Metopirone (Metyrapone) - Drug Interactions, Contraindications, Overdosage, etc

DRUG INTERACTIONS

Drug Interactions

Drugs affecting pituitary or adrenocortical function, including all corticosteroid therapy, must be discontinued prior to and during testing with Metopirone.

      The metabolism of Metopirone is accelerated by phenytoin; therefore, results of the test may be inaccurate in patients taking phenytoin within two weeks before. A subnormal response may occur in patients on estrogen therapy.

      Metopirone inhibits the glucuronidation of acetaminophen and could possibly potentiate acetaminophen toxicity.

OVERDOSAGE

Acute Toxicity

One case has been recorded in which a 6-year-old girl died after two doses of Metopirone, 2 g.

      Oral LD₅₀ in animals (mg/kg): rats, 521; maximum tolerated intravenous dose in one dog, 300.

Signs and Symptoms

The clinical picture of poisoning with Metopirone is characterized by gastrointestinal symptoms and by signs of acute adrenocortical insufficiency.

Cardiovascular System: Cardiac arrhythmias, hypotension, dehydration.

Nervous System and Muscles: Anxiety, confusion, weakness, impairment of consciousness.

Gastrointestinal System: Nausea, vomiting, epigastric pain, diarrhea.

Laboratory Findings: Hyponatremia, hypochloremia, hyperkalemia.

Combined Poisoning

In patients under treatment with insulin or oral antidiabetics, the signs and symptoms of acute poisoning with Metopirone may be aggravated or modified.

Treatment

There is no specific antidote. Besides general measures to eliminate the drug and reduce its absorption, a large dose of hydrocortisone should be administered at once, together with saline and glucose infusions.

Surveillance: For a few days blood pressure and fluid and electrolyte balance should be monitored.

CONTRAINDICATIONS

Metopirone is contraindicated in patients with adrenal cortical insufficiency, or hypersensitivity to Metopirone or to any of its excipients.