Method development and validation for simultaneous determination of lumefantrine and its major metabolite, desbutyl lumefantrine in human plasma using RP-HPLC/UV detection

A simple and rapid external standard calibration HPLC method for determination of lumefantrine in dried blood spot samples from malaria patients in Botswana

A simple external calibration liquid chromatography-diode array detector method was developed, validated, and applied for the determination of lumefantrine (Lum) in dried blood spot (DBS) samples collected from malaria patients in Botswana. The samples were validated in accordance with the United States Food and Drug Administration guidelines for bioanalytical methods after sample preparation using solid-liquid extraction. Separation was achieved using an XTerra C18 column (50 × 4.6 mm, 5 μm), and a binary solvent system of acetonitrile and water adjusted to pH 2.3 was used as the mobile phase. The validated method was applied for the determination of Lum in DBS samples collected from malaria patients infected with Plasmodium falciparum in Botswana. The calibration curve was linear between 0.5 and 12 μg/mL with a coefficient of determination (R2 ) of 0.9996. The limit of detection and the lower limit of quantification were 0.5 and 1.4 μg/mL, respectively. The efficiency of extraction measured as percentage recovery ranged between 84.2% and 107.8% at the three quality control (QC) levels, that is, low QC, mid QC, and high QC. In conclusion, data suggest that the method is suitable for the determination of trace Lum in biofluids and can also be used for therapeutic drug monitoring and pharmacokinetic profiling.

Lumefantrine plasma concentrations in uncontrolled conditions among patients treated with artemether-lumefantrine for uncomplicated plasmodium falciparum malaria in Mwanza, Tanzania

BACKGROUND

Therapeutic efficacy of artemether-lumefantrine is highly dependent on adequate systemic exposure to the partner drug lumefantrine particularly day 7 lumefantrine plasma concentration. There has been contradicting findings on the role of the cut-off values in predicting treatment outcomes among malaria patients in malaria endemic regions. This study assesses the day 3 and 7 lumefantrine plasma concentrations including related determinant factors and their influence on treatment outcomes among treated Tanzanian children and adults in uncontrolled conditions (real life condition).

METHODS

Data was nested from an efficacy study employing the WHO protocol, 2015 for monitoring antimalarial drug efficacy. Lumefantrine plasma concentration was measured by high performance liquid chromatography with ultraviolet (HPLC-UV).

RESULTS

Lumefantrine plasma concentrations below 175ng/ml and 200ng/ml on day 3 and 7 did not affect adequate clinical and parasitological response (ACPR) and recurrence of infection (p = 0.428 and 0.239 respectively). Age and baseline parasitemia were not associated to day 3 median lumefantrine plasma concentrations (p = 0.08 and 0.31 respectively) and day 7 lumefantrine plasma concentrations (p = 0.07 and 0.41 respectively). However, the day 3 and day 7 lumefantrine plasma concentrations were significantly higher in males compared to females (p = 0.03 and 0.042 respectively).

CONCLUSION

Lumefantrine plasma concentrations below cut-off points (175ng/ml and 200ng/ml) on day 3 and 7 did not influence treatment outcomes.

Determination of antimalarial drugs in pharmaceutical formulations and human blood by liquid chromatography: a review

Malaria is a life-threatening disease being treated by oral medication. This is the best treatment to reduce morbidity and mortality, prevent disease progression to the most severe form, lower the transmission of the disease and hinder the appearance of strains resistant to antimalarials. According to the World Health Organization, the most common antimalarial drugs are chloroquine, primaquine, mefloquine, lumefantrine, artemether, and artesunate in single dosage forms or fixed-dose combination. Within this context, the present review aims to show the evolution of different analytical methods that have been applied to the determination of these antimalarial drugs in pharmaceutical formulations and human blood by liquid chromatography in the last 10 years, along with statistical analyses of the methods.

Investigating In Vitro and Ex Vivo Properties of Artemether/Lumefantrine Double-Fixed Dose Combination Lipid Matrix Tablets Prepared by Hot Fusion

Highly lipophilic antimalarial drugs, artemether and lumefantrine, whilst an effective fixed-dose combination treatment to lower the malarial disease burden, are therapeutically hindered by low aqueous solubility and varied bioavailability. This work investigates the plausibility of directly compressed lipid matrix tablets, their role as lipid-based formulations and their future standing as drug delivery systems. Lipid matrix tablets were manufactured from solid lipid dispersions in various lipid:drug ratios employing hot fusion—the melt mixing of highly lipophilic drugs with polymer(s). Sequential biorelevant dissolution media, multiple mathematical models and ex vivo analysis utilizing porcine tissue samples were employed to assess drug release kinetics and more accurately predict in vitro performance. Directly compressed stearic acid tablets in a 0.5:1 lipid:drug ratio were deemed optimal within investigated parameters. Biorelevant media was of immense value for artemether release analysis, with formulation SA0.5C1 (Stearic Acid:double fixed dose in a 0.5:1 ratio (i.e., Stearic acid 70 mg + Lumefantrine 120 mg + Artemether 20 mg); CombiLac^® as filler (q.s.); and 1% w/w magnesium stearate) yielding a higher percentage of artemether release (97.21%) than the commercially available product, Coartem^® (86.12%). However, dissolution media lacked the specificity to detect lumefantrine. Nonetheless, stearic acid lipid:drug ratios governed drug release mechanisms. This work demonstrates the successful utilization of lipids as pharmaceutical excipients, particularly in the formulation of lipid matrix tablets to augment the dissolution of highly lipophilic drugs, and could thus potentially improve current malarial treatment regimens.

