A transdermal patch is a topically applied dosed 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 in the healing of a damaged body part, to improve patient compliance, treatment efficacy, and dose frequency while minimizing side effects. This review covers the production, methods of evaluation, qualities, 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 drawn towards the formulation and evaluation of transdermal patches with the help and applications of SNEDDS (Self Nano Emulsifying Drug Delivery System) using essential oil as a penetration enhancer and their future prospective.

The purpose of this study was to prepare, optimize and evaluate self nano emulsifying drug delivery system (SNEDDS) containing 18- β glycerrhetinic acid which enhances the dissolution profile or bioavailability of the drug in comparison to pure suspension of 18- β glycerrhetinic acid.18- β glycerrhetinic acid loaded SNEDDS having geranium oil as oil phase, tween 80 as a surfactant, and dimethyl sulfoxide (DMSO) as co-surfactant were prepared using pseudo ternary phase diagram and Box-Behnken experimental design was used to optimize the different formulations. Optimized formulations were characterized for self-emulsifying time, globule size, zeta potential, and drug release. The mean droplet size and PDI of the optimized formulation were found to be in a variation of 93.42 nm and 0.401 respectively. FTIR data showed no physicochemical interaction between excipients and drug. The encapsulation efficiency of optimised 18- β glycerrhetinic acid SNEDDS was found 80.12±1.52% , % transmittance was found 99.34±0.134% and the viscosity of all the formulations was found 0.8872 cp. Three-dimensional response surface plots and two-dimensional contour plots of the responses across the selected factors were constructed that explained the relationship between the independent and dependent variables. Release kinetics was calculated by using KinetDS3.0. It was concluded that prepared formulations were formulated with approximately desired mean droplet size confirmed by Box- Behnken experimental design as well as properly optimized and characterized.