Plasma Lumefantrine Concentrations Research Articles

A simple high-performance liquid chromatographic assay for concurrent quantification of lumefantrine and efavirenz in human plasma from malaria–HIV co-infected individuals

BackgroundAs per current treatment guidelines, artemether-lumefantrine and efavirenz-based antiretroviral therapy are recommended drugs for falciparum malaria and human immunodeficiency virus (HIV) infections, respectively. A liquid chromatography-ultraviolet detection method for simultaneous quantification of lumefantrine and efavirenz was developed and validated for efficacy and pharmacokinetic clinical studies. Lumefantrine and efavirenz were separated using a 100 × 4.6 mm × 3 µm Fortis C18 chromatographic column, and a multistep gradient mobile phase. Calibration curves were obtained with a series of standard solutions containing known concentrations of the chemical reference of both analytes prepared concomitantly in drug-free plasma. The assay was validated within the calibration ranges of 78.125–20,000 ng/mL for lumefantrine and 187.15–24,000 ng/mL for efavirenz. Stability assessment was carried out with or without heating the quality control sample to 58 °C for 45 min. The method was employed to measure the plasma concentrations of lumefantrine and efavirenz in a study conducted among malaria-HIV co-infected patients.ResultLumefantrine and efavirenz were well separated from each other and from the biological matrix. The method demonstrated a good recovery of 72.64% for lumefantrine and 117.17% for efavirenz. The intra- and inter-day accuracy presented as 95.36–105.14% for lumefantrine and 104.11–115% for efavirenz and precision ranged from 1.15 to 6.45% for lumefantrine and 0.43 to 13.12 for efavirenz, were within ± 15% at the three quality control levels. The analytes from both quality control lots and samples collected from HIV-malaria co-infected individuals were found to be stable post-deactivation of infectious virus by heating to 58 °C for 45 min.ConclusionThe assay is accurate, precise and shown to simultaneously measure the lumefantrine and EFV in human plasma.

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

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

Pharmacokinetic properties of the antimalarial combination therapy artemether–lumefantrine in normal-weight, overweight and obese healthy male adults

The component drugs in the widely used antimalarial artemisinin combination therapy artemether–lumefantrine are lipophilic, with the possibility that recommended fixed doses in adults may lead to subtherapeutic concentrations and consequent treatment failure in overweight/obese individuals with malaria. The aim of this study was to investigate the pharmacokinetic properties of artemether, lumefantrine and their active metabolites dihydroartemisinin and desbutyl-lumefantrine in 16 normal-weight, overweight and obese healthy male volunteers [body mass index (BMI) categories ≤25 kg/m², >25–≤30 kg/m² and >30 kg/m², respectively; absolute range 19.3–37.2 kg/m²]. Participants received the conventional six doses of artemether–lumefantrine over 3 days, each dose comprising 80 mg artemether plus 480 mg lumefantrine administered with 6.7 g fat, and blood samples were collected at pre-specified time-points over 14 days. Plasma drug/metabolite concentrations were measured using liquid chromatography-mass spectrometry and included in multi-compartmental population pharmacokinetic models. There was a non-significant trend to a lower area under the plasma concentration–time curve with a higher body weight or BMI for dihydroartemisinin and especially artemether which was attenuated when normalized for mg/kg dose, but this relationship was not evident in the case of the more lipophilic lumefantrine and its metabolite desbutyl-lumefantrine. Simulated Day 7 plasma lumefantrine concentrations were >200 µg/L (the threshold at which Plasmodium falciparum recrudescences are minimized) in all participants. These results indicate that there is no need for artemether–lumefantrine dose modification in overweight and obese patients with malaria.

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*3genotypeassociated 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 (AUC0-96h) 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.

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

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. 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. 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. 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.

