In vitro and ex vivo evaluation of a papain-loaded mucoadhesive buccal patch with potential antifibrotic and anticancer activity.

Oral submucous fibrosis (OSMF) and oral squamous cell carcinoma (OSCC) are characterized by aberrant extracellular matrix remodeling, chronic inflammation, and limited responsiveness to current local treatment modalities. In this study, we report the design and in vitro/ex vivo evaluation of a papain-loaded bilayer mucoadhesive buccal patch as a proof-of-concept platform for localized enzyme delivery. Papain, a plant-derived cysteine protease with collagenolytic activity, was incorporated into a biocompatible polymeric matrix to enable controlled, site-specific release within the buccal environment. The optimized formulation exhibited acceptable physicochemical properties, including uniform thickness, flexibility, near-neutral surface pH, sustained hydration, and controlled papain release within a clinically relevant residence window. In vitro biological evaluation demonstrated differential responses in HGF and CAL-27 cells, with reduced cytotoxicity toward normal fibroblasts and decreased viability, clonogenicity, migration, invasion, and three-dimensional spheroid outgrowth in carcinoma cells under experimental conditions. Ex vivo collagen degradation studies using rat tail tissue further supported the ability of the formulation to interact with collagen-rich matrices. Hemocompatibility testing indicated minimal hemolysis, suggesting preliminary blood compatibility. Collectively, these findings establish the formulation feasibility and biological plausibility of a papain-loaded mucoadhesive buccal patch (P-MABP) as a localized enzyme delivery system. While the results support its potential relevance for fibrotic and neoplastic oral conditions, further in vivo studies and mechanistic investigations are required to define therapeutic efficacy, safety, and translational applicability.