Formulation and optimization of mucoadhesive buccal patches of losartan potassium by using response surface methodology

BACKGROUND: This study was undertaken with an aim to systematically design a model of factors that would yield an optimized sustained release dosage form of an anti-hypertensive agent, losartan potassium, using response surface methodology (RSM) by employing 3(2) full factorial design. MATERIALS AND METHODS: Mucoadhesive buccal patches were prepared using different grades of hydroxypropyl methylcellulose (HPMC) (K4M and K100M) and polyvinylpyrrolidone-K30 by solvent casting method. The amount of the release retardant polymers – HPMC K4M (X(1)) and HPMC K100M (X(2)) was taken as an independent variable. The dependent variables were the burst release in 30 min (Y(1)), cumulative percentage release of drug after 8 h (Y(2)) and swelling index (Y(3)) of the patches. In vitro release and swelling studies were carried out and the data were fitted to kinetic equations. RESULTS: The physicochemical, bioadhesive, and swelling properties of patches were found to vary significantly depending on the viscosity of the polymers and their combination. Patches showed an initial burst release preceding a more gradual sustained release phase following a nonfickian diffusion process. DISCUSSION: The results indicate that suitable bioadhesive buccal patches with desired permeability could be prepared, facilitated with the RSM.