In the limited number of reports that have appeared on the clinical use of penicillin sodium, urticaria seems to be the chief, if not the only, evidence of sensitivity to this drug. Keefer1 reports 14 cases of urticaria out of 500 cases treated and Lyons2 12 cases of urticaria out of 209 treated. These reactions from commercial penicillin sodium, if predicated on a sensitization mechanism, are obviously not necessarily due to penicillin itself.
During the course of some studies designed to determine whether a correlation exists between the immediate local reactions obtained with certain lots of commercial penicillin sodium on intramuscular injection in man and those obtained by intracutaneous injection of the same material in rabbits and in man, a person, J. D. W., was injected intracutaneously in the left arm with four lots of commercial penicillin sodium representing the products of three different manufacturers. Each injection consisted