Does Amiodarone (amiodarone) help with tachycardia and does it cause hypotension (low blood pressure)?

From the Guidelines

Amiodarone is an effective medication for controlling heart rate in patients with arrhythmias, but it can cause a drop in blood pressure, especially when given intravenously at higher doses or too rapidly. The medication works by blocking multiple ion channels in the heart, including potassium, sodium, and calcium channels, as well as alpha and beta adrenergic receptors, which explains its effectiveness for various arrhythmias but also accounts for its potential to lower blood pressure 1. When taken orally for maintenance therapy, blood pressure effects are typically less pronounced than with IV administration. Patients starting amiodarone should be monitored for hypotension, particularly those with pre-existing low blood pressure or heart failure. Some key points to consider when using amiodarone include:

• Typical oral dosing begins with a loading dose of 400-600 mg daily for 1-2 weeks, followed by maintenance doses of 100-200 mg daily 1.
• Amiodarone is particularly effective for both supraventricular and ventricular arrhythmias, and it can be used to control the ventricular rate in patients with atrial fibrillation 1.
• The medication can cause extracardiac side effects, especially on long-term therapy, which may render it a second-line treatment in patients who are suitable for other antiarrhythmic drugs 1.
• Monitoring of liver and thyroid function should be performed at least every six months, as amiodarone can cause potentially harmful drug interactions and adverse effects 1. Overall, amiodarone is a valuable medication for controlling heart rate in patients with arrhythmias, but its potential to cause hypotension and other side effects must be carefully considered and monitored.

From the FDA Drug Label

In amiodarone-treated patients who require additional antiarrhythmic therapy, the initial dose of such agents should be approximately half of the usual recommended dose. Antihypertensives: Amiodarone should be used with caution in patients receiving ß- receptor blocking agents (e.g., propranolol, a CYP3A4 inhibitor) or calcium channel antagonists (e.g., verapamil, a CYP3A4 substrate, and diltiazem, a CYP3A4 inhibitor) because of the possible potentiation of bradycardia, sinus arrest, and AV block; Fentanyl: (CYP3A4 substrate) in combination with amiodarone may cause hypotension, bradycardia, and decreased cardiac output.

Amiodarone can help with heart rate by potentially causing bradycardia. It may also drop blood pressure (BP), as it can cause hypotension when used in combination with certain other medications, such as fentanyl 2. Key points to consider:

• Bradycardia and hypotension are potential side effects of amiodarone, especially when used with other medications 2.
• Amiodarone should be used with caution in patients receiving certain antihypertensives, such as beta blockers or calcium channel antagonists 2.
• The medication can cause cardiogenic shock in cases of overdose, which may require treatment with vasopressor drugs, positive inotropic agents, and volume expansion 2.

From the Research

Effect of Amiodarone on Heart Rate

• Amiodarone is effective in controlling heart rate in patients with atrial tachyarrhythmias, as shown in a study published in 2016 3.
• The study found that a loading dose of 300 mg intravenously, combined with an 800 mg oral dose on the first day, followed by 800 mg/day orally for 4 days, was effective in achieving a heart rate between 80 and 115 bpm within the first day and maintaining it during the next 4 days in patients with paroxysmal atrial tachyarrhythmias.
• The required dose of amiodarone to control heart rate is influenced by the type of atrial tachyarrhythmia and other conditions, such as the use of intravenous magnesium and fluid loading, which can enhance the heart rate decrease, while the use of dobutamine has an opposite influence 3.

Effect of Amiodarone on Blood Pressure

• Amiodarone is a potent coronary and peripheral vasodilator, which can lead to a decrease in blood pressure 4, 5.
• However, the effect of amiodarone on blood pressure is not consistently significant, and it can be safely used in patients with left ventricular dysfunction or congestive heart failure without causing significant cardiodepression 4, 5, 6.
• The use of amiodarone in patients with heart failure can even lead to an improvement in left ventricular ejection fraction and exercise capacity, without a significant decrease in blood pressure 6.

Overall Effect of Amiodarone

• Amiodarone is a highly effective antiarrhythmic medication that can be used to control both ventricular and atrial arrhythmias, with a low risk of proarrhythmic actions 4, 5, 7, 6.
• The medication has several side effects, including thyroid abnormalities, pulmonary fibrosis, and transaminitis, which require routine monitoring 4, 5, 7, 6.
• The overall objective of amiodarone therapy is to use the lowest dose that produces a defined therapeutic end point without causing serious side effects, and careful clinical surveillance is necessary to monitor its efficacy and safety 4, 5, 7, 6.