A phase I, double-blind, placebo-controlled study of the tolerance and pharmacokinetic behaviour of RP 59500

Abstract

The tolerance and pharmacokinetic behaviour of a new injectable streptogramin antibiotic, RP 59500 were evaluated on 26 healthy male volunteers in a double-blind, placebo-controlled, phase I study. The doses used were 1·4, 2·8, 4·6, 7·0, 9·8, 12·6, 16·8, 22·4 and 29·4 mg/kg; each dose was administered as a 1 h infusion to eight subjects, two of them receiving placebo. Blood levels of RP 59500 were measured by both microbiological and HPLC assays. At the end of the infusion, Cm for RP 59500 ranged from 0·95±0·22 to 24·20±8·82 mg/L. The apparent elimination half-life of the compound ranged from 1·27 to 1·53 h. RP 59500 did not significantly affect any of the laboratory or clinical assessments (blood pressure, pulse rate, ECG, peak expiratory flow rate). Reported adverse effects were of mild intensity; the most frequent event was mild pain or burning at the infusion site with doses of 7 mg/kg or higher. These results support further studies of RP 59500 in phase II clinical trials.