Transdermal Permeation Enhancing Potentials of Natural Products

: Skin is a formidable natural barrier that represents the most important obstacle in clinical practices pertaining to the cutaneous administration of exogenous molecules/drugs. As transdermal therapy systems offer a more dependable way of distributing drugs by way of permeation enhancers, it is vital to use tried-and-true augmentation procedures to increase topical bioavailability. The term “permeation enhancers” refers to compounds that can help medications penetrate the skin. Nowadays, skin permeation enhancers from natural origin have gained momentum and came into existence after researchers deciphered the remarkable potential for enhancement of transdermally administered drugs. They are regarded as non-toxic, pharmacologically inactive, non-allergenic, non-irritating, and safe compounds and allow for the transport of a wider range of drug classes through the stratum corneum. This review provides a thorough overview of natural products that can improve the permeation of both hydrophilic and lipophilic compounds by reversibly lowering skin barrier resistance. It then briefly describes their current status in light of structural activity relationship (SAR) studies, which demonstrate significant enhancer activities. This review aimed to highlight the ability of natural skin permeation enhancers to overcome the barriers of skin and demonstrate significant potential in the enhancement of transdermally administered drugs. Manual and electronic databases were used for the systematic search of literature and to extract those from inception up to 2022 using relevant key words. The main focus was to identify and report the natural skin permeation enhancers executing remarkable potential in the improvement of transdermally administered drugs from the published articles. Skin permeation enhancers from various natural sources have been demonstrated and exhibited remarkable potential in promoting the administration of larger groups of medications that are nontoxic, pharmacologically inactive, non-allergenic, non-irritating, and safe through the stratum corneum. This article offers a comprehensive overview of natural chemicals that can reduce skin barrier resistance and promote the penetration of both hydrophilic and lipophilic substances. On the basis of structure activity relationship (SAR) studies that have shown strong enhancer actions, it also provides a brief overview of the condition of natural products at the moment.