Lyophilized Polymer Matrices for Improved Transdermal Drug Delivery

Transdermal matrices when subjected to dry in air at room temperature usually contain uneven drug distribution due to migration of drug molecules during moisture evaporation.Such matrices do not show uniform release of the drug. The technique of lyophilization can successfully be used for the preparation of polymer matrices which minimize the possibilities of uneven drug distribution in matrix. The uniformity in drug distribution pattern also proved to be useful in reproducing the release kinetics and the channelised drug matrix resulted from the lyophilization further adds to the release rate of drug. Transdermal system(s) bearing captopril were developed using a low temperature casting method and aqueous based polymers viz., eudragit RL-100 and polyvinyl pyrrolidone (PVP). The developed system(s) were subjected to an in vitro characterization study. The results were compared with the transdermal systems of the same composition prepared at room temperature. The study revealed that the system(s) prepared using the low temperature casting method performed better in comparison to those prepared at room temperature. The developed system(s) followed zero order release kinetics.