OBJECTIVETo prepare the gastric retenting and chronopharmacologic drug delivery tablets containing sinomenine hydrochloride as a model drug, evaluate the effects of the coating layers formulation and technics on drug release behavior, and to elucidate the mechanism of drug release based on obtained results.

METHODThe gastric retenting and chronopharmacologic drug delivery tablets were prepared by press-coated technics. The types of disintegrants were chosen according to the expanding rate and the lag-time. The effects of formulation and technics of coating layer on the release characteristic of the drug were investigated by dissolution testing. The mechanism of drug release was proved by erosion test.

RESULTThe tablets had typical chronopharmacologic drug delivery properties with a lag time followed by a rapid release phase. CMS-Na was selected as the disintegrant. The lag-time was prolonged with the increase of the ratio of HPMC/carrrageenan and the amount of matrix material in coating layer. The compressing pressure and preparation method of coat material had minor influence on the lag-time of the tablets. Coating layer erosion and tablet core swelling were involved in the mechanism of drug release.

CONCLUSIONThe tablets had typical chronopharmacologic drug delivery properties. A suitable lag-time can be achieved by adjusting formulation of coating layer to meet the requirement of chronotherapy.