Incorporation of antihypertensive class IV drug in novel buccal film formulation

Chlorthalidone is a thiazide-like diuretic drug used in the treatment of hypertension. It belongs to class IV of Biopharmaceutical Classification System (BCS) and exhibits first pass metabolism leading to low bioavailability. The present work was undertaken to formulate mucoadhesive buccal film of chlorthalidone with an objective to improve bioavailability, therapeutic efficacy, and patient compliance. Film formulations were prepared by solvent casting method using a combination of different grades of hydrophilic polymer, Hydroxypropyl methylcellulose with suitable plasticizer. Other important excipients used were solubilizing agents to increase solubility and permeation enhancers to increase the permeability of the drug. The developed films were evaluated for physicochemical characteristics such as thickness, content uniformity, surface pH, and in vitro drug release etc. The optimized formulation containing a combination of hydrophilic and hydrophobic polymers showed good tensile strength, mucoadhesive strength and optimum in vitro diffusion results. The Ex vivo Drug permeation through porcine oral mucosa at the end of 8 hours was found to be 87.2±0.93%.