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Abuhelwa AY, Somogyi AA, Loo CK, Glue P, Barratt DT, Foster DJR. Population Pharmacokinetics and Pharmacodynamics of the Therapeutic and Adverse Effects of Ketamine in Patients with Treatment-Refractory Depression. Clin Pharmacol Ther 2022; 112:720-729. [PMID: 35560226 PMCID: PMC9540482 DOI: 10.1002/cpt.2640] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/30/2022] [Indexed: 02/06/2023]
Abstract
We aimed to develop population pharmacokinetic/pharmacodynamic (PK/PD) models that can effectively describe ketamine and norketamine PK/PD relationships for Montgomery–Åsberg Depression Rating Scale (MADRS) scores, blood pressure (BP), and heart rate (HR) following i.v., s.c., and i.m. ketamine administration in patients with treatment‐refractory depression. Ketamine PK/PD data were collected from 21 treatment‐refractory depressed participants who received ketamine (dose titration 0.1–0.5 mg/kg as single doses) by i.v., s.c., or i.m. administration. Model development used nonlinear mixed effect modeling. Ketamine and norketamine PK were best described using two‐compartment models with first‐order absorption after s.c. and i.m. administration. Estimated ketamine bioavailability after i.m. and s.c. was ~ 64% with indistinguishable first‐order absorption rate constants. Allometric scaling of body weight on all clearance and volumes of distribution improved the model fit. The delay in the concentration‐response relationship for MADRS scores was best described using a turnover model (turnover time ~ 42 hours), whereas for the BP and HR rates this was an immediate effect model. For all PD effects, ketamine alone was superior to models with norketamine concentration linked to an effect. No covariates were identified for PD effects. The estimated half‐maximal effective concentration from the MADRS score, BP, and HR were 0.44, 468, and 7,580 ng/mL, respectively. The integrated population models were able to effectively describe the PK/PD relationships for MADRS scores, BP, and HR after i.v., s.c., and i.m. ketamine administration. These findings allow for a deeper understanding of the complex relationships between route of ketamine administration and clinical response and safety.
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Affiliation(s)
- Ahmad Y Abuhelwa
- UniSA: Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, South Australia, Australia.,College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Andrew A Somogyi
- Discipline of Pharmacology, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia.,Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Colleen K Loo
- School of Psychiatry, University of New South Wales, Sydney, New South Wales, Australia.,Black Dog Institute, Randwick, New South Wales, Australia
| | - Paul Glue
- Department of Psychological Medicine, Dunedin School of Medicine, University of Otago, Otago, New Zealand
| | - Daniel T Barratt
- Discipline of Pharmacology, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - David J R Foster
- UniSA: Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, South Australia, Australia
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2
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Abstract
Opioids remain the major drug class for the treatment of acute, chronic and cancer pain, but have major harmful effects such as dependence and opioid-induced ventilatory impairment. Although no new typical opioids have come onto the market in the past almost 50 years, a plethora of new innovative formulations has been developed to meet the clinical need. This review is intended to shed light on new understanding of the molecular pharmacology of opioids, which has arisen largely due to the genomic revolution, and what new drugs may become available in the coming years. Atypical opioids have and are being developed which not only target the mu opioid receptor but other targets in the pain pathway. Biased mu agonists have been developed but remain 'unbiased' clinically. The contribution of drugs targeting non-mu opioid receptors either alone or as heterodimers shows potential promise but remains understudied. That gene splice variants of the mu opioid receptor produce multiple receptor isoforms in different brain regions, and may change with pain chronicity and phenotype, presents new challenges but also opportunities for precision pain medicine. Finally, that opioids also have pro-inflammatory effects not aligned with mu opioid receptor binding affinity implicates a fresh understanding of their role in chronic pain, whether cancer or non-cancer. Hopefully, a new understanding of opioid analgesic drug action may lead to new drug development and better precision medicine in acute and chronic pain relief with less patient harm.
