acitretine

Acitretin is an oral retinoid medication used in dermatology for the treatment of severe psoriasis and certain keratinization disorders. It is the active metabolite of etretinate and is marketed under brand names such as Soriatane. It is typically prescribed when other systemic therapies have failed or are unsuitable.

Indications for acitretin include severe chronic plaque psoriasis that is refractory to other treatments, pustular and erythrodermic forms of psoriasis, ichthyosis, and pityriasis rubra pilaris. Dosing is generally weight-based and may range from about 0.3 to 1 mg/kg per day, with treatment duration extending over months to years depending on response and tolerance.

Mechanism of action involves modulation of keratinocyte differentiation and proliferation through activation of retinoid receptors (RARs and RXRs). This leads to normalization of epidermal growth and keratinization, contributing to reduced scaling and inflammation.

Pharmacokinetics, metabolism, and interactions: Acitretin is administered orally and metabolized in the liver. Its half-life is about 49 hours, but conversion to etretinate can occur in the presence of alcohol, producing a much longer-lived metabolite with a prolonged risk of teratogenicity. Therefore, alcohol should be avoided during therapy and for at least two years after discontinuation. Acitretin exposure is eliminated mainly via urine and feces.

Safety and monitoring: Common adverse effects include dryness of the skin and mucous membranes (cheilitis), hair thinning, nail changes, and photosensitivity. Laboratory monitoring typically includes liver function tests and lipid panels, as retinoids can cause hepatotoxicity and hyperlipidemia. It is highly teratogenic; pregnancy must be avoided during treatment and for an extended period after stopping therapy. Caution is advised in liver disease, hyperlipidemia, and in the context of long-term use due to possible skeletal changes.