Abstract
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.
Highlights
Transdermal delivery systems (TDSs) are designed to provide a controlled and prolonged delivery of the drug substance across the skin and into the systemic circulation [1,2]
We aimed to investigate the effect of three adhesive matrices, including silicone, PIB, and acrylate on the performance characteristics of TDSs
While for the selection of adhesive matrix many factors are considered, including solubility, adhesion properties, and compatibility of the adhesive matrix with the drug [39], the permeation and release profile of the active from each matrix should be taken into consideration in early development stages as we showed low solubility in a matrix does not necessarily translate into a lower flux; rather, the matrix itself plays an integral role in drug release rate regardless of loading and saturation solubility
Summary
Transdermal delivery systems (TDSs) are designed to provide a controlled and prolonged delivery of the drug substance across the skin and into the systemic circulation [1,2]. TDS can be generally categorized into matrix-type and reservoir-type delivery systems. Drug in adhesive (DIA) systems are a type of matrix systems in which the drug is dissolved or dispersed in a polymeric matrix, which is layered between the backing membrane and a release liner [4,7]. In this design, pressure-sensitive adhesives (PSAs) are used as the matrix to hold the drug and control its delivery rate in addition to fulfilling their adhesion function [2,8]. Pressure-sensitive adhesives are viscoelastic materials that adhere to a substrate upon applying slight external pressure, exert strong holding force, and leave no residue after removal from a smooth surface [2,9]
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