Variations in serum concentrations of penicillin after injections of aqueous procaine penicillin G with and without oral probenecid.

Probenecid by inhibiting the renal excretion of penicillin raises its serum level (Boger, Beatty, Pitts, and Flippin, 1950; Burnell and Kirby, 1951; Meads, Knight, and Izlar, 1951; Frisk, Diding, and Wallmark, 1952), a pharmacological effect of which increasing use has been made in the treatment of gonorrhoea (Hilton, 1959; Jensen, Kvorning, and N0rredam, 1963; Holmes, Johnson, and Floyd, 1967; Holmes, Johnson, Stewart, and Kvale, 1968; Editorial B.M.J., 1968a; Olsen and Lomholt, 1969; Keys, Halverson, and Clarke, 1969). Willcox (1970), in a recent review, has drawn attention to the paucity of data on penicillin serum levels when the antibiotic is used, with or without probenecid, in the large doses now required to overcome partially resistant gonococci. Few patients have been studied and notable variations have been reported by different investigators and sometimes by the same investigator even on the same subjects. The purpose of this report is to provide data of serum levels attained with the dosage of aqueous procaine penicillin G currently recommended by the United States Public Health Service for the treatment of gonorrhoea in men (2-4 mega units) and women (4-8 mega units) with and without the addition of 2 g. probenecid.