Tretinoin, a retinoid, is the acid form of vit A. Topically, it decreases cohesiveness of follicular epithelial cells by stimulating mitosis and turnover. This causes extrusion of existing comedones and preventing formation of new ones. Additionally, it has a thinning effect on the stratum corneum. Systemically, it induces cellular differentiation and decreases proliferation of acute promyelocytic leukemia (APL) cells.
Mottled hyperpigmentation, roughness and fine wrinkling of photodamaged skin: As 0.02 or 0.05% cream: Apply a pea-sized amount onto entire face once daily at night. Therapeutic response may be seen after 6 mth.
Acne vulgaris: As 0.01-0.1% cream/ gel/ alcoholic soln: Apply once or bid, usually at bedtime, onto affected area which has been previously cleansed to remove excessive oiliness and dried. Therapeutic response may be seen after 6-8 wk.
Acute promyelocytic leukaemia:
Adult: Remission induction: 45 mg/m2 daily in 2 divided doses. Treatment is continued until 30 days after complete remission or up to 90 days, whichever occurs first.
Child: Remission induction: 1-16 yr Same as adult dose.