penetration enhancement

Transdermal absorption of the drugs are controlled primarily by physiochemical property of  stratum corneum.Intercellular lipid domain and lipoprotein gel offers major resistance to penetration of drugs through stratum corneum to deep into epidermis. Penetration enhancement techniques are designed to modify the physiochemical properties of stratum corneum and in some to deliver drugs by piercing the skin to bypass skin barrier. Skin penetration enhancement techniques have been developed to improve bioavailability and increase the range of drugs for which transdermal delivery is a viable option. Various chemical techniques like ion pairs, medical tattoos,prodrug administration, Inclusion of penetration enhancers, Metered dose transdermal spray etc. along with some  physical method of transdermal delivery including Iontophoresis,Electro-osmosis,Ultrasound,laser radiation etc. are reviewed in this article. Key words: Transdermal delivery, stratum corneum, penetration enhancement