Effects of attapulgite on sustained release performance of chitosan/sodium alginate microspheres

Attapulgite (ATP) was composited with sodium alginate (SA) to improve the sustained release properties of SA. Attapulgite/sodium alginate/chitosan composite microspheres (ASCM) were prepared by complex coacervation using ATP/SA composites as the core material of the microspheres and chitosan (CS) as the coating material. The effects of ATP on swelling, drug loading and sustained release of ASCM were investigated with diclofenac sodium (DS) as a model drug, and the optimum amount of ATP were obtained. The results show that ASCM exhibits excellent swelling and sustained release ability. Compared with sodium alginate/chitosan microspheres (SCM), the cumulative release of DS from ASCM (20%(wt) ATP/SA (w/w)) decreased from 58.8% to 38.7% after 2 h in phosphate buffer solution at pH 6.8. The study of drug release kinetics shows that the releasing processes are better fitted by first-order release kinetic model. The incorporation of ATP in microspheres improves the releasing performance of SA, and ASCM can be used as a potential sustained release carrier.