Abstract

1. Twenty-two compounds were tested for their ability to potentiate the antimalarial activity of sulfadiazine against Plasmodium gallinaceum in the chick.

2. Only the two 2 ,4-diamino-5-aryloxypyrimidines were able to potentiate sulfadiazine activity in this infection. One quarter of the minimum effective dose of the diaminopyrimidines plus one-sixteenth of the minimum effective dose of sulfadiazine was the minimum effective regimen when these compounds were administered concurrently.

3. The antimalarial activity of the diaminopyrimidines was partially in hibited by large oral doses of pteroylglutamic acid.