Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CARTIA XT vs AFEDITAB CR
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Diltiazem, a benzothiazepine calcium channel blocker, inhibits calcium ion influx across cardiac and vascular smooth muscle cells during depolarization, leading to vasodilation and reduced myocardial contractility and conduction velocity, particularly at the AV node.
Nifedipine is a dihydropyridine calcium channel blocker that inhibits the influx of calcium ions through L-type channels in vascular smooth muscle and cardiac muscle, leading to vasodilation and reduced myocardial contractility.
FDA-approved: hypertension,FDA-approved: chronic stable angina,FDA-approved: atrial fibrillation or flutter (rate control),Off-label: prevention of migraine,Off-label: anal fissure (topical)
Hypertension,Chronic stable angina,Vasospastic angina (Prinzmetal's angina)
Diltiazem hydrochloride extended-release capsules (CARTIA XT) are administered orally. For hypertension and angina, the typical adult dose is 180–360 mg once daily, initially 180 mg once daily, titrated to response.
30-60 mg orally once daily, extended-release; maximum 90 mg/day.
Terminal half-life 3-4.5 hours; prolonged in hepatic impairment (up to 15 hours) or with cimetidine.
Terminal elimination half-life is 6-11 hours; prolonged in hepatic impairment and elderly due to reduced clearance
Primarily hepatic via CYP3A4; extensive first-pass metabolism. Metabolites include desacetyldiltiazem (active, 25-50% potency).
Primarily hepatic via CYP3A4; undergoes extensive first-pass metabolism.
Renal (biliary/fecal minimal). 70-80% excreted as inactive metabolites in urine; 15% unchanged.
Renal (80% as inactive metabolites), fecal (15% as metabolites), unchanged drug (<1%)
40-50% bound to albumin.
92-98% bound to plasma proteins (primarily albumin)
Vd 5-10 L/kg; reflects extensive tissue distribution (highly lipophilic).
0.5-0.9 L/kg; high distribution indicates extensive tissue binding
IR: 30-40% (first-pass metabolism); ER (CARTIA XT): 30-40% relative to IR.
Oral extended-release: approximately 50-60% due to first-pass metabolism; absolute bioavailability is 45-60%
No specific dose adjustment is required for renal impairment. However, use with caution in patients with severe renal impairment (Cr Cl <30 m L/min) and monitor heart rate and blood pressure.
No adjustment required for any degree of renal impairment, but use with caution in patients with severe renal failure due to risk of hypotension.
Contraindicated in acute hepatic injury. For mild to moderate hepatic impairment (Child-Pugh class A/B), reduce starting dose by 50% and titrate slowly. For severe hepatic impairment (Child-Pugh class C), use is not recommended.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated.
Safety and efficacy in pediatric patients have not been established. No standard weight-based dosing guidelines are available.
Not recommended for use in pediatric patients; safety and efficacy not established.
In elderly patients (≥65 years), start at the lower end of the dosing range (e.g., 120–180 mg once daily) due to increased potential for bradycardia and hypotension; titrate cautiously.
Initiate at lower end of dosing range (30 mg once daily) due to increased sensitivity to hypotensive effects and potential for reduced hepatic clearance.
None
No FDA black box warning.
Heart failure: may worsen systolic function due to negative inotropic effects,Sick sinus syndrome or AV block: risk of bradycardia, heart block,Concomitant beta-blocker use: increased risk of bradycardia, heart failure,Hepatic impairment: reduce dose,Renal impairment: use caution,Abrupt discontinuation: may cause angina exacerbation,Sinus bradycardia: monitor heart rate
Hypotension, especially with immediate-release formulations,Peripheral edema,Hepatic impairment,Increased angina/acute MI upon withdrawal or dose escalation,Beta-blocker withdrawal,Congestive heart failure
Hypersensitivity to diltiazem or any component,Sick sinus syndrome (except with functioning pacemaker),Second- or third-degree AV block (except with pacemaker),Left ventricular systolic dysfunction (ejection fraction <40%) with pulmonary congestion,Severe hypotension (systolic BP <90 mm Hg),Concurrent use of ivabradine
Hypersensitivity to nifedipine or any component,Cardiogenic shock,Concomitant use with strong CYP3A4 inducers (e.g., rifampin),Kock pouch (ileostomy)
Avoid grapefruit and grapefruit juice as they can increase diltiazem levels and risk of side effects. Avoid high-fat meals close to dosing as they may affect absorption. Limit alcohol intake as it may worsen hypotension or dizziness.
Grapefruit juice increases nifedipine levels via CYP3A4 inhibition; avoid consumption. High-fat meals may delay absorption but do not alter overall exposure. Avoid alcohol as it can exacerbate vasodilation and hypotension.
