Serum concentrations of penicillin G in man following intramuscular injection in aqueous solution and in peanut oil-beeswax suspension

Abstract

1. 1. Serum penicillin levels were studied in 138 patients following the intramuscular injection of a single dose of crystalline sodium penicillin G in aqueous solution or in peanut oil-beeswax suspension. 2. 2. The aqueous solution was given at six dosage levels (0.15, 0.3, 0.6, 1.5, 3.0 and 10.0 mg./Kg.), totalling 18,000 to 1,200,000 units in the average adult. The median serum concentrations one-half, one, two, four, eight and twelve hours after the administration of penicillin at these varying dosages have been calculated and the pharmacologic significance of the resulting curves discussed. 3. 3. Peanut oil-beeswax mixtures were given in dosages of 1.5, 3.0 and 10.0 mg./Kg. The high degree of variation in individual lots precluded a discussion of average or median serum concentrations provided by the preparations currently available. 4. 4. Tables are presented which enable the physician to determine either the frequency at which a given dose should be injected or the dosage of penicillin which should be given at stated intervals in order to maintain a given concentration of penicillin in the plasma.