Chemical penetration enhancers (CPEs), which are also referred to as sorption promoters or
accelerants have several advantages in transdermal drug delivery. These are painlessness, noninvasiveness
and the capacity to increase in transdermal flux in comparison with passive diffusion. Several
investigators have used a number of chemical enhancers to demonstrate these important properties.
Studies have also been carried out to have a better understanding of the mechanisms of penetration enhancement.
It has been postulated that these compounds can enhance transdermal drug delivery by
perturbing the stratum corneum, increasing partition coefficient or increasing solubility. In this paper,
several compounds used in facilitating percutaneous penetration of drugs have been described and the
potential of using them for transdermal drug delivery highlighted. Special attention has been paid to cell-penetrating proteins
(protein transduction domains) as well as skin penetrating peptides. Ironically, these are substances that possess high
molecular weight themselves but are capable of creating pores through which drugs can penetrate into and through the
skin. Concerns relating to irritation and cytotoxicity and efforts to overcome them are discussed.
Keywords: Drug delivery, penetration enhancers, peptides, transdermal.
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