In vitro sensitivity of Plasmodium falciparum to sulfadoxine and pyrimethamine

Abstract

An in vitro microtechnique of Rieckmann et al., (1978) modified by Yisunsri and Rieckmann (1980) using 3 media, Waymouth, Waymouth plus 10% human serum, and RPMI, was assessed to determine the sensitivity of P. falciparum to sulfadoxine, pyrimethamine and its combination. The study confirmed the synergism between sulfadoxine and pyrimethamine. There was no interaction between media and drug tested. MIC1and MIC2of sulfadoxine in different media showed significant differences (p<0.001). No significant difference was observed in MIC1and MIC2of pyrimethamine in the three media used (p>0.05). For the sulfadoxine-pyrimethamine combination, MIC1and MIC2in Waymouth alone and plus 10% human serum showed no significance (p>0.05) while in RPMI it showed a positive correlation (p<0.001). MIC1might be more applicable for clinical evaluation than MIC2. At present Waymouth medium with 5% patient serum is considered to be the most suitable for testing sensitivity of malarial parasites.