1995 Volume 43 Issue 2 Pages 311-314
Delayed-release tablets of diltiazem hydrochloride (DIL) were prepared by using AL-15 type hydroxyethycellulose(HEC) as a matrix material. The tablet consisted of a core tablet containing 30 mg of DIL and an outer shell formed by compressing HEC. The lag time to start the rapid release of DIL was more prolonged in the tablets consisting of a smaller particle size (20-53 and 53-106 μm) of HEC than those of the larger particle size(106-250 and 250-355 μm). However, there was little difference in the release rate of DIL among the two kinds of tablets. The rate of water uptake was greater in the tablets prepared with the larger particle size than those with the smaller particle size. These results suggest that the rate of water uptake seems to be a rate limiting process in setting the lag time. Observation of the surface of the tablets by electron micrograph showed that with the larger the particle size the cavity grows larger and with the smaller the particle size the cavity grows smaller.The lag time was also prolonged with an increase in the amount of HEC. Consequently, the lag time can be controlled optionally by changing the particle size and/or the amount of HEC forming the outer shell. This delayed-release system using HEC will be useful for time-related symptoms which need time-controlled or site-specific delivery in the gastrointestinal tract.