Usefulness of day 7 lumefantrine plasma concentration as a predictor of malaria treatment outcome in under-fives children treated with artemether-lumefantrine in Tanzania

BackgroundDay 7 plasma lumefantrine concentration is suggested as a predictor for malaria treatment outcomes and a cut-off of ≥ 200 ng/ml is associated with day 28 cure rate in the general population. However, day 7 lumefantrine plasma concentration can be affected by age, the extent of fever, baseline parasitaemia, and bodyweight. Therefore, this study assessed the usefulness of day 7 lumefantrine plasma concentration as a predictor of malaria treatment outcome in under-fives children treated with generic or innovator drug-containing artemether-lumefantrine (ALu) in Tanzania.MethodsThis study was nested in an equivalence prospective study that aimed at determining the effectiveness of a generic ALu (Artefan®) in comparison with the innovator’s product (Coartem®). Children with uncomplicated malaria aged 6–59 months were recruited and randomized to receive either generic or innovator’s product. Children were treated with ALu as per World Health Organization recommendations. The clinical and parasitological outcomes were assessed after 28 days of follow up. PCR was performed to distinguish recrudescence and re-infections among children with recurrent malaria. Analysis of day 7 lumefantrine plasma concentration was carried out using a high-performance liquid chromatographic method with UV detection.ResultsThe PCR corrected cure rates were 98.7% for children treated with generic and 98.6% for those treated with the innovator product (p = 1.00). The geometric mean (± SD) of day 7 plasma lumefantrine concentration was 159.3 (± 2.4) ng/ml for the generic and 164 (± 2.5) ng/ml for the innovator groups, p = 0.87. Geometric mean (± SD) day 7 lumefantrine plasma concentration between cured and recurrent malaria was not statistically different in both treatment arms [158.5 (± 2.4) vs 100.0 (± 1.5) ng/ml, (p = 0.28) for generic arm and 158.5 (± 2.3) vs 251.2 (± 4.2) ng/ml, (p = 0.24) for innovator arm]. Nutritional status was found to be a determinant of recurrent malaria (adjusted hazardous ratio (95% confidence interval) = 3(1.1–8.2), p = 0.029.ConclusionUsing the recommended cut-off point of ≥ 200 ng/ml, day 7 plasma lumefantrine concentration failed to predict malaria treatment outcome in children treated with ALu in Tanzania. Further studies are recommended to establish the day 7 plasma lumefantrine concentration cut-off point to predict malaria treatment outcome in children.

Effect of Food/Beverage and Selected Drugs on the Oral Absorption of Artemether-Lumefantrine Tablet: an in situ and in vivo Study

Aim: This study aims at assessing the effect of some meals/beverage and selected drugs on oral absorption of artemether (ATM) and lumefantrine (LMF). Methods: In the in situ model, artemether-lumefantrine (AL) tablets were crushed and administered to anesthetized rabbits (n=2) via oral cannula either alone (CTR1) or with food components/beverage [i.e., starch (STC), albumin (ALB), sunflower oil (SFO) or carbonated drinks (CBS)] or drugs [i.e., lamivudine (LMV) or metronidazole (MTN)]. Blood samples were taken from cannulated carotid artery post dose administration. In the in vivo model, forty two healthy human subjects (28 male and 14 female) in groups of six persons received AL tablet alone (CRT2) or “eba” (cassava starch) with melon soup (EMS) or corn pap with milk and “akara” (fried beans cake) (PMA) or fruits (FTS) or CBS or drugs (i.e., LMV or MTN). ATM and LMF plasma concentrations were obtained simultaneously from plasma using reverse phase high pressure liquid chromatographic analysis. Results: There was significant reduction in ATM Ka due to STC, ALB, CBS, MTN and LMV (Ka ≤ 1.371 h-1) compared with CRT1 (3.567 h-1), p < 0.05). LMV and MTN also reduced the Ka and AUC of ATM and LMF, p < 0.05. Similarly, in vivo study showed significantly lower ATM AUC and Ka values for EMS (0.775 µghmL-1 and 0.041 h-1) and CBS (0.248 µghmL-1 and 4.155 h-1) compared with the CRT2 (6.090 µghmL-1 and 0.362 h-1). Conclusion: EMS or CBS resulted in significant reduction in the bioavailability of ATM and LMF and can influence the treatment outcomes.

Pregnancy and CYP3A5 Genotype Affect Day 7 Plasma Lumefantrine Concentrations.

