Development of polylactide and polyethylene vinyl acetate blends for the manufacture of vaginal rings.

Vaginal rings are currently being investigated fordelivery of HIV microbicides. However, vaginal rings are cur-rently manufactured form hydrophobic polymers such as sili-cone elastomer and polyethylene vinyl acetate (PEVA), whichdo not permit release of hydrophilic microbicides such as thenucleotide reverse transcriptase inhibitor tenofovir. Biodegrad-able polymers such as polylactide (PLA) may help increaserelease rates by controlling polymer degradation rather thandiffusion of the drug through the polymer. However, biodegrad-able polymers have limited flexibility making them unsuitablefor use in the manufacture of vaginal rings. This study demon-strates that by blending PLA and PEVA together it is possible toachieve a blend that has flexibility similar to native PEVA butalso allows for the release of tenofovir.