Can Norvasc (Amlodipine) Cause Bradycardia?
Amlodipine does NOT typically cause bradycardia at therapeutic doses and is specifically documented to avoid causing reflex tachycardia or cardiac conduction disturbances in normal clinical use. 1
Mechanism and Normal Clinical Effects
Amlodipine is a dihydropyridine calcium channel blocker that selectively acts on peripheral vascular smooth muscle, causing vasodilation without significant effects on cardiac conduction tissue at therapeutic doses 1
The FDA label explicitly states that amlodipine "does not change sinoatrial nodal function or atrioventricular conduction" in both animal models and humans 1
Chronic oral administration does not lead to clinically significant changes in heart rate, and blood pressure reductions occur "without a significant change in heart rate or plasma catecholamine levels" 1
Clinical trials in angina patients demonstrated that amlodipine "did not alter electrocardiographic intervals or produce higher degrees of AV blocks" 1
The drug "does not appear to cause postural hypotension, reflex tachycardia or cardiac conduction disturbances" in comparative studies 2
Critical Distinction: Overdose vs. Therapeutic Use
However, severe amlodipine overdose can paradoxically cause bradycardia, representing a loss of the drug's normal vascular selectivity:
In toxic doses, dihydropyridines lose their selective action on vascular territory and can depress cardiac automatism and conduction 3
Case reports document bradyarrhythmias including low atrial rhythm, prolonged PR interval, atrioventricular block, and bundle branch blocks in severe intoxication 3
An 81-year-old woman who ingested 250 mg of amlodipine (50 tablets) developed refractory bradycardia (45 bpm) with a serum level of 474.4 ng/mL, requiring isoproterenol infusion 4
Another case of severe overdose (450 mg) presented with bradycardia of 40 beats/min along with hypotension 5
Contrast with Non-Dihydropyridine Calcium Channel Blockers
This is fundamentally different from non-dihydropyridine calcium channel blockers (diltiazem, verapamil), which DO cause bradycardia at therapeutic doses:
Non-dihydropyridines have "more pronounced effects on cardiac tissue, including the sinoatrial and atrioventricular nodes, resulting in negative chronotropy" at normal doses 6
Guidelines specifically note that dihydropyridines cause "peripheral oedema, reflex tachycardia" while non-dihydropyridines cause "bradycardia, AVB" 6
The European Society of Cardiology distinguishes that non-dihydropyridines "decrease the sinus node discharge rate and slow atrioventricular nodal conduction" whereas dihydropyridines like amlodipine do not 6
Clinical Bottom Line
At therapeutic doses (2.5-10 mg daily), amlodipine does not cause bradycardia and is safe to use even in combination with beta-blockers without adverse electrocardiographic effects. 1 Bradycardia only occurs in massive overdose situations (typically >200 mg) where the drug loses its vascular selectivity. 4, 3, 5