|Systematic (IUPAC) name|
|6-[3-(1-adamantyl)-4-methoxy-phenyl] naphthalene-2-carboxylic acid|
|Trade names||Differin, Teva, Pimpal, Gallet, Adelene, Adeferin|
|Legal status||POM (UK) ℞-only (US)|
|Mol. mass||412.52 g/mol|
| (what is this?)
Mechanism of action 
Unlike tretinoin, adapalene does not bind to the cytosolic retinoic acid binding proteins but instead selectively binds to the nuclear retinoic acid receptor (RAR) subtypes RARβ and RARγ. This selective binding affinity may play a role in adapalene’s greater inhibition of keratinocyte differentiation than tretinoin, which was demonstrated in a study using keratinocyte transglutaminase expression as a marker. 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 comedone formation was demonstrated by a 50–60% reduction in comedone counts compared with vehicle.
Available forms 
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. As of June 2010, a 0.1% gel is also made by the generic company Teva. In Europe, only the 0.1% cream and 0.1% gel are available.
Drug 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.
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.
- Rolewski S (2003). "Clinical review: topical retinoids". Dermatol Nurs 15 (5): 447–50, 459–65. PMID 14619325.
- About Differin
- "Teva Introduces Adapalene Gel, 0.1%". PharmQD. 4 June 2010. Retrieved 30 Aug. 2011.
- Webber, Keith (2 June 2010). "FDA Approval Letter". Department of Health and Human Services. Retrieved 30 August 2011.
- Wolf JE, Kaplan D, Kraus SJ, et al. (2003). "Efficacy and tolerability of combined topical treatment of acne vulgaris with adapalene and clindamycin: a multicenter, randomized, investigator-blinded study". J Am Acad Dermatol 49 (3 Suppl): S211–7. doi:10.1067/S0190-9622(03)01152-6. PMID 12963897.
- Jain GK, Ahmed FJ (2007). "Adapalene pretreatment increases follicular penetration of clindamycin: in vitro and in vivo studies". Indian J Dermatol Venereol Leprol 73 (5): 326–9. doi:10.4103/0378-6323.34010. PMID 17921613.
- Martin B, Meunier C, Montels D, Watts O (October 1998). "Chemical stability of adapalene and tretinoin when combined with benzoyl peroxide in presence and in absence of visible light and ultraviolet radiation". Br J Dermatol. 139 Suppl 52: 8–11. doi:10.1046/j.1365-2133.1998.1390s2008.x. PMID 9990414.
- "DIFFERIN® (adapalene) Cream, 0.1% Label". FDA. May 25, 2000. Retrieved 4 Oct. 2011.
- Adapalene General Information, Patient Information, Contraindications and Interactions
- Epiduo Prescribing Information