Mid-infrared laser ablation of stratum corneum enhances in vitro percutaneous transport of drugs.
The precise removal of stratum corneum from cadaveric swine skin by a mid-infrared erbium:yttrium scandium gallium garnet laser (lambda = 2.79 microns; 250 microseconds pulse width) was assessed by electrical resistance measurements and documented by histology. The effects of stratum corneum removal by laser ablation and by adhesive tape-stripping on the in vitro penetration of 3H-hydrocortisone and 125I-gamma-interferon were determined. Excised swine skin was irradiated with laser (1 J/cm2; 31 mJ/pulse; 1 Hz; 2 mm spot diameter). For skin penetration studies, laser pulses were delivered to discrete 2-mm areas to ablate up to 12.6% of the total 3-cm2 stratum corneum diffusional area. Franz in vitro skin penetration chambers were used to measure the cumulative 48-h penetration of 3H-hydrocortisone and 125I-gamma-interferon in laser-treated and tape-stripped skin. Electrical resistance measurements and histologic studies demonstrated that 10-14 laser pulses at the above energy density were required to abolish skin resistance and selectively ablate stratum corneum without damage to adjacent dermal structures. Laser ablation of 12.6% of the surface area of stratum corneum produced a 2.8 and 2.1-times increase in permeability constant (kp) for 3H-hydrocortisone and 125I-gamma-interferon, respectively. These studies demonstrate that a pulsed mid-infrared laser can reliably and precisely remove the stratum corneum, facilitating penetration of large molecules such as 125I-gamma-interferon that cannot penetrate intact skin. This new technique may be useful for basic and clinical investigation of skin barrier properties.
Beckman Laser Institute and Medical Clinic, Irvine, California.
J S
JS
Nelson
J L
JL
McCullough
T C
TC
Glenn
W H
WH
Wright
L H
LH
Liaw
S L
SL
Jacques
D000279:Administration, Cutaneous; D000818:Animals; D001692:Biological Transport; D062109:Dermatologic Surgical Procedures; D006854:Hydrocortisone / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007259:Infrared Rays; D007371:Interferon-gamma / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007457:Iodine Radioisotopes; D053685:Laser Therapy / Q000379:methods*; D013552:Swine; D014316:Tritium
D007457:Iodine Radioisotopes; D014316:Tritium; D007371:Interferon-gamma; D006854:Hydrocortisone