The evaluation of sulfadiazine, sulfamethoxypyridazine (Midicel®) and sulphorthomidine (Fanzil®) alone or combined with pyrimethamine against drug-resistant strains of Plasmodium falciparum is reported. The results indicate that (1) combination of a sulfonamide with pyrimethamine enhanced the curative effect of either one alone, (2) when combined with pyrimethamine, Midicel and Fanzil were superior to sulfadiazine, and (3) of the regimens tested, 1.0 g Fanzil as a single oral dose given together with 50 mg pyrimethamine showed the most promise for the successful treatment of the multi-drug-resistant falciparum malarias. Factors limiting the usefulness of sulfonamides as antimalarials are discussed.
Cytology Section, LPC, NIAID, NIH, P. O. Box 190, Chamblee, Georgia.
Present address: Department of Pharmacology, Louisiana State University, School of Medicine, New Orleans, Louisiana.