Systemic Therapies: Retinoids

Systemic retinoids are Vitamin A derivatives that affect genes involved in the regulation of keratinocyte function and epidermal thickness. Isotretinoin is used in the treatment of acne vulgaris while acitretin is used for ichthyosis and papulosquamous conditions, such as psoriasis and pityriasis rubra pilaris.

The most common side effect that is experienced by essentially all patients is dry skin and mucous membranes. All patients should use moisturizers on their skin and lips liberally, and those who wear contacts might need lubricating eye drops. Some patients may experience muscular aches, especially young and physically active patients. These subside when the medication is stopped. Possible metabolic side effects include increased triglycerides and liver enzymes. A rare but important side effect is pseudotumor cerebri, or benign intracranial hypertension. Patients should stop the medication and alert their health care practitioner if they experience symptoms of this. In addition, patients must not take tetracycline antibiotics while on oral retinoids as this increases the risk of pseudotumor cerebri. The association between mood symptoms and use of isotretinoin is controversial but patients should be screened for any mood symptoms before starting isotretinoin and at follow-up visits. Acne tends to flare when isotretinoin is first started, so it should be initiated at lower dose and increased after the first month or two of therapy.

Female patients taking oral retinoids must not get pregnant, both Isotretinoin and Acitretin are known teratogens, category X. Two forms of birth control must be used and monthly pregnancy tests should be checked. Acitretin has a potentially long half-life and so pregnancy is to be avoided for 2 full years after completion of therapy.

Retinoid laboratory monitoring: liver enzymes, fasting lipids and pregnancy test at baseline, and repeated at 2 months or after dose changes. Pregnancy test monthly for the duration of treatment. In children taking acitretin for a long duration bone age can be assessed annually by x-ray.