Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CARDIZEM LA vs CALAN
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Cardizem LA (diltiazem) is a calcium channel blocker that inhibits calcium ion influx across cardiac and smooth muscle cells during depolarization, leading to negative inotropic, chronotropic, and dromotropic effects. It dilates coronary and peripheral arteries, reducing systemic vascular resistance and myocardial oxygen demand.
Verapamil inhibits calcium ion influx through voltage-gated L-type calcium channels in cardiac and vascular smooth muscle, leading to decreased myocardial contractility, slowed AV conduction, and vasodilation.
Hypertension,Chronic stable angina pectoris,Atrial fibrillation or atrial flutter (rate control),Paroxysmal supraventricular tachycardia (PSVT)
Angina pectoris (chronic stable, vasospastic, unstable),Essential hypertension,Supraventricular tachyarrhythmias (e.g., atrial fibrillation, atrial flutter, PSVT)
Oral, 180-360 mg once daily; initiate at 180 mg once daily, titrate to 240 mg, then 300 mg, then 360 mg once daily as needed.
Initial: 80-120 mg orally 3 times daily; maintenance: 240-480 mg/day in 3-4 divided doses. IV: 5-10 mg over 2 minutes, may repeat after 15-30 minutes.
Terminal elimination half-life: 5-8 hours after oral administration. For extended-release formulations, the half-life is similar but the prolonged absorption phase results in sustained plasma concentrations.
Terminal elimination half-life is 3-7 hours for immediate-release; can be prolonged to 12-16 hours with sustained-release due to slow absorption; increased in hepatic impairment.
Primarily hepatic via CYP3A4; undergoes extensive first-pass metabolism. Metabolites include N-desmethyl diltiazem (active), deacetyl diltiazem, and others.
Extensively metabolized in the liver via CYP3A4, CYP1A2, and CYP2C8 isoenzymes; undergoes N-dealkylation and O-demethylation; first-pass metabolism results in low bioavailability (20-35%).
Urine (2-4% unchanged, ~40% as metabolites); bile/feces (major route, ~60% as metabolites).
Approximately 70% renal (3-4% unchanged, remainder as metabolites) and 25% biliary/fecal.
70-80% bound to plasma proteins (mainly albumin).
Approximately 90% bound to plasma proteins, primarily albumin.
3-5 L/kg, indicating extensive tissue distribution.
Vd 4-5 L/kg; indicates extensive tissue distribution beyond plasma volume.
Oral: ~40% due to extensive first-pass metabolism; intravenous: 100%.
Oral bioavailability is 20-35% due to extensive first-pass hepatic metabolism; IV bioavailability is 100%.
No specific dose adjustment is required for decreased GFR; however, use with caution in severe renal impairment (Cr Cl <30 m L/min) due to potential accumulation.
Cr Cl <30 m L/min: reduce dose by 50% and monitor carefully.
Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: use is not recommended.
Child-Pugh A: 50% of normal dose; Child-Pugh B: 25% of normal dose; Child-Pugh C: contraindicated or use with extreme caution.
Safety and efficacy have not been established in pediatric patients; no standard pediatric dosing available.
Oral: 4-8 mg/kg/day in 3 divided doses; IV: 0.1-0.3 mg/kg over 2 minutes, max 5 mg.
Initiate at low end of dosing range (180 mg once daily) and titrate slowly due to increased risk of hypotension, bradycardia, and reduced hepatic clearance.
Start at lowest dose (e.g., 40 mg 3 times daily) and titrate slowly; monitor for hypotension and bradycardia.
None.
Contains verapamil hydrochloride. Risk of serious adverse effects including hypotension, bradycardia, AV block, and cardiac arrest. Must not be administered to patients with severe left ventricular dysfunction, cardiogenic shock, or sick sinus syndrome (unless paced).
Conduction abnormalities: May worsen sinus node dysfunction or AV block, especially in elderly or with beta-blockers.,Heart failure: Use with caution in patients with reduced left ventricular function.,Hypotension: May cause symptomatic hypotension, especially with concurrent vasodilators.,Hepatic impairment: Diltiazem is hepatically metabolized; use with caution in patients with hepatic impairment.,Abrupt withdrawal: May precipitate angina or hypertension exacerbation; taper dose.,Beta-blocker coadministration: Increased risk of bradycardia, AV block, and hypotension.
May cause hypotension, bradycardia, AV block, and exacerbation of heart failure. Avoid in patients with pre-existing conduction abnormalities. Use caution with beta-blockers, digoxin, and CYP3A4 inhibitors. Abrupt withdrawal may exacerbate angina. May increase lithium and carbamazepine levels.
Sick sinus syndrome (unless pacemaker present),Second- or third-degree AV block (unless pacemaker present),Systolic blood pressure <90 mm Hg,Acute myocardial infarction with pulmonary congestion,Known hypersensitivity to diltiazem,Concurrent use with rifampin (enzyme inducer reduces effectiveness)
Severe left ventricular dysfunction, cardiogenic shock, sick sinus syndrome (without pacemaker), second- or third-degree AV block (without pacemaker), atrial flutter/fibrillation with accessory bypass tract (e.g., WPW syndrome), concurrent use of IV beta-blockers.
Avoid grapefruit and grapefruit juice as they inhibit CYP3A4 and may increase diltiazem levels. Limit alcohol intake due to additive vasodilation and hypotension risk. No specific food restrictions otherwise, but maintain a heart-healthy diet low in sodium and saturated fats to support blood pressure and angina management.
Avoid grapefruit and grapefruit juice as they inhibit CYP3A4 metabolism, increasing verapamil levels and risk of toxicity. Limit alcohol intake as it may enhance hypotensive effects. High-fat meals may delay absorption but not extent; take consistently with regard to meals.
