Metycor (Metyrapone)

Metyrapone acts on adrenal steroidogenesis, making it useful for conditions involving cortisol excess or adrenal assessment.

• Cushing's syndrome (diagnostic testing and treatment): helps confirm hypercortisolism and can reduce cortisol levels in selected patients.
• Adrenal insufficiency (adjunct therapy): used to support cortisol production when endogenous synthesis is inadequate.
• Hypothalamic‑pituitary‑adrenal axis assessment: employed in dynamic testing to evaluate pituitary and adrenal reserve.

• Metyrapone selectively inhibits the enzyme 11‑beta‑hydroxylase in the adrenal cortex, blocking the final step of cortisol synthesis. By preventing conversion of 11‑deoxycortisol to cortisol, it reduces circulating cortisol concentrations and leads to accumulation of upstream precursors, which can be measured for diagnostic purposes or used therapeutically to modulate adrenal output.

Metyrapone may cause a range of adverse reactions, which are grouped by frequency and severity.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Headache: transient cranial discomfort.
• Dizziness or light‑headedness: often related to blood pressure changes.
• Hypertension: elevation of systolic or diastolic pressure.
• Fatigue: general feeling of tiredness.
• Mild electrolyte disturbances: such as mild hypokalemia.

Serious or Rare Side Effects

• Severe hypertension or hypertensive crisis.
• Acute adrenal insufficiency presenting with hypotension, vomiting, and hypoglycaemia.
• Allergic reactions: rash, pruritus, or anaphylaxis.
• Hepatic dysfunction: elevated liver enzymes.
• Severe electrolyte imbalance: marked hypokalemia or hyponatremia.

Before initiating Metycor, clinicians should consider several safety measures.

• Monitor cortisol levels: adjust therapy based on biochemical response.
• Assess blood pressure: watch for hypertension, especially in patients with cardiovascular risk.
• Evaluate electrolytes: check potassium and sodium regularly.
• Use cautiously in hepatic impairment: dose adjustment may be required.
• Avoid abrupt discontinuation: taper to prevent adrenal crisis.
• Store at ambient temperature below 25°C: keep in the original pack, protect from moisture.

Metycor can interact with other medicines that affect cortisol metabolism or share metabolic pathways.

Major Interactions (Avoid)

• Concurrent glucocorticoids: may mask adrenal insufficiency signs.
• Strong CYP3A4 inhibitors (e.g., ketoconazole): can increase metyrapone plasma concentrations.
• Potent CYP3A4 inducers (e.g., rifampicin): may reduce efficacy.

Moderate Interactions (Monitor Closely)

• Antihypertensives: blood pressure may rise, requiring dose adjustment.
• Diuretics: can exacerbate electrolyte disturbances.
• Antidepressants affecting serotonin: monitor for mood changes.
• Oral contraceptives: may alter steroid metabolism, requiring hormonal monitoring.