IN THE treatment of early syphilis it is thought advisable to administer sufficient amounts of penicillin at such intervals as will not quickly establish but also maintain maximum effective blood levels of the compound in order to secure the earliest possible healing of the open lesions. Doing so is not only for the purpose of securing prompt and sustained spirocheticidal concentrations in the blood but also, more important, for producing and maintaining maximum effective concentrations in the tissues, with special reference to the foci of infection, in order to destroy treponemes recovering from the effects of the compound before they resume multiplication.
For these purposes Parke, Davis & Company have made available a combination of procaine penicillin G with buffered crystalline sodium penicillin G, designated penicillin "S-R," for intramuscular injection in aqueous suspension. When suspensions are prepared as directed with sterile water, an isotonic solution of sodium chloride, or 5%