What Is Metyrapone?

Metyrapone is a medication prescribed to evaluate the functioning of the pituitary gland. This gland is responsible for instructing the adrenal gland to make cortisol, a chemical. Laboratory tests are performed after the patient takes the medication so that the doctor can determine whether proper amounts of cortisol are being manufactured. Metyrapone may also be used to treat Cushing's syndrome, a condition in which the body makes too much cortisol.

This medication is taken orally, or by mouth with food or milk. A patient may be prescribed one or two doses, which must be taken at the exact times specified by the physician. The following day, he must see his doctor to have blood and urine samples taken. These samples are sent to the laboratory for analysis. Sometimes, the patient may also be instructed to collect his urine for a day prior to taking the medicine, as well as on the day he takes the dosages.

The exact dosages of metyrapone that a child will take varies, depending on his body weight. An adult will typically be prescribed 2,000 to 3,000 milligrams (mg) taken as a single dosage on the day before the tests. When the doctor instructs the patient to divide this dosage, he will typically prescribe 750 mg to be taken every four hours, for a total of six doses.

Some side effects may occur, which should be reported to the prescribing physician if they become severe. Patients may experience nausea, headache, and drowsiness. Dizziness, lightheadedness, and increased sweating can also occur. Loss of appetite, vomiting, and stomach pain have also been reported. When taken on a long-term basis to treat Cushing's syndrome, metyrapone can also cause excessive hair growth, loss of scalp hair, and worsening acne.

More serious side effects require a doctor's immediate care. Patients have rarely reported an irregular heartbeat with long-term use of metyrapone, as well as a skin rash, rapid weight gain, and a fever. Sore throat, unusual fatigue, and swelling of the lower legs or feet have also been reported. Muscle cramps and unusual bruising may occur, and women may rarely experience an enlarged clitoris.

Before using metyrapone for diagnostic purposes or to treat Cushing's syndrome, patients must disclose their other medical conditions, medications, and supplements. It may be contraindicated for use by those who have porphyria, thyroid disease, and diabetes. Heart or liver disease, breast cancer, and hypoglycemia may also prevent a patient from using this drug. Metyrapone may interact with other drugs, including estrogens, acetaminophen, and hydantoins.