Systemic absorption of clindamycin after intravaginal administration of clindamycin phosphate ovule or cream

The absolute bioavailability of clindamycin phosphate vaginal ovule with comparison to a reference treatment of clindamycin phosphate sterile solution, as well as the relative bioavailability of the ovule compared to clindamycin phosphate vaginal cream, was evaluated in 12 healthy adult female volunteers. Subjects were randomly assigned to receive either the ovule or cream formulation intravaginally for 3 consecutive days during the two-way crossover portion of the study. During a third treatment period, all subjects received 100 mg of clindamycin as a 4-minute intravenous infusion of clindamycin phosphate sterile solution (10 mg/mL). Clindamycin concentrations in serum were assayed by a high-performance liquid chromatography method with detection by mass spectrometry. Pharmacokinetic analyses of the serum data indicated low systemic absorption of clindamycin from the vaginal cream (about 4%), consistent with results of previous bioavailability studies. Following intravaginal administration of the clindamycin phosphate ovule, systemic absorption averaged 30%, which was approximately sevenfold greater than after dosing with the vaginal cream. The higher drug absorption for the ovule may be related to differences in formulation effects on the vaginal membrane. Nevertheless, systemic exposure to clindamycin from the ovule is still considerably lower than from a therapeutic oral dose.