How Retinoids Work

By Sharafa Mohammed, Director of Design and Social Media

In 1971, a market for retinoids emerged. Dr. Albert Kligman, a dermatologist at the University of Pennsylvania, discovered tretinoin, also known as retinoic acid. He discovered that tretinoin, when used topically, worked well as a treatment for acne vulgaris, a form of chronic inflammatory dermatosis. Patients saw smoother skin, fewer wrinkles, and a more even pigmentation after using tretinoin.

Retinoids are a class of vitamin A derivatives that increase the rate of skin cell turnover. This means that dead skin cells shed and are replaced with young skin cells more frequently. In turn, this reduces acne since cells affected by Propionibacterium acnes, the primary bacteria implicated in acne breakouts, are being replaced more often.

Once tretinoin entered the market as a treatment for acne, researchers started to observe its effects on aging skin. Skin aging is an inevitable biological process which everyone undergoes, and symptoms usually include fine lines and wrinkles. In contrast, photoaging is premature skin aging due to cumulative ultraviolet radiation exposure (i.e. being in sunlight). Symptoms of photoaging are hyperplasia, atrophy, wrinkles, irregular hyperpigmentation, and enlarged pores. Retinoids reduce the appearance of fine lines and wrinkles by encouraging collagen production. Collagen is the protein that makes skin look youthful and plump. Retinoids were also found to fade age spots and actinic keratosis (spots that develop from years of sun exposure), even pigmentation, and stimulate the production of cutaneous blood vessels, which can improve overall complexion.

On a cellular level, retinoids regulate transcription factors including retinoic acid receptors (RAR) and retinoid X receptors (RXR) which are located within the nucleus of many cells. They also increase intercellular communication by binding to nuclear receptors and signaling nearby cells. As a result, retinoids are able to regulate cell proliferation and differentiation, control apoptosis, increase collagen production, and block the release of inflammatory triggers. Inflammation is a key aspect in acne vulgaris and psoriasis. With acne, post-inflammatory hyperpigmentation (PIH) results in an uneven skin tone with spots in areas where there previously were breakouts. The symptoms of psoriasis, being an autoimmune disease, are the result of inflammation that causes red, flaky plaques of skin. Anti-inflammatory activity in third generation retinoids has shown to be a promising treatment for psoriasis and has helped reverse the damage of PIH.

Retinol vs. Retinoids vs. Retinoic Acid

The retinoid family consists of vitamin A based chemicals that can treat skin conditions. Retinol is a specific type of retinoid and a pre-cursor of retinoic acid. Human skin has to convert any retinoid into retinoic acid in order to use it. However, tretinoin is pure retinoic acid itself, so it does not have to be metabolized by the skin. Retinol is also better suited for sensitive skin because it contains a less potent form of retinoic acid, whereas other retinoids can result in excessive dryness, redness, and itching. In addition, new generation retinoids are known to cause lesser irritation.

Retinoids are classified into four generations. As mentioned, third generation retinoids, adapalene and tazarotene, have great anti-inflammatory properties and can treat acne. Tazarotene is also prescribed to treat psoriasis.

Topical vs. Oral Retinoids

The First and Second Generations in Figure 1 contain both topical and oral retinoids. A topical retinoid is applied externally to problematic areas of the skin. The retinoid is usually in the form of a gel, cream, or ointment. An oral retinoid is taken in the form of a pill and the vitamin A derivative works from within the body to control the impact of the existing skin condition.

Retinol, tretinoin, adapalene, tazarotene and alitretinoin are topical retinoids. Alitretinoin is specifically used to treat Kaposi sarcoma while retinol and tretinoin have greater anti-aging benefits and adapalene and tazarotene are used to treat acne. Alitretinoin can also be prescribed orally as a treatment for chronic hand eczema. Acitretin and isotretinoin are oral retinoids. Isotretinoin is actually a famous drug that is more commonly known as Accutane, its initial brand name.

Depending on the severity and type of skin condition, doctors will prescribe either topical or oral retinoids. For mild to moderate acne, dermatologists prescribe topical retinoids; this is also the case for psoriasis. However, for more severe cases of acne or psoriasis, or if topical treatments fail to produce fulfilling results, dermatologists will prescribe oral retinoids. Acitretin is prescribed for severe psoriasis and isotretinoin is prescribed for severe acne.

Retinoids have been proven to combat inflammatory skin conditions. By binding to nuclear receptors and controlling cellular functions, retinoids can produce desirable results and can provide a youthful, even complexion. Consult a dermatologist to find out if adding a retinoid to your skincare regimen is suitable for you.

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