Acta Pharm. 50 (2000) 291-301

Original scientific paper  

Effect of different polymers on the release characteristics of carbamazepine from stable controlled-release tablets prepared by the air suspension and wet granulation techniques


Industrial Pharmacy Research Laboratory, School of Pharmacy, Tehran University of Medical Sciences, Tehran 14, Iran
Received March 1, 2000      Accepted October 17, 2000

The purpose of this work was to develop the controlled-release (CR) carbamazepine tablet using ethylcellulose and acrylic resins (Eudragits RSPO and S100) as retardant polymers. Two different procedures have been utilized. In method I, the prepared carbamazepine granules have been coated with different polymers by air suspension (Wurster) technique and then compressed into 24 h CR tablets. However, in method II, a wet granulation procedure was used to prepare the 12 h controlled-release matrix tablets. Both wet granulation and air suspension (Wurster) techniques were found reliable methods for preparation of carbamazepine controlled-release tablets. Triethylcitrate (TEC) has been used as plasticizer in all prepared formulations. The release properties of resulting tablets were evaluated in hydrochloric acid buffer (pH 2.5), acetate buffer (pH 4.5) and phosphate buffers (pH 6.8 and 7.5). The concentration of the polymer was the drug release rate determining factor.
One commercially available brand of carbamazepine CR tablets was included in the study for comparison. The release patterns were analyzed from the standpoint of diffusion-controlled process as well as zero-order and first-order kinetics. The influence of storage conditions (temperature and relative humidity) on the release of carbamazepine from 12 h CR tablets containing Eudragits RSPO+S100 has been evaluated. These tablets were found stable when stored under stress conditions.

Keywords: carbamazepine, drug release, controlled-release, stability, air suspension