Penicillin concentrations after increased doses of benzathine penicillin G for prevention of secondary rheumatic fever

Plasma penicillin levels were studied 2, 3, and 4 weeks after intramuscular benzathine penicillin G (BPG) doses of 1,200,000, 1,800,000, and 2,400,000 U. Proportions of patients with penicillin levels above 25 ng/ml at each week increased with increasing BPG dose. Further studies of higher-dose BPG for rheumatic fever prophylaxis are required.