In vitro and clinical correlates of mefloquine resistance of Plasmodium falciparum in eastern Thailand.

A series of isolates of Plasmodium falciparum from eastern Thailand was collected prior to and after treatment failure with mefloquine. Patterns of drug sensitivity to standard and new antimalarials were characterized by using an in vitro assay based on the inhibition of schizont maturation. In vitro levels of mefloquine sensitivity of isolates were correlated with clinical treatment failures.

A comparison of the in vitro activities of amodiaquine and desethylamodiaquine against isolates of Plasmodium falciparum.

The antimalarial activities of amodiaquine, the desethyl metabolite of amodiaquine, chloroquine, and mefloquine were evaluated against 35 field isolates of Plasmodium falciparum collected from eastern Thailand, October-December 1985, to define patterns of cross-resistance among these compounds. The assay system was based on the in vitro inhibition of schizont maturation. The parasites were generally sensitive to mefloquine (mean 50%-inhibitory concentrations = 9.