Formulation development of dual-compartment topical inserts combining tenofovir alafenamide and elvitegravir for flexible on-demand HIV prevention

Pre-exposure prophylaxis (PrEP) has emerged as a prominent approach for the prevention of HIV infections. While the latest advances have resulted in effective oral and injectable product options, there are still gaps in on-demand, event-driven, topical products for HIV prevention that are safe and effective. Here we describe the formulation development of a dual-compartment topical insert containing tenofovir alafenamide fumarate (TAF) and elvitegravir (EVG) that may be administered when needed, vaginally or rectally, pre- or post-coitus, for flexible HIV prophylaxis. Specifically, we describe the lab-scale formulation development, preclinical mucosal safety and pharmacokinetics (PK) testing in rabbits, long-term stability, and scale-up clinical manufacturing of the lead TAF/EVG (20 mg/16 mg) inserts, which are currently in clinical stages of development. As designed, the inserts are small, discreet and portable, offering a number of promising attributes, such as simple and robust direct-compression manufacturing, fast initial disintegration/dissolution, and suitable mechanical strengths showing low hardness (