Serum levels of penicillin and their variations after administration of benzathine penicillin in children.

During a study of the serum levels of penicillin necessary for the prophylaxis of rheumatic fever in children (Carron, Maillard, and Pellerat, 1961) we made some observations which could have practical importance in the treatment of syphilis. We observed certain variations in the serum levels after the administration of benzathine penicillin some of which appeared to be rather paradoxical. In general, our results showed satisfactory levels after benzathine penicillin and confirm the remarkable delayed effect of the preparation already reported by Szabo, Edwards, and Bruce (1951), Elias, Price, and Merrion (1951), Stollerman and Rusoff (1952), Mann, Rein, Bunn, Flax, and Morseburg (1953), Fletcher and Knappett (1953), Welch, Randall, and Hendricks (1953), Putnam and Roberts (1954), Nelson, Talbot, and Binns (1954), Mozziconacci, Gerbeaux, and Dupuy-Joie (1957), Wright, Welch, Wilner, and Roberts (1959). As penicillin has a treponemicidal action at levels between 0*004 and 0 010 unit (Eagle, Fleischman, and Musselman, 1950; Durel, Sausse, Collart, Roiron, and Borel, 1951; Durel and Borel, 1958), the time during which the serum level is sufficiently