Abstract
Now a day about 74% of drugs are taken orally and which are not as effective as desired. To overcome such problems transdermal drug delivery system (TDDS) was developed. Delivery of a drug through the skin to achieve a systemic effect of a drug is commonly known as transdermal drug delivery and differs from conventional topical drug delivery. Transdermal drug delivery system (TDDS) are dosage forms involves drug transport to viable epidermal and/or dermal tissues of the skin for local therapeutic effect while a very major fraction of a drug is transported into the systemic blood circulation. The adhesive of the transdermal drug delivery system (TDDS) is critical to the safety, efficacy and quality of the product. Topical administration of therapeutic agents offers many advantages over conventional oral and invasive methods of drug delivery. Many important advantages of transdermal drug delivery (TDDS) are limitation of hepatic first pass metabolism, enhancement of therapeutic efficiency and the maintenance of steady plasma level of the drug. Thus, this article provides an overview of types of transdermal patches, methods of preparation and its physicochemical methods of evaluation. KEYWORDS: Transdermal drug delivery system (TDDS), Topical drug delivery, Systemic blood circulation.