Controlled drug release through carboxymethyl‐chitosan/poly(vinyl alcohol) blend films

Carboxymethyl‐chitosan (CMCS)/poly(vinyl alcohol) (PVA) blend film was studied for an application as a coating material in the site‐specific drug delivery system. Films were prepared by blending varying amounts of 4 wt% CMCS with 4 wt% PVA, casting and drying at 50°C for 24 h. The cross‐sectional SEM micrograph of the film revealed that an increase in the amount of CMCS in the blend resulted in the film surface less smooth in the dry state and the network less uniform and more porous in the hydrated state, which became appreciable at 50%. The inclusion of CMCS in the blend also made the swelling of the films pH‐dependent, and lead to an increase in the degree of swelling with pH increase. When the permeation of three model drugs, salicylic acid, theophyline, and ornidazole, was studied using a static diffusion vessel, it followed a zero‐order kinetics and increased with an increase in the CMCS content in the blend, a decrease in the molecular weight of drug, an increase in the pH of medium, and a decrease in the film thickness. POLYM. ENG. SCI., 47:1373–1379, 2007.