Drug release from poly(acrylic acid) grafted poly(vinylidene fluoride) membrane bags in the gastrointestinal tract in the rat and dog

Stomach-specific drug delivery systems would be of value in treating diseas es of the upper gastrointestinal tract. The present study measured in vitro and in vivo drug release from pH-sensitive membrane bags, constructed of p oly(acrylic acid) grafted onto a poly(vinylidene fluoride) (PAA-PVDF) membr ane, which might be suitable for stomach-specific drug delivery. The used m odel drugs were propranolol-HCl (1.0 mg) and FITC-dextran MW 4400 (1.0 mg). Drug release in vivo was studied by inserting membrane bags into the stoma ch and proximal duodenum of anesthetized rats and dogs. At 30 and 180 min, the bags were removed from the lumens and residual drug content was determi ned. The release of either propranolol or FITC-dextran were comparable in b oth stomach and duodenum, showing that in vivo drug release did not depend on environmental pH. In vitro results suggested that these results could be explained by interactions between PAA and the mucous layers of the stomach and duodenum. (C) 2000 Elsevier Science B.V. All rights reserved.