Acitretin

Acitretin is an oral retinoid used for the treatment of severe psoriasis and certain keratinization disorders. It is a second-generation retinoid and the active metabolite of etretinate; brand names include Soriatane and Neotigason in various markets.

Indications include severe plaque psoriasis refractory to topical therapies and phototherapy, erythrodermic psoriasis, and disorders of keratinization such as ichthyosis and pityriasis rubra pilaris.

Mechanism: Acitretin modulates keratinocyte differentiation and proliferation by activating retinoic acid receptors, helping to normalize epidermal differentiation and reduce hyperproliferation. It also exerts anti-inflammatory effects that can contribute to skin improvement.

Administration and dosing: The usual oral dosing ranges from 25 to 50 mg daily, up to 75 mg daily in selected cases, with adjustments for response and tolerance. Time to improvement varies and some patients require several weeks to months of therapy. Dosing is guided by clinical response and adverse effects.

Safety: Acitretin is highly teratogenic; pregnancy must be avoided during therapy and for an extended period after stopping therapy (commonly at least 3 years) because alcohol during treatment can form etretinate, a long-lasting teratogen. Strict contraception is required for women of childbearing potential. It can cause hepatotoxicity and elevations in triglycerides and cholesterol; liver function tests and lipid panels should be monitored. Other common adverse effects include dry skin and mucous membranes, cheilitis, hair thinning, nail changes, and photosensitivity. Alcohol intake should be avoided during therapy to reduce the risk of etretinate formation.

Contraindications and monitoring: Contraindicated in pregnancy, lactation, significant liver disease, and hypersensitivity to retinoids. Regular monitoring includes baseline and periodic liver function tests, lipid panels, and pregnancy tests for women of childbearing potential.