title: Potentiation of antimalarial drug action by chlorpheniramine against multidrug-resistant Plasmodium falciparum in vitro.
abstract: Chlorpheniramine, a histamine H1 receptor antagonist, was assayed for in vitro antimalarial activity against multidrug-resistant Plasmodium falciparum K1 strain and chloroquine-resistant P. falciparum T9/94 clone, by measuring the 3H-hypoxanthine incorporation. Chlorphenirame inhibited P. falciparum K1 and T9/94 growth with IC50 values of 136.0+/-40.2 microM and 102.0+/-22.6 microM respectively. A combination of antimalarial drug and chlorpheniramine was tested against resistant P. falciparum in vitro. Isobologram analysis showed that chlorpheniramine exerts marked synergistic action on chloroquine against P. falciparum K1 and T9/94. Chlorpheniramine also potentiated antimalarial action of mefloquine, quinine or pyronaridine against both of the resistant strains of P. falciparum. However, chlorpheniramine antagonism with artesunate was obtained in both P. falciparum K1 and T9/94. The results in this study indicate that antihistaminic drugs may be promising candidates for potentiating antimalarial drug action against drug resistant malarial parasites.
authors.affiliation: Department of Biochemistry, Faculty of Science, Mahidol University, Rama VI road, Bangkok 10400, Thailand. scsnk@mahidol.ac.th
authors.forename: Sunan
authors.initials: S
authors.lastname: Nakornchai
authors.forename: Phattanapong
authors.initials: P
authors.lastname: Konthiang
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D037621:Artemisinins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000077332:Artesunate; D002744:Chlorpheniramine / Q000494:pharmacology*; D018432:Drug Resistance, Multiple; D004357:Drug Synergism; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D006801:Humans; D020128:Inhibitory Concentration 50; D016778:Malaria, Falciparum / Q000469:parasitology; D021261:Parasitic Sensitivity Tests; D010963:Plasmodium falciparum / Q000187:drug effects*; D012717:Sesquiterpenes / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013785:Thailand
chemical_list: D000962:Antimalarials; D037621:Artemisinins; D006634:Histamine H1 Antagonists; D012717:Sesquiterpenes; D002744:Chlorpheniramine; D000077332:Artesunate