Pregnancy and pharmacogenetics variation alter drug disposition and treatment outcome. The objective of this study was to investigate the effect of pregnancy and pharmacogenetics variation on day 7 lumefantrine (LF) plasma concentration and therapeutic responses in malaria-infected women treated with artemether-lumefantrine (ALu) in Tanzania. A total of 277 (205 pregnant and 72 nonpregnant) women with uncomplicated Plasmodium falciparum malaria were enrolled. Patients were treated with ALu and followed up for 28 days. CYP3A4, CYP3A5, and ABCB1 genotyping were done. Day 7 plasma LF concentration and the polymerase chain reaction (PCR) - corrected adequate clinical and parasitological response (ACPR) at day 28 were determined. The mean day 7 plasma LF concentrations were significantly lower in pregnant women than nonpregnant women [geometric mean ratio = 1.40; 95% confidence interval (CI) of geometric mean ratio (1.119-1.1745), P < 0.003]. Pregnancy, low body weight, and CYP3A5*1/*1 genotype were significantly associated with low day 7 LF plasma concentration (P < 0.01). PCR-corrected ACPR was 93% (95% CI = 89.4-96.6) in pregnant women and 95.7% (95% CI = 90.7-100) in nonpregnant women. Patients with lower day 7 LF concentration had a high risk of treatment failure (mean 652 vs. 232 ng/ml, P < 0.001). In conclusion, pregnancy, low body weight, and CYP3A5*1 allele are significant predictors of low day 7 LF plasma exposure. In turn, lower day 7 LF concentration is associated with a higher risk of recrudescence. SIGNIFICANCE STATEMENT: This study reports a number of factors contributing to the lower day 7 lumefantrine (LF) concentration in women, which includes pregnancy, body weight, and CYP3A5*1/*1 genotype. It also shows that day 7 LF concentration is a main predictor of malaria treatment. These findings highlight the need to look into artemether-LF dosage adjustment in pregnant women so as to be able to maintain adequate drug concentration, which is required to reduce treatment failure rates in pregnant women.

Severe Acute Malnutrition Results in Lower Lumefantrine Exposure in Children Treated With Artemether-Lumefantrine for Uncomplicated Malaria.

Severe acute malnutrition (SAM) has been reported to be associated with increased malaria morbidity in Sub‐Saharan African children and may affect the pharmacology of antimalarial drugs. This population pharmacokinetic (PK)‐pharmacodynamic study included 131 SAM and 266 non‐SAM children administered artemether‐lumefantrine twice daily for 3 days. Lumefantrine capillary plasma concentrations were adequately described by two transit‐absorption compartments followed by two distribution compartments. Allometrically scaled body weight and an enzymatic maturation effect were included in the PK model. Mid‐upper arm circumference was associated with decreased absorption of lumefantrine (25.4% decreased absorption per 1 cm reduction). Risk of recurrent malaria episodes (i.e., reinfection) were characterized by an interval‐censored time‐to‐event model with a sigmoid maximum‐effect model describing the effect of lumefantrine. SAM children were at risk of underexposure to lumefantrine and an increased risk of malaria reinfection compared with well‐nourished children. Research on optimized regimens should be considered for malaria treatment in malnourished children.

Artemether-lumefantrine dosing for malaria treatment in young children and pregnant women: A pharmacokinetic-pharmacodynamic meta-analysis.

BackgroundThe fixed dose combination of artemether-lumefantrine (AL) is the most widely used treatment for uncomplicated Plasmodium falciparum malaria. Relatively lower cure rates and lumefantrine levels have been reported in young children and in pregnant women during their second and third trimester. The aim of this study was to investigate the pharmacokinetic and pharmacodynamic properties of lumefantrine and the pharmacokinetic properties of its metabolite, desbutyl-lumefantrine, in order to inform optimal dosing regimens in all patient populations.Methods and findingsA search in PubMed, Embase, ClinicalTrials.gov, Google Scholar, conference proceedings, and the WorldWide Antimalarial Resistance Network (WWARN) pharmacology database identified 31 relevant clinical studies published between 1 January 1990 and 31 December 2012, with 4,546 patients in whom lumefantrine concentrations were measured. Under the auspices of WWARN, relevant individual concentration-time data, clinical covariates, and outcome data from 4,122 patients were made available and pooled for the meta-analysis. The developed lumefantrine population pharmacokinetic model was used for dose optimisation through in silico simulations. Venous plasma lumefantrine concentrations 7 days after starting standard AL treatment were 24.2% and 13.4% lower in children weighing <15 kg and 15–25 kg, respectively, and 20.2% lower in pregnant women compared with non-pregnant adults. Lumefantrine exposure decreased with increasing pre-treatment parasitaemia, and the dose limitation on absorption of lumefantrine was substantial. Simulations using the lumefantrine pharmacokinetic model suggest that, in young children and pregnant women beyond the first trimester, lengthening the dose regimen (twice daily for 5 days) and, to a lesser extent, intensifying the frequency of dosing (3 times daily for 3 days) would be more efficacious than using higher individual doses in the current standard treatment regimen (twice daily for 3 days). The model was developed using venous plasma data from patients receiving intact tablets with fat, and evaluations of alternative dosing regimens were consequently only representative for venous plasma after administration of intact tablets with fat. The absence of artemether-dihydroartemisinin data limited the prediction of parasite killing rates and recrudescent infections. Thus, the suggested optimised dosing schedule was based on the pharmacokinetic endpoint of lumefantrine plasma exposure at day 7.ConclusionsOur findings suggest that revised AL dosing regimens for young children and pregnant women would improve drug exposure but would require longer or more complex schedules. These dosing regimens should be evaluated in prospective clinical studies to determine whether they would improve cure rates, demonstrate adequate safety, and thereby prolong the useful therapeutic life of this valuable antimalarial treatment.

