Mefloquine levels in patients with mefloquine resistant Plasmodium falciparum in the eastern part of Thailand.

ABSTRACT

A total of 99 patients with uncomplicated falciparum malaria who attended the malaria clinic in Bo Rai, Trat Province were treated with a single oral dose of MSP 3 tablets (Fansimef; equivalent to 750 mg of mefloquine) concurrently with primaquine (30 mg). The aim of the study was to detect RII and RIII types of response with 3 tablets of MSP. Seven (8.1%) and 22 patients (25.3%) had RII and RIII types of response, respectively, and 58 (66.8%) had no parasitemia on Day-7 (S or RI response). Mefloquine concentrations on Day-3 after treatment in patients in the S/RI group were significantly higher than those with early treatment failure (RII, RIII), with the respective mean (SD) values of 1,959 (696) and 1,622 (863) ng/ml. The mean concentrations of mefloquine in these patients with RII and RIII types of response were higher than those with a sensitive response in a previous study. The result suggests that Plasmodium falciparum strains in this part of the country are highly resistant to mefloquine and that blood levels of mefloquine on Day-3 may also be a good indicator of treatment outcome in this particular area.