Lonardo, E.C. and T. A. Roy (2000). A Novel Use of an In Vitro Percutaneous Absorption Procedure to Assess Absorption Potential of Human Vaginal Tissue. The Toxicologist. 54(1). Abstract # 692.

polydimethylsiloxane - 63148-62-9

Vaginal epithelium is permeable to a wide variety of compounds. Unfortunately, quantitative data on the extent of absorption are often lacking. The in vitro percutaneous absorption procedure is valuable in developmental stages of vaginal drug delivery systems. It allows for direct risk assessment and eliminates ethical and safety concerns associated with human in vivo testing. By using an in vitro technique, the absorption potential of polydimethylsiloxane (PDMS) was assessed through human vaginal tissue. In vitro percutaneous absorption experiments (96 hr) were performed with two PDMS samples (350 cSt and 10 cSt). Infinite doses (10 mg/cm2) were applied to the donor side of split thickness human abdominal skin sections (reference standard) and full-thickness human vaginal tissue mounted in Franz in vitro diffusion cells. In order to facilitate the measurement of percutaneous absorption, doses were spiked with the respective 14C-PDMS (350 cSt or 10 cST) prior to the study. Based on [14C]PDMS, the dermal flux rate for the infinite dose of 350 cSt PDMS was 0.31 and 1.98 ng/cm2/hr for the abdominal skin and vaginal tissue respectively. For the 10 cSt PDMS, flux rates were 0.52 and 5.52 ng/cm2/hr for the abdominal skin and vaginal tissue respectively. Although vaginal absorption of 350 and 10 cSt PDMS is 6 and 10 times greater respectively, than through abdominal tissue, less than 0.01% of the PDMS was absorbed through the dermal barrier regardless of tissue or viscosity of PDMS. This novel in vitro approach allows for direct determination of vaginal bioavailability of drug products or vehicles either intended or not intended to be absorbed into the blood stream and is a promising tool for vaginal therapeutic drug development.