Adapalene

Adapalene 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.^[1] It is effective against acne conditions where comedones are predominant.

History[edit]

Adapalene is a research product of Galderma Laboratories, France.^{[citation needed]} Adapalene was approved in 1996 by the U.S. Food and Drug Administration (FDA) for use in the treatment of acne.^{[citation needed]}

Mechanism of action[edit]

Unlike tretinoin, adapalene inhibits keratinocyte differentiation. This inhibition of keratinocyte differentiation and proliferation is responsible for adapalene’s comedolytic effect. It has both exfoliating and anti-inflammatory effects. In an in vivo study, adapalene’s ability to reduce comedo formation was demonstrated by a 50–60% reduction in comedo counts compared with vehicle.

Available forms[edit]

In the United States, adapalene is available under the brand name Differin in three different preparations: 0.1% cream, 0.1% gel, and 0.3% gel.^[2] The 0.1% gel is available as a generic made by Teva.^[3][4] It is also available combined with benzoyl peroxide under the brand nameEpiduo.^[5] In Europe, only the 0.1% cream and 0.1% gel are available. Adapalene is currently marketed by Galderma under the trade names Differin in some countries, and Adaferin inIndia.^[6] It is mostly available in 0.1% w /w gel form.

Pharmacology[edit]

Drug interactions[edit]

Adapalene has been shown to enhance the efficacy of topical clindamycin, although adverse effects are also increased.^[7] 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.^[8]

Unlike tretinoin (Retin-A), adapalene has also been shown to retain its efficacy when applied at the same time as benzoyl peroxidedue to its more stable chemical structure.^[9]

Pharmacokinetics[edit]

Absorption of adapalene through the skin is low. A study with six acne patients treated once daily for five days with two grams of adapalene cream applied to 1000 cm² of skin found no quantifiable amounts, or less than 0.35 ng/mL of the drug, in the patients' blood plasma.