Effect of pharmacogenetics on plasma lumefantrine pharmacokinetics and malaria treatment outcome in pregnant women

BackgroundPregnancy has considerable effects on the pharmacokinetic properties of drugs used to treat uncomplicated Plasmodium falciparum malaria. The role of pharmacogenetic variation on anti-malarial drug disposition and efficacy during pregnancy is not well investigated. The study aimed to examine the effect of pharmacogenetics on lumefantrine (LF) pharmacokinetics and treatment outcome in pregnant women.MethodsPregnant women with uncomplicated falciparum malaria were enrolled and treated with artemether-lumefantrine (ALu) at Mkuranga and Kisarawe district hospitals in Coast Region of Tanzania. Day-7 LF plasma concentration and genotyping forCYP2B6 (c.516G>T, c.983T>C), CYP3A4*1B, CYP3A5 (*3, *6, *7) and ABCB1 c.4036A4G were determined. Blood smear for parasite quantification by microscopy, and dried blood spot for parasite screening and genotyping using qPCR and nested PCR were collected at enrolment up to day 28 to differentiate between reinfection from recrudescence. Treatment response was recorded following the WHO protocol.ResultsIn total, 92 pregnant women in their second and third trimester were included in the study and 424 samples were screened for presence of P. falciparum. Parasites were detected during the follow up period in 11 (12%) women between day 7 and 28 after treatment and PCR genotyping confirmed recrudescent infection in 7 (63.3%) women. The remaining four (36.4%) pregnant women had reinfection: one on day 14 and three on day 28. The overall PCR-corrected treatment failure rate was 9.0% (95% CI 4.4–17.4). Day 7 LF concentration was not significantly influenced by CYP2B6, CYP3A4*1B and ABCB1 c.4036A>G genotypes. Significant associations between CYP3A5 genotype and day 7 plasma LF concentrations was found, being higher in carriers of CYP3A5 defective variant alleles than CYP3A5*1/*1 genotype. No significant influence of CYP2B6, CYP3A5 and ABCB1 c.4036A>Genotypes on malaria treatment outcome were observed. However, CYP3A4*1B did affect malaria treatment outcome in pregnant women followed up for 28 days (P = 0.018).ConclusionsGenetic variations in CYP3A4 and CYP3A5may influence LF pharmacokinetics and treatment outcome in pregnant women.

Malaria prevalence, severity and treatment outcome in relation to day 7 lumefantrine plasma concentration in pregnant women.

