[Sustained-release effect of the direct compressed 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 theophylline was extended independently of the medium pH. The drug release mechanism of the tablet was investigated by measuring the dissolution behavior of such excipients as chitosan and NaAlg. It was shown that at the lower pH the drug release was accompanied with the dissolution of chitosan, while at the neutral pH it was controlled by the gelation and dissolution of NaAlg. Further more by the oral administration of the tablet to beagle dogs, the sustained release of theophylline was also confirmed by some bioavailability parameters. Thus the chitosan tablet with 10% NaAlg was expected to be a pH-independent sustained release dosage form.