Potentiation of sulphadimidine by 2,4-diaminopteridines and other 6,7-disubstituted 2,4-diaminopteridines against Eimeria infections of chicks.

Six 2,4-diaminopteridines substituted in the 6 and 7 positions were tested as potentiators of sulphadimidine against Eimeria tenella. 2,4-Diamino-6,7-di-isopropylpteridine and 2,4-diamino-1'-propylindolo(2',3':6,7)pteridine were selected for further study. Both potentiated sulphadimidine against E. tenella and the di-isopropylpteridine potentiated it against E. necatrix. A 10% mixture of the di-isopropylpteridine with sulphadimidine (or other sulphonamides) appears to offer advantages in the treatment of E. tenella and still more of E. necatrix.