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Affiliation(s)
- Andrew A Somogyi
- Discipline of Pharmacology, University of Adelaide, Adelaide, Australia
| | - Stefan T Musolino
- Discipline of Pharmacology, University of Adelaide, Adelaide, Australia
| | - Daniel T Barratt
- Discipline of Physiology, University of Adelaide, Adelaide, Australia
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3
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Andriguetti NB, Barratt DT, Tucci J, Pumuye P, Somogyi AA. Instability of Efavirenz Metabolites Identified During Method Development and Validation. J Pharm Sci 2021; 110:3362-3366. [PMID: 34175301 DOI: 10.1016/j.xphs.2021.06.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 06/20/2021] [Accepted: 06/21/2021] [Indexed: 11/27/2022]
Abstract
Accurate quantification of efavirenz metabolites in patient samples is required to investigate their potential contribution to efavirenz adverse events. This study aimed to validate a LC-MS/MS method to quantify and investigate the stability of efavirenz and metabolites in human plasma. Compounds were extracted from plasma by supported liquid extraction and resolved on a C18 column. Validation was performed following FDA bioanalytical method validation guidelines. Stability under common conditions of sample pre-treatment and storage were assessed. Efavirenz and 8-hydroxyefavirenz were stable for all conditions tested. 7-Hydroxyefavirenz and 8,14-dihydroxyefavirenz were not stable in plasma at room temperature for 24 h (46%-69% loss), -20°C for 90 days (17%-50% loss), or 60°C for 1 h (90%-95% loss). Efavirenz and 8-hydroxyefavirenz concentrations in HIV/AIDS patient (n=5) plasma prepared from pre-treated (60°C for 1 h) whole blood varied from 517-8564 ng/mL and 131-813 ng/mL, respectively. 7-Hydroxyefavirenz and 8,14-dihydroxyefavirenz concentrations were below validated lower limits of quantification (0.25 and 0.5 ng/mL, respectively), most likely due to sample pre-treatment. This is the first report of 7-hydroxyefavirenz and 8,14-dihydroxyefavirenz instability under conditions commonly used in preparation of samples from HIV/AIDS patients. Alternative biosafety measures to heat pre-treatment must therefore be used for accurate quantification of plasma 7-hydroxyefavirenz and 8,14-dihydroxyefavirenz.
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Affiliation(s)
| | - Daniel T Barratt
- Discipline of Physiology, Adelaide Medical School, University of Adelaide, Adelaide, Australia
| | - Joseph Tucci
- Department of Pharmacy & Biomedical Sciences, La Trobe University Bendigo Campus, Bendigo, Australia
| | - Paul Pumuye
- School of Medicine and Health Sciences, University of Papua New Guinea, National Capital District, Papua New Guinea
| | - Andrew A Somogyi
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, Australia
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Barratt DT, Sia AT, Tan EC, Somogyi AA. Innate Immune and Neuronal Genetic Markers are Highly Predictive of Postoperative Pain and Morphine Patient-Controlled Analgesia requirements in Indian but not Chinese or Malay hysterectomy patients. Pain Med 2021; 22:2648-2660. [PMID: 34015137 DOI: 10.1093/pm/pnab172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/11/2021] [Accepted: 05/18/2021] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Pain severity and opioid requirements in the postoperative period show substantial and clinically significant inter-patient variation due mainly to factors such as age, surgery type and duration. Genetic factors have not been adequately assessed except for the neuronal OPRM1 rs1799971 and COMT rs4680, whereas the contribution of innate immune signalling pathway genetics was seldom investigated. SETTING Hospital surgical ward. SUBJECTS 107 Indian, 184 Malay and 750 Han Chinese women undergoing total hysterectomy surgery. METHODS Morphine consumption, pre- and post-operative pain were evaluated in relation to genetic variability comprising 19 SNPs in 14 genes involved in glial activation, inflammatory signalling and neuronal regulation plus OPRM1 (1 SNP) and COMT (3 SNPs). RESULTS Pre- and post-operative pain and age were associated with increased and decreased morphine consumption, respectively. In Chinese patients, only 8% of the variability in consumption could be explained by these nongenetic and genetic (BDNF, IL1B, IL6R, CRP, OPRM1, COMT, MYD88) factors. However, in Indian patients, 41% of morphine consumption variability could be explained by age (explaining <3%) and variants in OPRM1 rs1799971, CRP rs2794521, TLR4 rs4986790, IL2 rs2069762, COMT rs4818, TGFB1 rs1800469 and IL6R rs8192284 when not controlling for postoperative pain. CONCLUSIONS This is the highest known value reported for genetic contributions (38%) to morphine use in the acute postoperative pain setting. Our findings highlight the need to incorporate both genetic and non-genetic factors and, consider ethnicity-dependent and non-additive genotypic models, when assessing factors that contribute to variability in opioid use.
