Permeation of Sulfonylureas through Cellulose and Dimethylpolysiloxane Membranes

Abstract

The permeation of sulfonylureas through cellulose and dimethylpolysiloxane membranes was investigated as part of a series of pharmaceutical studies on sulfonylureas. In the case of cellulose membrane, the permeability decreased with increase in the molecular volume of sulfonylureas. The activation energy of permeation was close to that of diffusion of usual organic medicinals in water. The effect of pH on the permeation was negligibly small under the conditions used in this study. These results suggested that the permeation of sulfonylureas through cellulose membrane proceeds by diffusion through pores. In the case of dimethylpolysiloxane membrane, at pH 2, the permeability constants, P, of tolbutamide, chlorpropamide, glyclopyramide and tolazamide were 16.15, 5.13, 2.33 and 0.95×10^-8 cm²·sec^-1, respectively, and the diffusion constants of the four drugs were all calculated to be (14.92±1.39)×10^-7 cm²·sec^-1. The results for tolbutamide indicate that the rate of permeation of sulfonylureas through the membrane is pH-dependent because only the undissociated species can permeate through the membrane.