Diltiazem ER
CARDIZEM CD
Pronunciation: dil-TYE-a-zem
“Dill ties a Cardigan”
What it isDiltiazem extended-release (CARDIZEM CD, 1991) blocks L-type calcium channels; hypertension and chronic stable angina.
Why this oneOnce-daily form replaces an IR tablet dosed 3-4x daily; it usually causes less constipation and myocardial depression than verapamil.
What limits itBradycardia, heart block and edema limit it; avoid systolic heart failure. CYP3A4 inhibition raises many statin and other substrate exposures.
Diltiazem ER prescription history
Animated chart of estimated U.S. prescriptions per year, Calcium-channel blockers (1981–2026). Diltiazem ER enters in 1982 (estimated).
FDA-approved for
- hypertension (1991)
- chronic stable angina (1991)
Principal riskBradycardia and heart block; a potent CYP3A4 inhibitor
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityBradycardia, heart block and hypotension; overdose can cause refractory cardiogenic shock.
FDA label
Read the full label on DailyMed ↗
NO BOXED WARNINGS
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Hypertension | Adults | 180-240 mg QD (monotherapy) | 240-360 mg QD | 480 mg QD |
| Chronic stable angina / angina due to coronary artery spasm | Adults | 120 or 180 mg QD | individualize | 480 mg QD |
Titration Hypertension: maximum effect usually by 14 days; schedule adjustments accordingly. Angina: titrate over a 7- to 14-day period
Renal Undefined
Hepatic Increased half-life and ~69% higher bioavailability in cirrhosis; titrate cautiously (start low)
Instructions
- Once-daily extended-release capsule
- Patients controlled on diltiazem may switch to ER at nearest equivalent total daily dose
- Avoid consumption of alcohol (may accelerate diltiazem release)
Available strengths
- ER cap 60, 90, 120, 180, 240, 300, 360, 420 mg
Contraindications
- Sick sinus syndrome except with a functioning ventricular pacemaker
- Second- or third-degree AV block except with a functioning ventricular pacemaker
- Hypotension (less than 90 mm Hg systolic)
- Acute myocardial infarction and pulmonary congestion documented by x-ray on admission
Cautions
- Cardiac conduction: prolongs AV node refractory period; may cause bradycardia or AV block (additive with beta-blockers/digitalis)
- Congestive heart failure — worsening reported with pre-existing ventricular impairment
- Hypotension
- Acute hepatic injury (usually transient transaminase elevations)
- Dermatologic reactions (may progress to erythema multiforme/exfoliative dermatitis)
Adverse reactions
- Headache, dizziness, bradycardia, first-degree AV block, edema, asthenia
Pregnancy Animal studies showed embryo/fetal lethality and skeletal abnormalities; use only if potential benefit justifies risk
Lactation Diltiazem excreted in human milk (may approximate serum levels); use alternative feeding if drug essential
Cost
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Memory aids: interaction avatars
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Self-check
- How does diltiazem ER frequency compare with IR?
Once daily instead of 3–4 times daily. - Which heart-failure type should avoid diltiazem ER?
Systolic heart failure.