Photomechanical transdermal delivery: the effect of laser confinement.
OBJECTIVE
Photomechanical waves can transiently permeabilize the stratum corneum and facilitate the delivery of drugs into the epidermis and dermis. The present study was undertaken to assess the effect of pulse characteristics to the penetration depth of macromolecules delivered into the skin.


METHODS
Photomechanical waves were generated by confined ablation with a Q-switched ruby laser. Fluorescence microscopy of frozen biopsies was used to assay the delivery of macromolecules through the stratum corneum and determine the depth of penetration.


RESULTS
Photomechanical waves generated by confined ablation of the target have a longer rise time and duration than those generated by direct ablation. Confined ablation required a lower radiant exposure (from approximately 7 J/cm(2) to approximately 5 J/cm(2)) for an increase in the depth of delivery (from approximately 50 microm to approximately 400 microm).


CONCLUSIONS
Control of the characteristics of the photomechanical waves is important for transdermal delivery as they can affect the depth of drug penetration into the dermis.
Lee
S
S
Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Boston Massachusetts 02114, USA.
McAuliffe
D J
DJ
Flotte
T J
TJ
Kollias
N
N
Doukas
A G
AG
D000279:Administration, Cutaneous; D000818:Animals; D003911:Dextrans / Q000008:administration & dosage*; D007834:Lasers; D046911:Macromolecular Substances; D008297:Male; D051381:Rats; D012867:Skin / Q000473:pathology*; D013997:Time Factors
D003911:Dextrans; D046911:Macromolecular Substances