Diltiazem vs Verapamil
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Diltiazem (Cardizem) and verapamil (Calan) are both non-dihydropyridine calcium channel blockers used for hypertension, angina, and cardiac arrhythmias [1][2]. They differ from dihydropyridine CCBs like amlodipine by having significant effects on heart rate and cardiac conduction in addition to blood pressure lowering.
Both medications slow the heart rate and reduce cardiac conduction velocity, making them useful for rate control in atrial fibrillation and flutter [1][2]. However, they differ in their relative cardiac versus vascular effects and side effect profiles.
Verapamil has the strongest cardiac effects (most negative inotropy and chronotropy) among CCBs, while diltiazem has a more balanced profile between cardiac and vascular effects [1][2][3].
Diltiazem vs Verapamil: Side-by-side comparison
| Category | Diltiazem | Verapamil |
|---|---|---|
| Drug Class | Non-dihydropyridine calcium channel blocker | Non-dihydropyridine calcium channel blocker |
| Generic Name | Diltiazem HCl | Verapamil HCl |
| Brand Name | Cardizem, Tiazac | Calan, Verelan, Isoptin |
| FDA Approved For | Hypertension, angina, SVT/AF rate control | Hypertension, angina, SVT/AF rate control, cluster headache |
| How It Works | Blocks L-type calcium channels (balanced cardiac/vascular) | Blocks L-type calcium channels (stronger cardiac effects) |
| Dosage Forms | Tablets, ER capsules/tablets (30-420 mg), IV | Tablets, ER capsules/tablets (40-480 mg), IV |
| Typical Dose | 120-360 mg/day (ER once daily) | 120-480 mg/day (ER once daily) |
| Constipation Rate | 5-10% | 25-40% |
| Negative Inotropy | Moderate | Strong (highest among CCBs) |
| Heart Rate Effect | Moderate reduction | Strong reduction |
| Cost (Generic) | $10-$25/month | $10-$25/month |
| Migraine Prevention | Limited evidence | Established evidence |
Efficacy: How well does each drug work?
For hypertension, both are effective and recommended by JNC guidelines [3]. Both lower blood pressure through vasodilation and reduced cardiac output. Diltiazem and verapamil produce comparable blood pressure reductions at standard doses.
For atrial fibrillation rate control, both are guideline-recommended first-line agents [3]. They effectively slow ventricular rate by blocking AV nodal conduction. Head-to-head comparisons suggest similar rate control efficacy.
For angina, both reduce myocardial oxygen demand through heart rate reduction and vasodilation [1][2]. Verapamil may provide slightly superior antianginal effects due to its stronger cardiac effects.
Verapamil has unique evidence for migraine prevention and cluster headache prophylaxis — indications where diltiazem has less supporting data [2].
Side effects comparison
Constipation is verapamil's most notable side effect, affecting up to 25-40% of patients and often limiting its use [2]. This is significantly more common than with diltiazem (5-10%) [1]. Verapamil inhibits smooth muscle contraction throughout the GI tract.
Both cause dizziness, headache, peripheral edema (less than dihydropyridine CCBs), and bradycardia [1][2]. Both can worsen heart failure symptoms due to negative inotropic effects and are contraindicated in patients with decompensated HF, severe bradycardia, or advanced AV block [1][2].
Neither should be combined with beta-blockers without careful monitoring, as the combination can cause severe bradycardia, heart block, or heart failure [1][2]. Both interact with simvastatin (requiring dose limits), digoxin, and cyclosporine.
Cost comparison
Convenience and dosing
Both are available in immediate-release (dosed 3-4 times daily) and extended-release (once or twice daily) formulations [1][2]. ER formulations are preferred for hypertension and chronic rate control. Diltiazem is also available as IV infusion for acute rate control in hospital settings. Both have multiple generic ER options.
Which is right for you?
Diltiazem is generally preferred for most patients due to its lower incidence of constipation and more balanced cardiac/vascular profile [1][3]. It is the most commonly prescribed non-dihydropyridine CCB.
Verapamil may be preferred for migraine prevention (unique evidence base), cluster headache prophylaxis, and situations where stronger cardiac rate control is needed [2]. However, constipation must be proactively managed.
Both are contraindicated with severe heart failure, advanced heart block, and should be used cautiously with beta-blockers [1][2].
This information is for educational purposes only. Consult your cardiologist or healthcare provider.
Frequently asked questions
References
- [Regulatory] Diltiazem HCl (Cardizem) prescribing information. Bausch Health. https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/018602s093lbl.pdf Accessed 2025-06-15.
- [Regulatory] Verapamil HCl (Calan) prescribing information. Pfizer. https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/018817s049lbl.pdf Accessed 2025-06-15.
- [Regulatory] Whelton PK, et al. 2017 ACC/AHA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults. J Am Coll Cardiol. 2018;71(19):e127-e248. https://doi.org/10.1016/j.jacc.2017.11.006 Accessed 2025-06-15.
- [Observational] GoodRx price comparison: diltiazem and verapamil. https://www.goodrx.com Accessed 2025-06-15.
Written and fact-checked by PrescriptionDrugs.org Editorial Team
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