Diltiazem
CARDIZEM
What it isNon-dihydropyridine calcium channel blocker; rate control in atrial fibrillation, angina and hypertension.
Why this oneCompared with verapamil, it causes less constipation and myocardial depression while retaining AV-nodal rate control.
What limits itNegative inotrope: avoid in reduced EF. A moderate CYP3A4 inhibitor, which matters with statins and tacrolimus.
FDA-approved for
- angina (1982)
- hypertension (~1985)
- atrial fibrillation (~1992)
Off-label
- anal fissure (topical)
FDA label
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| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Chronic stable angina; angina due to coronary artery spasm | Adults | 30 mg QID (before meals and at bedtime) | 180–360 mg/day divided TID–QID | 360 mg/day (usual optimum range upper limit) |
Titration Increase gradually at 1–2 day intervals until optimum response.
Renal Undefined (no dosing data; titrate with particular caution).
Hepatic Undefined (no dosing data; titrate with particular caution).
Instructions
- May be swallowed whole, crushed, or chewed; do not split
- Take before meals and at bedtime
Contraindications
- Sick sinus syndrome (except with functioning ventricular pacemaker)
- Second- or third-degree AV block (except with functioning ventricular pacemaker)
- Hypotension (systolic <90 mm Hg)
- Acute myocardial infarction with pulmonary congestion on x-ray
Cautions
- Cardiac conduction effects (bradycardia, AV block)
- Congestive heart failure
- Symptomatic hypotension
- Acute hepatic injury (rare)
Adverse reactions
- Edema
- Headache
- Nausea
- Dizziness
- Rash
- Asthenia
Pregnancy Animal embryo/fetal lethality and skeletal abnormalities; use only if potential benefit justifies risk.
Lactation Undefined.
NO BOXED WARNINGS
Principal riskBradycardia and heart block; a moderate CYP3A4 inhibitor
Cost, est. cash$4–$80/month
Generic entry1992
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityBradycardia, heart block and hypotension; overdose can cause refractory cardiogenic shock.
Mechanism of action: Diltiazem ballicule
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Memory aids: mascots and interaction avatars
