Summarybackground Artemether-lumefantrine (AL) is the only fixed, artemisinin-based combination antimalarial drug which is registered internationally and deployed on a large scale. Absorption of the hydrophobic lipophilic lumefantrine component varies widely between individuals and is greatly increased by fat coadministration; but patients with acute malaria are frequently nauseated and anorexic, making dietary advice difficult to comply with. The aim of this study was to describe the doseresponse relationship between coadministration of fat and relative lumefantrine bioavailability, in order to determine the minimum amount of fat necessary to optimize absorption.method We conducted a multiple crossover pharmacokinetic study in 12 healthy volunteers. This compared the area under the plasma concentration-time curve (AUC) for lumefantrine after administration of a single dose of AL in the fasting state given with 0, 10, 40, 150 and 500 ml of soya milk corresponding to 0, 0.32, 1.28, 4.8 and 16 g of fat. All volumes of milk supplements were tested in all subjects with a 3-to 4-week washout period in-between.results A dose-response relationship was demonstrated between the volume of soya milk administered and lumefantrine bioavailability. AL administration with soya milk increased the lumefantrine AUC more than five fold. The population mean estimated volume of soya milk required to obtain 90% of maximum effect (in terms of lumefantrine AUC) was 36 ml (corresponding to 1.2 g of fat).conclusions Coadministration of artemether-lumefantrine with a relatively small amount of fat (as soya milk) was required to ensure maximum absorption of lumefantrine in healthy adult volunteers.

Summaryobjective To determine the efficacy of artemether-lumefantrine malaria treatment, as an alternative to artesunate + mefloquine, which is becoming ineffective in some areas of the Thai-Cambodian border. With the per-protocol analysis, the cure rate was 71.1% in study AL2002, 86.5% in study AL2003 and 92.4% in study AM2003. All the data were PCR corrected. The artemether-lumefantrine cure rate was unexpectedly low in 2002, but it increased with food supplementation in 2003. There was a significant difference (P ¼ 0.02) in lumefantrine plasma concentrations between adequate clinical and parasitological responses and treatment failure cases. In vitro susceptibility to lumefantrine was reduced for isolates sampled from patients presenting with treatment failure, but the difference was not statistically different from isolates sampled from patients who were successfully treated.conclusion Treatment failure cases of artemether-lumefantrine are most probably because of low levels of lumefantrine blood concentration. Further investigations are necessary to determine whether resistance of Plasmodium falciparum isolates to lumefantrine is present in the region.

Artemether-lumefantrine has become one of the most widely used antimalarial drugs in the world. The objective of this study was to determine the population pharmacokinetic properties of lumefantrine in pregnant women with uncomplicated multidrug-resistant Plasmodium falciparum malaria on the northwestern border of Thailand. Burmese and Karen women (n ‫؍‬ 103) with P. falciparum malaria and in the second and third trimesters of pregnancy were treated with artemether-lumefantrine (80/480 mg) twice daily for 3 days. All patients provided five capillary plasma samples for drug quantification, and the collection times were randomly distributed over 14 days. The concentration-time profiles of lumefantrine were assessed by nonlinear mixed-effects modeling. The treatment failure rate (PCR-confirmed recrudescent infections at delivery) was high; 16.5% (95% confidence interval, 9.9 to 25.1). The population pharmacokinetics of lumefantrine were described well by a two-compartment open model with first-order absorption and elimination. The final model included interindividual variability in all pharmacokinetic parameters and a linear covariate relationship between the estimated gestational age and the central volume of distribution. A high proportion of all women (40%, 41/103) had day 7 capillary plasma concentrations of <355 ng/ml (which corresponds to approximately <280 ng/ml in venous plasma), a threshold previously associated with an increased risk of therapeutic failure in nonpregnant patients in this area. Predictive modeling suggests that a twice-daily regimen given for 5 days would be preferable in later pregnancy. In conclusion, altered pharmacokinetic properties of lumefantrine contribute to the high rates of failure of artemether-lumefantrine treatment in later pregnancy. Dose optimization is urgently needed.Pregnancy has considerable effects on the pharmacokinetic properties of many of the drugs used to treat uncomplicated Plasmodium falciparum malaria. Whereas blood chloroquine and quinine concentrations are relatively unaffected (1, 25), artesunate, artemether, dihydroartemisinin, sulfadoxine, atovaquone, proguanil, and cycloguanil concentrations are all reduced in later pregnancy (14,(30)(31)(32)(33). The reductions are often substantial, and as a result, antimalarial cure rates in pregnancy for any given antimalarial drug tend to be lower (24, 34). Unfortunately, pregnant women are especially vulnerable to malaria and the fetus is adversely affected.The fixed combination of artemether and lumefantrine is the result of research undertaken by Chinese scientists and has become the most widely used coformulated artemisinin-based combination therapy (ACT). Artemether-lumefantrine has proved effective (cure rates, Ͼ97%) and safe in adults and children in trials conducted throughout the areas of the world affected by malaria (2,13,15,20,23,35,43,44,59). There is a reluctance to prescribe new drugs to pregnant women, and there have been concerns over the safety of artemisinin derivatives in early pregnancy. The curr...

