title: Plasmodium falciparum: mefloquine resistance produced in vitro.
abstract: Camp and Smith strains of the human malaria parasite Plasmodium falciparum became resistant to mefloquine after continuous cultivation in the presence of the drug. The 50% inhibitory dose (ID(50)) values for mefloquine, as assessed by [(3)H]hypoxanthine incorporation, were found to have increased 4-fold, from 3 mug/l to 12 mug/l. The ID(50) values obtained by morphological examination of the cultures increased 10-fold. Resistance was stable in both strains either when grown in a drug-free medium or when kept frozen in liquid nitrogen. The mefloquine-resistant Camp strain remained sensitive to chloroquine and amodiaquine, and became slightly more resistant to quinine; there was increased sensitivity to pyrimethamine. The mefloquine-resistant Smith strain remained sensitive to amodiaquine and resistant to pyrimethamine; there was increased resistance to quinine, and an increase in sensitivity to chloroquine.
mesh_terms: D000962:Antimalarials / Q000494:pharmacology; D002460:Cell Line; D002478:Cells, Cultured; D004352:Drug Resistance, Microbial; D015767:Mefloquine; D008826:Microbial Sensitivity Tests; D010963:Plasmodium falciparum / Q000187:drug effects*; D011804:Quinolines / Q000494:pharmacology*
chemical_list: D000962:Antimalarials; D011804:Quinolines; D015767:Mefloquine