IN-VITRO ACTIVITY OF ARTEMETHER AGAINST AFRICAN ISOLATES (SENEGAL) OFPLASMODIUM-FALCIPARUM IN COMPARISON WITH STANDARD ANTIMALARIAL-DRUGS

The in vitro activity of artemether against 56 African isolates of Pla smodium falciparum from Senegal was evaluated using an isotope-based d rug susceptibility semi-microtest. The 50% inhibitory concentration (I C50) values for artemether were in a narrow range from 0.8 to 15.2 nM (mean IC50 = 3.43 nM) and the 95% confidence interval (CI) was 2.50-4. 36 nM. Artemether was equally effective on chloroquine-sensitive and c hloroquine-resistant isolates (mean IC50 = 346 nM, 95% CI = 2.08-4.84 nM versus mean IC50 = 2.80 nM, 95% CI = 2.00-3.60 nM). There was a sig nificant positive correlation between responses to artemether and mefl oquine (r(2) = 0.36, P < 0.001), artemether and quinine (r(2) = 0.085, P < 0.05), artemether and halofantrine (r(2) = 0.075, P < 0.05), quin ine and mefloquine (r(2) = 0.205, P < 0.01), quinine and halofantrine (r(2) = 0.124, P < 0.05), and mefloquine and halofantrine (r(2) = 0.80 1, P < 0.001). A positive correlation between these drugs suggests in vitro cross-resistance or at least in vitro cross-susceptibility.