Ibuprofen Did Not Cause the Bradycardia
Ibuprofen 600mg did not cause the bradycardia—metoprolol succinate (the beta-blocker) is the culprit. NSAIDs like ibuprofen are not associated with bradycardia and do not have rate-lowering effects on the heart 1.
Why Metoprolol Is Responsible
- Beta-blockers cause bradycardia through direct effects on the SA and AV nodes, which is a well-established mechanism 1.
- Bradycardia is one of the most common adverse effects of metoprolol, occurring in approximately 15.9% of patients in clinical trials, with rates dropping below 40 bpm in some cases 2.
- The FDA label explicitly warns that "bradycardia, including sinus pause, heart block, and cardiac arrest have occurred with the use of metoprolol" 2.
Why Ibuprofen Is Not the Cause
- NSAIDs like ibuprofen do not have direct cardiac chronotropic effects and are not listed among medications known to cause bradycardia 1.
- The medications documented to cause bradycardia include beta-blockers, nondihydropyridine calcium channel blockers (diltiazem, verapamil), digoxin, amiodarone, sotalol, and ivabradine—but not NSAIDs 1.
Important Clinical Context
- Young adults on metoprolol can develop symptomatic bradycardia, particularly if the dose is too high or if there are drug interactions 3, 4.
- Women are at particularly high risk for metoprolol-induced bradycardia, with studies showing women have 50-80% higher metoprolol exposure than men at the same dose, leading to a 15-fold increased risk of bradycardia in the highest concentration group 4.
What to Do About the Bradycardia
- If the patient has symptomatic bradycardia (heart rate <50-60 bpm with dizziness, lightheadedness, or syncope), hold the metoprolol immediately 3.
- Reduce the metoprolol dose by 50% once symptoms resolve and heart rate improves, rather than stopping it completely, as abrupt discontinuation can cause severe exacerbation of angina, myocardial infarction, and ventricular arrhythmias 3, 2.
- Monitor heart rate and blood pressure within 1-2 weeks after dose reduction 3.
Common Pitfall to Avoid
Do not blame the ibuprofen or stop it unnecessarily—the bradycardia is from the metoprolol, and ibuprofen can be continued safely if needed for pain or inflammation. The focus should be on adjusting the beta-blocker dose appropriately 1, 2.