TOXICITY AND EFFICACY OF PENICILLIN

¹ From the Merck Institute for Therapeutic Research, Rahway, N. J.

1. Crude penicillin is toxic for mice when given intravenously in single doses of 0.5, 1.0, 1.5 and 2.0 grams per kgm. More highly purified preparations appeared to be less toxic than the crude preparation when compared on a weight basis.

2. When given subcutaneously penicillin is well tolerated by mice in daily doses of 1.6 grams per kgm. over a 5 day period. Under the same conditions 3.2 grams per kgm. are lethal for some mice.

3. The toxic dose of crude penicillin appears to be about 64 times the effective dose as determined by subcutaneous injection in mice.

4. On the basis of weight, penicillin appears to be more effective than sulfanilamide and its derivatives in streptococcal, pneumococcal and staphylococcal infections in mice.

5. Penicillin had no apparent effect in experimental infections caused by Mycobacterium tuberculosis, Trypanosoma equiperdum or the influenza virus PR8.