Does nifedipine cause bradycardia (abnormally slow heart rate)?

From the Guidelines

Nifedipine does not typically cause bradycardia and may actually cause reflex tachycardia in some patients. Nifedipine is a calcium channel blocker primarily used to treat hypertension and angina. It works by blocking calcium channels in blood vessels, causing them to relax and dilate, which lowers blood pressure. While some calcium channel blockers (particularly verapamil and diltiazem) can slow heart rate, nifedipine belongs to the dihydropyridine class which has minimal direct effects on the heart's electrical conduction system, as noted in a study published in the European Heart Journal 1.

In fact, the sudden drop in blood pressure from nifedipine can trigger a compensatory reflex increase in heart rate as the body attempts to maintain blood pressure. This is especially common with immediate-release formulations. For this reason, extended-release formulations are generally preferred for most patients to avoid rapid blood pressure drops and reflex tachycardia. If a patient experiences unusual heart rate changes while taking nifedipine, they should consult their healthcare provider, as this could indicate another underlying issue or an interaction with other medications. According to a study published in the Journal of the American College of Cardiology 1, nifedipine's side effects include hypotension, dizziness, flushing, nausea, constipation, and edema, but bradycardia is not typically listed as a common side effect.

Some key points to consider when prescribing nifedipine include:

• Monitoring blood pressure regularly to avoid hypotension
• Avoiding immediate-release nifedipine due to the risk of rapid blood pressure drops and reflex tachycardia
• Being cautious when combining nifedipine with other medications that may interact with it
• Considering alternative calcium channel blockers, such as verapamil or diltiazem, if heart rate slowing is desired, as these medications have been shown to have a beneficial effect on mortality rates in patients with left ventricular dysfunction 1.

From the FDA Drug Label

With nifedipine extended-release tablets, these decreases in blood pressure are not accompanied by any significant change in heart rate Although, like other members of its class, nifedipine causes a slight depression of sinoatrial node function and atrioventricular conduction in isolated myocardial preparations, such effects have not been seen in studies in intact animals or in man In formal electrophysiologic studies, predominantly in patients with normal conduction systems, nifedipine administered as the immediate release capsule has had no tendency to prolong atrioventricular conduction or sinus node recovery time, or to slow sinus rate.

Nifedipine does not cause a significant change in heart rate in humans, and it does not tend to slow the sinus rate or prolong atrioventricular conduction in patients with normal conduction systems 2.

From the Research

Nifedipine and Bradycardia

• Nifedipine is a calcium channel blocker that can have varying effects on heart rate, depending on the individual and their health conditions 3, 4.
• In a patient with autonomic neuropathy, nifedipine was found to induce bradycardia, which is inconsistent with its typical effect of inducing tachycardia in normally innervated hearts 3.
• However, in other studies, nifedipine has been shown to have a neutral effect on heart rate or even cause a slight increase in heart rate due to its vasodilating action 5, 6.
• One study found that nifedipine did not significantly change heart rate in patients with essential hypertension, while another study found that it caused a slight decrease in heart rate in spontaneously hypertensive rats 6, 7.
• The effect of nifedipine on heart rate may be influenced by the presence of other health conditions, such as autonomic neuropathy, or the use of other medications, such as beta-blockers 3, 4.

Factors Influencing Nifedipine's Effect on Heart Rate

• The dose of nifedipine used can impact its effect on heart rate, with higher doses potentially leading to greater changes in heart rate 5, 4.
• The presence of other health conditions, such as hypertension or autonomic neuropathy, can also influence the effect of nifedipine on heart rate 3, 6.
• The use of other medications, such as beta-blockers, can interact with nifedipine and impact its effect on heart rate 4, 7.