Retinoids.

Retinoids are vitamin A derivatives that have therapeutic benefit in the treatment of hyperkeratotic genodermatosis, psoriasis, and acne. Isotretinoin (Accutane), a first-generation retinoid, is used in the treatment of cystic acne. Etretinate (Tegison), a second-generation retinoid, is used in the treatment of severe psoriasis. Third-generation drugs are currently being tested. Side effects and long-term toxicity are of concern. Etretinate in combination with ultraviolet B and psoralen-ultraviolet A (PUVA) is especially beneficial in the treatment of psoriasis.