Study on absorption and in vitro release properties of diclofenac sodium on acid-treated and heat-treated attapulgite clay

Effects of the concentration of acid-treated, heated temperature and absorption time on adsorption and in vitro release properties of attapulgite clay for diclofenac sodium were studied. The results showed that the adsorption ratio of acid-activated attapulgite clay for diclofenac sodium increased evidently with the increase of HCl concentration from 0 to 12mol/L. The adsorption ratio of nature attapulgite clay for diclofenac sodium was only 19.7%, however, the attapulgite clay treated with 12mol/L HCl increased to 62.4%. The cumulative dissolution of diclofenac sodium on acid-treated attapulgite clay decreased with the increase of absorption amount. The absorption ratio of heat-treated attapulgite clay for diclofenac sodium increased from 100℃ to 300℃, and then decreased with further increasing heated temperature, and the cumulative dissolution of diclofenac sodium on heat-treated attapulgite clay showed the same tendence. The absorption ratio and cumulative dissolution of diclofenac sodium increased with increasing of absorption time before 4h, and tended to steady after 6h. The in vitro release profile of diclofenac sodium from absorbent product followed Higuchi kinetics.