Pharmacological Characteristics of a New Generation Local Retinoid

Overview

Adapalene is a useful new drug in the treatment of acne due to its tolerance and stability of effect.It is suitable in combination with other local and systemic drugs, e.g. antimicrobial preparations orbenzoyl peroxide. After combined treatment and administration of adapalene alone the patientscollaboration improves due to more comfortable use and much weaker irritant potential of this newsubstance. A number of authors confirm the reduced skin irritation.In the treatment of skin diseases some natural and synthetic retinoids are used. E.g. retinoic acidand one of its isomers, 13-cis retinoic acid (13-cis RA), are used as local and systemic drugs in acne.Considerable skin irritation caused by retinoic acid is the reasonwhy retinoids with a better relationbetween the therapeutic effect and side effects are sought. A modern chemical and pharmacologicalprogramme led to the discovery of a new synthetic retinoid, adapalene, which is effective andtolerated better by patients than retinoic acid.Pharmacological studies in vitro and in vivo provided evidence of the activity of adapalene asregards proliferation and differentiation of cells and tissues. Adapelene has also an anti-inflammatoryeffect which is due to its anti-AP1 action. It enters selective interactions with nuclear receptorsRAR
and RAR and its effect on proliferation and differentiation can be blocked by the antagonistofRAR
-.AsRAR
are not expressed inhumankeratinocytes, it is certain that the effect of adapaleneon this main cellular type of epidermis is mediated by interaction with RAR. The unique pharmacologicalproperties of adapalene explain - due to the improved tolerance - its better therapeuticeffect as compared with tretinoin.

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