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Affiliation(s)
- Daniel T Barratt
- Discipline of Pharmacology, Adelaide Medical School, Faculty of Health & Medical Sciences, University of Adelaide, Adelaide, 5005, Australia
| | - Alex T Sia
- SingHealth-Duke-NUS Academic Clinical Programme, Singapore.,Department of Women's Anesthesia, KK Women's and Children's Hospital, Singapore, Singapore
| | - Ene-Choo Tan
- SingHealth-Duke-NUS Academic Clinical Programme, Singapore.,KK Research Centre, KK Women's and Children's Hospital, Singapore, Singapore
| | - Andrew A Somogyi
- Discipline of Pharmacology, Adelaide Medical School, Faculty of Health & Medical Sciences, University of Adelaide, Adelaide, 5005, Australia.,Department of Clinical Pharmacology, Royal Adelaide Hospital, Adelaide, 5001, Australia
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Sallustio BC, Noll BD, Hu R, Barratt DT, Tuke J, Coller JK, Russ GR, Somogyi AA. Tacrolimus dose, blood concentrations and acute nephrotoxicity, but not CYP3A5/ABCB1 genetics, are associated with allograft tacrolimus concentrations in renal transplant recipients. Br J Clin Pharmacol 2021; 87:3901-3909. [PMID: 33646566 DOI: 10.1111/bcp.14806] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 02/02/2021] [Accepted: 02/17/2021] [Indexed: 12/16/2022] Open
Abstract
AIMS Long-term use of the immunosuppressant tacrolimus is limited by nephrotoxicity. Following renal transplantation, the risk of nephrotoxicity may be determined more by allograft than by blood tacrolimus concentrations, and thus may be affected by donor CYP3A5 and ABCB1 genetics. Little is known regarding factors that determine tacrolimus intrarenal exposure. METHODS This study investigated the relationship between trough blood (C0Blood ) and allograft (CGraft ) tacrolimus concentrations and tacrolimus dose, haematocrit, genetics, acute nephrotoxicity, rejection status, delayed graft function, and time post-transplant. C0Blood and CGraft were quantified in 132 renal transplant recipients together with recipient and donor CYP3A5 (rs776746) and ABCB1 3435 (rs1045642) genotypes. RESULTS C0Blood ranged from 2.6 to 52.3 ng/mL and CGraft from 33 to 828 pg/mg tissue. Adjusting for dose, recipients who were CYP3A5 expressors had lower C0Blood compared to nonexpressors, whilst delayed graft function was associated with higher C0Blood . Linear regression showed that the significant predictors of CGraft were C0Blood (point-wise P = 7 × 10-10 ), dose (P = .004) acute nephrotoxicity (P = .002) and an interaction between C0Blood and acute tacrolimus nephrotoxicity (P = .0002), with an adjusted r2 = 0.35 and no contribution from donor or recipient CYP3A5 or ABCB1 genotype. The association between CGraft and acute nephrotoxicity depended on one very high CGraft (828 pg/mg tissue). CONCLUSIONS Recipient and donor CYP3A5 and ABCB1 3435C>T genotypes are not determinants of allograft tacrolimus exposure in kidney transplant recipients. However, tacrolimus dose and C0Blood were significant predictors of CGraft , and the relationship between C0Blood and CGraft appeared to differ in the presence or absence of acute nephrotoxicity.