FDA Pregnancy Category C. First trimester: No adequate studies; potential for embryotoxicity. Second and third trimesters: May cause fetal bradycardia, hypotension, hypoglycemia; risk of intrauterine growth restriction. Use only if benefit outweighs risk.
Teratogenic effects not established; first trimester: no data in humans, animal studies show no teratogenicity; second and third trimesters: risk of fetal hypoxia, intrauterine growth restriction (IUGR), and oligohydramnios; may cause neonatal hypotension, bradycardia, and hypoglycemia if used near term. Contraindicated in pregnancy for hypertension; use only if benefit outweighs risk (e.g., tocolysis).
Diltiazem is excreted in breast milk with a milk-to-plasma ratio of approximately 0.5-1.0. Limited data suggest low risk to infant, but consider monitoring for bradycardia and hypotension. Use with caution.
Nifedipine excreted into breast milk; M/P ratio approximately 0.42-0.77; limited human data; no adverse effects reported in infants; use with caution during breastfeeding.
No specific dose adjustments recommended; increased clearance in pregnancy may require dose titration based on clinical response. Monitor for hypotension and bradycardia. Use lowest effective dose.
Plasma clearance may increase due to higher volume of distribution and metabolism; no specific dose adjustment recommended; titrate based on maternal blood pressure and response; avoid around labor due to tocolytic effect.
CARTIA XT is a sustained-release formulation of diltiazem, a calcium channel blocker. Avoid use in patients with sick sinus syndrome or second/third-degree AV block without a pacemaker. Titrate slowly to prevent hypotension. Monitor heart rate and blood pressure regularly. Use with caution in hepatic or renal impairment. Can be used for rate control in atrial fibrillation but not for conversion. Swallow capsules whole; do not crush or chew.
AFEDITAB CR is a controlled-release formulation of nifedipine, a dihydropyridine calcium channel blocker. Avoid grapefruit juice as it inhibits CYP3A4 metabolism, increasing nifedipine levels. Use cautiously in patients with aortic stenosis or left ventricular dysfunction due to risk of hypotension. Do not crush or chew tablets; intact shell may appear in stool.
Take this medication exactly as prescribed, usually once daily. Swallow the capsule whole; do not crush, chew, or open it.,Do not stop taking this medication suddenly without consulting your doctor, as it may worsen your condition.,Avoid drinking grapefruit juice or eating grapefruit while taking this medication.,Inform your doctor if you experience dizziness, lightheadedness, slow heartbeat, swelling of ankles/feet, or shortness of breath.,This medication may cause dizziness or drowsiness; avoid driving or operating machinery until you know how it affects you.,Keep a regular schedule for taking this medication to maintain consistent levels in your blood.
Swallow the tablet whole; do not crush, chew, or break it.,Avoid grapefruit juice while taking this medication.,Do not discontinue abruptly; taper under medical supervision.,Report symptoms of hypotension like dizziness or fainting.,Limit alcohol intake as it may worsen side effects.,Monitor for fluid retention (ankle swelling) and notify doctor if worsening.
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 CARTIA XT vs AFEDITAB CR, answered by our medical review team.
CARTIA XT is a Calcium Channel Blocker that works by Diltiazem, a benzothiazepine calcium channel blocker, inhibits calcium ion influx across cardiac and vascular smooth muscle cells during depolarization, leading to vasodilation and reduced myocardial contractility and conduction velocity, particularly at the AV node.. AFEDITAB CR is a Calcium Channel Blocker that works by Nifedipine is a dihydropyridine calcium channel blocker that inhibits the influx of calcium ions through L-type channels in vascular smooth muscle and cardiac muscle, leading to vasodilation and reduced myocardial contractility.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CARTIA XT and AFEDITAB CR 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 CARTIA XT is: Diltiazem hydrochloride extended-release capsules (CARTIA XT) are administered orally. For hypertension and angina, the typical adult dose is 180–360 mg once daily, initially 180 mg once daily, titrated to response.. The standard adult dose of AFEDITAB CR is: 30-60 mg orally once daily, extended-release; maximum 90 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 CARTIA XT and AFEDITAB CR 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. CARTIA XT is classified as Category C. FDA Pregnancy Category C. First trimester: No adequate studies; potential for embryotoxicity. Second and third trimesters: May cause fetal bradycardia, hypotension, hypoglycemia; r. AFEDITAB CR is classified as Category C. Teratogenic effects not established; first trimester: no data in humans, animal studies show no teratogenicity; second and third trimesters: risk of fetal hypoxia, intrauterine gro. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.