Abstract
Transdermal drug delivery system (TDDS) is a novel approach for delivering drugs across the skin. Most of the drugs are administered orally and are found not to be as effective as expected. To surmount these problems, TDDS was emerged and eventually these are having many advantages over other conventional drug delivery system. The potential of using the intact skin as the route of drug administration to the human body has been recognized for several decades and used as a site of drug administration successfully for both local and systemic effects, however, stratum corneum of skin act as barrier to drug penetration. This is overcome by the use of penetration enhancing techniques which increases the penetration ability and bioavailability of drugs depending upon various factors. Different types of transdermal patches have been formulated and used for TDDS. Over the years, the number of patches formulation has not increased much and formulation procedure is almost same. Many methods have been used in enhancing TDDS to further increase the permeation, bioavailability and therapeutic efficacy of drug. This review article describes briefly about the advantages and disadvantages of TDDS, skin, transportation through the skin, factors affecting permeability, permeation enhancers. Classification, components, types and preparation of TDDS is also discussed. Evaluation methods and recent enhancement techniques are also discussed in this review article. The overall study of TDDS is covered in this review article and this may lead to get lot of interests and topic of research in researchers in future.