Amiodarone injection

Generic name: Amiodarone

Drug class: Antiarrhythmic agent

Dosage form: Injection

Route of administration: Intravenous (IV)

Dose:

• Loading dose: 150 mg IV over 10 minutes, followed by 360 mg IV over the next 6 hours (1 mg/min for 6 hours), then 540 mg IV over the next 18 hours (0.5 mg/min for 18 hours). Total loading dose: 1,050 mg over 24 hours.
• Maintenance dose: 0.5 mg/min IV for 18 hours, then transition to oral therapy as appropriate.

Mechanism of action: Amiodarone is a class III antiarrhythmic agent that prolongs phase 3 of the cardiac action potential, leading to increased refractory periods in the heart’s conduction system. It also exhibits properties similar to class I, II, and IV antiarrhythmics, affecting sodium, potassium, and calcium channels, as well as beta-adrenergic receptors, thereby stabilizing cardiac rhythm.

Drug usage cases:

• Treatment and prevention of life-threatening ventricular arrhythmias, including ventricular fibrillation and ventricular tachycardia.
• Management of atrial fibrillation and atrial flutter, particularly when other treatments are ineffective or contraindicated.
• Off-label use in the management of paroxysmal supraventricular tachycardia (PSVT) and atrial tachycardia.

Drug contraindications:

• Hypersensitivity to amiodarone or any of its components.
• Sinus bradycardia, sinoatrial block, or sick sinus syndrome without a functioning pacemaker.
• Second- or third-degree atrioventricular (AV) block without a functioning pacemaker.
• Severe hepatic impairment.
• Thyrotoxicosis that cannot be controlled by conventional means.
• Concurrent use with other antiarrhythmic agents that may induce torsades de pointes.
• Severe respiratory failure, circulatory collapse, or severe hypotension.
• Known hypersensitivity to iodine.
• Use in neonates, infants, and children up to 3 years old due to the presence of benzyl alcohol in the formulation.

Side effects:

• Common: Nausea, vomiting, fatigue, tremor, constipation, photosensitivity, and corneal microdeposits.
• Serious: Pulmonary toxicity (e.g., interstitial pneumonitis, pulmonary fibrosis), liver toxicity (e.g., hepatitis, cirrhosis), thyroid dysfunction (e.g., hypothyroidism, hyperthyroidism), optic neuropathy, and bradycardia.
• Cardiac: QT interval prolongation, torsades de pointes, and other arrhythmias.
• Dermatologic: Blue-gray skin discoloration, especially with prolonged use.
• Neurologic: Peripheral neuropathy, ataxia, and peripheral vasodilation leading to hypotension.

Warnings:

• Use only in life-threatening arrhythmias unresponsive to other treatments.
• Monitor ECG and blood pressure continuously during administration.
• Be aware of potential drug interactions, especially with other antiarrhythmics, beta-blockers, calcium channel blockers, and drugs that prolong the QT interval.
• Regular monitoring of thyroid, liver, and pulmonary function is recommended due to potential toxicities.
• Use caution in patients with pre-existing lung disease, as amiodarone can exacerbate pulmonary conditions.
• Discontinue use if signs of pulmonary toxicity, liver dysfunction, or thyroid abnormalities occur.
• Avoid grapefruit juice during treatment, as it can increase amiodarone levels and the risk of side effects.
• Be aware of potential photosensitivity; advise patients to avoid excessive sun exposure and use protective measures.
• Use caution when transitioning from IV to oral therapy; adjust dosages of concomitant medications as needed.

Use during pregnancy or breastfeeding:

Amiodarone is classified as a pregnancy category D medication, indicating potential risks to the fetus. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Amiodarone is excreted in breast milk and can affect the nursing infant; therefore, breastfeeding is not recommended during treatment. Women who are pregnant or planning to become pregnant should discuss the risks and benefits of amiodarone therapy with their healthcare provider. Women who are breastfeeding should discontinue nursing during treatment with amiodarone.