Alternative Methods to Animal Studies for the Evaluation of Topical/ Transdermal Drug Delivery Systems.

It is critical to develop an effective understanding of the interaction between the drug, delivery system and skin in order to predict and assess skin penetration and permeation. Experimental models for the assessment of topical and transdermal delivery systems must permit evaluation of these complex interactions. Whilst in the past, animal models were commonly used, recent regulatory guidelines, based on 3R principles (refinement, reduction, replacement), encourage the rational use of animals.