Improved spreading and enhanced delivery of actives into the deeper layers of the epidermis and the dermis are useful properties in applications such as anti-acne, skin whitening and scalp treatment. One way to achieve these improvements is with a skin adjuvant such as dimethyl isosorbide, as this article demonstrates in the case of hydrophilic actives delivered from formulations for self-tanning.
Many cosmetic formulations and over-the-counter products contain ingredients that need to be delivered into the skin to produce their unique and/or therapeutic effects. These active ingredients are either oil- or water-soluble or dispersible and can be delivered out of a variety of systems such as emulsions, gels or ointments. The target site for delivery is very often the epidermis and/or around the hair follicle.
Sufficiently high concentrations can be difficult to achieve due to the skin’s natural barrier function, the stratum corneum. When the active ingredient to be delivered is water-soluble, such as hyaluronic acid or dihydroxyacetone, delivery becomes an even greater challenge due to the hydrophobic nature of the stratum corneum on the one hand and the rapid evaporation of the carrier (water) upon application of the product to the skin on the other hand. The latter results in precipitation of the ingredient, rendering it unavailable for skin penetration.
Excerpt Only This is a shortened version or summary of the article that appeared in the Mar. 1, 2005 issue of Cosmetics & Toiletries magazine. The full content is not currently available online.