Caffeic Acid in Dermatological Formulations: In Vitro Release Profile and Skin Absorption

Caffeic acid (CA) is a cinnamic acid derivative, found in many vegetable products, with powerful antioxidant activity, the ability to increase collagen production and capacity to prevent premature aging of the skin. The classic emulsions of CA are widely used by the consumer to provide a pleasant, refreshing sensorial experience; however, preparations developed in the form of dry film are presented as a technological alternative due to its facile and safe transportation. The aim of this study was to evaluate the release, permeation, and retention of CA in a film and emulsion through in vitro experiments.

The release evaluation of CA from the emulsion and the film was performed using modified Franz diffusion cells, with an area of 1.77 cm², using Microette equipment (Hanson Research) with a cellulose membrane. The evaluation of the permeation of CA from the formulations was conducted using a similar technique of release, except that a biological membrane was used.

High release of active compound and reduced permeation was observed, indicating that CA was able to be retained in the epidermis/dermis, where it should have the desired action. The concentration of caffeic acid in the skin was higher for the film formulation than for the emulsion. This demonstrates a greater efficiency of this type of innovative release system, besides its facile and safe transportation.

The formulations tested in this paper can release caffeic acid with a Higuchi kinetic profile, in which release of active ingredient occurs by a diffusion process. The film formulations exhibited a lower permeation rate and higher retention in the skin, which is essential for a cosmetic product. The concentration of CA in the skin was also higher for the film formulation when compared to the emulsion. This demonstrates a greater efficiency of this type of innovative release system, in addition to its easy and safe transportation. Therefore, it is possible to suggest CA as a promising substance for dermal use due to its antioxidant, anti-inflammatory, antimicrobial, and collagen production stimulating activity.