A formulation of mifepristone, marketed under the brand name Korlym, has been approved to control hyperglycemia or type 2 diabetes in adults with endogenous Cushing's syndrome who aren't candidates for surgery or who haven't responded well to surgery. Korlym is the first drug approved for endogenous Cushing's syndrome, a rare, multisystem disorder characterized by excessive cortisol production in the adrenal glands. Korlym blocks cortisol receptors, preventing cortisol from producing glucose, although circulating cortisol levels remain high. The drug shouldn't be used in the treatment of type 2 diabetes that's not related to endogenous Cushing's syndrome.
Mifepristone has strong antiprogestational effects and is already approved (under the trade name Mifeprex) for the medical termination of a pregnancy of 49 days or less in length. Mifeprex tablets contain 200 mg of mifepristone; Korlym contains 300 mg of mifepristone. The higher dose is what creates the cortisol-receptor blockade. Korlym, a pregnancy category X drug, carries a boxed warning that it should never be used in pregnant women because it will terminate the pregnancy. However, if a woman has endogenous Cushing's syndrome, the risk of pregnancy is extremely small. As a progesterone receptor antagonist, mifepristone will also interfere with the effectiveness of a hormonal contraceptive.
Korlym's most common adverse effects (occurring in 20% or more of patients) are nausea, fatigue, headache, arthralgia, vomiting, peripheral edema, dizziness, decreased appetite, and endometrial hypertrophy. Other potentially serious adverse effects include adrenal insufficiency, low potassium levels, vaginal bleeding, and QT interval prolongation. Korlym creates multiple, significant, and potentially dangerous drug interactions through the cytochrome P-450 (CYP) isoenzyme system. It is an inhibitor of CYP3A, CYP2C8/2C9, and CYP2B6. Nurses should confirm the compatibility of every other drug a patient takes concurrently with Korlym; some drugs need to be avoided and some require dosage changes when they're taken with Korlym.
To best provide Korlym to the limited population with endogenous Cushing's syndrome, the manufacturer has voluntarily proposed distributing the drug through a central pharmacy. To read the Food and Drug Administration news release regarding the approval, go to http://1.usa.gov/zn9G9D.