Metyrapone
Mechanism :
Metyrapone inhibits 11 beta-hydroxylase, preventing the conversion of 11-deoxycortisol to cortisol.
Indication :
- ACTH function testing: Diagnostic test for hypothalamic-pituitary ACTH function
- Off-label: Cushing Syndrome
Contraindications :
Hypersensitivity to metyrapone or any component of the formulation; patient with adrenal cortical insufficiency.
Dosing :
ACTH function testing:
Single-dose/overnight test:
30 mg/kg PO (Maximum: 3 g) at midnight.
Multiple-dose test:
15 mg/kg (Minimum: 250 mg; maximum: 750 mg) PO every 4 hours for 6 doses.
Adverse Effect :
Hypotension, dizziness, headache, sedation, allergic skin rash, abdominal discomfort, nausea, vomiting, bone marrow depression.
Interaction :
Acetaminophen: Metyrapone may increase the serum concentration of Acetaminophen.
Phenytoin and Fosphenytoin: May decrease the serum concentration of Metyrapone.
Hepatic Dose :
No dose adjustments are recommended.