Dosing and uses of Metopirone (metyrapone)
Adult dosage forms and strengths
capsule
- 250mg
ACTH Diagnostic Test
Single dose test
- 30 mg/kg PO at midnight; not to exceed 3 g/dose
Multiple dose test
- 750 mg PO q4hr x6 doses
Administration
4 days prior to administration, collect and test a control 24-hour urine specimen for 17-hydroxycorticosteroids (17-OHCS) or 17-Ketogenic steroids (17-KGS) (alternatively, urinary tetrahydrodeoxycortisol, THS)
On the following day, perform corticotropin test to rule out adrenocortical insufficiency
May take with milk or food to reduce GI irritation
Cushing's Syndrome Treatment (Off-label)
250 mg PO q4hr; not to exceed 6 g/day
Pediatric dosage forms and strengths
capsule
- 250mg
ACTH Diagnostic Test
15 mg/kg or 300 mg/m² PO q4hr x6 doses; manufacturer recommends minimum single dose of 250 mg
Administration
4 days prior to administration, collect and test a control 24-hour urine specimen for 17-hydroxycorticosteroids (17-OHCS) or 17-Ketogenic steroids (17-KGS) (alternatively, urinary tetrahydrodeoxycortisol, THS)
On the following day, perform corticotropin test to rule out adrenocortical insufficiency
May take with milk or food to reduce GI irritation
Metopirone (metyrapone) adverse (side) effects
Frequency not defined
Abdominal discomfort
Bone marrow depression (rare)
Decr leukocyte count (rare)
Dizziness
Fall in arterial blood pressure
Headache
Nausea
Pulse rate incr
Sedation
Vertigo
Warnings
Contraindications
Adrenocortical insufficiency
Hypersensitivity
Cautions
May cause CNS depression, which may impair physical or mental abilities
Discontinue all corticosteroid therapy prior to, and during metyrapone test
Discontinue phenytoin at least 2 wk before metyrapone test
Pregnancy/lactation
Pregnancy and lactation
Pregnancy category: C
Lactation: unknown, use with caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Metopirone (metyrapone)
Mechanism of action
Inhibits formation of cortisol, corticosterone, and aldosterone
Pharmacokinetics
Half-life elimination: 1.9 hr (metyrapone)
Onset: Within 24 hr of administration (peak steroid excretion)
Peak Plasma: 1.2 mcg/mL
Metabolism: Liver and kidney; metabolized to an active reduced metabolite
Enzyme Inhibited: 11-beta-hydroxylase
Excretion: ~40% in urine (37% as glucuronide conjugates, 3% as the reduced metabolite and 0.5% unchanged)