Category C. First trimester: No adequate studies in humans; animal studies show embryotoxicity and fetotoxicity at high doses. Second and third trimesters: Risk of fetal bradycardia, hypotension, and growth restriction; avoid use if possible.
First trimester: No increased risk of major malformations observed in human studies; animal studies show fetal toxicity at high doses. Second and third trimesters: May cause fetal bradycardia, hypotension, and impaired placental perfusion; avoid use for pregnancy-induced hypertension due to risk of fetal hypoxia.
Diltiazem is excreted in breast milk; M/P ratio not established. Limited data suggest low levels; however, monitor infant for bradycardia, hypotension, and feeding difficulties. Use with caution.
Verapamil (CALAN) is excreted into breast milk; M/P ratio approximately 0.6. The relative infant dose is low (estimated <5% of maternal weight-adjusted dose). No adverse effects reported in breastfed infants. Caution in preterm infants or those with renal impairment.
No standard dose adjustment; pharmacokinetic changes (increased volume of distribution, altered protein binding) may necessitate titration based on clinical response. Avoid in first trimester if possible.
Pregnancy may increase clearance of verapamil; monitoring of therapeutic effect advised. Dose may need adjustment based on clinical response. Avoid use in pregnancy-induced hypertension.
CARDIZEM LA is a once-daily extended-release formulation of diltiazem, a non-dihydropyridine calcium channel blocker. It is useful for hypertension and chronic stable angina. Avoid use in patients with second- or third-degree AV block, sick sinus syndrome without pacemaker, hypotension (SBP <90 mm Hg), or acute MI with pulmonary congestion. Monitor heart rate and PR interval, as it can cause bradycardia and AV block. Contraindicated with IV beta-blockers; caution with oral beta-blockers due to additive negative chronotropic effects. CYP3A4 substrate; avoid strong inhibitors/inducers. Do not crush or chew capsules; can sprinkle contents on applesauce for patients with swallowing difficulties. Max antihypertensive effect may take 2 weeks. Withdrawal may cause angina exacerbation; taper if discontinuing. Use with caution in heart failure with reduced ejection fraction (HFr EF) due to negative inotropic effects.
Calan (verapamil) is a class IV antiarrhythmic and calcium channel blocker. Use caution in patients with hepatic impairment due to reduced clearance; dose adjustment may be needed. Avoid in patients with pre-existing bradycardia, second- or third-degree AV block, or sick sinus syndrome unless a pacemaker is present. May increase digoxin levels; monitor digoxin concentrations. Use with caution in patients with hypertrophic cardiomyopathy. For IV administration, have calcium gluconate available to reverse hypotension or bradycardia. Not recommended for use in acute myocardial infarction or cardiogenic shock.
Take exactly as prescribed, usually once daily. Swallow capsule whole; do not crush or chew. If you have trouble swallowing, you may open the capsule and sprinkle the beads on a spoonful of applesauce; swallow immediately without chewing.,This medication helps lower blood pressure and reduce chest pain (angina). It may take up to 2 weeks to see the full effect on blood pressure. Keep taking it even if you feel well.,Avoid drinking grapefruit juice or eating grapefruit while taking this medication as it can increase side effects.,Common side effects include swelling in legs/ankles, headache, dizziness, or flushing. Report slow heartbeat, severe dizziness, fainting, or shortness of breath to your doctor.,Do not stop taking this medication suddenly, as it may worsen chest pain or cause a heart attack. Your doctor will tell you how to taper the dose if needed.,Limit alcohol consumption, as it may increase dizziness or lower blood pressure further.,Inform all healthcare providers you are taking CARDIZEM LA, especially before surgery or dental procedures.
Take exactly as prescribed; do not skip doses or stop abruptly without consulting your doctor.,Avoid grapefruit juice as it can increase verapamil levels and risk of side effects.,If you miss a dose, take it as soon as you remember unless it is almost time for the next dose; do not double the dose.,Avoid alcohol as it may worsen side effects like dizziness or low blood pressure.,Report symptoms of bradycardia (slow heart rate), palpitations, shortness of breath, or swelling of ankles/feet.,This medication may cause dizziness; avoid driving or operating machinery until you know how it affects you.,Do not consume grapefruit or its juice during treatment.,Keep a regular medication schedule and do not change brands without doctor approval.
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 LA vs CALAN, answered by our medical review team.
CARDIZEM LA is a Calcium Channel Blocker that works by Cardizem LA (diltiazem) is a calcium channel blocker that inhibits calcium ion influx across cardiac and smooth muscle cells during depolarization, leading to negative inotropic, chronotropic, and dromotropic effects. It dilates coronary and peripheral arteries, reducing systemic vascular resistance and myocardial oxygen demand.. CALAN is a Calcium Channel Blocker that works by Verapamil inhibits calcium ion influx through voltage-gated L-type calcium channels in cardiac and vascular smooth muscle, leading to decreased myocardial contractility, slowed AV conduction, and vasodilation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CARDIZEM LA and CALAN 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 LA is: Oral, 180-360 mg once daily; initiate at 180 mg once daily, titrate to 240 mg, then 300 mg, then 360 mg once daily as needed.. The standard adult dose of CALAN is: Initial: 80-120 mg orally 3 times daily; maintenance: 240-480 mg/day in 3-4 divided doses. IV: 5-10 mg over 2 minutes, may repeat after 15-30 minutes.. 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 LA and CALAN 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 LA is classified as Category C. Category C. First trimester: No adequate studies in humans; animal studies show embryotoxicity and fetotoxicity at high doses. Second and third trimesters: Risk of fetal bradycardi. CALAN is classified as Category C. First trimester: No increased risk of major malformations observed in human studies; animal studies show fetal toxicity at high doses. Second and third trimesters: May cause fetal . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.