Chitosan-(poly)acrylic acid polyelectrolyte complexes: Enhanced mucoadhesion and sustained drug release in vaginal tablets

Polyelectrolyte complexes (PECs) have emerged as promising vehicles for medical applications, attributable to their non-toxicity, non-immunogenicity, and ability for controlled drug release. Notably, their inherent mucoadhesive properties are being leveraged for sustained drug delivery across mucosal barriers, including vaginal, ocular, nasal, and buccal membranes. This study delves into the formulation and effects of chitosan-(poly)acrylic acid-based PEC for vaginal tablet applications. A comparative analysis of various polymer combinations was conducted, emphasizing the differential impacts of low versus high-molecular weight chitosan. Results highlighted that PECs augmented the flowability of powder mixtures and bolstered the tablets' physical properties. Moreover, PEC-enhanced formulations exhibited a pronounced increase in swelling efficiency, with swelling index values reaching up to 92.67% ± 1.90, ensuring structural integrity during dissolution. In ex vivo mucoadhesion tests, tablets from PEC mixes demonstrated extended adhesion, surpassing 48 hours for certain formulations. The optimized PEC formulation successfully achieved sustained drug release while retaining tablet adhesion for the duration of the release period.