Abstract
A new sulfonamide, sulfacytine (1-ethyl-N-sulfanilylcytosine) has a short half-life, is highly soluble throughout the usual urinary pH range, and urinary excretion is almost entirely as the free or microbiologically active form. Experimental mouse infections demonstrate a 2- to 3-fold bacteriostatic activity compared to sulfisoxazole. Plasma and urine concentrations following three dose schedules of sulfacytine (2 grams/day, 1 gram/day, 0·5 grams/day) were determined over a 7-day period by both colorimetric and microbiologic assay methods. These were compared to sulfonamide levels produced by the standard dose of sulfisoxazole (4 grams/day). Excellent agreement was found between the two methods, indicating that the colorimetric assay for free sulfacytine should accurately reflect microbiologic activity. Fifty per cent (50%) of the total daily dose given initially produces prompt levels so is the proper loading dose. By comparison to sulfisoxazole urine levels, 1 gram/day of sulfacytine appears to be the proper dose, produces urine concentrations at least 10 times the highest MIC found for sensitive microorganisms.
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