Development and Characterization of a Mucoadhesive Buccal Patch of Carvedilol: In Vitro and In Vivo Evaluation for Enhanced Bioavailability

Objective: Hypertension remains a leading contributor to cardiovascular morbidity worldwide, necessitating improved therapeutic strategies for effective long-term management. Carvedilol (CDL), a non-selective β-adrenergic blocker with additional α₁-blocking activity, is clinically effective but suffers from extensive first-pass metabolism and limited oral bioavailability. The present study was undertaken to design and evaluate a mucoadhesive buccal patch of carvedilol to enhance systemic availability and antihypertensive efficacy through transmucosal delivery. Methods: Mucoadhesive buccal patches were formulated using the solvent-casting technique, employing tamarind seed polymer (TSP) as a natural mucoadhesive polymer in combination with ethyl cellulose as a release-modifying agent. The formulation variables were systematically optimized to obtain a patch with desirable mechanical strength, mucoadhesion, and controlled drug release. The optimized formulation (CMBP-8) was evaluated for its physicochemical properties, surface morphology, folding endurance, surface pH, swelling behavior, mucoadhesion time, in vitro drug release, and in vivo pharmacokinetic performance. Drug–excipient compatibility and solid-state characteristics were investigated using FTIR, DSC, and powder X-ray diffraction (P-XRD) analyses. Results: The optimized carvedilol mucoadhesive buccal patch (CMBP-8) exhibited a prolonged mucoadhesion time of 408 min and 94.68% cumulative drug release, with excellent physicochemical characteristics, including 94.05±0.64% drug content, 250±1.52 folding endurance, and a surface pH of 6.81±0.28. SEM analysis demonstrated a smooth and homogeneous surface morphology, while DSC and PXRD confirmed the conversion of carvedilol from a crystalline to an amorphous, molecularly dispersed state within the polymeric matrix, indicating successful drug incorporation. In vivo pharmacokinetic studies showed a significant increase in AUC₀–∞ from 561.63±17.64 to 1535.72±38.54 ng·h/ml, corresponding to a relative bioavailability of 273.45% compared with pure carvedilol, confirming enhanced systemic drug exposure through buccal delivery. Conclusion: The developed carvedilol mucoadhesive buccal patch offers a promising alternative to conventional oral dosage forms by improving bioavailability and antihypertensive efficacy, thereby supporting its potential for further translational and clinical development.