Abstract

Asymmetric membrane-controlled porosity osmotic pumps of cellulose acetate with different pore forming agents such as glycerol, polyethylene glycol and dibutyl phthalate, were fabricated and studied for osmotic release behavior from the system. The effects of various pore-forming agents on the physical characteristics of the polymer film like tensile strength, weight variation, wall thickness, surface area, porosity and void volume were studied as a function of pore forming agent. The asymmetric membrane capsules were fabricated by dip-coating process using stainless steel mold pins of the shape of capsule body and cap and were evaluated for in situ formation of delivery pores. The effect of pore forming agents on the porosity of asymmetric membrane was characterized by scanning electron microscopy, and also by void volume determination of each membrane. Dye-test revealed that the fabricated systems followed osmotic release. Scanning electron microscopy revealed that the porosity depends upon the concentration and type of pore forming agent used. However no significant effect on the thickness and weight variation of asymmetric membrane capsule were observed, but the tensile strength of the film varied with the concentration and type of pore forming agent used. Film with polyethylene glycol-400 as pore forming agent exhibited good tensile strength.