Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CARDIZEM vs ADALAT
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Diltiazem inhibits calcium influx into cardiac and vascular smooth muscle cells during depolarization by binding to L-type calcium channels. This results in coronary vasodilation, decreased myocardial oxygen demand, and negative chronotropic and inotropic effects.
Dihydropyridine calcium channel blocker; inhibits calcium ion influx across cardiac and vascular smooth muscle cells, reducing peripheral vascular resistance and blood pressure.
Angina pectoris (chronic stable, vasospastic),Atrial fibrillation or atrial flutter (rate control),Hypertension
Hypertension,Chronic stable angina,Vasospastic angina (Prinzmetal's angina)
Oral: 30-120 mg three to four times daily; extended-release: 120-360 mg once daily. IV: Initial 0.25 mg/kg (max 25 mg) bolus over 2 minutes, may repeat in 15 minutes (0.35 mg/kg); maintenance: 5-15 mg/hour continuous infusion.
10-20 mg orally three times daily; extended-release: 30-60 mg orally once daily; maximum 120 mg/day.
Terminal elimination half-life is 3.0-4.5 hours in healthy adults; may be prolonged to 7-9 hours in elderly, hepatic impairment, or renal impairment; clinically relevant for dosing frequency.
Terminal elimination half-life: 2-5 hours (immediate-release); 8-14 hours (extended-release). Context: shorter half-life necessitates multiple daily dosing for immediate-release; extended-release allows once-daily dosing.
Hepatic via CYP3A4; undergoes extensive first-pass metabolism; metabolites: desacetyl diltiazem (active, 40-50% potency), N-demethylated, and deacetylated forms.
Hepatic via CYP3A4; extensive first-pass metabolism; metabolites are inactive.
Primarily hepatic metabolism with extensive first-pass effect; approximately 2-4% excreted unchanged in urine; fecal excretion accounts for about 65% of dose as metabolites; renal excretion accounts for about 35% of dose as metabolites.
Renal: 70-80% as metabolites; Fecal: 15-20% as metabolites; <1% unchanged in urine
77-87% bound to plasma proteins, primarily albumin.
92-98% bound to plasma proteins (albumin and alpha-1-acid glycoprotein)
3-5 L/kg; large Vd indicates extensive tissue binding and distribution.
0.8-1.2 L/kg. Clinical meaning: indicates extensive tissue distribution, consistent with high lipophilicity.
Oral: 40-50% due to significant first-pass metabolism (range 30-60% across individuals); IV: 100%.
Oral immediate-release: 45-60% (due to first-pass metabolism); extended-release: 60-85% (due to slower release and reduced first-pass effect).
No specific dose adjustment for renal impairment; use with caution in severe renal dysfunction (Cr Cl <30 m L/min) with close monitoring of heart rate and blood pressure.
No dose adjustment required for GFR ≥30 m L/min; for GFR <30 m L/min, use with caution and reduce initial dose by 50%.
Child-Pugh Class A: No adjustment. Class B: Reduce total daily dose by 25-50%. Class C: Avoid use; if necessary, consider further dose reduction with careful monitoring.
Child-Pugh Class A: no adjustment; Class B: reduce dose by 50%; Class C: avoid use or reduce by 75%.
Oral: 1.5-2 mg/kg/day divided every 6-8 hours, maximum 3.5 mg/kg/day. Extended-release not recommended in children. IV: Use only with caution; dosing not well established; typical initial bolus 0.1-0.3 mg/kg over 2 minutes, maximum 10 mg; infusion 0.5-5 mcg/kg/min.
0.25-0.5 mg/kg/dose orally every 6-8 hours; maximum 3 mg/kg/day. Extended-release not recommended.
Start at lower end of dosing range: oral immediate-release 30 mg three times daily; extended-release 120 mg once daily. Increase slowly. IV: Lower initial bolus (0.15-0.2 mg/kg) and infusion rates (2-5 mg/hour). Monitor for hypotension and bradycardia.
Start at 10 mg orally twice daily; titrate slowly due to increased sensitivity and risk of hypotension.
There is no FDA black box warning for CARDIZEM (diltiazem).
None
Symptomatic hypotension,Bradycardia or heart block (especially in sick sinus syndrome or AV block without pacemaker),Worsening heart failure in patients with reduced ventricular function,Hepatic injury (rare but elevated liver enzymes reported),Concomitant use with beta-blockers may increase risk of bradycardia and heart failure,Digitalis toxicity risk increased when used with digoxin,May exacerbate myasthenia gravis,Acute generalized exanthematous pustulosis (AGEP) and other severe cutaneous reactions,Gradual withdrawal recommended for chronic therapy to avoid angina exacerbation,May lower blood pressure, use with caution in patients with hypotension,Use in renal impairment: monitor carefully
May cause hypotension, especially in patients on beta-blockers or with poor cardiac reserve,Risk of increased angina and/or myocardial infarction upon initiation or dose increase,Peripheral edema,Stevens-Johnson syndrome and toxic epidermal necrolysis (rare),Hepatic impairment,Exacerbation of angina on withdrawal
Hypersensitivity to diltiazem or any component,Sick sinus syndrome (except with functioning ventricular pacemaker),Second- or third-degree AV block (except with functioning pacemaker),Severe hypotension (systolic < 90 mm Hg),Acute myocardial infarction with pulmonary congestion,Atrial fibrillation or flutter associated with accessory bypass tract (e.g., WPW syndrome; risk of ventricular tachycardia or fibrillation),Cardiogenic shock,Concurrent use with ivabradine,Lactation (due to potential adverse effects in infants)
Hypersensitivity to nifedipine,Cardiogenic shock,Significant aortic stenosis,Concurrent use with rifampin,Pregnancy (category C)
Avoid grapefruit and grapefruit juice as they inhibit CYP3A4 and can increase diltiazem levels, leading to toxicity. High-fat meals may increase absorption of some extended-release formulations; take with consistent meals. Alcohol may increase the risk of hypotension and dizziness. Maintain adequate hydration and avoid excessive salt intake to control blood pressure.
