Abstract
Fansimef is a new antimalarial schizontocide that contains mefloquine, pyrimethamine, and sulfadoxine with a weight ratio of 1:20:10. This antimalarial combination is highly active against multidrug-resistant strains of Plasmodium falciparum. H-2-receptor antagonists (cimetidine, famotidine, and ranitidine) are reversible competitive blockers of histamine at H-2-receptor and do not affect the H-1-receptor. These are potent inhibitors of all phases of gastric acid secretion. They do so by binding to H-2-receptors on the parietal cells of stomach. The effect of various dissolution mediums with respect to pH on these drug-drug interactions and in vitro availability reveals that availability of antimalarial drugs increased to a smaller extent in the presence of H-2-receptors. The influence of temperatures on these interactions has been examined to elucidate the mechanism of these interactions. Antimalarial drugs could be administrated concurrently with H-2-receptor antagonist (cimetidine and famotidine); however, ranitidine should not be given because availability was almost suppressed in the presence of antimalarial drugs.