SUSTAINED-RELEASE EFFECT OF THE DIRECT CO MPRESSED TABLET BASED ON CHITOSAN AND NA ALGINATE

In the dissolution test of tablets prepared by the direct compression of chitosan with 10% sodium alginate (NaAlg), the release of theophyll ine was extended independently of the medium pH. The drug release mech anism of the tablet was investigated by measuring the dissolution beha vior of such excipients as chitosan and NaAlg. It was shown that at th e lower pH the drug release was accompanied with the dissolution of ch itosan, while at the neutral pH it was controlled by the gelation and dissolution of NaAlg. Further more by the oral administration of the t ablet to beagle dogs, the sustained release of theophylline was also c onfirmed by some bioavailability parameters. Thus the chitosan tablet with 10% NaAlg was expected to be a pH-independent sustained release d osage form.