AN INVITRO INVESTIGATION INTO THE SUITABILITY OF PH-DEPENDENT POLYMERS FOR COLONIC TARGETING

The effect of a pH-dependent polymer coating, Eudragit S, on its ability to protect a model drug and control its release from rapidly disintegrating tablets has been examined in vitro. Conditions were chosen to mimic those likely to occur during transit from the mouth to the colon. Dissolution was affected by coating thickness and pH. At a given pH, the nature of the buffer system dramatically affected dissolution and disintegration. Profiling experiments involving pH changes and mimicking the extremes of conditions prevailing in vivo indicated that release of drug may commence in the duodenum or not at all.