Abstract
Nearly 300 of the 2,4-diaminopyrimidines were tested against bird and rodent plasmodia and the effective standard dose (a 50% reduction in parasitemia) was established for each drug. Chicks and mice were used as the exptl. hosts of the plasmodia so treated. Daraprim was the most active antimalarial of all those tested. The results were also checked against the reaction of the standard antimalarials such as quinine and proguanil. Further tests against a monkey infecting plasmodium indicate that Daraprim does not easily cause the establishment of drug-resistant strains of the plasmodium and at the same time has a normal effect on proguanil-resistant strains.