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.