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Affiliation(s)
- Benedetta C Sallustio
- Department of Clinical Pharmacology, Basil Hetzel Institute, The Queen Elizabeth Hospital, Woodville South, SA, 5011, Australia.,Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, SA, 5000, Australia
| | - Benjamin D Noll
- School of Pharmacy and Medical Sciences, University of South Australia, Australia, Adelaide, SA, 5000, Australia
| | - Rong Hu
- Department of Pharmacy, Guangzhou Women's and Children's Medical Centre, Guangzhou Medical University, Guangzhou, China
| | - Daniel T Barratt
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, SA, 5000, Australia
| | - Jonathan Tuke
- ARC Centre for Excellence for Mathematical and Statistical Frontiers, School of Mathematical Sciences, Adelaide, SA, 5000, Australia.,School of Mathematical Sciences, Adelaide, SA, 5000, Australia
| | - Janet K Coller
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, SA, 5000, Australia
| | - Graeme R Russ
- Central Northern Adelaide Renal and Transplantation Services, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia
| | - Andrew A Somogyi
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, SA, 5000, Australia
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Hu R, Barratt DT, Coller JK, Sallustio BC, Somogyi AA. No Major Effect of Innate Immune Genetics on Acute Kidney Rejection in the First 2 Weeks Post-Transplantation. Front Pharmacol 2020; 10:1686. [PMID: 32153387 PMCID: PMC7045476 DOI: 10.3389/fphar.2019.01686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 12/24/2019] [Indexed: 12/03/2022] Open
Abstract
Background Innate immunity contributes to acute rejection after kidney transplantation. Genetic polymorphisms affecting innate immunity may therefore influence patients’ risk of rejection. IL2 -330T > G, IL10 -1082G > A, -819C > T, and -592C > A, and TNF -308G > A are not associated with acute rejection incidence in Caucasian kidney transplant recipients receiving a calcineurin inhibitor, ciclosporin or tacrolimus (TAC). However, other important innate immune genetic polymorphisms have not yet been extensively studied in recipients and donors. In addition, innate immunogenetics have not been investigated in kidney transplant cohorts receiving only TAC as the calcineurin inhibitor. Objective To investigate the effect of recipient and donor CASP1, CRP, IL1B, IL2, IL6, IL6R, IL10, MYD88, TGFB, TLR2, TLR4, and TNF genetics on acute kidney rejection in the first 2 weeks post-transplant in TAC-treated kidney transplant recipients. Methods This study included 154 kidney transplant recipients and 81 donors successfully genotyped for 17 polymorphisms in these genes. All recipients were under triple immunosuppressant therapy of TAC, mycophenolate mofetil, and prednisolone. Recipient and donor genotype differences in acute rejection incidence within the first 2 weeks post-transplantation were assessed by logistic regression, adjusting for induction therapy, human leukocyte antigen mismatches, kidney transplant number, living donor, and peak panel-reactive antibody scores. Results A trend (Cochran-Armitage P = 0.031) of increasing acute rejection incidence was observed from recipient IL6 -6331 T/T (18%) to T/C (25%) to C/C (46%) genotype [C/C versus T/T odds ratio (95% confidence interval) = 6.6 (1.7 to 25.8) (point-wise P = 0.017)]. However, no genotype differences were significant after Bonferroni correction for multiple comparisons. Conclusions This study did not detect any statistically significant effects of recipient or donor innate immune genetics on acute rejection incidence in the first 2 weeks post-transplantation. However, the sample size was small, and future larger studies or meta-analyses are required to demonstrate conclusively if innate immune genetics such as IL6 influence the risk of acute rejection after kidney transplantation.
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Affiliation(s)
- Rong Hu
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Daniel T. Barratt
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Janet K. Coller
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Benedetta C. Sallustio
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
- Department of Clinical Pharmacology, The Queen Elizabeth Hospital, Adelaide, SA, Australia
| | - Andrew A. Somogyi
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
- Department of Clinical Pharmacology, Royal Adelaide Hospital, Adelaide, SA, Australia
- *Correspondence: Andrew A. Somogyi,
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7
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Somogyi AA, Barratt DT, Phillips EJ, Moore K, Ilyas F, Gabb GM. High and variable population prevalence of HLA-B*56:02 in indigenous Australians and relation to phenytoin-associated drug reaction with eosinophilia and systemic symptoms. Br J Clin Pharmacol 2019; 85:2163-2169. [PMID: 31206740 DOI: 10.1111/bcp.14025] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 05/19/2019] [Accepted: 06/02/2019] [Indexed: 12/17/2022] Open
Abstract
Phenytoin drug reaction with eosinophilia and systemic symptoms (DRESS) in 3 Aboriginal Australians positive for HLA-B*56:02 has been previously reported. We report the allele frequency of HLA-B*56:02 in 2 South Australian populations, 1 Aboriginal (4.8%, 95% confidence interval 2.4-7.8%) and the other European (0%). We compared the frequency with publicly available information on HLA-B*56:02 status in other Indigenous Australian (n = 4) and European Australian cohorts (n = 1). In the Indigenous Australian cohorts, HLA-B*56:02 allele frequency ranged from 1.3 to 19%. We also describe an additional case of phenytoin DRESS (RegiSCAR DRESS score 7) in an Aboriginal Australian that was associated with HLA-B*56:02 and with CYP2C9*1/*3 genotype. In Aboriginal Australians, phenytoin DRESS appears distinctly linked to HLA-B*56:02 with an allele carriage rate substantially higher than in Europeans, but also with considerable regional variation. Investigations of human leucocyte antigen and other contributing genes and severe adverse drug reactions in understudied non-European populations are required to optimize safe medication use and inform risk mitigation strategies.
