Zopiclone and Bradycardia
Zopiclone does not typically cause bradycardia as an adverse effect based on available evidence. While many medications can induce various arrhythmias, zopiclone is not documented to cause bradycardia in clinical guidelines or research studies.
Pharmacological Profile of Zopiclone
Zopiclone is a cyclopyrrolone hypnotic that acts on the GABA-A receptor complex at a site closely related to, but distinct from, the benzodiazepine binding site 1. It is primarily used for the short-term treatment of insomnia and should not be prescribed for more than 4 weeks 2.
The most commonly reported adverse effects of zopiclone include:
- Bitter taste (reported by <10% of patients)
- Dry mouth
- Minimal impairment to psychomotor performance and mental alertness the morning after use 1
Cardiac Effects of Zopiclone
Unlike many other medications that can affect cardiac function, zopiclone has not been specifically associated with bradycardia in the medical literature:
No mention in cardiac guidelines: Major cardiology guidelines, including those from the American Heart Association and European Society of Cardiology, do not list zopiclone among medications known to cause bradycardia 3.
Absence in drug-induced arrhythmia literature: The American Heart Association's scientific statement on drug-induced arrhythmias does not include zopiclone among medications that can trigger bradyarrhythmias 4.
Clinical trials and post-marketing surveillance: Data from clinical trials and post-marketing surveillance including over 30,000 patients showed that zopiclone's tolerability profile is similar to placebo, with the exception of bitter taste 2. Bradycardia was not identified as a significant adverse effect.
Medications Known to Cause Bradycardia
For comparison, medications that are documented to cause bradycardia include:
- Amiodarone: May cause bradycardia, heart block, and other cardiac conduction abnormalities 3
- Lithium: Can cause bradycardia even at therapeutic levels 5
- Certain antipsychotics: Cases of symptomatic bradycardia have been reported with ziprasidone and aripiprazole 6
- Opioids: Can lead to bradycardia and vasodilation 7
Management of Drug-Induced Bradycardia
Although zopiclone is not associated with bradycardia, it's worth noting the standard management of drug-induced bradycardia for context:
For symptomatic bradycardia, first-line treatment is atropine 0.5 to 1 mg IV repeated every 3 to 5 minutes as needed up to 1.5 to 3 mg total 3.
If atropine is ineffective, consider epinephrine (2 to 10 μg/min) or dopamine (2 to 10 μg/kg/min) 3.
Transcutaneous pacing may be considered when full-dose atropine fails 3.
Conclusion
Based on the available evidence, zopiclone does not appear to cause bradycardia as an adverse effect. Its cardiovascular safety profile is generally favorable when used as directed for the short-term management of insomnia. If a patient on zopiclone develops bradycardia, clinicians should consider other potential causes or contributing factors rather than attributing it to zopiclone therapy.