Metyrapone

12.1 Mechanism of Action The pharmacological effect of Metopirone is to reduce cortisol and corticosterone production by inhibiting the 11-beta-hydroxylation reaction in the adrenal cortex. Removal of the strong inhibitory feedback mechanism exerted by cortisol results in an increase in adrenocorticotropic hormone (ACTH) production by the pituitary. With continued blockade of the enzymatic steps leading to production of cortisol and corticosterone, there is a marked increase in adrenocortical secretion of their immediate precursors, 11-desoxycortisol and desoxycorticosterone, which are weak suppressors of ACTH release, and a corresponding elevation of these steroids in the plasma and of their metabolites in the urine. These metabolites are readily determined by measuring urinary 17‑hydroxycorticosteroids (17-OHCS) or 17-ketogenic steroids (17-KGS). Because of these actions, Metopirone is used as a diagnostic test, with urinary 17-OHCS measured as an index of pituitary ACTH responsiveness. Metopirone may also suppress biosynthesis of aldosterone, resulting in a mild natriuresis.

1 INDICATIONS AND USAGE Metopirone is indicated, in combination with other diagnostic tests, for the diagnosis of adrenal insufficiency in adult and pediatric patients. Metopirone is indicated, in combination with other diagnostic tests, for the diagnosis of adrenal insufficiency in adult and pediatric patients. ( 1 )

2 DOSAGE AND ADMINISTRATION Single-Dose Short Test: 30 mg/kg at midnight ( 2.2 ) 2.1 Important Information Before Conducting Metopirone Testing Stop drugs affecting pituitary or adrenocortical function before administration of Metopirone in accordance with half-life of the drugs (consider at least 5 half-lives to avoid any interference with Metopirone testing). [see Drug Interactions (7.1) ] . Assess ability of patient's adrenals to respond to exogenous ACTH before Metopirone is employed as a test [see Warnings and Precautions (5.1) ] . 2.2 Single-Dose Short Test- Recommended Dose and Interpretation This test, usually given on an outpatient basis, determines plasma 11-desoxycortisol and/or ACTH levels after a single dose of Metopirone. Patients with suspected adrenocortical insufficiency based on the test results previously performed should be hospitalized overnight as a precautionary measure ( see Warnings and Precaution (5.1) ). Recommended Dose In adult and pediatric patients, the recommended single dose is 30 mg/kg (maximum 3 grams of Metopirone) administered at midnight with milk/yogurt or snack. The blood sample for the assay is taken early the following morning (7:30-8:00 a.m.). After the blood sample is collected, a prophylactic dose of glucocorticoid may be considered for patients with high risk for acute adrenal insufficiency. Interpretation of 11‑desoxycortisol and ACTH Levels After Metopirone Administration Approximately 8 hours after administration of Metopirone, evaluate the values of ACTH and 11-desoxycortisol. Normal values will depend on the method used to determine ACTH and 11‑desoxycortisol levels. An intact HPA axis function is generally indicated by an increase in 11‑desoxycortisol to over 70 mcg/L. Because of an overlap between a normal ACTH response and an abnormal ACTH response, the ACTH response alone cannot be used to distinguish between healthy individuals and those with adrenal insufficiency.

6 ADVERSE REACTIONS The following adverse reactions associated with the use of Metopirone were identified in clinical trials or postmarketing reports. Because these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Cardiovascular System: Hypotension Gastrointestinal System: Nausea, vomiting, abdominal discomfort or pain Central Nervous System: Headache, dizziness, sedation Dermatologic System: Allergic rash Hematologic System: Leukopenia, anemia, and/or thrombocytopenia Adverse reactions include: hypotension, nausea, vomiting, abdominal discomfort or pain, headache, dizziness, sedation, allergic rash, leukopenia, anemia, and/or thrombocytopenia. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Direct Success Inc. at 844-597-6373 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

7 DRUG INTERACTIONS Anticonvulsants, psychotropic, hormone preparations, corticosteroids, antithyroid agents, cyproheptadine: may affect the results of the metyrapone test. ( 7.1 ) Acetaminophen: Avoid concomitant use with Metopirone. ( 7.2 ) 7.1 Effect of Other Drugs on Metopirone Anticonvulsants, psychotropic drugs, hormone preparations, corticosteroids, antithyroid agents and cyproheptadine may affect the results of the Metopirone test. If these drugs cannot be withdrawn, the necessity of carrying out the Metopirone test should be reviewed. 7.2 Effect of Metopirone on Other Drugs Acetaminophen Metopirone inhibits the glucuronidation of acetaminophen, which may decrease elimination of acetaminophen and lead to increased risk of adverse reactions related to acetaminophen. Avoid concomitant use of Metopirone with acetaminophen.