Amino acid derivatives as transdermal permeation enhancers.

Transdermal permeation enhancers are compounds that temporarily decrease skin barrier properties to promote drug flux. In this study, we investigated enhancers with amino acids (proline, sarcosine, alanine, β-alanine, and glycine) attached to hydrophobic chain(s) via a biodegradable ester link. The double-chain lipid-like substances displayed no enhancing effect, whereas single-chain substances significantly increased skin permeability.