Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DILACOR XR 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 ion influx across cardiac and vascular smooth muscle cells, resulting in dilation of coronary and systemic arteries, decreased myocardial contractility, and reduced sinoatrial and atrioventricular conduction velocity.
Dihydropyridine calcium channel blocker; inhibits calcium ion influx across cardiac and vascular smooth muscle cells, reducing peripheral vascular resistance and blood pressure.
Angina pectoris due to coronary artery spasm (Prinzmetal's variant angina),Chronic stable angina,Essential hypertension
Hypertension,Chronic stable angina,Vasospastic angina (Prinzmetal's angina)
180 to 240 mg orally once daily, administered on an empty stomach; maximum dose 480 mg once daily.
10-20 mg orally three times daily; extended-release: 30-60 mg orally once daily; maximum 120 mg/day.
Terminal half-life: 6-12 hours (prolonged in elderly, hepatic impairment, or with CYP3A4 inhibitors)
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.
Extensively metabolized in the liver via CYP3A4; undergoes deacetylation and N-demethylation.
Hepatic via CYP3A4; extensive first-pass metabolism; metabolites are inactive.
Renal (70% as metabolites, 3-4% as unchanged drug); biliary/fecal (25-30%)
Renal: 70-80% as metabolites; Fecal: 15-20% as metabolites; <1% unchanged in urine
98-99% bound to serum albumin and alpha-1-acid glycoprotein
92-98% bound to plasma proteins (albumin and alpha-1-acid glycoprotein)
1.1-1.8 L/kg (high Vd indicates extensive tissue binding)
0.8-1.2 L/kg. Clinical meaning: indicates extensive tissue distribution, consistent with high lipophilicity.
Oral: 40-50% (first-pass metabolism; food does not affect extent)
Oral immediate-release: 45-60% (due to first-pass metabolism); extended-release: 60-85% (due to slower release and reduced first-pass effect).
GFR 30-60 m L/min: initiate at 120 mg once daily, titrate cautiously; GFR <30 m L/min: not recommended due to risk of accumulation.
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: initiate at 120 mg once daily; Child-Pugh Class B or C: avoid use.
Child-Pugh Class A: no adjustment; Class B: reduce dose by 50%; Class C: avoid use or reduce by 75%.
Safety and effectiveness in pediatric patients have not been established; no dosing recommendations.
0.25-0.5 mg/kg/dose orally every 6-8 hours; maximum 3 mg/kg/day. Extended-release not recommended.
Start at low end of dosing range (120 mg once daily) due to increased systemic exposure and risk of hypotension; titrate slowly.
Start at 10 mg orally twice daily; titrate slowly due to increased sensitivity and risk of hypotension.
None.
None
May cause hypotension, bradycardia, and heart block; avoid in patients with sick sinus syndrome or second- or third-degree AV block without a pacemaker; caution in patients with congestive heart failure; may increase risk of digitalis toxicity; abrupt withdrawal may worsen angina.
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
Sick sinus syndrome (except in presence of functioning ventricular pacemaker), second- or third-degree AV block (except with pacemaker), hypotension (systolic < 90 mm Hg), acute myocardial infarction with pulmonary congestion, hypersensitivity to diltiazem, concurrent use of ivabradine.
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 plasma concentrations, leading to increased risk of adverse effects. Avoid high-fat meals as they may affect the absorption of the extended-release formulation.
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.
DILACOR XR (diltiazem) is a calcium channel blocker with limited human pregnancy data. In animal studies, at doses up to 5 times the maximum recommended human dose, no teratogenic effects were observed. However, embryofetal toxicity (increased fetal loss, growth retardation) occurred at maternally toxic doses. First trimester: No adequate human studies; risk cannot be excluded. Second and third trimesters: Use only if clearly needed; may cause maternal hypotension and reduced uteroplacental blood flow, potentially leading to fetal hypoxia and growth restriction. U. S. FDA Pregnancy 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 breast milk. The milk-to-plasma (M/P) ratio ranges from 0.7 to 0.9. Limited data suggest infant exposure is low (approximately 1% of maternal weight-adjusted dose). No adverse effects reported in breastfed infants. Caution advised; monitor infant for bradycardia, hypotension, and sedation. Alternative agents may be preferred.
Excreted in breast milk; M/P ratio ~0.85. Consider risks versus benefits; monitor infant for hypotension.
Plasma volume and renal clearance increase during pregnancy, potentially reducing diltiazem concentrations. However, specific pharmacokinetic studies are lacking. Clinical response and blood pressure should guide dosing. Start at the lowest effective dose and titrate based on maternal heart rate and blood pressure. Avoid sustained-release formulations if rapid titration needed; immediate-release may be used. Monitor for hypotension, which may worsen uteroplacental perfusion. No specific dose adjustment recommended in published guidelines; use caution and individualized dosing.
No standard dose adjustment; monitor clinical response and blood pressure; may require lower doses due to vasodilation effects.
DILACOR XR is a sustained-release formulation of diltiazem, a calcium channel blocker. Do not crush or chew the capsule; swallowing whole is essential for extended-release properties. Monitor heart rate and blood pressure regularly due to risk of bradycardia and hypotension. Use with caution in patients with reduced hepatic function as diltiazem undergoes extensive first-pass metabolism. Avoid concurrent use with strong CYP3A4 inhibitors (e.g., ketoconazole) as they can increase diltiazem levels. In patients with atrial fibrillation or flutter, it may be used for rate control but contraindicated in sick sinus syndrome or second/third-degree AV block without a 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.
Swallow DILACOR XR capsules whole; do not crush, chew, or break them.,Take this medication exactly as prescribed, usually once daily. Do not stop suddenly without consulting your doctor.,Avoid grapefruit and grapefruit juice as they can increase the effects and side effects of diltiazem.,Limit alcohol intake as it may increase the risk of dizziness or fainting.,Notify your doctor if you experience slow heartbeat, shortness of breath, swelling of ankles/feet, or severe dizziness.,Keep a record of your blood pressure and pulse at home and bring it to appointments.,Do not take other medications, including over-the-counter products or herbal supplements, without consulting your healthcare provider.
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 DILACOR XR vs ADALAT, answered by our medical review team.
DILACOR XR is a Calcium Channel Blocker that works by Diltiazem inhibits calcium ion influx across cardiac and vascular smooth muscle cells, resulting in dilation of coronary and systemic arteries, decreased myocardial contractility, and reduced sinoatrial and atrioventricular conduction velocity.. 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 DILACOR XR 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 DILACOR XR is: 180 to 240 mg orally once daily, administered on an empty stomach; maximum dose 480 mg once daily.. 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 DILACOR XR 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. DILACOR XR is classified as Category C. DILACOR XR (diltiazem) is a calcium channel blocker with limited human pregnancy data. In animal studies, at doses up to 5 times the maximum recommended human dose, no teratogenic . 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.