Does oral Amiodarone (antiarrhythmic medication) affect blood pressure?

From the Guidelines

Oral amiodarone can affect blood pressure, typically causing mild to moderate hypotension in some patients. When administered orally, amiodarone may lower blood pressure through its vasodilatory effects and negative inotropic properties, though these effects are generally less pronounced than with intravenous administration. Patients starting oral amiodarone therapy should be monitored for blood pressure changes, particularly during the loading phase when higher doses (typically 800-1600 mg daily for 1-2 weeks) are used before transitioning to maintenance doses (typically 200-400 mg daily) 1. The hypotensive effect is more likely to occur in patients with pre-existing heart failure, those on other antihypertensive medications, or those with compromised cardiac function.

The mechanism involves peripheral vasodilation due to calcium channel blocking properties and alpha-adrenergic receptor blockade. Additionally, amiodarone's effect on thyroid function (both hypothyroidism and hyperthyroidism) can indirectly impact blood pressure regulation 1. Clinicians should consider baseline blood pressure assessment before initiating therapy and periodic monitoring thereafter, with appropriate adjustment of other antihypertensive medications if necessary. According to the 2014 AHA/ACC/HRS guideline, oral amiodarone may be useful for ventricular rate control when other measures are unsuccessful or contraindicated 1.

Some key points to consider when using oral amiodarone include:

• Monitoring for blood pressure changes, especially during the loading phase
• Being aware of the potential for hypotension, particularly in patients with pre-existing heart failure or compromised cardiac function
• Considering the effects of amiodarone on thyroid function and its potential impact on blood pressure regulation
• Adjusting other antihypertensive medications as necessary to minimize the risk of hypotension.

It is essential to weigh the benefits of oral amiodarone against its potential risks, including its effects on blood pressure, and to closely monitor patients during therapy 1.

From the FDA Drug Label

Amiodarone HCl injection has been reported to produce negative inotropic and vasodilatory effects in animals and humans In clinical studies of patients with refractory VF or hemodynamically unstable VT, treatment-emergent, drug related hypotension occurred in 288 of 1836 patients (16%) treated with amiodarone HCl injection Fentanyl: (CYP3A4 substrate) in combination with amiodarone may cause hypotension, bradycardia, and decreased cardiac output. The most common adverse effects leading to discontinuation of amiodarone HCl injection therapy were hypotension (1.6%), asystole/cardiac arrest/EMD (1.2%), VT (1. 1%), and cardiogenic shock (1%).

Oral amiodarone can affect blood pressure. It can cause hypotension due to its vasodilatory effects. The incidence of hypotension is significant, with 16% of patients experiencing treatment-emergent, drug-related hypotension in clinical studies. Additionally, oral amiodarone can interact with other medications, such as fentanyl, to cause hypotension, bradycardia, and decreased cardiac output 2, 2, 2.

From the Research

Effects of Oral Amiodarone on Blood Pressure

• The study published in the International Journal of Cardiology in 2007 3 found that oral amiodarone did not significantly alter blood pressure in patients with atrial fibrillation.
• In contrast, the study published in Acta Pharmacologica et Toxicologica in 1986 4 found that intravenous amiodarone caused a pronounced but transient fall in mean aortic blood pressure in dogs, which was attributed to the solvent used in the drug.
• However, the same study found that the electrophysiologic effects of amiodarone were not affected by the solvent, and that rapid tachyphylaxis occurred after the initial injection.
• The other studies 5, 6, 7 did not provide direct evidence on the effects of oral amiodarone on blood pressure.

Comparison with Other Antiarrhythmic Drugs

• The study published in the Journal of Cardiology in 2016 6 compared the effectiveness of different antiarrhythmic drugs, including amiodarone, for rhythm control of atrial fibrillation, but did not report on the effects of these drugs on blood pressure.
• The study published in the American Journal of Cardiology in 2014 7 compared the safety of sotalol versus amiodarone in patients with atrial fibrillation and coronary artery disease, but also did not report on the effects of these drugs on blood pressure.

Overall Findings

• The available evidence suggests that oral amiodarone does not have a significant effect on blood pressure, at least in the context of atrial fibrillation treatment 3.
• However, the effects of intravenous amiodarone on blood pressure may be different, and may be influenced by the solvent used in the drug 4.