Abstract
Background: Transdermal patch is a transdermal delivery system that can overcome problems in conventional drug administration, such as oral drug administration. Patches can provide controlled drug release and have advantages over oral administration, such as avoiding first-pass metabolism, increasing drug bioavailability, avoiding adverse effects on the gastrointestinal (GI) tract, minimizing patient variability, maintaining a constant drug in plasma, and providing a stable therapeutic effect. The effectiveness of a patch is determined by the drug's ability to release from the patch matrix and penetrate the stratum corneum. The methods used to make the patches are divided into single layer, multi-layer, reservoir system, and matrix system patches. The basic components of a patch are polymer matrix, membrane, drug, permeation enhancer, pressure-sensitive adhesives, backing film, release liner, and plasticizer.
Methods of review: This review refers to several previously published data regarding physical characteristics and transdermal drug release. This review also explains the patch as a transdermal drug delivery system.
Conclusion: This review focuses on patch analysis methods after the manufacturing process, such as physical characteristics test, in vitro drug release test, in vitro skin permeation test, skin irritation test, and stability test, as well as some explanations related to transdermal drug delivery system.

Key words: Patch, transdermal, characteristics, in vitro release, in vitro skin permeation