Evaluation of Two In Vitro Human Skin Equivalents (Epiderm™ and Skin[sup(2)]™ Model ZK1300) for Assessing the Skin Irritation Potential of Personal Care Products and Chemicals

INTRODUCTION Cosmetic products frequently undergo modification or reformulation, in order to improve perfor­ mance or to enhance acceptability. Formulation changes may range from adjustments in existing component levels, to substitutions with established cosmetic ingredients, or to the introduction of new or unique materials with known safety profiles. Under many circumstances, it may be appropriate to proceed directly to clinical evaluation. In other cases, it may be more prudent, convenient, or efficient to use in vitro test systems to forecast relative dermal irritancy potential. The purpose of this study was to evaluate two promising in vitro human skin equivalent models and to compare the results obtained for shampoo formulations with clinical results obtained in a repeat application soap chamber test.