Topical retinoids

Retinoids are one of the main treatments used for the topical management of skin conditions. They are of great interest to scientists because of the polymorphism of their biological activities and the major role they play in the control of cell proliferation and differentiation. Vitamin A acid (all-trans-retinoic acid [ATRA], tretinoin), the principal skin metabolite of vitamin A, has been used for more than 40 years to treat acne vulgaris. It was first indicated and still is indicated for the treatment of this disorder, but has since also been used to treat various keratinisation disorders. A major breakthrough was achieved when the molecule was found to be effective for the treatment of photodamaged skin 20 years ago. Other topical retinoids have since been developed with their activity profiles being determined more and more specifically each time. These include adapalene, tazarotene or 9-cis-retinoic acid. Retinoids are therefore not an outdated class of molecules about to be eclipsed.

This chapter will focus on the description of topical ATRA, a true representative of the retinoid class. Its proven and less proven indications will be described first and then information will be given on the more recent molecules. The data presented was obtained by performing an analysis of the literature using Medline and the terms “retinoids (MESH term)” and “topical OR cream OR gel”. We restricted our research to publications in English only and we performed an analysis of level of evidence of the trials [1].