Diltiazem vs Cardizem: No Clinical Difference
Diltiazem and Cardizem are the same medication—Cardizem is simply the brand name for diltiazem. There is no difference in efficacy, mechanism of action, or clinical usage between generic diltiazem and brand-name Cardizem for treating hypertension and angina 1.
Mechanism and Clinical Effects
Both formulations work identically as calcium channel blockers (benzothiazepine class) by:
- Inhibiting calcium influx during membrane depolarization in cardiac and vascular smooth muscle 1
- Dilating coronary arteries (both epicardial and subendocardial), which relieves coronary artery spasm and increases oxygen supply 1
- Reducing myocardial oxygen demand through decreases in heart rate and systemic blood pressure 1
- Slowing AV nodal conduction and decreasing sinus node discharge rate, making it useful for rate control 2
Approved Indications
Both generic diltiazem and Cardizem are FDA-approved for:
- Chronic stable angina 1
- Angina due to coronary artery spasm (vasospastic angina) 1
- Hypertension (though this requires higher doses than angina treatment) 3
Clinical Usage Guidelines
For Hypertension and Stable Angina
The American Heart Association and American College of Cardiology recommend diltiazem as:
- First-line alternative when β-blockers are contraindicated or produce intolerable side effects in patients with hypertension and chronic stable angina 2
- Preferred over dihydropyridine calcium channel blockers (like nifedipine) when rate control is needed 2
- Symptom relief agent for patients already receiving nitrates and β-blockers 2
For Acute Coronary Syndromes
In NSTE-ACS (unstable angina/NSTEMI):
- Diltiazem shows trends toward benefit when administered early to patients without heart failure 2
- Can be used safely for symptom control in the absence of clinically significant LV dysfunction 2
- The DATA trial demonstrated that intravenous diltiazem decreased death, MI, and recurrent ischemia at 35 days and 6 months 2
Critical Dosing Considerations
Common Dosing Error
Diltiazem is frequently underdosed in clinical practice:
- For hypertension: The effective dose is commonly 360 mg/day, yet 70% of prescriptions are for 180-240 mg/day 3
- For angina: The typical effective dose is 240 mg/day 3
- FDA data shows a clear linear dose-response relationship through 480-540 mg/day for blood pressure lowering 3
- The 90-120 mg/day range is essentially a "no-effect dose" 3
Formulation-Specific Dosing
- Immediate-release: 30-90 mg four times daily 2
- Sustained-release: 120-360 mg once daily 2
- Maximum recommended dose: Up to 480 mg/day 4
Absolute Contraindications
Do not use diltiazem (generic or Cardizem) in patients with:
- Left ventricular systolic dysfunction or heart failure 2, 4
- Significant sinus or AV node dysfunction 2, 4
- Hypotension 4
- Advanced cardiac block without a pacemaker 4
Critical Drug Interaction Warning
Exercise extreme caution when combining diltiazem with β-blockers:
- This combination increases risk of significant bradyarrhythmias and heart failure 2, 4
- The synergistic effect can depress LV function and sinus/AV node conduction 2
- When both are needed, close monitoring is mandatory 2
Comparative Efficacy Data
Diltiazem demonstrates equivalent outcomes to other major antihypertensive classes:
- The INVEST trial showed no difference between verapamil (similar non-dihydropyridine CCB) and atenolol in cardiovascular death, MI, or revascularization in 22,000 hypertensive patients with chronic CAD 2
- The NORDIL study found similar overall cardiovascular event rates for diltiazem versus diuretic/β-blocker combination 2
- Diltiazem shows similar efficacy to β-blockers in relieving anginal symptoms 2
Pharmacokinetic Profile
Both formulations share identical pharmacokinetics: