Abstract:
The delivery of retinyl palmitate (RP) from several vehicles, including those containing nonionic surfactant vesicles (NSV), was investigated in vitro. Both excised hairless mouse and human skin were utilized as model membranes in permeation experiments. Intact retinyl palmitate was not detected in the receptor. Following application of various NSV preparations to hairless mouse skin, the label accumulated in the receptor at a rate comparable to or greater than from mineral oil. The opposite occurred with excised human skin. Penetration into the receptor from a vesicle preparation, mineral oil and alcohol, was commensurate with accumulation in viable human skin tissue. Most of the label residing within human skin following application of the NSV preparation was found in the stratum corneum to an extent significantly greater than for either of the other vehicles. Because of the importance of storage in the stratum corneum, hairless mouse skin is not a good model for RP permeation. Also, vesicle preparations augment retention of hydrophobic substances in stratum corneum with potential for extended effect.