Vol. 2, Issue 6 (2013)

Author(s):
Debjit Bhowmik, KP.Sampath Kumar

Abstract:
Transdermal patches delivers drug across skin to the circulatory system to achieve therapeutic effects  or to provide local effect of drugs. As one of the fastest growing drug administration routes, it has several advantages compared to other traditional delivery methods: controlled release rate, more stable plasma concentration, noninvasive administration, less frequent dosing, and simple application without professional medical aids. The protective function of human skin imposes physicochemical limitations to the type of permeant that can traverse the barrier. For a drug to be delivered passively via the skin it needs to have adequate lipophilicity and also a molecular weight <500 Da. These requirements have limited the number of commercially available products based on transdermal or dermal delivery. Various strategies have emerged over recent years to optimize delivery and these can be categorized into passive and active methods. The passive approach entails the optimization of formulation or drug carrying vehicle to increase skin permeability. Passive methods, however do not greatly improve the permeation of drugs with molecular weights >500 Da. Magnetophoresis is a method of enhancement of drug permeation across biological barriers by the application of magnetic field. The general acceptability of transdermal products by patients is very high, which is also evident from the increasing market for transdermal products. The transdermal drug delivery market, worth $12.7 billion dollars in 2005, is expected to reach $32 billion in 2015.