Abstract
The activity of sulfapyrazine against infections with beta hemolytic streptococci has been compared with that of sulfadiazine, sulfathiazole, sulfapyridine and sulfanilamide. (1) Against infections with either strain C203 or Schw, single large doses of sulfapyrazine were considerably more effective than similar doses of sulfathiazole, sulfapyridine or sulfanilamide and were essentially identical in activity with sulfadiazine. (2) Against infections with strain C203, repeated small doses of sulfapyrazine were again more effective than similar doses of sulfathiazole, sulfapyridine or sulfanilamide. In general, the smaller the dosage, the greater the difference between the effectiveness of sulfapyrazine and that of these three sulfonamides. At all dose levels, however, sulfapyrazine and sulfadiazine were nearly identical in activity. (3) Against infections with four freshly isolated strains of streptococci, all of which were more susceptible to the sulfonamides than strain C203, the activity of repeated doses of very small quantities of sulfapyrazine was considerably greater than that of sulfathiazole, sulfapyridine and sulfanilamide and was equal to that of sulfadiazine.
The sulfonamide concentrations in the blood have been determined following administration of various doses of the different drugs. This study showed that sulfapyrazine differed from sulfadiazine, sulfathiazole, sulfapyridine and sulfanilamide in several important respects. First, the maximum concentration of sulfapyrazine in the blood on the smallest dose was larger than that of any other sulfonamide excepting sulfadiazine; secondly, the concentration of sulfapyrazine in the blood increased to a smaller extent with increase in dosage than that of any other drug, with the result that the maximum concentration on the largest dose was lower than that of any other sulfonamide; thirdly, the concentrations of sulfapyrazine were maintained at a uniform level for a longer period than were those of the other compounds. This study also showed that the concentrations of sulfadiazine in the blood were larger than those of the other four drugs.
These latter data have suggested that in the treatment of streptococcal infections the superior activity of sulfapyrazine, and also of sulfadiazine, over that of equal doses of the other sulfonamides is due to the absorption and excretion characteristics of the two drugs that make possible the maintenance of effective concentrations in the blood at all times between treatments. This suggestion is supported by the observation that the activities of all five drugs were essentially identical when the average concentrations in the blood were the same.
The possible place of sulfapyrazine in sulfonamide therapy has been briefly discussed.
Footnotes
- Received November 24, 1942.
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