hours (range: 1104-1756 ng/ml); however, very high concentrations were sustained through 24 hours. (+)-cPQ was two orders of magnitude lower than (-)-cPQ, and in a few subjects it was detected but only under the limit of quantification. In vitro studies with primary human hepatocytes also suggested more rapid metabolism of (-)-PQ compared with (+)-PQ. The results suggest more rapid metabolism of (-)-PQ to (-) cPQ compared with (+)-PQ. Alternatively, (+)-PQ or (+)-cPQ could be rapidly converted to another metabolite(s) or distributed to tissues. This is the first clinical report on enantioselective pharmacokinetic profiles of PQ and cPQ and supports further clinical evaluation of individual PQ enantiomers.
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Affiliation(s)
- Babu L Tekwani
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Bharathi Avula
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Rajnish Sahu
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Narayan D Chaurasiya
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Shabana I Khan
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Surendra Jain
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Pius S Fasinu
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - H M T Bandara Herath
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Donald Stanford
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - N P Dhammika Nanayakkara
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - James D McChesney
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Travis W Yates
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Mahmoud A ElSohly
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Ikhlas A Khan
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Larry A Walker
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
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