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Affiliation(s)
- Andrew A Somogyi
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, Australia.,Department of Clinical Pharmacology, Royal Adelaide Hospital, Adelaide, Australia
| | - Daniel T Barratt
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, Australia
| | - Elizabeth J Phillips
- Department of Medicine, Pharmacology, Oates Institute for Experimental Therapeutics, Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, Tennessee, USA.,Institute for Immunology and Infectious Diseases, Murdoch University, Murdoch, Australia
| | - Kylies Moore
- Department of Pharmacy, Royal Adelaide Hospital, Adelaide, Australia
| | - Fahmida Ilyas
- General Medicine, Royal Adelaide Hospital, Adelaide, Australia
| | - Genevieve M Gabb
- General Medicine, Royal Adelaide Hospital, Adelaide, Australia.,Department of Medicine, University of Adelaide, Adelaide, Australia
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Hu R, Barratt DT, Coller JK, Sallustio BC, Somogyi AA. CYP3A5*3
and ABCB1
61A>G Significantly Influence Dose-adjusted Trough Blood Tacrolimus Concentrations in the First Three Months Post-Kidney Transplantation. Basic Clin Pharmacol Toxicol 2018; 123:320-326. [DOI: 10.1111/bcpt.13016] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 03/20/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Rong Hu
- Discipline of Pharmacology; Adelaide Medical School; University of Adelaide; Adelaide SA Australia
| | - Daniel T. Barratt
- Discipline of Pharmacology; Adelaide Medical School; University of Adelaide; Adelaide SA Australia
| | - Janet K. Coller
- Discipline of Pharmacology; Adelaide Medical School; University of Adelaide; Adelaide SA Australia
| | - Benedetta C. Sallustio
- Discipline of Pharmacology; Adelaide Medical School; University of Adelaide; Adelaide SA Australia
- Department of Pharmacology; Queen Elizabeth Hospital; Adelaide SA Australia
| | - Andrew A. Somogyi
- Discipline of Pharmacology; Adelaide Medical School; University of Adelaide; Adelaide SA Australia
- Department of Clinical Pharmacology; Royal Adelaide Hospital; Adelaide SA Australia
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Barratt DT, Cox HK, Menelaou A, Yeung DT, White DL, Hughes TP, Somogyi AA. CYP2C8 Genotype Significantly Alters Imatinib Metabolism in Chronic Myeloid Leukaemia Patients. Clin Pharmacokinet 2016; 56:977-985. [DOI: 10.1007/s40262-016-0494-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Abstract
1. Imatinib is metabolized to N-desmethyl imatinib by CYPs 3A4 and 2C8. The effect of CYP2C8*3 genotype on N-desmethyl imatinib formation was unknown. 2. We examined imatinib N-demethylation in human liver microsomes (HLMs) genotyped for CYP2C8*3, in CYP2C8*3/*3 pooled HLMs and in recombinant CYP2C8 and CYP3A4 enzymes. Effects of CYP-selective inhibitors on N-demethylation were also determined. 3. A single-enzyme Michaelis-Menten model with autoinhibition best fitted CYP2C8*1/*1 HLM (n = 5) and recombinant CYP2C8 kinetic data (median ± SD Ki = 139 ± 61 µM and 149 µM, respectively). Recombinant CYP3A4 showed two-site enzyme kinetics with no autoinhibition. Three of four CYP2C8*1/*3 HLMs showed single-enzyme kinetics with no autoinhibition. Binding affinity was higher in CYP2C8*1/*3 than CYP2C8*1/*1 HLM (median ± SD Km = 6 ± 2 versus 11 ± 2 µM, P=0.04). CYP2C8*3/*3 (pooled HLM) also showed high binding affinity (Km = 4 µM) and single-enzyme weak autoinhibition (Ki = 449 µM) kinetics. CYP2C8 inhibitors reduced HLM N-demethylation by 47-75%, compared to 0-30% for CYP3A4 inhibitors. 4. In conclusion, CYP2C8*3 is a gain-of-function polymorphism for imatinib N-demethylation, which appears to be mainly mediated by CYP2C8 and not CYP3A4 in vitro in HLM.
