Design and evaluation of a two-layer floating tablet for gastric retentionusing cisapride as a model drug

A new kind of two-layer floating tablet for gastric retention (TFTGR) with cisapride as a model drug was developed. The in vitro drug release was dete rmined, and the resultant buoyancy and the time-buoyancy curve were plotted . Because of the sodium bicarbonate added to the floating layer when immers ed in simulated gastric fluid (SGF) the tablet expands and rises to the sur face, where the drug is gradually released. The in vitro drug release of th is kind of two-layer dosage was controlled by the amount of hydroxypropylme thylcellulose (HPMC) in the drug-loading layer. Generally, the more HPMC, t he slower the drug releases. Because cisapride has greater solubility in SG F than simulated intestinal fluid (SIF), its in vitro drug dissolution in S GF is faster than in SIF, One of the distinguishing characteristics of this kind of tablet is the separate regulation of buoyancy and drug release. Th e idea developed in this experiment can be used as a general model for the design of other tablets for gastric retention.