Plasma Penicillin Levels from Oral Penicillins V and G and Intramuscular Penicillin G.

Oral penicillin V gave higher and better sustained levels of penicillin activity in the plasma than oral buffered potassium penicillin G at each of 3 dosage levels, viz. 200000, 400000 and 1 million units. Intramuscular penicillin G yielded higher and better sustained levels than oral penicillin V in equivalent doses given at levels of 400000 or 1 million units. An i. m. dose of 200000 units of penicillin G produced higher peak levels and these occurred earlier but they were less well sustained than with this amount of oral penicillin V; the total amount of penicillin absorbed from this amount of penicillin was not significantly different for these 2 dosage forms. Persons over 60 years of age attained peak levels later; in general they had higher and better sustained levels of penicillin in the plasma from any given dose than did younger individuals.