thumb|Adapalene Gel, sold as trade name Differin in China
Adapalene, sold under the brand name Differin among others, is a third-generation topical retinoid primarily used in the treatment of mild-moderate acne, and is also used off-label to treat keratosis pilaris as well as other skin conditions. Studies have found adapalene is as effective as other retinoids, while causing less irritation. It also has several advantages over other retinoids. The adapalene molecule is more stable compared to tretinoin and tazarotene, which leads to less concern for photodegradation. The Swiss company Galderma developed adapalene.
Medical uses
Per the recommendations of the Global Alliance on Improving Outcomes of Acne, retinoids such as adapalene are considered first-line therapy in acne treatment and are to be used either independently or in conjunction with benzoyl peroxide and/or an antimicrobial agent, like clindamycin, for maximum efficacy. An adapalene/benzoyl peroxide combination medication is also available. Furthermore, adapalene, like other retinoids, increases the efficacy and penetration of other topical acne medications that are used in conjunction with topical retinoids as well as hastens the improvement of the postinflammatory hyperpigmentation caused by acne. its availability is otherwise restricted to prescription drugs. A version of adapalene, oleyl adapalenate, is available for broader skincare and cosmetic usage.
Side effects
Of the three topical retinoids, adapalene is often regarded as the best tolerated. It can cause mild adverse effects such as photosensitivity, irritation, redness, dryness, itching, and burning, experience a brief sensation of warmth or stinging, as well as dry skin, peeling and redness during the first two to four weeks using the medication. These effects are considered mild and usually decrease over time. Thus far, there is no evidence that the cream causes problems in the baby if used during pregnancy.
Topical adapalene has poor systemic absorption and results in low blood levels (less than 0.025 mcg/L) even after long term use, suggesting that there is low risk of harm for a nursing infant.
Interactions
Adapalene has been shown to enhance the efficacy of topical clindamycin, although adverse effects are also increased. Application of adapalene gel to the skin 3–5 minutes before application of clindamycin enhances penetration of clindamycin into the skin, which may enhance the overall efficacy of the treatment as compared to clindamycin alone.
Pharmacology
Unlike the retinoid tretinoin (Retin-A), adapalene has also been shown to retain its efficacy when applied at the same time as benzoyl peroxide due to its more stable chemical structure. Furthermore, photodegradation of the molecule is less of a concern in comparison to tretinoin and tazarotene. Adapalene is also regarded as an anti-inflammatory agent, as it suppresses the inflammatory response stimulated by the presence of Cutibacterium acnes, Its agonism of the gamma subtype is largely responsible for adapalene's observed effects. In fact, when adapalene is applied in conjunction with a retinoic acid receptor gamma antagonist, adapalene loses clinical efficacy.
Retinization is a common temporary phenomenon reported by patients when initiating use of retinoids. Within the initial period of treatment, skin can become red, irritated, dry and may burn or itch from retinoid application; however, this tends to resolve within four weeks with once a day use.
History
Adapalene was a research product of the Swiss company Galderma and was patented in Luxembourg in 1986 and in the US in 1988. Adapalene was approved as a prescription medication in 1996 by the US Food and Drug Administration (FDA) for use in the treatment of acne. In 2016, the US FDA approved adapalene gel 0.1% for over-the-counter (OTC) sale, marking the first time a formerly prescription-only retinoid became available without a prescription for acne treatment.
Research
A study has concluded that adapalene can be used to treat plantar warts and may help clear lesions faster than cryotherapy. A computational study claims that adapalene can be used as a potential entry inhibitor for Omicron variant of SARS-CoV-2.