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ObjectivesTo evaluate pharmacokinetics (PK) of a single dose of an investigational 2% clindamycin phosphate vaginal gel in healthy women by assessment of plasma and vaginal clindamycin concentrations over 7 days, and assess safety.MethodsSingle-centre, Phase 1, single-dose PK study. Blood and vaginal samples were collected daily and safety was evaluated through to Day 7.ResultsTwenty-one subjects were enrolled; 20 completed the study. Plasma clindamycin concentrations demonstrated quantifiable values in all subjects through to 24 h post-dose, remaining above the limits of quantification (LOQ) through to 48 h for the majority of subjects. Systemic exposure (AUC0–t) was 1179 (range 62–3822) h·ng/mL. Arithmetic mean AUC0–24 was 818 (range 51–3287) h·ng/mL. Vaginal clindamycin phosphate levels were relatively high 24 h following administration in 15/21 subjects (6 subjects had values >400 µg/g and 9 had values of 100–400 µg/g). The levels dropped in most participants to below the LOQ 2 days following dosing. In a few participants, levels remained elevated for several days. Maximal amounts of vaginal clindamycin occurred on Day 2 with a mean value of 30.3 µg. One treatment-emergent adverse event (TEAE) of moderate-severity headache not related to study drug was reported and resolved on Day 1. No TEAEs were related to physical examinations, pelvic examinations, laboratory values or vital signs.ConclusionsThe vaginal concentrations of clindamycin phosphate plus the clindamycin plasma profile over time are consistent with release of drug from the investigational gel over 24 to 72 h. A single dose was well tolerated.