Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DILT-CD vs CALAN
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 ion influx during depolarization of cardiac and vascular smooth muscle cells, thereby reducing intracellular calcium levels. It decreases sinoatrial and atrioventricular nodal conduction and dilates coronary and peripheral arteries.
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,Variant angina,Atrial fibrillation or atrial flutter (rate control),Paroxysmal supraventricular tachycardia
Angina pectoris (chronic stable, vasospastic, unstable),Essential hypertension,Supraventricular tachyarrhythmias (e.g., atrial fibrillation, atrial flutter, PSVT)
180-360 mg PO once daily (extended-release); 300-540 mg PO once daily for hypertension; 120-480 mg PO once daily for angina; IV: 0.25 mg/kg bolus over 2 min, then 5-15 mg/hr continuous infusion.
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 7-10 hours; clinically relevant in hepatic impairment (prolonged to 14-20 hours) and in elderly
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.
Hepatic via CYP3A4; undergoes deacetylation and N-demethylation.
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%).
Renal 2-4% unchanged; extensive hepatic metabolism; 60-70% fecal, 30-40% renal as metabolites
Approximately 70% renal (3-4% unchanged, remainder as metabolites) and 25% biliary/fecal.
85-90% bound to plasma proteins (primarily albumin and alpha-1-acid glycoprotein)
Approximately 90% bound to plasma proteins, primarily albumin.
3-5 L/kg; large Vd indicates extensive tissue binding, with highest concentrations in liver, lung, and spleen
Vd 4-5 L/kg; indicates extensive tissue distribution beyond plasma volume.
Oral immediate-release: 40-60% (first-pass effect); oral sustained-release: 30-50%; IV: 100%
Oral bioavailability is 20-35% due to extensive first-pass hepatic metabolism; IV bioavailability is 100%.
No dosage adjustment required for mild-moderate renal impairment; use caution and consider dose reduction 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 25-50%; Child-Pugh C: contraindicated or use with extreme caution, reduce dose by at least 50%.
Child-Pugh A: 50% of normal dose; Child-Pugh B: 25% of normal dose; Child-Pugh C: contraindicated or use with extreme caution.
Not FDA-approved for pediatric use; off-label dosing for hypertension: extended-release initial 2.5-5 mg/kg/day PO once daily, max 10 mg/kg/day up to 360 mg daily; for supraventricular tachycardia: IV bolus 0.1-0.3 mg/kg over 2 min, may repeat after 30 min, max 10 mg/dose.
Oral: 4-8 mg/kg/day in 3 divided doses; IV: 0.1-0.3 mg/kg over 2 minutes, max 5 mg.
Start at lower end of dosing range (e.g., 120 mg PO once daily for hypertension); titrate slowly; monitor for hypotension, bradycardia, and constipation; consider reduced initial dose due to altered pharmacokinetics.
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).
May cause bradycardia, heart block, or heart failure exacerbation,Use caution in patients with impaired left ventricular function,May cause hypotension, especially in patients with aortic stenosis,May increase digoxin and cyclosporine levels,Abrupt withdrawal may exacerbate angina,Hepatic impairment may require dose adjustment,Avoid use in patients with sick sinus syndrome or second/third-degree AV block without pacemaker
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 (except with functioning pacemaker),Second- or third-degree AV block (except with pacemaker),Hypotension (systolic <90 mm Hg),Acute myocardial infarction with pulmonary congestion,Known hypersensitivity to diltiazem,Concomitant use with dantrolene (risk of ventricular fibrillation),Concurrent use with ivabradine
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; they inhibit CYP3A4 and increase diltiazem levels, raising risk of toxicity. High-fat meals may increase absorption; take with food to reduce gastrointestinal upset. Alcohol may enhance hypotension and dizziness; limit consumption.
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.
DILT-CD is a formulation of diltiazem, a calcium channel blocker. In animal studies, diltiazem has been associated with fetal skeletal abnormalities and reduced fetal weight at high doses. Human data are limited; however, diltiazem is generally avoided in the first trimester due to potential teratogenic effects. In the second and third trimesters, use is cautioned due to risks of maternal hypotension and possible fetal hypoxia. Diltiazem crosses the placenta and may cause fetal bradycardia.
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 into breast milk in small amounts; the estimated infant dose is approximately 1% of the maternal weight-adjusted dose. The milk-to-plasma ratio (M/P) is reported as 0.5-1.0. Caution is advised due to potential cardiovascular effects in the nursing infant, though limited data suggest low risk. Monitor infant for bradycardia and hypotension.
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.
Pregnancy may increase diltiazem clearance due to expanded plasma volume and enhanced hepatic metabolism. Dose adjustments may be needed to maintain efficacy; however, specific pharmacokinetic studies for DILT-CD are lacking. Generally, use the lowest effective dose and monitor clinical response. Titrate based on maternal blood pressure and heart rate.
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.
DILT-CD is a calcium channel blocker (non-dihydropyridine) used for hypertension and angina. It has negative chronotropic and dromotropic effects; avoid in patients with sick sinus syndrome or second/third-degree AV block without a pacemaker. Monitor heart rate and PR interval. May increase digoxin levels; co-administration requires dose adjustment. Contraindicated with IV beta-blockers due to risk of bradycardia and heart failure.
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; do not crush or chew extended-release capsules.,May cause dizziness or lightheadedness; avoid driving until you know how this medication affects you.,Report slow heartbeat, shortness of breath, or swelling in your ankles or feet.,Limit alcohol intake as it may increase side effects.,Avoid grapefruit and grapefruit juice as they can increase drug levels and side effects.
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 DILT-CD vs CALAN, answered by our medical review team.
DILT-CD is a Calcium Channel Blocker that works by Diltiazem inhibits calcium ion influx during depolarization of cardiac and vascular smooth muscle cells, thereby reducing intracellular calcium levels. It decreases sinoatrial and atrioventricular nodal conduction and dilates coronary and peripheral arteries.. 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 DILT-CD 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 DILT-CD is: 180-360 mg PO once daily (extended-release); 300-540 mg PO once daily for hypertension; 120-480 mg PO once daily for angina; IV: 0.25 mg/kg bolus over 2 min, then 5-15 mg/hr continuous infusion.. 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 DILT-CD 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. DILT-CD is classified as Category C. DILT-CD is a formulation of diltiazem, a calcium channel blocker. In animal studies, diltiazem has been associated with fetal skeletal abnormalities and reduced fetal weight at hig. 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.