Tazarotene is converted to its active form,("tazarotenic acid'), by rapid deesterification in

most biological systems."Tarazotenic acid" binds to and regulates gene expression

through all three members of the RAR family of retinoid nuclear receptors, RARα, RARβ,

and RARγ.

Like tretinoin, tazarotene modulates cell differentiation and proliferation in a wide range of

 tissues.

Psoriasis:Improvement in psoriatic patients appears to occur in association with

restoration of normal cutaneous morphology, reduction of the inflammatory markers

 ICAM-1 and HLA-DR and the diminution of markers of epidermal hyperplasia and

abnormal differentiation such as elevated keratinocyte transglutaminase, involucrin and

keratin16.
Tazarotene blocks induction of epidermal ornithine decarboxylase (ODC) activity in the

 hairless mouse by the tumour promoter 12-O-tetradecanoylphorbol 13-acetate (TPA).

 ODC catalyses the first step in polyamine synthesis and is associated with cell

proliferation and hyperplasia; both ODC activity and
hyperplasia are elevated in the epidermal layer of the psoriatic plaque.
In cultured human keratinocytes, and in the psoratic plaque, tazarotene suppresses

expression of MRP8, an inflammatory marker present in psoriatic epidermis at high levels

and blocks the synthesis of cornified envelopes and envelope precursors.
Cornified envelope buildup is an element of psoriatic scale formation. Tazarotene also

induces the expression of TIG3 (tazarotene-induced gene 3), a tumour suppressor, which

may inhibit epidermal hyperproliferation in treated plaques. Tazarotene, therefore, has

multiple effects on keratinocyte differentiation and proliferation, as well as on inflammatory processes which contribute to the pathogenesis of psoriasis.

Acne: Tazarotene is a member of the acetylenic class of retinoids. Retinoids are

recognised as fundamental mediators of cell differentiation and proliferation.
Directly or indirectly, tazarotene is thought to act against several of the factors that

contribute to acne vulgaris. Its primary mechanism of action is to normalise the

keratinisation pattern in acne and decrease the coherence of follicular keratinocytes, thus achieving a comedolytic effect against existing comedones and preventing the development of new microcomedones.Tazarotene may also have direct or indirect activity against

inflammatory acne.