Can Cinnarizine Cause Bradycardia?
Cinnarizine does not typically cause bradycardia, despite its calcium channel-blocking properties. The available evidence suggests that bradycardia is not a clinically significant adverse effect of this medication, even in overdose situations.
Evidence from Overdose Cases
The most direct evidence comes from pediatric overdose data:
In a documented case of severe cinnarizine overdose (18 times the recommended pediatric dose), no bradycardia or hemodynamic instability was observed despite the patient experiencing significant neurologic complications including stupor and seizures 1
The manufacturing company's database of 23 overdose cases (1972-2004) reported no instances of bradycardia or cardiovascular complications related to the calcium channel-blocking properties of cinnarizine 1
The primary adverse effects in overdose were neurologic (altered consciousness, extrapyramidal symptoms, convulsions, vomiting) rather than cardiac 1
Mechanism and Clinical Context
While cinnarizine does possess calcium channel-blocking properties along with antihistaminic, antiserotoninergic, and antidopaminergic effects 1, its cardiac effects differ from traditional calcium channel blockers:
Standard calcium channel blockers like verapamil and diltiazem are well-documented to cause bradyarrhythmias as common pharmacological effects 2
Animal studies show cinnarizine can affect cardiac arrhythmias in ischemic conditions, but these effects are dose-dependent and do not specifically involve bradycardia 3
Important Clinical Caveats
The primary concern with cinnarizine is extrapyramidal side effects and depression, not cardiac arrhythmias:
Cinnarizine can induce parkinsonism, akathisia, and depression due to its antidopaminergic properties, even in young patients after short treatment courses 4
These extrapyramidal effects can persist for weeks to months after drug withdrawal 4
Monitoring recommendations for cinnarizine overdose should focus on neurologic complications (altered consciousness, seizures, extrapyramidal symptoms) rather than cardiac monitoring for bradycardia 1