Avoid grapefruit and grapefruit juice; they inhibit CYP3A4 and increase nifedipine serum concentrations, leading to enhanced hypotensive effects and risk of toxicity. Grapefruit interaction persists for 24 hours; separate consumption by at least 4 hours if unavoidable, but preferable to avoid entirely. Avoid alcohol which can increase hypotension. High-fat meals may reduce absorption of extended-release formulations; take consistently with or without food.
No adequate studies in pregnant women. In animal studies, diltiazem (Cardizem) has been shown to cause skeletal abnormalities and increased fetal mortality at doses 5-10 times the maximum recommended human dose. Based on animal data and human experience with calcium channel blockers, risk cannot be ruled out. Use only if potential benefit justifies risk to fetus. Category C.
First trimester: Limited human data; animal studies show embryotoxicity. Second/third trimester: May cause fetal hypoxia due to maternal hypotension; risk of preterm labor inhibition. Category C.
Diltiazem is excreted in human milk. A study reported a milk-to-plasma (M/P) ratio of approximately 0.9. The estimated infant dose is 1-2% of maternal weight-adjusted dose. Caution is advised; consider waiting 3-4 hours after dose before breastfeeding to minimize exposure.
Excreted in breast milk; M/P ratio ~0.85. Consider risks versus benefits; monitor infant for hypotension.
Increased plasma volume and altered protein binding in pregnancy may reduce diltiazem concentrations; consider dose titration based on clinical response. No specific dose adjustment established; monitor therapeutic effect.
No standard dose adjustment; monitor clinical response and blood pressure; may require lower doses due to vasodilation effects.
Cardizem (diltiazem) is a non-dihydropyridine calcium channel blocker used for hypertension, angina, and atrial fibrillation/atrial flutter. It is contraindicated with IV beta-blockers due to risk of bradycardia and heart block. In AF, use IV form for rate control but avoid in WPW due to risk of ventricular pre-excitation. Diltiazem is metabolized by CYP3A4; caution with strong inhibitors like clarithromycin or grapefruit juice. For hypertension, start at 30 mg TID or extended-release once daily. Monitor heart rate and PR interval; avoid in sick sinus syndrome or second/third-degree AV block without pacemaker.
Adalat (nifedipine) is a dihydropyridine calcium channel blocker. Use immediate-release capsules only for hypertensive emergencies, not chronic treatment due to risk of reflex tachycardia and unpredictable hypotension. Extended-release formulations are preferred for stable angina and hypertension. Avoid grapefruit juice as it increases nifedipine levels via CYP3A4 inhibition. Monitor for peripheral edema, gingival hyperplasia, and constipation. Contraindicated in cardiogenic shock, severe aortic stenosis, and within 4 weeks of myocardial infarction.
Take this medication exactly as prescribed; do not crush or chew extended-release capsules.,Avoid grapefruit and grapefruit juice while taking this medication.,If you miss a dose, take it as soon as you remember unless it is almost time for your next dose; do not double the dose.,Do not stop taking this medication abruptly, as it may worsen your condition.,Common side effects include dizziness, headache, and swelling in the ankles/feet; contact your doctor if you experience slow heartbeat, shortness of breath, or fainting.,This medication may cause dizziness or lightheadedness; avoid driving or operating machinery until you know how it affects you.
Swallow extended-release tablets whole; do not crush, chew, or split.,Avoid grapefruit and grapefruit juice while taking this medication.,Report persistent swelling of ankles/feet, gum tenderness or bleeding, or severe dizziness.,Do not stop abruptly; taper under medical supervision to avoid rebound hypertension.,Take at the same time each day; if a dose is missed, skip it if near next dose.,May cause dizziness; avoid driving until you know how it affects you.,Increase fluid and fiber intake to prevent constipation.,Store at room temperature away from light and moisture.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about CARDIZEM vs ADALAT, answered by our medical review team.
CARDIZEM is a Calcium Channel Blocker that works by Diltiazem inhibits calcium influx into cardiac and vascular smooth muscle cells during depolarization by binding to L-type calcium channels. This results in coronary vasodilation, decreased myocardial oxygen demand, and negative chronotropic and inotropic effects.. ADALAT is a Calcium Channel Blocker that works by Dihydropyridine calcium channel blocker; inhibits calcium ion influx across cardiac and vascular smooth muscle cells, reducing peripheral vascular resistance and blood pressure.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CARDIZEM and ADALAT depend on the specific clinical indication. These are both Calcium Channel Blocker agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of CARDIZEM is: Oral: 30-120 mg three to four times daily; extended-release: 120-360 mg once daily. IV: Initial 0.25 mg/kg (max 25 mg) bolus over 2 minutes, may repeat in 15 minutes (0.35 mg/kg); maintenance: 5-15 mg/hour continuous infusion.. The standard adult dose of ADALAT is: 10-20 mg orally three times daily; extended-release: 30-60 mg orally once daily; maximum 120 mg/day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between CARDIZEM and ADALAT in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. CARDIZEM is classified as Category C. No adequate studies in pregnant women. In animal studies, diltiazem (Cardizem) has been shown to cause skeletal abnormalities and increased fetal mortality at doses 5-10 times the . ADALAT is classified as Category C. First trimester: Limited human data; animal studies show embryotoxicity. Second/third trimester: May cause fetal hypoxia due to maternal hypotension; risk of preterm labor inhibiti. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.