Gamma-scintigraphic study of the gastrointestinal transit and in vivo dissolution of a controlled release diclofenac sodium formulation in xanthan gum matrices

A xanthan gum matrix controlled release tablet formulation containing diclo fenac sodium was evaluated in vitro acid was found to release the drug at a uniform rate. The gastrointestinal transit behaviour of the formulation as determined by gamma scintigraphy, using healthy male volunteers under fast ed and fed conditions, indicated that gastric emptying was delayed with foo d intake. In contrast, the small intestinal transit remained practically un changed under both food statuses. Therefore, the delay in caecal arrival ob served in the fed state can be attributed to the delay in gastric emptying. Rate of diclofenac sodium absorption was generally higher in the fed state compared to the fasted state, however the total amount absorbed under both food statuses remained practically the same. The rate of in vivo dissoluti on of the drug in the fed state was faster compared to that in the fasted s tate. Thus, at the time of caecal arrival, in vivo dissolution was complete in the fed state, unlike in the fasted state, where almost 60% of the drug was delivered to the colon. (C) 2000 Elsevier Science B.V. All rights rese rved.