A modified SILCS contraceptive diaphragm for long-term controlled release of the HIV microbicide dapivirine

BackgroundThere is considerable interest in developing new multipurpose prevention technologies to address women's reproductive health needs. This study describes an innovative barrier contraceptive device — based on the SILCS diaphragm — that also provides long-term controlled release of the lead candidate anti-HIV microbicide dapivirine.Study DesignDiaphragm devices comprising various dapivirine-loaded polymer spring cores overmolded with a nonmedicated silicone elastomer sheath were fabricated by injection molding processes. In vitro release testing, thermal analysis and mechanical characterization were performed on the devices.ResultsA diaphragm device containing a polyoxymethylene spring core loaded with 10% w/w dapivirine provided continuous and controlled release of dapivirine over a 6-month period, with a mean in vitro daily release rate of 174 mcg/day. The mechanical properties of the new diaphragm were closely matched to the SILCS diaphragm.ConclusionsThe study demonstrates proof of concept for a dapivirine-releasing diaphragm with daily release quantities potentially capable of preventing HIV transmission. In discontinuous clinical use, release of dapivirine may be readily extended over 1 or more years.