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Expected pharmacological effect
Causality assessment · Expected pharmacological effect
Verapamil (non-dihydropyridine CCBs) and Bradycardia / AV block: is the FAERS signal real?
A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.
Verapamil (non-dihydropyridine CCBs) ↔ Bradycardia / AV block
n=213 co-reports · PRR 19.9 · ROR 20.9
Verapamil slows the heart by blocking calcium channels in the AV node, so bradycardia and heart block are the direct, predictable extension of its pharmacology rather than idiosyncratic effects. The risk is dose-related and is greatest with other rate-slowing drugs or in patients with conduction disease, which is why the drug is avoided in some arrhythmias and heart failure. The 213 co-reports (PRR 19.9) reflect both the real effect and verapamil's use for hypertension and arrhythmias.
Regulatory basis: verapamil prescribing information (bradycardia/AV block warning; contraindications in certain arrhythmias and heart failure).
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Bradycardia occurs during treatment and resolves after withdrawal |
| Strength | met | PRR 20 on a modest co-report count |
| Consistency | met | Reproduced across calcium-channel-blocker practice |
| Specificity | met | Shared with diltiazem and other AV-node-slowing drugs |
| Biological gradient | partial | Dose-related and worse with conduction disease |
| Plausibility | met | AV-node calcium-channel blockade is the mechanism |
| Coherence | met | Coheres with the labelled contraindications |
| Experiment | partial | Dechallenge (withdrawal) reverses it; no randomized trial |
| Analogy | met | Analogous to bradycardia with diltiazem and beta-blockers |
This page's own qualitative read, not an automated/citation-gated assessment.
✗ No ClinicalTrials.gov results-posting trial in the top search hits for verapamil captured bradycardia or AV block as a coded event; such a familiar, monitorable effect is handled by clinical and ECG monitoring rather than coded into trial AE tables.