Clinical Proof for Validity of the »Formulating for Efficacy« Concept: Enhanced Skin Delivery Results in Enhanced Skin Efficacy and Both Can Be Predicted

The »Formulating for Efficacy« concept is a systematic approach to simultaneously optimize the driving force of the active ingredient (so that it partitions in larger quantities into the stratum corneum) and reduce its concentration in the formulation without a loss of clinical efficacy. Its ultimate aim is to optimize the clinical efficacy via enhancement of the skin delivery of the active principle at the lowest possible concentration, i.e. at minimal cost. The validity of this approach was initially demonstrated through the use of in vitro skin penetration methodology. A formulation containing 2% octadecenedioic acid that was optimized in this way for skin delivery resulted in 3.5-fold higher concentrations in the viable skin layers than those obtained from a non-delivery optimized formulation containing the same amount of active ingredient. In this paper, clinical studies using the same optimized and non-optimized formulations, as those in the in vitro ABSTRACT