J. Rich, P. Kortesuo, M. Ahola
Jan 5, 2001
Citations
1
Influential Citations
22
Citations
Quality indicators
Journal
International journal of pharmaceutics
Abstract
The purpose of this study was to develop a biodegradable polymeric carrier system for toremifene citrate based on epsilon-caprolactone/DL-lactide copolymers and silica xerogel. The effect of the molecular weight of poly(epsilon-caprolactone-co-DL-lactide) affecting the release rate of toremifene citrate from copolymer/silica xerogel composites was evaluated by in vitro dissolution study. Lower and higher molecular weight copolymers (LMW 60000 g/mol and HMW 300000 g/mol) were used in the devices. Drug release was compared from the (copolymer/drug) matrix device and the (copolymer/drug impregnated silica xerogel) composite device. Hydrolysis of the copolymer devices was evaluated by water absorption, weight loss and change of molecular weight by size exclusion measurements (SEC). Controlled release of toremifene citrate was obtained from both matrix and composite devices and the release rate was most affected by the initial molecular weight of the copolymer. Throughout the study better results were obtained with LMW devices, since drug release was steady for nearly 1 year and no changes in the release rate were observed. The drug release was diffusion controlled from both LMW matrix and composite devices. Incorporation of toremifene citrate into the silica xerogel was found to enhance the drug release rate. The copolymer matrices degraded by random hydrolytic chain scission and, unexpectedly, HMW P(CL/LA) degraded faster than LMW P(CL/LA). The release of toremifene citrate from HMW devices was not complete before the second stage of polymer degradation began.