Enhanced penetration strategies for transdermal delivery

Transdermal delivery offers several advantages in drug distribution, including convenience, painless administration, avoidance of first-pass metabolism, and ease of termination. However, the natural protective barriers of the skin, such as the stratum corneum, the topmost layer of skin, limit the systemic absorption of external therapeutics via transdermal delivery. Therefore, extensive application of transdermal delivery in medical treatment has been limited. Over the past few years, many formulation strategies and physical technologies, therefore, have been developed to enhance transdermal delivery. This review summarizes various formulation strategies proposed for transdermal delivery and their application in medical treatment.