HERBAL PENETRATION ENHANCERS AND TERPENES: AN OVERVIEW

The delivery of drug through skin offers many advantages over the other routes of drug administration. However the protective upper layer of the skin, stratum corneum behaves like a challenging barrier for the penetration of majority of drugs. Use of herbal penetration enhancers which penetrate into human skin and shows reduction in the barrier resistance is widely accepted in transdermal drug delivery. The mechanism behind herbal enhancers involves the disruption of intercellular lipid and/ or keratin domains as it enhances drug partitioning into tissue and also improves the solubility of drug. Now a days, many herbal penetration enhancers are included in GRAS (generally recognised as safe substances) list and they possess low side effects and irritancy in comparison with synthetic chemicals like solvents, azones or surfactants etc. Previous reports revealed that the usage of herbal skin permeability enhancers also termed as bioenhancers in particular terpenes may be beneficial over the synthetic/isolated enhancers while comparing their safety and efficacy profile during transdermal and percutaneous delivery process.