Drug release speed is determined by the complex relationships between the polymer matrix used, the layer thickness, membrane permeability, if any, and the content and concentration of drug. When API is suspended in either a reservoir or inert polymer matrix, it is important to assess its physical form, drug particle size, and the formation of agglomerates. Gateway Analytical has developed a method using Raman Chemical Imaging to characterize multilayer polymer systems such as transdermal patches including the heterogeneity of the Active Pharmaceutical Ingredient (API) in reservoir transdermal patches.
https://info.gatewayanalytical.com/transdermal-patch-app-form