Influence of selected polymorphisms in disposition genes on lumefantrine pharmacokinetics when coadministered with efavirenz

BACKGROUND

Coadministration of artemether-lumefantrine and efavirenz has been shown to result in significant interactions. The influence of functional genetic polymorphisms in selected CYPs on the magnitude of this interaction was investigated in pregnant and nonpregnant adults.

METHOD

A standard 3-day regimen of artemether-lumefantrine was administered to each patient on steady-state efavirenz-based antiretroviral therapy (ART). Pharmacokinetic parameters were obtained from intensive plasma concentration-time data. Genotyping data were tested for compliance with Hardy-Weinberg equilibrium by Chi-square test. Linear regressions, Mann-Whitney U-test or Kruskal-Wallis tests were conducted to examine the association of lumefantrine plasma level with CYP2B6 c.516G>T, NR1I3 152c-1089T>C, CYP2B6 c.983T>C, CYP3A5*3 and CYP3A4*22.

RESULTS

Among a total of 69 malaria-HIV coinfected patients (34 nonpregnant and 35 pregnant), median (interquartile range) age was 33 (27-36.5) years and body weight was 59.5 (50-67.5) kg. In nonpregnant group, CYP2B6 c.516G>T was significantly associated with lower log Cday 7 of lumefantrine using multivariate linear regressions (β = -0.239; P = 0.013). In 59% of women with CYP2B6 c.516T, Cday 7 of lumefantrine was below the target of 280 ng/mL compared to 47% in the noncarriers. CYP2B6 c.983T>C significantly associated with higher log Cday 7 of desbutyl lumefantrine in both pregnant (β = 0.383; P = 0.033) and nonpregnant (β = 0.395; P = 0.023) groups. Composite genotypes for both CYP2B6 Single-nucleotide polymorphisms strongly associated with lumefantrine plasma concentration. An associative trend between lumefantrine pharmacokinetics and NR1I3 152c-1089T>C genotypes indicated that 70% of the Cday 7 of lumefantrine in those with NR1I3 152c-1089TT genotype was below 280 ng/mL compared to 53% in those with NR1I3 152c-1089CC or CT genotype.

CONCLUSION

The findings revealed that the efavirenz-lumefantrine interaction was accentuated in the group with CYP2B6 c.516T, c.983C and NR1I3 152c-1089T alleles. This warrants further investigations of other drug-drug interactions for optimising dosing in genetically defined subgroups, particularly during drug development.

Effect of CYP3A5*3 genotypes on lumefantrine plasma concentrations among malaria-HIV-infected women

Aim: We aimed to assess the effect of a functional polymorphism of CYP3A5 on lumefantrine pharmacokinetics. Patients & methods: Sixty-nine women diagnosed with malaria received standard doses of artemether-lumefantrine. Concentration-time data for lumefantrine and genotyping data were obtained for each participant. Pharmacokinetic-genotype associative relationships were assessed using linear regressions, Mann-Whitney U-test or Kruskal-Wallis statistics. Results: Average age and weight (standard deviation) of the patients were 33 (6.8) years and 59.5 (11.6) kg, respectively. CYP3A5*3 genotype associated with the log-transformed maximum concentration with the median (interquartile range) values of 8279 (6516-13,420) and 6331 (4093-8631) ng/ml (p = 0.032) among the carriers and noncarriers of CYP3A5*3, respectively. Besides, the NR1I3 c.152-1089T>C genotypes had an associative trend with the lumefantrine area under the curve (AUC_0-96h) and clearance. Conclusion: CYP3A5*3 genetic variant is associated with a high maximum plasma concentration of lumefantrine. This warrants further investigations on the association between CYP3A5*3 gene variants, lumefantrine pharmacokinetics and electrophysiological effect.