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Affiliation(s)
- Muhammad Suleman Khan
- a Discipline of Pharmacology, School of Medical Sciences, University of Adelaide , Adelaide , Australia and
| | - Daniel T Barratt
- a Discipline of Pharmacology, School of Medical Sciences, University of Adelaide , Adelaide , Australia and.,b Centre for Personalised Cancer Medicine, University of Adelaide , Adelaide , Australia
| | - Andrew A Somogyi
- a Discipline of Pharmacology, School of Medical Sciences, University of Adelaide , Adelaide , Australia and.,b Centre for Personalised Cancer Medicine, University of Adelaide , Adelaide , Australia
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Abstract
Methadone is the major opioid substitution therapy for opioid dependence. Dosage is highly variable and is often controlled by the patient and prescriber according to local and national policy and guidelines. Nevertheless many genetic factors have been investigated including those affecting its metabolism (CYP2B6-consistent results), efflux transport (P-gp-inconsistent results), target μ-opioid receptor (μ-opioid receptor-inconsistent results) and a host of other receptors (DRD2) and signaling elements (GIRK2 and ARRB2; not replicated). None by themselves have been able to substantially explain dosage variation (the major but not sole end point). When multiple genes have been combined such as ABCB1, CYP2B6, OPRM1 and DRD2 a greater contribution to dosage variation was found but not as yet replicated. As stabilization of dosage needs to be made rapidly, it is imperative that larger internationally based studies be instigated so that genetic contribution to dosage can be properly assessed, which may or may not tailor to different ethnic groups and each country’s policy towards an outcome that benefits all.
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Affiliation(s)
- Andrew A Somogyi
- Discipline of Pharmacology, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide 5005, Australia
- Department of Clinical Pharmacology, Royal Adelaide Hospital, Adelaide, 5005, Australia
| | - Daniel T Barratt
- Discipline of Pharmacology, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide 5005, Australia
| | - Robert L Ali
- Discipline of Pharmacology, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide 5005, Australia
- DASSA World Health Organization Collaborating Centre for Research in the Treatment of Drug & Alcohol Problems, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide 5005, Australia
| | - Janet K Coller
- Discipline of Pharmacology, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide 5005, Australia
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13
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Grace PM, Hurley D, Barratt DT, Tsykin A, Watkins LR, Rolan PE, Hutchinson MR. Harnessing pain heterogeneity and RNA transcriptome to identify blood-based pain biomarkers: a novel correlational study design and bioinformatics approach in a graded chronic constriction injury model. J Neurochem 2012; 122:976-94. [PMID: 22697386 DOI: 10.1111/j.1471-4159.2012.07833.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A quantitative, peripherally accessible biomarker for neuropathic pain has great potential to improve clinical outcomes. Based on the premise that peripheral and central immunity contribute to neuropathic pain mechanisms, we hypothesized that biomarkers could be identified from the whole blood of adult male rats, by integrating graded chronic constriction injury (CCI), ipsilateral lumbar dorsal quadrant (iLDQ) and whole blood transcriptomes, and pathway analysis with pain behavior. Correlational bioinformatics identified a range of putative biomarker genes for allodynia intensity, many encoding for proteins with a recognized role in immune/nociceptive mechanisms. A selection of these genes was validated in a separate replication study. Pathway analysis of the iLDQ transcriptome identified Fcγ and Fcε signaling pathways, among others. This study is the first to employ the whole blood transcriptome to identify pain biomarker panels. The novel correlational bioinformatics, developed here, selected such putative biomarkers based on a correlation with pain behavior and formation of signaling pathways with iLDQ genes. Future studies may demonstrate the predictive ability of these biomarker genes across other models and additional variables.
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Affiliation(s)
- Peter M Grace
- Discipline of Pharmacology, School of Medical Sciences, University of Adelaide, Adelaide, Australia.
