An open-label, two-period, crossover study of the systemic bioavailability in healthy women of clindamycin phosphate from two vaginal cream formulations

Background: A clindamycin phosphate 2% single-dose vaginal cream (CSDVC) formulation has been designed to provide release of clindamycin equivalent to 7 daily doses of a conventional clindamycin phosphate 2% vaginal cream (CVC). Objective: The purpose of this study was to compare the systemic bioavailability of clindamycin from 1 dose of CSDVC with that from 1 dose from a 7-day regimen of CVC in healthy women. Methods: This was a single-center, open-label, randomized, 2-period, 2-sequence crossover study that enrolled healthy, nonpregnant, adult women. Subjects were randomly assigned to receive a single 5-g intravaginal dose of CSDVC or CVC. Blood samples were then collected for 96 hours after study medication administration. Subjects were crossed over after a 14-day washout period, and received a single dose of the other medication. Blood samples were then collected for 96 hours after administration of the second drug. The plasma clindamycin pharmacokinetic profiles were determined, using a validated assay with a lower limit of detection of 0.2 ng/mL, and compared between treatments. Results: The median age of women was 43.5 years (range, 18-66 years), the median weight was 65.0 kg (range, 47.7-91.8 kg), and the median body mass index was 25.4 kg/m(2) (range, 19.2-34.7 kg/m(2)). AUC from time 0 to the last detectable concentration (AUC(0-t)) and from time 0 to infinity (AUC(0-infinity)) and Cm,x were significantly lower with CSDVC than with CVC (geometric means of 98.61 vs 794.21 ng (.) h/mL for AUC(0-t), 100.33 vs 809.14 ng (.) h/mL for AUC(0-infinity), and 3.18 vs 42.27 ng/mL for C-max; all comparisons, P < 0.001 between formulations). Overall bioavailability of clindamycin from CSDVC was similar to 12% of that from CVC, as measured by AUC. The arithmetic mean T-max was significantly longer with CSDVC (26.4 vs 9.8 hours; P < 0.007). There were 18 adverse events reported during this study. The most common adverse event with each formulation was headache (CSDVC, 10%; CVC, 25%). Conclusion: Systemic bioavailability of clindamycin was significantly lower and systemic absorption was significantly slower with the CSDVC formulation than with the single dose of 7-day CVC formulation in these healthy volunteers.