indication

Used to treat psoriasis, acne and sun damaged skin (photodamage).

pharmacology

Tazarotene is a prodrug and a member of the acetylenic class of retinoids. Following topical application, tazarotene undergoes esterase hydrolysis to form its active metabolite, tazarotenic acid. When treating acne tazarotene may be taken in conjunction with an oral antibiotic. Tazarotene has been shown in peer-reviewed double blinded studies to reduce: mottling and hyperpigmentation, sallowness, fine wrinkling and coarse wrinkling in sun damaged skin. Histological studies have shown that long term (greater than 1 year) use of Tazarotene is associated with a significant reduction in atypical melanocytes and keratocytes - cells considered to be precursors of skin cancer. Some studies have shown long term use of Tazarotene to be associated with increased collagen production and better organization of skin collagen bundles.

mechanism of action

Although the exact mechanism of tazarotene action is not known, studies have shown that the active form of the drug (tazarotenic acid) binds to all three members of the retinoic acid receptor (RAR) family: RARa, RARb, and RARg, but shows relative selectivity for RARb, and RARg and may modify gene expression. It also has affinity for RXR receptors.

toxicity

Excessive topical use may lead to marked redness, peeling, or discomfort. Oral ingestion of the drug may affect liver function causing hypertriglyceridemia. Other symptoms may include conjunctival irritation, hair loss, headache, edema, fatigue, dermatitis, nausea, and visual disturbances. Oral administration of this material to rats and rabbits at doses of 0.20 mg/kg/day (rabbits) and 0.25 mg/kg/day (rats) resulted in developmental toxicity. A no effect level of 0.05 mg/kg/day was established. Similar teratogenic effects have been reported for other retinoid compounds.

biotransformation

Undergoes esterase hydrolysis in skin to form its active metabolite, tazarotenic acid. Tazarotenic acid is further metabolized in skin and, after systemic absorption, hepatically metabolized to sulfoxides, sulfones, and other polar products for elimination.

absorption

Minimal systemic absorption of tazarotene occurs due to its rapid metabolism in the skin to the active metabolite, tazarotenic acid, which can be systemically absorbed and further metabolized. Gender had no influence on the systemic bioavailability of tazarotenic acid.

half life

The half-life of the active form of the drug, tazarotenic acid, is approximately 18 hours in normal and psoriatic patients.

route of elimination

Tazarotene and tazarotenic acid were metabolized to sulfoxides, sulfones and other polar metabolites which were eliminated through urinary and fecal pathways.