Isotretinoin

Isotretinoin is an oral retinoid used to treat severe nodular acne that has not responded to other therapies. It is the 13-cis-retinoic acid form of vitamin A and can produce long-lasting remission after a single course in many patients.

Mechanism of action includes shrinking the sebaceous glands and markedly reducing sebum production, normalizing follicular keratinization, and exerting anti-inflammatory effects. These actions decrease comedones and inflammatory lesions and reduce the risk of scarring.

Indications and course: isotretinoin is typically reserved for severe nodular acne, acne with scarring, or acne that is resistant to antibiotics. Dosing usually ranges from 0.5 to 1 mg/kg per day for about 4 to 6 months, with a common goal of a cumulative dose of roughly 120 to 150 mg/kg. Some patients may require adjustments for tolerability or response.

Contraindications and precautions: pregnancy is absolutely contraindicated due to high teratogenic risk; female patients generally must participate in a risk-management program and use effective contraception throughout treatment and for some time after. Isotretinoin is also contraindicated in significant liver disease or markedly elevated triglycerides, and caution is advised with lactation, severe psychiatric history, or known hypersensitivity. Vitamin A supplementation should be avoided to prevent hypervitaminosis A. Interactions may include alcohol and certain antibiotics such as tetracyclines, which can increase risks of adverse effects.

Adverse effects and monitoring: common effects include dry skin and lips (cheilitis), dry eyes, nasal mucosa irritation, and joint pains. Less frequent effects involve mood changes, headaches, and, rarely, inflammatory bowel disease. Baseline and periodic monitoring of liver function tests and lipid levels are recommended, along with regular pregnancy testing for those who can become pregnant.

Regulatory note: due to teratogenicity, isotretinoin is subject to restricted-use programs in many countries. Brand names have included Accutane and Roaccutane, with generics now widely available.