Can Cardizem CD Be Taken Twice Daily for Angina?
No, Cardizem CD (diltiazem controlled-delivery) should not be taken twice daily—it is specifically formulated for once-daily administration. 1
Understanding Cardizem CD Formulation
Cardizem CD is an extended-release formulation designed for controlled delivery over 24 hours, maintaining consistent blood levels with once-daily dosing. 1 The "CD" designation specifically indicates "controlled delivery," which distinguishes it from immediate-release diltiazem that requires multiple daily doses. 1
Proper Dosing for Cardizem CD
For angina management:
- Starting dose: 120-180 mg once daily 1
- Usual maintenance range: 120-360 mg once daily 1
- Typical effective dose for angina: 240 mg once daily 1
- Maximum dose: 360-420 mg once daily 1
The once-daily formulation provides consistent 24-hour drug delivery, eliminating the need for twice-daily dosing. 1
Alternative Diltiazem Formulations
If twice-daily dosing is clinically necessary, slow-release (SR) formulations of diltiazem are available that can be dosed twice daily at 120-360 mg daily in divided doses. 1 However, this represents a different formulation than Cardizem CD.
Key Distinctions:
- Immediate-release diltiazem: 30-90 mg four times daily 2, 1
- Slow-release diltiazem: 120-360 mg daily in 2-3 divided doses 1
- Cardizem CD (extended-release): 120-420 mg once daily 1
Clinical Efficacy Evidence
Diltiazem is highly effective for chronic stable angina regardless of formulation. Studies demonstrate that controlled-release diltiazem given twice daily is equally potent and safe as conventional diltiazem given four times daily. 3 Higher doses (360 mg/day) show superior efficacy compared to lower doses, with significant improvements in exercise duration and time to angina onset. 4
For variant (vasospastic) angina specifically, diltiazem is a preferred agent and reduces cardiovascular events by 94% in angina frequency. 5
Critical Contraindications for Diltiazem
Absolute contraindications (do not use): 1
- Second- or third-degree AV block without functioning pacemaker
- Sick sinus syndrome without pacemaker
- Decompensated systolic heart failure or severe LV dysfunction
- Cardiogenic shock
- Wolff-Parkinson-White syndrome with atrial fibrillation/flutter
- Hypotension (systolic BP <90 mmHg)
Exercise extreme caution when combining with beta-blockers due to increased risk of profound bradycardia, AV block, and heart failure. 2, 1
Guideline Recommendations for Angina
When beta-blockers are contraindicated or produce intolerable side effects, heart rate-slowing calcium channel blockers like diltiazem offer an appropriate alternative for angina management. 2 Diltiazem can be used for ongoing or recurring ischemia-related symptoms in patients already receiving adequate doses of nitrates and beta-blockers, or in those unable to tolerate these agents. 2
Common Pitfalls to Avoid
- Never split or crush Cardizem CD tablets, as this destroys the controlled-release mechanism 1
- Do not routinely combine with beta-blockers without close monitoring for bradycardia and heart block 1
- Avoid in patients with PR interval >0.24 seconds or any degree of heart block without pacemaker 1
- Monitor for peripheral edema, which is dose-related and more common in women; consider adding diuretics if problematic 1
Monitoring Requirements
After initiating or changing diltiazem dose: 1
- Reassess patient in 1 month
- Monitor blood pressure and heart rate regularly
- Watch for return of anginal symptoms
- Assess for signs of heart failure in at-risk patients
- Check liver function tests if clinically indicated