Microextraction by packed sorbent and high performance liquid chromatography for simultaneous determination of lumefantrine and desbutyl-lumefantrine in plasma samples

A bioanalytical method for the determination of lumefantrine and its metabolite desbutyl-lumefantrine in plasma samples using microextraction by packed sorbent (MEPS) and high-performance liquid chromatography was developed and validated. A complete factorial planning and surface response approach were employed to optimize the extraction parameters sample volume, dilution, aspirated sample volume and extraction cycles. The method employed C18 MEPS sorbent and diazepam as internal standard (IS). Separation was performed on a Luna C18 column (250 mm × 4.6 mm, 5 μm) at 35 °C, with mobile phase composed of acetonitrile and 0.05 % trifluoroacetic acid (68:32, v/v), detection at 305 nm and injection volume of 25 μL. The developed method showed to be selective, precise, accurate and linear in the range of 50-5000 ng/mL for lumefantrine and desbutyl-lumefantrine. Using the optimized MEPS procedure, high recovery rates were obtained for both analytes and IS (92.2 %-99.0 %). The method was successfully applied for the determination of lumefantrine and its metabolite in human plasma samples after oral administration of lumefantrine tablets in healthy volunteers.

Quantitative determination of the antimalarials artemether and lumefantrine in biological samples: A review

Malaria is a worldwide health issue, with 216 million cases reported in 2016. Due to the widespread resistance of Plasmodium falciparum to conventional drugs, the first line treatment recommended by World Health Organization for uncomplicated malaria is artemisinin-based combined therapy (ACT), which combines two drugs with different mechanisms of action. The association of artemether and lumefantrine is the most common ACT used in the clinical practice. However, there have been reports of clinical artemisinin and derivatives partial resistance, which is defined as delayed parasite clearance. In this context, the monitoring of drug concentration in biological matrices is essential to evaluate treatment response, the need of dose adjustment and the occurrence of dose dependent adverse effects. Furthermore, it is also important for pharmacokinetic studies and in the development of generic and similar drugs. Determination of antimalarial drugs in biological matrices requires a sample pre-treatment, which involves drug extraction from the matrix and analyte concentration. The most used techniques are protein precipitation (PP), liquid-liquid extraction (LLE) and solid phase extraction (SPE). Subsequently, a liquid chromatography step is usually applied to separate interferences that could be extracted along with the analyte. Finally, the analytes are detected employing techniques that must be selective and sensitive, since the analyte might be present in trace levels. The most used approach for detection is tandem mass spectrometry (MS-MS), but ultraviolet (UV) is also employed in several studies. In this article, a review of the scientific peer-review literature dealing with validated quantitative analysis of artemether and/or lumefantrine in biological matrices, from 2000 to 2018, is presented.

Effect of Pregnancy on the Pharmacokinetic Interaction between Efavirenz and Lumefantrine in HIV-Malaria Coinfection

Artemether-lumefantrine is often coadministered with efavirenz-based antiretroviral therapy for malaria treatment in HIV-infected women during pregnancy. Previous studies showed changes in lumefantrine pharmacokinetics due to interaction with efavirenz in nonpregnant adults. The influence of pregnancy on this interaction has not been reported. This pharmacokinetic study involved 35 pregnant and 34 nonpregnant HIV-malaria-coinfected women receiving efavirenz-based antiretroviral therapy and was conducted in four health facilities in Nigeria. Participants received a 3-day standard regimen of artemether-lumefantrine for malaria treatment, and intensive pharmacokinetic sampling was conducted from 0.5 to 96 h after the last dose. Plasma efavirenz, lumefantrine, and desbutyl-lumefantrine were quantified using validated assays, and pharmacokinetic parameters were derived using noncompartmental analysis. The median middose plasma concentrations of efavirenz were significantly lower in pregnant women (n = 32) than in nonpregnant women (n = 32) at 1,820 ng/ml (interquartile range, 1,300 to 2,610 ng/ml) versus 2,760 ng/ml (interquartile range, 2,020 to 5,640 ng/ml), respectively (P = 0.006). The lumefantrine area under the concentration-time curve from 0 to 96 h was significantly higher in pregnant women (n = 27) at 155,832 ng · h/ml (interquartile range, 102,400 to 214,011 ng · h/ml) than nonpregnant women at 90,594 ng · h/ml (interquartile range, 58,869 to 149,775 ng · h/ml) (P = 0.03). A similar trend was observed for the lumefantrine concentration at 12 h after the last dose of lumefantrine, which was 2,870 ng/ml (interquartile range, 2,180 to 4,880 ng/ml) versus 2,080 ng/ml (interquartile range, 1,190 to 2,970 ng/ml) in pregnant and nonpregnant women, respectively (P = 0.02). The lumefantrine-to-desbutyl-lumefantrine ratio also tended to be lower in pregnant women than in nonpregnant women (P = 0.076). Overall, pregnancy tempered the extent of efavirenz-lumefantrine interactions, resulting in increased lumefantrine exposure. However, any consideration of dosage adjustment for artemether-lumefantrine to enhance exposure in this population needs to be based on data from a prospective study with safety and efficacy endpoints.