Percutaneous permeation measurement of topical phthalocyanine by photoacoustic technique

Abstract

This investigation have studied photoacoustic (PA) technique to percutaneous permeation of topical hydroxy-(29H,31H-phthalocyaninate) aluminum (PcAlOH) on pig ear skin. The PcAlOH was incorporated in an emulsion (O/W) (1 mg/dl) with assessed stability parameters of: pH, short and long term stability tests (in the several conditions). The skin was prepared through a heat separation technique, and with a scalpel, the outer skin of the cartilage was removed. The skins were then cut into 4 cm2 pieces and treated with sodium bromide 2 mol/L for 6 h at 37 °C. The epidermis layer was washed with purified water, dried, and stored under reduced pressure until use. The skin permeation kinetics was determined by photoacoustic technique in an open photoacoustic cell. Short (after preparation) and long-term stability tests showed no phase separation. The emulsion developed pH 7.6 and after incorporating the pH was unchanged. The typical times for percutaneous permeation of the emulsion base and emulsion + PcAlOH were 182 (±6) and 438 (±3) s, respectively. This study indicated that the formulations containing PcAlOH have stabile characteristics and show promising results in absorption into the skin. The presence of the photosensitive agent in the formulation contributed significantly to the greater absorption time than observed in the base formulation. The used photoacoustic technical to examine the penetration kinetics of PcAlOH in pig ear skin was adequate and may be employed in the determination of the percutaneous permeation of phthalocyanines.