Colon-specific Study Of Diclofenac Sodium Coated Tablets,

In this study diclofenac sodium was used as a model drug and incorporated into tablets (diameter 6mm). The potential of water-insoluble polymers ethylcellulose (EC) and cellulose acetate (CA) as coating materials has been investigated.The behavior of colon-specific delivery tablets coated with EC has been evaluated in vitro. Three parameters were critical in lowering the release of diclofenac sodium, the decreasing of the concentration of the pore former, the increasing of the coat weight and the swelling agent. Moreover, osmotic pressure promoting agent, coating solvent, overall core weight, different drug and core diameter were also important for the drug release. Whereas other factors: rotation, dissolution medium had no effect on drug release. Since the application of polymer aqueous dispersion coating has drown much attention during the past decade, we selected BC aqueous-dispersion: Surelease~ as coating material. Tablets coated with Surelease containing certain pore former can also be design to establish a lag time for a period of 5 h. In this work, the effect of different pore former, the concentration of pore former, curing time and coat weight has been studied through orthogonal experimental design. On the other hand, CA was also prepared as coating material for colon-specific delivery system of diclofenac sodium. The process3factors that affect the drug release character were studied. By analyzing the experimental data, the drug release mechanism was proposed and a novel colon-specific formulation was prepared.To evaluated the correlation between the in vitro diclofenac sodium release and in vivo diclofenac sodium absorption. The pharmarcokinetics of the diclofenac sodium tablets with pore former of 10%, coat weight of 5% and with pore former of 15%, coat weight of 7.3% were studied at the basis of formulation-screening. The result indicated that DCF was released at a maximum rate between 3.8 and 6 h in vivo which corresponded to the colonic arrival time as expected.The stability of this kind of the coating tablet through the formulation-optimization was investigated. The results showed that humidity and temperature have great effect on physical stability of colon-specific tablets whereas light had not effect.The article provided the technologies available for trigger colon-specific drug delivery using time as the release trigger.