Tretinoin.  A review of its pharmacological properties and clinical efficacy in the topical treatment of photodamaged skin. 
Tretinoin (all-trans-retinoic acid) is a retinol (vitamin A) derivative which has been evaluated as a topical treatment for the symptoms of photodamaged skin.  In several well-controlled clinical trials, the proportion of patients showing improvement was significantly higher with 0.01 or 0.05% tretinoin cream than with placebo for criteria such as global assessment, fine and coarse wrinkling, pigmentation and roughness.  Improvements in the overall severity of photodamage were also significantly greater with tretinoin than with placebo.  The extent of clinical improvement with tretinoin has generally been moderate, but cytological and histological studies have shown that extensive changes in the epidermis and dermis occur during treatment.  However, the permanency and clinical significance of these changes has yet to be fully evaluated.  Topical tretinoin has also demonstrated potential for the treatment and eradication of premalignant skin growths such as actinic keratoses, and may be useful as combination therapy with fluorouracil in this indication.  Dermatitis (the retinoid skin reaction) is the most common adverse event experienced by patients receiving topical tretinoin; this condition may persist for up to 3 months, but is usually mild or moderate in nature.  Thus, topical tretinoin has been shown to be an effective form of treatment for the characteristic signs of photodamaged skin.  Its ability to produce significant, albeit moderate, clinical improvements in symptoms such as fine wrinkling, roughness and pigmentation, together with its relatively mild or moderate adverse event profile, suggests that it is likely to be of considerable value in this indication.  The treatment and eradication of potentially malignant growths such as actinic keratoses may also prove to be an important application for topical tretinoin.