Glutaraldehyde cross-linked chitosan microspheres for controlled release of centchroman

Glutaraldehyde cross-linked chitosan microspheres were prepared for controlled release of centchroman, a nonsteroidal contraceptive. The cross-linked microspheres with low-molecular-weight (LMW) chitosan (260 kg mol(-1)) have shown maximum degree of swelling (287 wt %) but were found to be poor in loading and release behavior for centchroman. The microspheres with medium-molecular-weight (MMW) chitosan (1134 kg mol(-1)) have shown 250 wt % degree of swelling and 37.5 wt % loading of centchroman, but microspheres with high-molecular-weight (HMW) chitosan (2224 kg mol(-1)) have shown a low degree of swelling (150 wt %) and centchroman loading (30 wt %). The microspheres with MMW chitosan have released 82 wt % of loaded centchroman in a controlled release manner within a period of 70 h in comparison to low- (260 kg mol(-1)) and high-MW (2224 kg mol(-1)) chitosan microspheres. The chitosan microspheres with 62 wt % degree of deacetylation (DDA) were more efficient in the controlled release of centchroman in comparison to chitosan microspheres with low (48 wt %) and high-DDA (75 wt %). The fractional release of centchroman (M-t/M-infinity) from chitosan microspheres was used to predict the mechanism of drug release and to determine the diffusion constant (D) of centchroman. (C) 2007 Elsevier Ltd. All rights reserved.