CHLOROQUINE RESISTANCE IS NOT ASSOCIATED WITH DRUG-METABOLISM IN PLASMODIUM-FALCIPARUM

Chloroquine-sensitive and -resistant clones of Plasmodium falciparum w ere incubated in vitro with [H-3]chloroquine for 16 hr, and the result ing culture supernatants and cell pellets were analyzed by highperform ance liquid chromatography for evidence of chloroquine metabolism. Aft er separation by normal- or reverse-phase chromatography, there was no evidence of drug metabolism by the chloroquine-resistant P. falciparu m. However, a single, unidentified, radiolabeled metabolite, which did not coelute with desethylchloroquine, was produced by 1 of the chloro quine-sensitive clones. Thus, chloroquine resistance does not appear t o be due to drug metabolism by the resistant parasites.