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Artemether-lumefantrine efficacy is reduced by once-daily dosing, because absorption of lumefantrine is dose limited. At currently recommended doses, this antimalarial should be given twice daily in a 3-day regimen, with food containing fat.

Oral artesunate plus mefloquine and artemether-lumefantrine are highly effective for the treatment of uncomplicated falciparum malaria in Laos.

The combination of artemether (ARM) and lumefantrine is currently the first-line treatment of uncomplicated falciparum malaria in mainland Tanzania. While the exposure to lumefantrine has been associated with the probability of adequate clinical and parasitological cure, increasing exposure to artemether and the active metabolite dihydroartemisinin (DHA) has been shown to decrease the parasite clearance time. The aim of this analysis was to describe the pharmacokinetics and pharmacodynamics of artemether, dihydroartemisinin, and lumefantrine in African children with uncomplicated malaria. In addition to drug concentrations and parasitemias from 50 Tanzanian children with falciparum malaria, peripheral parasite densities from 11 asymptomatic children were included in the model of the parasite dynamics. The population pharmacokinetics and pharmacodynamics of artemether, dihydroartemisinin, and lumefantrine were modeled in NONMEM. The distribution of artemether was described by a two-compartment model with a rapid absorption and elimination through metabolism to dihydroartemisinin. Dihydroartemisinin concentrations were adequately illustrated by a one-compartment model. The pharmacokinetics of artemether was time dependent, with typical oral clearance increasing from 2.6 liters/h/kg on day 1 to 10 liters/h/kg on day 3. The pharmacokinetics of lumefantrine was sufficiently described by a one-compartment model with an absorption lag time. The typical value of oral clearance was estimated to 77 ml/h/kg. The proposed semimechanistic model of parasite dynamics, while a rough approximation of the complex interplay between malaria parasite and the human host, adequately described the early effect of ARM and DHA concentrations on the parasite density in malaria patients. However, the poor precision in some parameters illustrates the need for further data to support and refine this model.Artemisinin-based combination therapy is generally accepted as treatment of choice for acute uncomplicated Plasmodium falciparum malaria (31). A fixed-dose combination containing artemether (ARM) and lumefantrine (LUM) is currently the first-line treatment of uncomplicated falciparum malaria in mainland Tanzania. The rationale behind combining ARM with LUM is to make use of the disparate pharmacokinetic profiles of the two drugs and thereby improve treatment efficacy and delay development of drug resistance. While ARM and its primary active metabolite dihydroartemisinin (DHA) are rapidly eliminated, LUM is slowly cleared from the body.

The World Health Organization recommends the use of artemisinin-based combination therapies (ACTs) for the treatment of uncomplicated malaria. The two most widely adopted ACT regimens are artemether (AR)-lumefantrine (LR) (the combination is abbreviated AL) and amodiaquine (AQ)-artesunate (AS). Pharmacokinetic (PK) data informing the optimum dosing of these drug regimens is limited, especially in children. We evaluated PK parameters in Ugandan children aged 5 to 13 years with uncomplicated malaria treated with AL (n ‫؍‬ 20) or AQ-AS (n ‫؍‬ 21), with intensive venous sampling occurring at 0, 2, 4, 8, 24, and 120 h following administration of the last dose of 3-day regimens of AL (twice daily) or AQ-AS (once daily). AS achieved an estimated maximum concentration in plasma (C max ) of 51 ng/ml and an area under the concentration-time curve from time zero to infinity (AUC 0-ؕ ) of 113 ng ⅐ h/ml; and its active metabolite, dihydroartemisinin (DHA), achieved a geometric mean C max of 473 ng/ml and an AUC 0-ؕ of 1,404 ng ⅐ h/ml. AR-DHA exhibited a C max of 34/119 ng/ml and an AUC 0-ؕ of 168/382 ng ⅐ h/ml, respectively. For LR, C max and AUC 0-ؕ were 6,757 ng/ml and 210 g ⅐ h/ml, respectively. For AQ and its active metabolite, desethylamodiaquine (DEAQ), the C max s were 5.2 ng/ml and 235 ng/ml, respectively, and the AUC 0-ؕ s were 39.3 ng ⅐ h/ml and 148 g ⅐ h/ml, respectively. Comparison of the findings of the present study to previously published data for adults suggests that the level of exposure to LR is lower in children than in adults and that the level of AQ-DEAQ exposure is similar in children and adults. For the artemisinin derivatives, differences between children and adults were variable and drug specific. The PK results generated for children must be considered to optimize the dosing strategies for these widely utilized ACT regimens.