Isotretinoin, INN,, first marketed as Accutane by Hoffmann-La Roche, is a medication used mostly for cystic acne. It is also a chemotherapy treatment used in brain, pancreatic and other cancers. It is used to treat harlequin-type ichthyosis, a usually lethal skin disease, and lamellar ichthyosis. Its effects are systemic and nonselective. It is a retinoid, meaning it is related to vitamin A, and is found in small quantities naturally in the body.