BackgroundDay 7 plasma concentrations of lumefantrine (LF) can serve as a marker to predict malaria treatment outcome in different study populations. Two main cut-off points (175 and 280 ng/ml) are used to indicate plasma concentrations of LF, below which treatment failure is anticipated. However, there is limited data on the cumulative risk of recurrent parasitaemia (RP) in relation to day 7 LF plasma concentrations in pregnant women. This study describes the prevalence, severity, factors influencing treatment outcome of malaria in pregnancy and day 7 LF plasma concentration therapeutic cut-off points that predicts treatment outcome in pregnant women.MethodsThis was a one-arm prospective cohort study whereby 89 pregnant women with uncomplicated Plasmodium falciparum malaria receiving artemether-lumefantrine (ALu) participated in pharmacokinetics and pharmacodynamics study. Blood samples were collected on days 0, 2, 7, 14, 21 and 28 for malaria parasite quantification. LF plasma concentrations were determined on day 7. The primary outcome measure was an adequate clinical and parasitological response (ACPR) after treatment with ALu.ResultsThe prevalence of malaria in pregnant women was 8.1 % (95 % CI 6.85–9.35) of whom 3.4 % (95 % CI 1.49–8.51) had severe malaria. The overall PCR-uncorrected treatment failure rate was 11.7 % (95 % CI 0.54–13.46 %). Low baseline hemoglobin (<10 g/dl) and day 7 LF concentration <600 ng/ml were significant predictors of RP. The median day 7 LF concentration was significantly lower in pregnant women with RP (270 ng/ml) than those with ACPR (705 ng/ml) (p = 0.016). The relative risk of RP was 4.8 folds higher (p = 0.034) when cut-off of <280 ng/ml was compared to ≥280 ng/ml and 7.8-folds higher (p = 0.022) when cut-off of <600 ng/ml was compared to ≥600 ng/ml. The cut-off value of 175 ng/ml was not associated with the risk of RP (p = 0.399).ConclusionsPregnant women with day 7 LF concentration <600 ng/ml are at high risk of RP than those with ≥600 ng/ml. To achieve effective therapeutic outcome, higher day 7 venous plasma LF concentration ≥600 ng/ml is required for pregnant patients than the previously suggested cut-off value of 175 or 280 ng/ml for non-pregnant adult patients.

Artemether-lumefantrine treatment of uncomplicated Plasmodium falciparum malaria: a systematic review and meta-analysis of day 7 lumefantrine concentrations and therapeutic response using individual patient data.

BackgroundAchieving adequate antimalarial drug exposure is essential for curing malaria. Day 7 blood or plasma lumefantrine concentrations provide a simple measure of drug exposure that correlates well with artemether-lumefantrine efficacy. However, the ‘therapeutic’ day 7 lumefantrine concentration threshold needs to be defined better, particularly for important patient and parasite sub-populations.MethodsThe WorldWide Antimalarial Resistance Network (WWARN) conducted a large pooled analysis of individual pharmacokinetic-pharmacodynamic data from patients treated with artemether-lumefantrine for uncomplicated Plasmodium falciparum malaria, to define therapeutic day 7 lumefantrine concentrations and identify patient factors that substantially alter these concentrations. A systematic review of PubMed, Embase, Google Scholar, ClinicalTrials.gov and conference proceedings identified all relevant studies. Risk of bias in individual studies was evaluated based on study design, methodology and missing data.ResultsOf 31 studies identified through a systematic review, 26 studies were shared with WWARN and 21 studies with 2,787 patients were included. Recrudescence was associated with low day 7 lumefantrine concentrations (HR 1.59 (95 % CI 1.36 to 1.85) per halving of day 7 concentrations) and high baseline parasitemia (HR 1.87 (95 % CI 1.22 to 2.87) per 10-fold increase). Adjusted for mg/kg dose, day 7 concentrations were lowest in very young children (<3 years), among whom underweight-for-age children had 23 % (95 % CI −1 to 41 %) lower concentrations than adequately nourished children of the same age and 53 % (95 % CI 37 to 65 %) lower concentrations than adults. Day 7 lumefantrine concentrations were 44 % (95 % CI 38 to 49 %) lower following unsupervised treatment. The highest risk of recrudescence was observed in areas of emerging artemisinin resistance and very low transmission intensity. For all other populations studied, day 7 concentrations ≥200 ng/ml were associated with >98 % cure rates (if parasitemia <135,000/μL).ConclusionsCurrent artemether-lumefantrine dosing recommendations achieve day 7 lumefantrine concentrations ≥200 ng/ml and high cure rates in most uncomplicated malaria patients. Three groups are at increased risk of treatment failure: very young children (particularly those underweight-for-age); patients with high parasitemias; and patients in very low transmission intensity areas with emerging parasite resistance. In these groups, adherence and treatment response should be monitored closely. Higher, more frequent, or prolonged dosage regimens should now be evaluated in very young children, particularly if malnourished, and in patients with hyperparasitemia.Electronic supplementary materialThe online version of this article (doi:10.1186/s12916-015-0456-7) contains supplementary material, which is available to authorized users.

