title: Lack of cross-resistance to 4-aminoquinolines in chloroquine-resistant Plasmodium falciparum in vitro.
abstract: The potencies of 10 quinoline-containing antimalarials, including chloroquine, amodiaquine, CM-2,999-2K, quinine, mefloquine, SN-6911, SN-11875, SN-12108, SN-12308, and SN-12309, were determined in vitro against five strains of Plasmodium falciparum characterized in vivo and in vitro by various degrees of sensitivity to chloroquine. These strains included the chloroquine-sensitive strains Honduras and FCC1, and R1-resistant line FCR3TC, and the R3-resistant strains FCR1 and Viet Nam Smith (VNS). The potency of chloroquine varied 100-fold in these strains, with minimum inhibitory concentrations (MIC) ranging from 3.2 X 10(-9) M in FCC1 to 3.2 X 10(-7) M in FCR1. The other drugs had different patterns; SN-12108 had an MIC of 3.2 X 10(-9) M in FCC1, Honduras, and FCR1, and 3.2 X 10(-8) M in VNS. However, SN-6911 (3-methylchloroquine), amodiaquine, and mefloquine showed little or no variation in potency among these strains. There was no correlation between sensitivity to chloroquine and any other drug. This lack of cross-resistance in vitro must be taken into account in consideration of theories of chloroquine action in these parasites.
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D002738:Chloroquine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D010963:Plasmodium falciparum / Q000187:drug effects*; D011803:Quinine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: D000962:Antimalarials; D002738:Chloroquine; D011803:Quinine