Engineering vaginal film platform for mucoadhesion and sustained drug release for HIV-1 prevention

User adherence contributes to the effectiveness of topical pre-exposure prophylactic products designed to protect against human immunodeficiency virus type 1 (HIV-1) infection. Long-acting approaches that do not require daily or coitally-dependent use could potentially improve user adherence. This study aims to develop a long-acting vaginal film to deliver an integrase inhibitor, MK-2048, for prevention of HIV-1 infection. To this end, a film platform fabricated with thiolated chitosan and poly(lactide-co-Ɛ-caprolactone) (PLACL) was designed to achieve long residence time and sustained drug release profile, respectively. A series of PLACLs were synthesized with different lactic acid (LA) to caprolactone (CL) ratios and were chemically and thermally characterized. Films containing thiolated chitosan and PLACL copolymers were manufactured using solvent-casting and characterized for their physicochemical properties. The in vitro release of MK-2048 formulated in thiomer PLACL films was tested. The lead film composed of thiomers and PLACL 80 showed comparable elasticity with the marketed VCF® film (vaginal contraceptive film) and slower drug release rate compared to other compositions. The tissue mucoadhesion and permeability of MK-2048 were significantly improved by incorporation of thiolated chitosan in the film matrix. Importantly, the film showed no evidence of toxicity in excised human ectocervical tissue and demonstrated comparable anti-HIV activity as free MK-2048. The lead film evaluated in pigtail macaques showed drug concentrations above the IC₉₅ (41 nM) in vaginal fluids and tissues for a period of at least 2 weeks, with no evidence of toxicity. Overall, these in vitro and in vivo studies demonstrate that this strategy can be applied to rationally develop polymeric film platforms that can sustain drug release in vivo, potentially improving user adherence.