Determination of Fifty Percent Inhibitory Concentrations (IC50) of Antimalarial Drugs against Plasmodium Falciparum Parasites in a Serum-Free Medium

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  • Biomedical Sciences Research Center and Clinical Research Center, Kenya Medical Research Institute, Zoology Department, Kenyatta University, Infectious Diseases Division, Naval Medical Research Institute, USAMRU-Kenya, Walter Reed Army Institute of Research, Nairobi, Kenya

Plasmodium falciparum chemosensitivity to the various antimalarial drugs is presently determined in the laboratory by setting up multiple microcultures of the parasite and estimating the amount of growth inhibition caused by known concentrations of drug. Parasite growth inhibition is assessed either by microscopy, radiolabeled substrate uptake, or calorimetrically. The obligate requirement for serum in this assay presents difficulties in the direct comparison of results among laboratories. We now have evidence that antimalarial drug sensitivity assays can be reliably performed in a serum-free medium. The overall comparison of 50% inhibitory concentration (IC50) values obtained with serum-free media (bovine albumin, Cohn fraction V [BAM] and BAM combined with glucose and lipids-cholesterol-rich mixture) and those obtained in serum-supplemented medium was r = 0.56; n = 60; P < 0.01.