Studies on the toxicity and action of diaminodiphenyl-sulfone (DDS) in avian and simian malaria.

Interest in the schizontocidal activity of diaminodiphenylsulfone (DDS) and in its possible use in malaria chemoprophylaxis has recently been revived. Studies on its toxicity and action in avian and simian malaria show that its chronic toxicity in monkeys is similar to that of the established antimalarials and that it lacks causal prophylactic, gametocidal and sporontocidal activity against Plasmodium gallinaceum.DDS is also inferior to the established antimalarials in its schizontocidal activity against P. gallinaceum, while against P. knowlesi its activity is of the same order as that of proguanil and against P. cynomolgi it is more effective than quinine, mepacrine, pyrimethamine, chloroquine and proguanil but less effective than sulfadiazine.Rapid selection of a DDS-resistant strain of P. cynomolgi was achieved. The absence of cross-resistance between DDS and pyrimethamine indicates that their action on plasmodia is effected through different metabolic pathways. Although both drugs individually have a tendency to select resistant parasite strains, a combination of the two may obviate the risk of resistance being built up.