CYP2B6*6 genotype and high efavirenz plasma concentration but not nevirapine are associated with low lumefantrine plasma exposure and poor treatment response in HIV-malaria-coinfected patients.

We investigated the influence of efavirenz (EFV)- or nevirapine (NVP)-based antiretroviral therapy (ART) on lumefantrine plasma exposure in HIV-malaria-coinfected patients and implication of pharmacogenetic variations. A total of 269 HIV patients with uncomplicated falciparum malaria on NVP-based ART (NVP-arm), EFV-based ART (EFV-arm) or not receiving ART (control-arm) were enrolled and treated with artemether-lumefantrine. Day-7 lumefantrine, baseline EFV and NVP plasma concentrations, and CYP2B6*6,*18, CYP3A4*1B, CYP3A5*3,*6,*7, ABCB1 c.3435C>T and ABCB1 c.4036A>G genotypes were determined. The median day-7 lumefantrine plasma concentration was significantly lower in the EFV-arm compared with that in NVP- and control-arm. High EFV plasma concentrations and CYP2B6*6/*6 genotype significantly correlated with low lumefantrine plasma concentrations and high rate of recurrent parasitemia. No significant effect of NVP-based ART on lumefantrine exposure was observed. In conclusion, owing to long-term CYP3A induction, EFV-based ART cotreatment significantly reduces lumefantrine plasma exposure leading to poor malaria treatment response, which is more pronounced in CYP2B6 slow metabolizers.

Development and validation of a LC-MS/MS method for the quantitation of lumefantrine in mouse whole blood and plasma.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of the antimalarial drug, lumefantrine (LF), in mouse whole blood and plasma. The analyte was extracted using a protein precipitation method followed by chromatographic separation on a Phenomenex Luna, PFP (50mm×2.0mm, 5μm) analytical column with a mobile phase consisting of acetonitrile and 0.1% formic acid (formic acid:water, 1:1000, v/v) at a ratio of 3:7 (v/v), delivered at a constant flow rate of 0.5ml/min. Stable isotope labeled lumefantrine (D9-LF) was used as the internal standard. Multiple reaction monitoring was performed using the transitions m/z 530.1→m/z 347.9 and m/z 539.1→m/z 347.9 for the quantification of LF and D9-LF, respectively. Calibration curves were constructed over the concentration range 15.6-4000ng/ml. The mean intra- and inter-assay accuracy values for the analysis of LF in WB was 103% (%CV=5.5) and 99.5% (%CV=5.5), respectively. The mean intra- and inter-assay accuracy values for the analysis of LF in plasma was 93.7% (%CV=3.5) and 93.9% (%CV=5.5), respectively. No significant matrix effect was observed during the method validation. The validated method was applied to an absorption study in mice, to determine and compare LF concentrations in whole blood and plasma samples. Results of the statistical analysis using a linear mixed effects growth curve model concluded that there was no significant difference (p-value=0.668) between WB and plasma LF concentrations. This method utilizes a small sample volume of 20μl, facilitating low blood collection volumes and a short chromatographic run time of 3min which allows for high sample throughput analysis.

Outcome of artemether-lumefantrine treatment for uncomplicated malaria in HIV-infected adult patients on anti-retroviral therapy.

