Serum concentrations of penicillin following the administration of crystalline procaine penicillin G in oil.

THE use of peanut oil and beeswax suspensions of amorphous calcium penicillin and of the sodium and potassium salts of crystalline penicillin G for delaying its absorption when injected intramuscularly is well known. The recent preparation of the crystalline procaine salt of penicillin G has afforded the opportunity for studying the absorption of a relatively insoluble salt.1 , 2 Procaine penicillin is a true salt derived by the stoechiometric combination of procaine hydrochloride and sodium penicillin G. Calculated on the basis of a potency for crystal-line sodium penicillin G at 1667 units per milligram, the theoretical potency of crystalline procaine penicillin G . . .