Gs. Macleod et al., An in vitro investigation into the potential for bimodal drug release frompectin/chitosan/HPMC-coated tablets, INT J PHARM, 188(1), 1999, pp. 11-18
The influence of disintegrant on the water uptake and subsequent disintegra
tion force developed was investigated in a simple tablet formulation. The r
esults indicated that a reasonable correlation existed between water uptake
and disintegration force for the disintegrants screened with cross linked
polyvinyl pyrrolidone (PVP XL) showing a proportionally higher disintegrati
on force for the amount of water imbibed. Two tablet formulations, intended
to promote accelerated drug release in the colon, were prepared, with and
without PVP XL, and film coated with a mixture of pectin, chitosan and HPMC
. The two systems showed different drug release rates which were influenced
by the pH of the dissolution medium. In the presence of pectinolytic enzym
e, drug release was faster when compared to release in buffer alone for bot
h systems although the mechanism differed for each. Drug release in simulat
ed gastrointestinal conditions showed a bimodal profile with the increased
drug release rate being triggered by the action of pectinolytic enzymes. (C
) 1999 Elsevier Science B.V. All rights reserved.