Currently, oral drug delivery and parenteral drug delivery are used for the treatment of various diseases. In the oral drug delivery system, due to the first-pass metabolism and acidic environment of the gastrointestinal route, the drug exposes to acids and enzymes present in the gastrointestinal tract, which may lead to degradation of the compound, which ultimately results in poor bioavailability of the molecule. On the other hand, the parenteral drug delivery system has its own disadvantages as it is invasive and needs skilled personnel for administration. To overcome these problems, the transdermal drug delivery system is introduced as a novel approach, and recently there is tremendous interest in transdermal drug delivery systems. A transdermal patch is a medicated adhesive patch winch that is placed onto the skin to deliver the appropriate dose of the drug through the skin and directly into the bloodstream. In this, transdermal patches are prepared for drug penetration through the skin layer (Stratum corneum barrier). To avoid the stratum corneum barrier, the microneedle-based transdermal drug delivery system is advantageous. Microneedles are classified into solid microneedles, coated microneedles, dissolving microneedles, hollow microneedles, and hydrogel-forming microneedles. This review provides information regarding transdermal drug delivery, a factor that can affect the transdermal delivery, ingredients used in the formulation of TDDS, drug penetration, different types of methods for formulations, and some advanced techniques such as microneedles.
INTRODUCTION:Recently, there is growing interest in the novel drug delivery system for existing drug molecules. The novel drug delivery system offers to increased safety and efficiency of a drug molecule and also improves patient compliance. Transdermal drug delivery systems (TDDS) are self-contained and discrete dosage forms. Another advantage of the TDDS is that the dose is reduced as compared to the oral route of drug delivery 1 .