Osmotically controlled drug delivery systems produced from organic solutions and aqueous dispersions of cellulose acetate

Abstract

The use of aqueous colloidal dispersions of cellulose acetate instead of organic solutions is proposed as an alternative way to obtain osmotic tablets. At the same plasticizer level, the semipermeable membranes produced from latices were more permeable to water and swelled to a greater extent than those prepared from organic solutions. Consequently, the release rate of the model drug potassium chloride from coated tablets produced from aqueous dispersions was higher and the time delay before constant release was shorter. Generally, the permeability and the solute release rate varied over a wide range, depending on the physico-chemical properties and concentration of plasticizer and on the coating conditions (coating temperature, rate of coating and drying duration). Plasticizers with low vapor pressure gave more permeable films. The mechanical properties of the membranes were also examined and strong films could also be produced from aqueous dispersions, despite the mechanism involved in the formation of such films.