ABSTRACT
Push versus Pull Mechanisms for Penetration Enhancers .............................................................. 52 Basis for Prodrugs as Penetration Enhancers.................................................................................. 52 Acyl versus Soft Alkyl Promoieties .................................................................................................. 54 Mechanisms for Penetration Enhancement ..................................................................................... 54
Decrease Crystal Lattice Energy by Masking Hydrogen Bond Donor Functional Groups ........................................................................................................ 54
Incorporation of Water Solubility Enhancing Functional Groups into the Promoiety .................................................................................................................... 59
Conclusion ........................................................................................................................................ 62 References......................................................................................................................................... 63
A penetration enhancer is by definition anything that is used to improve the delivery of a chemical substance across some chemical barrier. For the present purposes, we are interested in defining chemical, as opposed to physical-, electrical-, or mechanical-based approaches to improving the delivery of a drug into or through the skin: improving dermal or transdermal delivery, respectively, or collectively improving the topical delivery of a drug. These same chemical-based approaches could also be used to improve the delivery of cosmeceuticals but there the task would be specifically only for improving their dermal delivery.
