QUANTITATIVE COMPARISONS OF THE ACTIVITY OF SULFANILAMIDE, SULFAPYRIDINE, SULFATHIAZOLE AND SULFADIAZINE AGAINST ESCHERICHIA COLI IN VIVO AND IN VITRO

¹ From the Department of Pharmacology and Experimental Therapeutics, The Johns Hopkins University, Baltimore

The drug-diet method was shown to be unsatisfactory for treatment of an E. coli infection in mice. More or less constant blood concentrations could be maintained by administration of drugs per os, by tubing, according to suitable dosage schedules. The optimal duration of therapy for this infection was found to be 12 to 14 hours. The therapeutic activity of four drugs was determined on the basis of blood concentrations maintained for 10 to 12 hours or longer. On the basis of blood concentrations in milligrams per cent, sulfapyridine was 6 times, sulfathiazole 10 times and sulfadiazine 11 times as active as sulfanilamide in vivo. The estimated error of each of these activity ratios was ±10 per cent. On the basis of minimal inhibitory concentration in milligrams per cent, sulfapyridine was 16 times, and sulfathiazole and sulfadiazine 64 times as active as sulfanilamide in vitro.