Cardizem CD (Diltiazem) Dosing and Management Strategy
For hypertension, Cardizem CD (diltiazem extended-release) should be started at 180-240 mg once daily and titrated up to 360 mg daily for optimal blood pressure control. For angina, the starting dose is typically lower at 120-180 mg once daily.
Dosing Recommendations
Hypertension
- Starting dose: 180-240 mg once daily
- Maintenance dose: 240-360 mg once daily
- Maximum dose: Up to 480 mg daily for resistant hypertension
Angina
- Starting dose: 120-180 mg once daily
- Maintenance dose: 180-360 mg once daily
- Titration: Increase dose at 1-2 week intervals based on clinical response
Pharmacokinetics of Cardizem CD
- Extended-release (CD) formulation provides consistent 24-hour blood pressure control with once-daily dosing 1
- Steady-state plasma concentrations are achieved within 2-3 days of consistent dosing
- Therapeutic blood levels (≥40 ng/mL) are typically achieved with doses ≥240 mg/day 2
Clinical Considerations
Efficacy
- Research shows a clear linear dose-response relationship through the 480-540 mg/day range 3
- Many patients are underdosed in clinical practice, with 70% of prescriptions being for 180-240 mg despite evidence that 360 mg/day is often required for optimal hypertension control 3
- For angina, diltiazem CD 180 mg once daily significantly improves exercise tolerance and reduces angina frequency even when added to existing beta-blocker or nitrate therapy 4
Contraindications
- Absolute contraindications: Heart failure with reduced ejection fraction, severe left ventricular dysfunction, second or third-degree AV block without pacemaker 5, 6
- Relative contraindications: Concomitant beta-blocker therapy without careful monitoring (risk of synergistic depression of cardiac function) 6
Special Populations
- Elderly: Consider starting at lower doses (120-180 mg daily) due to potentially enhanced response 6
- Renal/hepatic impairment: No specific dosing recommendations available; use caution and titrate slowly 7
Monitoring and Follow-up
- Assess blood pressure response at trough (24 hours post-dose) to ensure adequate 24-hour coverage
- Monitor for common side effects: edema, dizziness, flushing, bradycardia
- If inadequate response at maximum tolerated dose, consider adding a second agent from a different class
Common Pitfalls to Avoid
- Underdosing: Many clinicians prescribe suboptimal doses (180-240 mg) for hypertension when 360 mg is often needed 3
- Inappropriate use in heart failure: Avoid in patients with pulmonary edema or severe LV dysfunction 5
- Drug interactions: Use caution when combining with beta-blockers due to potential for excessive bradycardia and heart block 6
- Immediate-release confusion: Cardizem CD is distinct from immediate-release diltiazem, which requires multiple daily dosing (3-4 times daily) 6
Cardizem CD's once-daily formulation offers convenience and improved adherence compared to multiple daily dosing regimens required with immediate-release diltiazem, while maintaining consistent 24-hour blood pressure and angina control.