Pharmacokinetics of mefloquine in combination with sulfadoxine-pyrimethamine and primaquine in male Thai patients with falciparum malaria.

The pharmacokinetics of mefloquine (M) were studied in 59 male Thai patients with falciparum malaria. Mefloquine was administered alone (750 mg orally; group 1), or with primaquine (PQ, 45 mg; group 2), or in combination with sulfadoxine (1.5 g) + pyrimethamine (75 mg) (MSP; group 3), or as MSP + PQ (group 4). All patients in groups 1, 2 and 4 initially responded to treatment, but two patients from group 1 had RI recrudescent infections. One patient in group 3 failed to respond to treatment and was considered to have RII resistance, while a further patient from this group had RI recrudescence. The pharmacokinetic parameters for group 1 and group 3 were not significantly different. Co-administration of primaquine alone had no significant effect on the pharmacokinetics of mefloquine, but there was a statistically significant decrease in the terminal elimination half-life of mefloquine for group 4 relative to that for group 3.