BackgroundMalaria and HIV infections are both highly prevalent in sub-Saharan Africa, with HIV-infected patients being at higher risks of acquiring malaria. The majority of antiretroviral (ART) and anti-malarial drugs are metabolized by the CYP450 system, creating a chance of drug-drug interaction upon co-administration. Limited data are available on the effectiveness of the artemether-lumefantrine combination (AL) when co-administered with non-nucleoside reverse transcriptase inhibitors (NNRTIs). The aim of this study was to compare anti-malarial treatment responses between HIV-1 infected patients on either nevirapine- or efavirenz-based treatment and those not yet on ART (control-arm) with uncomplicated falciparum malaria, treated with AL.MethodThis was a prospective, non-randomized, open-label study conducted in Bagamoyo district, with three arms of HIV-infected adults: efavirenz-based treatment arm (EFV-arm) n = 66, nevirapine-based treatment arm (NVP-arm) n = 128, and control-arm n = 75, with uncomplicated malaria. All patients were treated with AL and followed up for 28 days. The primary outcome measure was an adequate clinical and parasitological response (ACPR) after treatment with AL by day 28.ResultsDay 28 ACPR was 97.6%, 82.5% and 94.5% for the NVP-arm, EFV-arm and control-arm, respectively. No early treatment or late parasitological failure was reported. The cumulative risk of recurrent parasitaemia was >19-fold higher in the EFV-arm than in the control-arm (Hazard ratio [HR], 19.11 [95% confidence interval {CI}, 10.5–34.5]; P < 0.01). The cumulative risk of recurrent parasitaemia in the NVP-arm was not significantly higher than in the control-arm ([HR], 2.44 [95% {CI}, 0.79–7.6]; P = 0.53). The median (IQR) day 7 plasma concentrations of lumefantrine for the three arms were: 1,125 ng/m (638.8-1913), 300.4 ng/ml (220.8-343.1) and 970 ng/ml (562.1-1729) for the NVP-arm, the EFV-arm and the control-arm, respectively (P < 0.001). In all three arms, the reported adverse events were mostly mild.ConclusionAfter 28 days of follow-up, AL was statistically safe and effective in the treatment of uncomplicated malaria in the NVP-arm. The results of this study also provide an indication of the possible impact of EFV on the performance of AL and the likelihood of it affecting uncomplicated falciparum malaria treatment outcome.

Lopinavir/ritonavir significantly influences pharmacokinetic exposure of artemether/lumefantrine in HIV-infected Ugandan adults

BackgroundTreatment of HIV/malaria-coinfected patients with antiretroviral therapy (ART) and artemisinin-based combination therapy has potential for drug interactions. We investigated the pharmacokinetics of artemether, dihydroartemisinin and lumefantrine after administration of a single dose of 80/480 mg of artemether/lumefantrine to HIV-infected adults, taken with and without lopinavir/ritonavir.MethodsA two-arm parallel study of 13 HIV-infected ART-naive adults and 16 HIV-infected adults stable on 400/100 mg of lopinavir/ritonavir plus two nucleoside reverse transcriptase inhibitors (ClinicalTrials.gov, NCT 00619944). Each participant received a single dose of 80/480 mg of artemether/lumefantrine under continuous cardiac function monitoring. Plasma concentrations of artemether, dihydroartemisinin and lumefantrine were measured.ResultsCo-administration of artemether/lumefantrine with lopinavir/ritonavir significantly reduced artemether maximum concentration (Cmax) and area under the concentration–time curve (AUC) [median (range): 112 (20–362) versus 56 (17–236) ng/mL, P = 0.03; and 264 (92–1129) versus 151 (38–606) ng · h/mL, P < 0.01]. Dihydroartemisinin Cmax and AUC were not affected [66 (10–111) versus 73 (31–224) ng/mL, P = 0.55; and 213 (68–343) versus 175 (118–262) ng · h/mL P = 0.27]. Lumefantrine Cmax and AUC increased during co-administration [2532 (1071–5957) versus 7097 (2396–9462) ng/mL, P < 0.01; and 41 119 (12 850–125 200) versus 199 678 (71 205–251 015) ng · h/mL, P < 0.01].ConclusionsCo-administration of artemether/lumefantrine with lopinavir/ritonavir significantly increases lumefantrine exposure, but decreases artemether exposure. Population pharmacokinetic and pharmacodynamic trials will be highly valuable in evaluating the clinical significance of this interaction and determining whether dosage modifications are indicated.

Early clinical development of artemether-lumefantrine dispersible tablet: palatability of three flavours and bioavailability in healthy subjects

