This is the third article in a series discussing effects of occlusion on skin. Previously, we reviewed the effects of occlusion on the percutaneous absorption (C&T November 2003) and on wound healing (C&T April 2004). The present article focuses and summarizes the adverse effects of occlusion.
Occlusion enhances skin hydration and increases percutaneous absorption of applied substances with exception. On the other hand, it may also increase the penetration of irritants and/or antigens entering into skin and hence may increase irritant and allergic contact dermatitis. Additionally, occlusion compromises skin barrier function by impairing passive transepidermal water loss at the application site, and hence aggravates the irritant effect of applied compounds.
Transdermal drug delivery systems (TDDS) are typically occlusive patches placed on the skin surface for 1-7 days while delivering drugs into the systemic circulation5 and have been extensively investigated because of potential advantages over oral and other administration routes.7However, local reactions (i.e., irritation and/or sensitization) have become obstacles in the design and application of TDDS in clinic situations.