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14
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Barratt DT, Coller JK, Hallinan R, Byrne A, White JM, Foster DJR, Somogyi AA. ABCB1 haplotype and OPRM1 118A > G genotype interaction in methadone maintenance treatment pharmacogenetics. Pharmgenomics Pers Med 2012; 5:53-62. [PMID: 23226062 PMCID: PMC3513228 DOI: 10.2147/pgpm.s29272] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Indexed: 11/23/2022]
Abstract
BACKGROUND Genetic variability in ABCB1, encoding the P-glycoprotein efflux transporter, has been linked to altered methadone maintenance treatment dose requirements. However, subsequent studies have indicated that additional environmental or genetic factors may confound ABCB1 pharmacogenetics in different methadone maintenance treatment settings. There is evidence that genetic variability in OPRM1, encoding the mu opioid receptor, and ABCB1 may interact to affect morphine response in opposite ways. This study aimed to examine whether a similar gene-gene interaction occurs for methadone in methadone maintenance treatment. METHODS Opioid-dependent subjects (n = 119) maintained on methadone (15-300 mg/day) were genotyped for five single nucleotide polymorphisms of ABCB1 (61A > G; 1199G > A; 1236C > T; 2677G > T; 3435C > T), as well as for the OPRM1 118A > G single nucleotide polymorphism. Subjects' methadone doses and trough plasma (R)-methadone concentrations (C(trough)) were compared between ABCB1 haplotypes (with and without controlling for OPRM1 genotype), and between OPRM1 genotypes (with and without controlling for ABCB1 haplotype). RESULTS Among wild-type OPRM1 subjects, an ABCB1 variant haplotype group (subjects with a wild-type and 61A:1199G:1236C:2677T:3435T haplotype combination, or homozygous for the 61A:1199G:1236C:2677T:3435T haplotype) had significantly lower doses (median ± standard deviation 35 ± 5 versus 180 ± 65 mg/day, P < 0.01) and C(trough) (78 ± 22 versus 177 ± 97 ng/mL, P < 0.05) than ABCB1 wild-type subjects. Among subjects with the most common ABCB1 haplotype combination (wild-type with 61A:1199G:1236T:2677T:3435T), the OPRM1 118 A/G genotype was associated with a significantly higher C(trough) than 118 A/A (250 ± 126 versus 108 ± 36 ng/mL, P = 0.016). No ABCB1 haplotype group or OPRM1 genotype was associated with dose or C(trough) without taking into account confounding genetic variability at the other locus. Therefore, two interacting pharmacogenetic determinants of methadone maintenance treatment response were identified, ie, ABCB1, where variants are associated with lower methadone requirements, and OPRM1, where the variant is associated with higher methadone requirements. CONCLUSION These opposing pharmacogenetic effects therefore need to be considered in combination when assessing methadone maintenance treatment pharmacogenetics.
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Affiliation(s)
- Daniel T Barratt
- Discipline of Pharmacology, School of Medical Sciences, University of Adelaide, Adelaide, South Australia
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Abstract
Opioids are used for acute and chronic pain and dependency. They have a narrow therapeutic index and large interpatient variability in response. Genetic factors regulating their pharmacokinetics (metabolizing enzymes, transporters) and pharmacodynamics (receptors and signal transduction elements) are contributors to such variability. The polymorphic CYP2D6 regulates the O-demethylation of codeine and other weak opioids to more potent metabolites with poor metabolizers having reduced antinociception in some cases. Some opioids are P-glycoprotein substrates, whereas, ABCB1 genotypes inconsistently influence opioid pharmacodynamics and dosage requirements. Single-nucleotide polymorphisms in the mu opioid receptor gene are associated with increasing morphine, but not methadone dosage requirements and altered efficacy of mu opioid agonists and antagonists. As knowledge regarding the interplay between genes affecting opioid pharmacokinetics including cerebral kinetics and pharmacodynamics increases, our understanding of the role of pharmacogenomics in mediating interpatient variability in efficacy and side effects to this important class of drugs will be better informed. Opioid drugs as a group have withstood the test of time in their ability to attenuate acute and chronic pain. Since the isolation of morphine in the early 1800s by Friedrich Sertürner, a large number of opioid drugs beginning with modification of the 4,5-epoxymorphinan ring structure were developed in order to improve their therapeutic margin, including reducing dependence and tolerance, ultimately without success.
