Carboxymethyl modification of Cassia obtusifolia galactomannan and its evaluation as sustained release carrier

Carboxymethylation of Cassia obtusifolia galactomannan was carried out by Williamsons synthesis. Modification of galactomannan was confirmed by Fourier-transform infrared and ¹H-Nuclear magnetic resonance spectroscopy. The degree of carboxymethyl substitution was found to be 1.69. Carboxymethylation was observed to increase the powder flow, solubility and swelling, while decrease the viscosity and alter the compression characteristics from elastic to plastic. The results of X-ray diffraction and scanning electron microscopy studies indicated increase in degree of crystallinity. The modified gum was used for preparing diclofenac sodium-loaded, Ca²⁺-gelled beads which were coated with gastroresistant Eudragit-L100. The formulation of beads was optimized using central composite experimental design. The optimal formulation of beads contained carboxymethylated Cassia galactomannan-2.85%,w/v and calcium chloride -15%,w/v, which showed yield -185.4%, entrapment-95.41% and release of 93.32% of diclofenac over 24 h. The release of diclofenac followed first-order kinetics by Super case-II transport. Thus, carboxymethyl Cassia galactomannan appears suitable for sustained drug delivery.