Previous studies have shown that the proton pump inhibitor omeprazole has a
ntimalarial activity in vitro. The interactions of omeprazole with commonly
used antimalarial drugs were assessed in vitro. Omeprazole and quinine com
binations were synergistic; however, chloroquine and omeprazole combination
s were antagonistic. Artemisinin drugs had additive antimalarial activities
with omeprazole.