Skin ablation by physical techniques for enhancing dermal/transdermal drug delivery

Physical ablation can be an effective drug-permeation-enhancement strategy forpromoting drug delivery into or across the skin. The control- led ablation of the stratum corneum (SC), the predominant barrier for drug absorption, is achieved by ablative techniques incorporating the use of lasers, microneedles, microdermabrasion, and radiofrequency. It has been demonstrated that ablative approaches used for enhancing drug transport provide some advantages, including increased bioavailability, fast treatment time, and quick recovery of SC integrity. In recent years the concept of using ablative techniques to treat skin has attracted increasing attention. This review describes recent developments using skin-ablative approaches for drug-permeation enhancement. This review systematically introduces the concepts and enhancement mechanisms of variousphysical ablative methods, highlighting the potential of these techniques for greatly increasing drug absorption via the skin. In this review, we principally focus on the small-molecule drugs approved by the US FDA for clinical use. The macromolecules and nanoparticles as the model permeants are not the focus of this review since they have not until recently been extensively applicable in clinical situations. Finally, future developments and trends are anticipated.