1. Global Research & Development, Avon Products, Inc., Suffern, New York, USA
2. ^*Wellman Laboratories of Photomedicine, Massachusetts General Hospital and Department of Dermatology, Harvard Medical School, Boston, Massachusetts, USA

Correspondence: Gopinathan K. Menon, Ph.D., Avon Products, Inc., Avon Place, Suffern, New York 10901, USA. Email: gopi.menon@avon.com

¹Present address: Johnson & Johnson Consumer Products, 199 Grandview Road, Skillman, New Jersey, USA

Received 30 August 2002; Revised 24 January 2003; Accepted 20 February 2003; Published online 30 June 2003.

Abstract

Photomechanical waves (high amplitude pressure transients generated by lasers) have been shown to permeabilize the stratum corneum in vivo and facilitate the transport of macromolecules into the viable epidermis. The permeabilization of the stratum corneum is transient and its barrier function recovers. Sites on the volar forearm of humans were exposed to photomechanical waves and biopsies were obtained immediately after the exposure and processed for electron microscopy. Electron microscopy showed an expansion of the lacunar spaces within the stratum corneum lipid bilayers but no changes in the organization of the secreted lamellar bodies at the stratum corneum–stratum granulosum boundary. The combination of photomechanical waves and sodium lauryl sulfate enhances the efficiency of transdermal delivery and delays the recovery of the barrier function of the stratum corneum. Electron microscopy from sites exposed to photomechanical waves and sodium lauryl sulfate showed that the lacunar spaces expanded significantly more and the secreted lamellar bodies also appeared to be altered. In either case, there were no changes in the papillary dermis. These observations support the hypothesis that the photomechanical waves induce the expansion of the lacunar spaces within the stratum corneum leading to the formation of transient channels.