The lumefantrine plasma concentration profile is the main determinant of efficacy of artemether-lumefantrine. Amplification in pfmdr1 determines lumefantrine susceptibility and, therefore, treatment responses when plasma lumefantrine levels are subtherapeutic.
BackgroundArtemisinin combination treatments (ACT) are recommended as first line treatment for falciparum malaria throughout the malaria affected world. We reviewed the efficacy of a 3-day regimen of mefloquine and artesunate regimen (MAS3), over a 13 year period of continuous deployment as first-line treatment in camps for displaced persons and in clinics for migrant population along the Thai-Myanmar border.Methods and Findings3,264 patients were enrolled in prospective treatment trials between 1995 and 2007 and treated with MAS3. The proportion of patients with parasitaemia persisting on day-2 increased significantly from 4.5% before 2001 to 21.9% since 2002 (p<0.001). Delayed parasite clearance was associated with increased risk of developing gametocytaemia (AOR = 2.29; 95% CI, 2.00–2.69, p = 0.002). Gametocytaemia on admission and carriage also increased over the years (p = 0.001, test for trend, for both). MAS3 efficacy has declined slightly but significantly (Hazards ratio 1.13; 95% CI, 1.07–1.19, p<0.001), although efficacy in 2007 remained well within acceptable limits: 96.5% (95% CI, 91.0–98.7). The in vitro susceptibility of P. falciparum to artesunate increased significantly until 2002, but thereafter declined to levels close to those of 13 years ago (geometric mean in 2007: 4.2 nM/l; 95% CI, 3.2–5.5). The proportion of infections caused by parasites with increased pfmdr1 copy number rose from 30% (12/40) in 1996 to 53% (24/45) in 2006 (p = 0.012, test for trend).ConclusionArtesunate-mefloquine remains a highly efficacious antimalarial treatment in this area despite 13 years of widespread intense deployment, but there is evidence of a modest increase in resistance. Of particular concern is the slowing of parasitological response to artesunate and the associated increase in gametocyte carriage.
Background. Dihydroartemisinin-piperaquine (DP) is a fixed-combination antimalarial drug increasingly deployed in Southeast Asia. The current regimen involves 4 doses given over 3 days. Simplification of the dose regimen should facilitate treatment adherence and thereby increase effectiveness.Methods. In a randomized, controlled, 3-arm trial conducted along the northwestern border of Thailand, the standard 4-dose course of DP (DP4) was compared to an equivalent dose given as a once-daily regimen (DP3) and to the standard treatment of mefloquine-artesunate (MAS3).Results. A total of 499 patients were included in the study. Times to fever and parasite clearance were similar in all groups. The PCR genotyping-adjusted cure rates at day 63 after treatment initiation were 95.7% (95% confidence interval [95% CI], 92.2%-98.9%) for MAS3, 100% for DP4, and 99.4% (95% CI, 98.1%-100%) for DP3. The DP4 and DP3 cure rates were significantly higher than that for MAS3 ( and , respectively). P p .008 P p .03 All regimens were well tolerated. There were 3 deaths (1 in the MAS3 group and 2 in the DP3 group), all of which were considered to be unrelated to treatment. Rates of other adverse events were comparable between the groups, except for diarrhea, which was more common in the DP4 group ( vs. the MAS3 group). P p .05 Conclusions. A once-daily, 3-dose regimen of DP is a highly efficacious treatment for multidrug-resistant falciparum malaria. This simple, safe, and relatively inexpensive fixed combination could become the treatment of choice for falciparum malaria.
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