Effect of casting solvent and polymer on permeability of propranolol hydrochloride through membrane controlled transdermal drug delivery system

In the present work, cellulose acetate and ethyl cellulose films were prepared and evaluated as rate controlling membrane for transdermal drug delivery systems. In each case films were prepared using solutions of the polymer in various solvents to evaluate the influence of the solvent used on the mechanical and permeability properties of the films. Acetone-methanol (8:2), chloroform-methanol (8:2), dichloromethane-methanol (8:2) and ethyl acetate-methanol (8:2) were used as solvents in the preparation of cellulose acetate and ethyl cellulose films. Dibutyl phthalate or propylene glycol at a concentration of 40% w/w of the polymer was used as a plasticizer in the preparation films. The method of moulding was found to be giving thin uniform films. The dry films were evaluated for physical appearance, thickness uniformity, folding endurance, water vapour transmission, drug diffusion and permeability coefficient. Both water vapour transmission and Drug diffusion rate followed zero order kinetics. The mechanism of drug release was governed by Peppas model. The diffusion exponent of release profiles (slope) has a value of 1.0360-1.3147 (n>1), which indicates non anomalous transport diffusion. The results obtained in the present study thus indicated that the polymers and solvents used in the preparation of films have shown significant influence on the water vapour transmission, drug diffusion and permeability of the films. Area of patches ranging from 1.29- 4.53 cm 2 were found to yield the desired release rate of propranolol hydrochloride. Cellulose acetate films employed with ethyl acetate:methanol in 8:2 ratio as casting solvent yielded low area (1.29 cm 2 ) of patch with desired release rate.