Improving the Safety of

Vaginal administration and the uterine first pass effect allow for preferential delivery of drugs to the reproductive tract. Dimethylacetamide has previously been shown to delay preterm birth in a pregnant mouse model when given intraperitoneally but the effectiveness of a vaginal nanoformulation of dimethylacetamide has yet to be tested. The purpose of this study was to compare the two formulations of dimethylacetamide for efficacy in rescuing pups from preterm birth in an inflammation-induced mouse model, effects on the maternal fetal interface, and pharmacokinetic profiles in maternal plasma. Timed pregnant CD1 mice were given a 1.56 mg/kg intraperitoneal dose of lipopolysaccharide followed by 3 doses of either vaginal dimethylacetamide or intraperitoneal dimethylacetamide. Mice were monitored for 48 hours and times of deliveries were recorded. Additionally, CD1 mice in late gestation were given a single dose of either vaginal or intraperitoneal dimethylacetamide and blood was drawn at 3 different time points following administration. Vaginal administration of dimethylacetamide had similar efficacy in delaying inflammation induced preterm birth as intraperitoneal administration but resulted in lower concentrations in the systemic circulation and decreased effects on the maternal fetal interface. Vaginal nanoformulations should be explored for their potential therapeutic value for the delay of preterm birth.