Metopiron (Metyrapone)

Metyrapone acts on adrenal steroid synthesis pathways and is employed in specific endocrine conditions.

• Cushing's syndrome: reduces excess cortisol production to improve clinical symptoms.
• Diagnostic testing of adrenal insufficiency: blocks cortisol synthesis to evaluate adrenal reserve.
• Hypercortisolism evaluation: assists clinicians in confirming endogenous excess cortisol levels.

• Metyrapone inhibits the enzyme 11-beta-hydroxylase in the adrenal cortex, preventing the final step of cortisol biosynthesis. By blocking this conversion, cortisol production falls, leading to a compensatory rise in ACTH and accumulation of upstream steroid precursors, which can be measured for diagnostic purposes.

Metyrapone may cause a range of adverse reactions, from mild to serious.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Dizziness: transient light‑headedness, especially on standing.
• Headache: occasional tension‑type headache.
• Fatigue: feeling of reduced energy or tiredness.

Serious or Rare Side Effects

• Adrenal insufficiency: severe cortisol deficiency requiring urgent medical attention.
• Hyponatremia: low blood sodium levels that may cause confusion or seizures.
• Severe allergic reaction: rash, swelling, or difficulty breathing.
• Hypotension: marked drop in blood pressure leading to fainting.
• Hypoglycemia: low blood glucose, particularly in patients with diabetes.

Use of Metopiron requires careful clinical monitoring and patient counseling.

• Monitor cortisol levels: assess hormonal response after initiation.
• Assess electrolytes: watch for sodium and potassium disturbances.
• Use cautiously in hepatic impairment: metabolism may be altered.
• Avoid abrupt discontinuation: taper to prevent adrenal crisis.
• Pregnancy and lactation: safety not established; weigh risks and benefits.
• Store at room temperature: keep in the original pack, protect from moisture.

Metyrapone can affect and be affected by other medicines; some combinations should be avoided while others need close observation.

Major Interactions (Avoid)

• Ketoconazole: strong CYP3A4 inhibition may increase metyrapone levels.
• Rifampin: potent CYP inducer can reduce efficacy of metyrapone.
• Exogenous glucocorticoids: may counteract the intended cortisol‑lowering effect.

Moderate Interactions (Monitor Closely)

• Antidepressants (SSRIs, SNRIs): may influence adrenal hormone balance.
• Antihypertensives: blood pressure changes may be accentuated.
• Diuretics: electrolyte shifts can be amplified, requiring monitoring.