The adhesive capacity in dermal administration is important to ensure retention at the site of application, and active ingredient-release key for the product to exert its action either at the skin surface or within deeper layers.18 Recently, a polymeric honeycomb matrix (using carbomer cross-linked polymers, carbomer copolymer type B and homopolymer type A), which helps structure the active drug and provide a uniform distribution of both active and moisturizing/ hydrating ingredients (sodium hyaluronate, soluble collagen, glycerin) at the surface of the skin, has been deployed for the delivery of micronized tretinoin (Figure 1). The formulation also contains small amounts of mineral oil. Mineral oils are used in skin care products due to their excellent skin tolerance, as well as their antimitotic and cleansing properties and the broad viscosity options they provide. Mineral oils are not percutaneously absorbed and with an absence of dermal uptake do not become systemically available;19 at low concentrations they exhibit no comedogenicity potential.20 The concomitant use of moisturizers and humectants can enhance efficacy, alleviate dryness, and improved skin comfort. Sodium hyaluronate is a powerful humectant that attracts and holds onto water, is smaller than hyaluronic acid, and able to penetrate more freely into the deeper layers of the skin. Unlike some moisturizers, sodium hyaluronate doesn’t leave a “greasy” feel to the skin. Collagen, too, is an important component for cosmetic formulation, where it is an effective natural humectant with high substantivity. Glycerin has been shown to have a number of additional benefits beyond increasing the hydration of the stratum corneum (SC) structural elements. It prevents SC phase transition, is keratolytic, influences the protective function of the skin against irritation and penetration of substances through the SC, plasticizes the SC, reduces tissue scattering, stabilizes skin collagen, and accelerates the healing process.This polymeric matrix and vehicle lotion formulation provide
