EVALUATION OF A CULTURED SKIN EQUIVALENT AS A MODEL MEMBRANE FOR IONTOPHORETIC TRANSPORT

Recently, cultured skin equivalents of human origin have become available. These materials, also known as living skin equivalents (LSEs), are made up of human cells and matrix equivalents normally present in skin. LSEs closely resemble human skin, consisting of a dermis and a stratified epidermis with a well-differentiated stratum corneum (Ponec et al., Toxicity screening of N-alkylazacycloheptan-2-one derivatives in cultured human skin cells: structure-toxicity relationships, J. Pharm. Sci., 78 (1989) 738-741; Ponec et al., Nitroglycerin and sucrose permeability as quality markers for reconstructed human epidermis, Skin Pharmacol., 3 (1990) 126-135) but lack the structural appendages found in human skin (e.g., hair follicles, sweat glands). This paper will discuss a preliminary evaluation of a cultured skin equivalent as a model membrane for in vitro screening experiments of iontophoretic candidates. Transport rates of pindolol hydrochloride, synthetic salmon calcitonin and benzyl alcohol are compared across both guinea pig skin (a common in vitro model membrane) and the cultured skin equivalent. Preliminary results with a cultured skin model indicate that this material may be useful as a model membrane for in vitro experiments. The results obtained using the LSE correlate well with those obtained with guinea pig skin in vitro. The iontophoretic flux of pindolol through both membranes was indistinguishable from one another. Similar results are also reported for synthetic salmon calcitonin and benzyl alcohol.