Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CARDIZEM SR 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 inhibits calcium ion influx across cardiac and vascular smooth muscle cell membranes during depolarization, leading to negative inotropic, chronotropic, and dromotropic effects, and vasodilation.
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.
Hypertension,Angina pectoris due to coronary artery spasm (Prinzmetal's variant angina),Chronic stable angina (classic effort-associated angina)
Hypertension,Chronic stable angina,Vasospastic angina (Prinzmetal's angina)
Oral: Initial dose 60-120 mg twice daily; titrate to maximum 360 mg/day divided into two doses.
30-60 mg orally once daily, extended-release; maximum 90 mg/day.
3.0-4.5 hours for diltiazem; metabolites (e.g., desacetyldiltiazem) up to 10 hours. Clinical context: dosing interval adjustment in hepatic impairment.
Terminal elimination half-life is 6-11 hours; prolonged in hepatic impairment and elderly due to reduced clearance
Primarily hepatic via CYP3A4; undergoes extensive first-pass metabolism.
Primarily hepatic via CYP3A4; undergoes extensive first-pass metabolism.
Renal: 2-4% unchanged; hepatic metabolism: ~60-70% (including active metabolites); fecal: ~30-40%.
Renal (80% as inactive metabolites), fecal (15% as metabolites), unchanged drug (<1%)
Approximately 70-80%, primarily to albumin and alpha-1-acid glycoprotein.
92-98% bound to plasma proteins (primarily albumin)
3.1-5.1 L/kg; large Vd indicates extensive tissue distribution (e.g., myocardium, vascular smooth muscle).
0.5-0.9 L/kg; high distribution indicates extensive tissue binding
Oral (sustained-release): approximately 40-50% due to first-pass metabolism; variable among formulations.
Oral extended-release: approximately 50-60% due to first-pass metabolism; absolute bioavailability is 45-60%
For GFR < 10 m L/min: Use with caution and reduce dose by 25-50%; consider extended dosing interval.
No adjustment required for any degree of renal impairment, but use with caution in patients with severe renal failure due to risk of hypotension.
Child-Pugh Class B: Reduce dose by 50%; Child-Pugh Class C: Use not recommended.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated.
Safety and efficacy not established; no specific weight-based dosing guidelines available.
Not recommended for use in pediatric patients; safety and efficacy not established.
Initial dose 60 mg twice daily; titrate slowly due to increased risk of bradycardia and hypotension.
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.
Cardiac conduction abnormalities: bradycardia, AV block, sick sinus syndrome,Heart failure: use with caution in patients with compromised ventricular function,Hypotension,Hepatic impairment,Concomitant use with beta-blockers may increase risk of bradycardia and AV block,Abrupt discontinuation may exacerbate angina
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
Sick sinus syndrome (except in patients with a functioning artificial ventricular pacemaker),Second- or third-degree AV block (except in patients with a functioning artificial ventricular pacemaker),Hypotension (systolic blood pressure < 90 mm Hg),Acute myocardial infarction with pulmonary congestion,Known hypersensitivity to diltiazem
Hypersensitivity to nifedipine or any component,Cardiogenic shock,Concomitant use with strong CYP3A4 inducers (e.g., rifampin),Kock pouch (ileostomy)
Grapefruit and grapefruit juice increase diltiazem levels by inhibiting CYP3A4 metabolism; avoid concurrent use. No other significant food restrictions. Alcohol may enhance hypotensive effects and increase risk of 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. No adequate studies in pregnant women. In animal studies, diltiazem has been shown to cause embryofetal toxicity (skeletal abnormalities, reduced fetal weight) at doses 5-10 times the maximum recommended human dose. Risk to fetus cannot be ruled out; use only if potential benefit justifies potential 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 into human breast milk at low concentrations. Estimated infant dose is <1% of maternal weight-adjusted dose. M/P ratio not established. Although risk to nursing infant is likely low, caution is advised. Monitor infant for bradycardia, hypotension, and feeding difficulties.
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 adjustment guidelines for pregnancy; however, pharmacokinetic changes in pregnancy (increased volume of distribution, altered hepatic metabolism) may require dose titration based on clinical response and tolerability. Start at lowest effective dose and monitor closely.
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.
Cardizem SR is a sustained-release calcium channel blocker indicated for hypertension and angina. Onset: 2-3 hours, duration: 12-24 hours. Avoid concurrent use with beta-blockers due to risk of bradycardia and heart block. Contraindicated in sick sinus syndrome (unless pacemaker), second- or third-degree AV block, hypotension (SBP <90 mm Hg), and acute MI with pulmonary congestion. Monitor liver function and renal function; dose adjustment needed in hepatic impairment. Use caution in patients with decreased left ventricular function (ejection fraction <40%). Do not crush or chew capsules; swallow whole.
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, with or without food, at the same time each day.,Swallow the capsule whole; do not crush, chew, or open it.,Avoid grapefruit and grapefruit juice while on this medication; they can increase the drug's effect and risk of side effects.,Do not stop taking this medication suddenly; abrupt discontinuation may worsen chest pain or increase blood pressure.,Contact your healthcare provider if you experience slow heartbeat, fainting, dizziness, shortness of breath, or swelling of the legs/ankles.,Limit alcohol consumption as it may increase the risk of side effects such as dizziness or fainting.,Inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding.,Keep all appointments to check your blood pressure and heart rhythm.
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 CARDIZEM SR vs AFEDITAB CR, answered by our medical review team.
CARDIZEM SR is a Calcium Channel Blocker that works by Diltiazem inhibits calcium ion influx across cardiac and vascular smooth muscle cell membranes during depolarization, leading to negative inotropic, chronotropic, and dromotropic effects, and vasodilation.. 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 CARDIZEM SR 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 CARDIZEM SR is: Oral: Initial dose 60-120 mg twice daily; titrate to maximum 360 mg/day divided into two doses.. 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 CARDIZEM SR 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. CARDIZEM SR is classified as Category C. FDA Pregnancy Category C. No adequate studies in pregnant women. In animal studies, diltiazem has been shown to cause embryofetal toxicity (skeletal abnormalities, reduced fetal we. 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.