A transdermal patch is a topically applied adhesive patch that delivers a medication dose directly into the blood. The patch allows for the safe delivery of a drug to the targeted site, ideally by a permeable layer covering a reservoir of the drug by melting small patches of drug embedded in the adhesive, which is one benefit of transdermal drug delivery over most types of pharmaceutical deliveries, including oral, topical, intramuscular, intravenous, and several others. This can also help heal a damaged body part, improving patient compliance, treatment efficacy, and dose frequency while minimizing the side effects. This review covers the production, methods of evaluation, quality, use of penetration enhancers, and pros and downsides of transdermal patches, as well as the benefits of essential oil as a penetration enhancer. Compared to chemical enhancers, essential oils have shown the ability to break down the stratum corneum layer, allowing drugs to penetrate deeper into the skin. Essential oils are excellent penetration enhancers for the skin. These penetration enhancers are cost-effective, biocompatible, readily available, non-toxic, chemically modifiable, and possibly biodegradable. In this review, attention has been paid to the formulation and evaluation of transdermal patches with the help of SNEDDS (self-nano-emulsifying drug delivery systems) using essential oil as a penetration enhancer, and their future prospects.
Keywords: Transdermal drug delivery system, permeation enhancer, essential oil, SNEDDS, nanocarriers, stratum corneum layer.