Topical drug delivery in humans with a single photomechanical wave

Purpose. Assess the feasibility of in vivo topical drug delivery in humans with a single photomechanical wave. Methods. Photomechanical waves were generated with a 23 nsec Q-switched ruby laser. In vivo fluorescence spectroscopy was used as an elegant non-invasive assay of transport of 5- aminolevulinic acid into the skin following the application of a single photomechanical wave. Results. The barrier function of the human stratum corneum in vivo may be modulated by a single (11 0 nsec) photomechanical compression wave without adversely affecting the viability and structure of the epidermis and dermis. Furthermore, the stratum corneum barrier always recovers within minutes following a photomechanical wave. The application of the photomechanical wave did not cause any pain. The dose delivered across the stratum corneum depends on the peak pressure and has a threshold at ~ 350 bar. A 30% increase in peak pressure, produced a 680% increase in the amount delivered. Conclusions. Photomechanical waves may have important implications for transcutaneous drug delivery.