Vitamin A derivatives, retinoids can be natural or synthetic and have been used since 1962 for the treatment of acne. They continue to be a primary treatment and maintenance therapy for most forms of acne. Tretinoin, isotretinoin, adapalene, and tazarotene are examples of retinoid compounds, with each binding to certain receptors in skin cells that regulate the expression of genes which affect various aspects of acne development. Of these four, all have been found to reduce existing comedones, prevent formation of new lesions, inhibit inflammatory factors, and help regulate the growth and proliferation of skin cells. It should be noted that the topical version of isotretinoin does not reduce the size of sebaceous glands and the output of sebum, unlike when it is taken orally. Dermatologists may also recommend adding antimicrobial treatment to retinoid therapy in cases of inflammatory acne.¹

Topical retinoids are available in creams of varying strengths, gels, and solutions. Some even come microencapsulated or specially formulated to keep the retinoid molecules near the skin surface to exert the maximum benefit. Tretinoin formulations are also available in gradual release formulas to help minimize the degradation of the active retinoids by light. One type of retinoid, retinaldehyde, is available in cosmetics for acne patients.¹

One side effect of retinoid treatment is skin irritation—especially in tretinoin, the first retinoid used for acne. Human studies demonstrate that isotretinoin, adapalene, and naturally-occurring retinoyl β-glucuronide are similarly effective to tretinoin in reducing acne lesions, and all are better tolerated. For black patients with acne adapalene may be a better treatment choice than tretinoin, demonstrating significantly better results against inflammatory acne and with much less skin irritation. Some studies show that tazarotene may be more effective and less irritating than tretinoin at reducing papules and blackheads, but adapalene is still better tolerated with similar results.¹

No topical retinoids are recommended for use during pregnancy due to the possible risk of birth defects.¹ In 2005 the FDA approved iPledge, a program that mandates a pregnancy test before starting isotretinoin treatment and the use of two forms of birth control the month prior to starting treatment as well as during and for one month after.² Although this requirement does not apply in certain European countries, acne patients in the U.S. must participate in the iPledge contraception program to be eligible for an isotretinoin prescription.^1-2