Serum concentrations of penicillin after intramuscular administration of procaine, benzyl, and benethamine penicillin in children with pneumonia.

Serum concentrations of penicillin were measured in 37 children with pneumonia. The mean serum concentration of penicillin was greater than 1.0 microgram/mL for 11 hours after intramuscular administration of 48,000 U/kg benethamine penicillin compound (nine children), for 26 hours after 48,000 U/kg aqueous procaine penicillin (10 children), and for 40 hours after 79,000 U/kg aqueous procaine penicillin (seven children). After intramuscular administration of 35,000 U/kg benzyl penicillin in 11 children, the serum concentration was 13.3 +/- 7.4 micrograms/mL (mean +/- SD) 30 minutes after the injection, and 4.9 +/- 3.2 micrograms/mL after 3 hours. Our findings lend support to the World Health Organization recommendation that children with mild pneumonia in developing countries be given daily intramuscular injections of 50,000 U/kg aqueous procaine penicillin.