Formulating for Efficacy

The document discussed the importance of delivering active ingredients in cosmetics to the correct location in the skin at the right concentration and duration to ensure efficacy. It introduced a theoretical approach using the relative polarity index to select suitable emollients for enhancing skin penetration of active ingredients. Practical examples supported this approach, showing that the choice and control of the emollient system could regulate the delivery and efficacy of cosmetic formulations. Additionally, experiments suggested that emulsifier systems might also influence the delivery of active ingredients to specific skin layers, although general rules could not yet be established.