Sensitivity to artemisinin, mefloquine and quinine of Plasmodium falciparum in northwestern Thailand

Abstract

The increasing drug resistance of Plasmodium falciparum is a worldwide problem. The objective of the study was the assessment of the in vitro activity of artemisinin, mefloquine and quinine, in an area where P. falciparum is multi-drug resistant. The sensitivity tests were based on measuring the drug-dependent inhibition of schizont maturation. For the 43 successfully tested isolates the mean effective concentrations (IC50and IC90) for artemisinin were 0.0081 and 0.1372 μM, respectively. For mefloquine the IC50was 0.1260 μM and the IC90was 3.7345 μM. Quinine showed an IC50of 0.2155 μM and an IC90of 2.5040 μM. All tested drugs showed a significant reduction in the effectiveness, compared with the results of former years. This suggests a further rise of resistance of local P. falciparum, which is alarming especially for artemisinin and quinine. © 2010 Springer-Verlag.