Matrix-type transdermal delivery systems (TDS) are comprised of the drug dissolved or dispersed in a pressure-sensitive adhesive (PSA) matrix and are designed to provide a controlled delivery through the skin and into systemic circulation. PSAs can directly affect the permeation, release, and performance characteristics of the system. In this study we aimed to design and characterize transdermal delivery systems formulated with lidocaine-as the model drug-loaded in different PSAs, including silicone, polyisobutylene (PIB), and acrylate. TDS containing lidocaine at its saturation points were prepared by the solvent casting method. In vitro permeation studies across dermatomed porcine ear skin were performed using Franz diffusion cells. In vitro release studies were carried out using USP apparatus 5 (paddle over disk). The cumulative amount permeated from the acrylate was significantly higher than silicone and PIB. The acrylate TDS contained a ten times higher drug amount than silicone TDS, but the permeation flux was only two folds higher. Results also showed the release of drug does not linearly correlate to saturation, as the silicone TDS comprising of the lowest amount of drug loading, showed the highest percentage release indicating the choice of PSA affected the drug release and permeation profile.
Keywords: in vitro permeation; in vitro release; lidocaine; matrix type; pressure-sensitive adhesive; transdermal delivery systems.