Transdermals as Novel Drug Delivery System: An Review
Skin penetration enhancement techniques have been developed to improve bioavailability and increase the range of drugs for which topical and transdermal delivery is a better therapeutic response. Transdermal drug delivery systems (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 drug is transported into the systemic blood circulation. Several important advantages of transdermal drug delivery are limitation of hepatic first pass metabolism, enhancement of therapeutic efficiency and maintenance of steady plasma level of the drug. Skin of an average adult body covers a surface of approximately 2 m2 and receives about one-third of the blood circulating through the body. Skin is an effective medium for absorption of the drug takes place and enters the circulatory system. The adhesive of the transdermal drug delivery system 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. Enhancement via modification of the stratum corneum by hydration, chemical enhancers acting on the structure of the stratum corneum lipids and keratin, partitioning and solubility effects are also discussed. Thus the aim of this review work is to focus on the recent innovations in Transdermal Drug Delivery Systems which can be a platform for the research and development of pharmaceutical drug dosage form for Transdermal Drug Delivery. The main disadvantage to transdermal delivery systems stems from the fact that the skin is a very effective barrier as a result, only medications those molecules are small enough to penetrate the skin can be delivered in this method.