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Affiliation(s)
- Andrew A Somogyi
- Discipline of Pharmacology, School of Medical Sciences, University of Adelaide, Adelaide, Australia.
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Coller JK, Barratt DT, Dahlen K, Loennechen MH, Somogyi AA. ABCB1 genetic variability and methadone dosage requirements in opioid-dependent individuals. Clin Pharmacol Ther 2006; 80:682-90. [PMID: 17178268 DOI: 10.1016/j.clpt.2006.09.011] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Accepted: 09/11/2006] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES The most common treatment for opioid dependence is substitution therapy with another opioid such as methadone. The methadone dosage is individualized but highly variable, and program retention rates are low due in part to nonoptimal dosing resulting in withdrawal symptoms and further heroin craving and use. Methadone is a substrate for the P-glycoprotein transporter, encoded by the ABCB1 gene, which regulates central nervous system exposure. This retrospective study aimed to investigate the influence of ABCB1 genetic variability on methadone dose requirements. METHODS Genomic deoxyribonucleic acid was isolated from opioid-dependent subjects (n = 60) and non-opioid-dependent control subjects (n = 60), and polymerase chain reaction-restriction fragment length polymorphism and allele-specific polymerase chain reaction were used to determine the presence of single nucleotide polymorphisms at positions 61, 1199, 1236, 2677, and 3435. ABCB1 haplotypes were inferred with PHASE software (version 2.1). RESULTS There were no significant differences in the allele or genotype frequencies of the individual single nucleotide polymorphisms or haplotypes between the 2 populations. ABCB1 genetic variability influenced daily methadone dose requirements, such that subjects carrying 2 copies of the wild-type haplotype required higher doses compared with those with 1 copy and those with no copies (98.3 +/- 10.4, 58.6 +/- 20.9, and 55.4 +/- 26.1 mg/d, respectively; P = .029). In addition, carriers of the AGCTT haplotype required significantly lower doses than noncarriers (38.0 +/- 16.8 and 61.3 +/- 24.6 mg/d, respectively; P = .04). CONCLUSION Although ABCB1 genetic variability is not related to the development of opioid dependence, identification of variant haplotypes may, after larger prospective studies have been performed, provide clinicians with a tool for methadone dosage individualization.
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Affiliation(s)
- Janet K Coller
- Discipline of Pharmacology, School of Medical Sciences, The University of Adelaide, and Department of Clinical Pharmacology, Royal Adelaide Hospital, SA, Australia.
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Barratt DT, Coller JK, Somogyi AA. Association between the DRD2 A1 allele and response to methadone and buprenorphine maintenance treatments. Am J Med Genet B Neuropsychiatr Genet 2006; 141B:323-31. [PMID: 16583408 DOI: 10.1002/ajmg.b.30319] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The TaqI A polymorphism (A(1)) of the dopamine D(2) receptor gene (DRD2), although not a specific predictor of opioid dependence, has been strongly associated with high levels of prior heroin use and poor treatment outcomes among methadone maintenance patients. The aims of this study were to confirm these findings via a retrospective analysis of A(1) allele frequency in methadone (n = 46) and buprenorphine (n = 25) patients, and non-opioid-dependent controls (n = 95). Subjects were genotyped at the DRD2 TaqI A locus using PCR amplification followed by TaqI restriction enzyme digestion and gel electrophoresis. For methadone and buprenorphine subjects, heroin use (prior to treatment), treatment outcomes, and withdrawal occurrence were determined from comprehensive case notes. No significant differences in A(1) allele frequency (%) were observed between: methadone (19.6%), buprenorphine (18.0%), and control (17.9%) groups (P > 0.7); successful and poor treatment outcome groups, methadone: 20.0% and 19.2%, respectively (P = 1.0); buprenorphine: 18.4% and 20.0%, respectively (P = 1.0). Also, there were no significant relationships between TaqI A genotype and prior heroin use (P = 0.47). However, among the successful methadone subjects, significantly fewer A(1) allele carriers experienced withdrawal than non-A(1) carriers (P = 0.04). In conclusion, the DRD2 genotype effects did not affect opioid maintenance treatment outcomes. This suggests the need for a further prospective investigation into the role of the DRD2 A(1) allele in heroin use and response to maintenance pharmacotherapies for opioid dependence.
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Affiliation(s)
- Daniel T Barratt
- Discipline of Pharmacology, School of Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia.
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