Amiodarone Hydrochloride

How it works

It mainly blocks cardiac potassium channels to prolong the action potential and refractory period, with additional sodium and calcium channel blocking and beta-adrenergic antagonist actions.

Prescribing in practice

• Cumulative thyroid, hepatic, pulmonary and ocular toxicity together with QT prolongation mandates baseline checks, periodic monitoring and avoidance of unnecessary QT-prolonging combinations.
• The extremely long half-life means drug interactions, including with warfarin and digoxin, continue for weeks after discontinuation.
• The intravenous route may cause profound hypotension and venous irritation, so dilute appropriately and prefer central administration for continued infusion.

Monitoring

Check thyroid and liver function before treatment and periodically thereafter, with ECG monitoring and chest or eye review where clinically indicated.

Counselling the patient

• Protect skin from sunlight to reduce photosensitivity reactions.
• Report new cough, breathlessness, visual disturbance or signs of an over- or under-active thyroid.
• Avoid grapefruit juice and inform other prescribers about long-lasting interactions.

Evidence & guidelines

Use is supported by NICE guidance on arrhythmia management and resuscitation algorithms, with MHRA communications underlining the need for organ-toxicity monitoring.