BackgroundEfforts to ease administration and enhance acceptability of the oral anti-malarial artemether-lumefantrine (A-L) crushed tablet to infants and children triggered the development of a novel dispersible tablet of A-L. During early development of this new formulation, two studies were performed in healthy subjects, one to evaluate the palatability of three flavours of A-L, and a second one to compare the bioavailability of active principles between the dispersible tablet and the tablet (administered crushed and intact).MethodsStudy 1 was performed in 48 healthy schoolchildren in Tanzania. Within 1 day, all subjects tasted a strawberry-, orange- and cherry-flavoured oral A-L suspension for 10 seconds (without swallowing) in a randomized, single-blind, crossover fashion. The palatability of each formulation was rated using a visual analogue scale (VAS). Study 2 was an open, randomized crossover trial in 48 healthy adults given single doses of A-L (80 mg artemether + 480 mg lumefantrine) with food. The objectives were to compare the bioavailability of artemether, dihydroartemisinin (DHA) and lumefantrine between the dispersible tablet and the tablet administered crushed (primary objective) and intact (secondary objective).ResultsStudy 1 showed no statistically significant difference in VAS scores between the three flavours but cherry had the highest score in several ratings (particularly for overall liking). Study 2 demonstrated that the dispersible and crushed tablets delivered bioequivalent artemether, DHA and lumefantrine systemic exposure (area under the curve [AUC]); mean ± SD AUC0-tlast were 208 ± 113 vs 195 ± 93 h.ng/ml for artemether, 206 ± 81 vs 199 ± 84 h.ng/ml for DHA and 262 ± 107 vs 291 ± 106 h.μg/ml for lumefantrine. Bioequivalence was also shown for peak plasma concentrations (Cmax) of DHA and lumefantrine. Compared with the intact tablet, the dispersible tablet resulted in bioequivalent lumefantrine exposure, but AUC and Cmax values of artemether and DHA were 20-35% lower.ConclusionsConsidering that cherry was the preferred flavour, and that the novel A-L dispersible tablet demonstrated similar pharmacokinetic performances to the tablet administered crushed, a cherry-flavoured A-L dispersible tablet formulation was selected for further development and testing in a large efficacy and safety study in African children with malaria.

Liquid chromatography–tandem mass spectrometry for the simultaneous quantitation of artemether and lumefantrine in human plasma: Application for a pharmacokinetic study

A liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC–ESI-MS/MS) method for the simultaneous quantitation of artemether and lumefantrine in human plasma was developed and validated. Artesunate was used as an internal standard (IS). The analytes were extracted by a protein precipitation procedure and separated on a reversed-phase Zorbax SB-Ciano column with a mobile phase composed of methanol and 10 mM aqueous ammonium acetate containing 0.2% (v/v) acetic acid and 0.1% (v/v) formic acid. Multiple reaction monitoring was performed using the transitions m/ z 316 → m/ z 267, m/ z 530 → m/ z 348 and m/ z 402 → m/ z 267 to quantify artemether, lumefantrine and artesunate, respectively. Calibration curves were constructed over the range of 10–1000 ng/mL for artemether and 10–18,000 ng/mL for lumefantrine. The lower limit of quantitation was 10 ng/mL for both drugs. The mean R.S.D. values for the intra-run precision were 2.6% and 3.0% and for the inter-run precision were 3.6% and 4.6% for artemether and lumefantrine, respectively. The mean accuracy values were 102.0% and 101.2% for artemether and lumefantrine, respectively. No matrix effect was detected in the samples. The validated method was successfully applied to determine the plasma concentrations of artemether and lumefantrine in healthy volunteers, in a one-dose pharmacokinetic study, over the course of 11 days.

The effect of food consumption on lumefantrine bioavailability in African children receiving artemether-lumefantrine crushed or dispersible tablets (Coartem®) for acute uncomplicatedPlasmodium falciparummalaria

Artemether-lumefantrine (AL) is first-line treatment for uncomplicated malaria in many African countries. Concomitant food consumption may affect absorption of lumefantrine but data in the most important target population, i.e. children, are lacking. Therefore, we evaluated the effect of food intake on oral lumefantrine bioavailability in African children with malaria. In a randomised, investigator-blinded, multicentre phase III efficacy trial, 899 infants and children with acute uncomplicated Plasmodium falciparum malaria received six doses of AL according to body weight over 3 days either as crushed tablets (Coartem) or as dispersible tablets. Single blood samples were obtained for lumefantrine plasma concentration determination in a subset of 621 patients, and a two-compartment pharmacokinetic model was constructed. The mean observed lumefantrine plasma concentration for crushed tablet and dispersible tablet, respectively, was 100% and 55% higher with a concomitant meal at the time of dose intake than when taken alone. Similarly, consumption of milk (the most common meal) increased model-estimated lumefantrine bioavailability by 57% (90% CI: 29-96%) with crushed tablets and 65% (90% CI: 28-109%) with dispersible tablets compared to no food. The 28-day PCR-corrected cure rate (primary study endpoint) in the evaluable population was 582/587 [99.1% (95% CI: 98.0-99.7%)] and was not related to food intake. AL was highly efficacious. Concomitant food intake increased lumefantrine absorption in children with malaria.