THE EXPERIMENTAL BASIS FOR A METHOD FOR THE QUANTITATIVE EVALUATION OF THE EFFECTIVENESS OF CHEMOTHERAPEUTIC AGENTS AGAINST STREPTOCOCCUS INFECTION IN MICE

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

Incorporation of sulfanilamide in the food of mice appears to be the most satisfactory method of maintaining a nearly constant blood concentration of the drug. The mouse eats with sufficient regularity and frequency to insure the continuous presence of sulfanilamide in the intestine. The daily drug intake per mouse can be converted into average blood concentration by using a predetermined factor.

There is no significant difference between prefeeding and immediate treatment with sulfanilamide, but delaying treatment four hours after infection causes a significant decrease in the number of mice surviving. Different blood concentrations of drug used for 1, 2, 3 and 6 days show that dosage-survival curves are obtained.

On the basis of the data obtained in the present study, a method is outlined for the quantitative evaluation of the effectiveness of chemotherapeutic agents against streptococcus infections in mice. Comparisons of different drugs, or of the same drug under different conditions, can be made by determining the daily drug intake necessary to produce the same response (50 per cent survival). This Median Survival Dose (S.D.₅₀) can be converted to Median Survival Blood Concentration (S.B.C.₅₀) by the use of an appropriate factor.

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