ABSTRACT:
It is remarkable fact that, in the new millennium Transdermal drug delivery system (TDDS) still account for more than 40% dosages forms administered to man. The principle reason for their continued popularity include their ease of manufacturer, their convenience of dosing and their stability compared with solid, liquid and semisolid presentation. TDDS delivery of drug through skin to the systemic circulation provides a convenient route of administration for a variety of clinical Indications. In TDDS wider range of drug is limited due to significant barrier to penetration across the skin, which is associated with outer most stratum cornium layer of epidermis. Various approaches are utilized for enhancement of penetration to bypass the stratum cornium such as optimisation of drug and vehicle properties, by stratum cornium modification, electrically based technique; Structure based technique and velocity-based technique. This review highlights physical and chemical parameters of various methods used in TDDS.