Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CARDIZEM CD 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 is a calcium channel blocker that inhibits calcium ion influx across cardiac and vascular smooth muscle cell membranes, resulting in dilation of coronary arteries and peripheral arterioles, and decreased myocardial contractility and conduction velocity.
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,Chronic stable angina,Variant angina
Hypertension,Chronic stable angina,Vasospastic angina (Prinzmetal's angina)
Hypertension: 180-360 mg once daily orally. Angina: 120-360 mg once daily orally. Maximum dose: 480 mg/day.
30-60 mg orally once daily, extended-release; maximum 90 mg/day.
Terminal elimination half-life: 6-8 hours (single dose), prolonged to 10-15 hours with multiple dosing or in elderly/hepatic impairment. Clinical context: Therapeutic steady-state achieved in 2-4 days.
Terminal elimination half-life is 6-11 hours; prolonged in hepatic impairment and elderly due to reduced clearance
Hepatic via CYP3A4; also undergoes deacetylation; substrate of P-glycoprotein.
Primarily hepatic via CYP3A4; undergoes extensive first-pass metabolism.
Renal: ~2-4% (unchanged), Hepatic metabolism to multiple metabolites; ~65% renal (metabolites), ~35% fecal/biliary. Total clearance: 5-7 m L/kg/min.
Renal (80% as inactive metabolites), fecal (15% as metabolites), unchanged drug (<1%)
70-80% bound primarily to albumin (70%), also alpha-1 acid glycoprotein (10%). Binding saturable at high concentrations.
92-98% bound to plasma proteins (primarily albumin)
Approximately 5.3 L/kg. Meaning: Extensive tissue distribution (3-5 L/kg); reflects high lipophilicity and wide distribution beyond plasma.
0.5-0.9 L/kg; high distribution indicates extensive tissue binding
Extended-release (Cardizem CD): ~40% (range 35-45%) due to extensive first-pass metabolism. Immediate-release: ~40-50%. IV: 100%.
Oral extended-release: approximately 50-60% due to first-pass metabolism; absolute bioavailability is 45-60%
No specific GFR-based adjustment required, but use caution in severe renal impairment (Cr Cl <30 m L/min).
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 A: start with 120 mg once daily. Child-Pugh Class B: start with 120 mg once daily, titrate cautiously. Child-Pugh Class C: contraindicated.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated.
Not approved for pediatric use; safety and efficacy not established.
Not recommended for use in pediatric patients; safety and efficacy not established.
Start at lower end of dosing range (120 mg once daily) due to increased risk of hypotension and bradycardia; titrate slowly.
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.
May cause hypotension,Risk of heart failure exacerbation in patients with impaired ventricular function,May slow AV conduction, leading to bradycardia or AV block,Hepatic and renal impairment caution,May exacerbate symptoms in patients with hypertrophic cardiomyopathy
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 presence of functioning ventricular pacemaker),Second- or third-degree AV block (except in presence of functioning ventricular pacemaker),Hypotension (systolic < 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 juice may increase diltiazem serum concentrations; avoid concurrent ingestion. Alcohol may enhance hypotensive effects. No significant food restrictions otherwise.
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.
Diltiazem, the active ingredient in Cardizem CD, is classified as Pregnancy Category C. Animal studies have demonstrated embryotoxicity and teratogenicity (skeletal abnormalities) at doses 5-10 times the maximum recommended human dose. There are no adequate and well-controlled studies in pregnant women. In humans, exposure during the first trimester may be associated with a small increased risk of congenital anomalies, particularly cardiac defects, though data are limited. During the second and third trimesters, use may be associated with potential risks of fetal growth restriction and preterm labor due to maternal hypotension and decreased uteroplacental perfusion. The drug should only be used if the potential benefit justifies the potential risk to the fetus.
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 milk at low concentrations; the milk-to-plasma (M/P) ratio is approximately 0.8. Limited data suggest that the estimated infant daily dose is less than 1% of the maternal weight-adjusted dose. While adverse effects in breastfed infants have not been reported, caution is advised due to potential for cardiovascular effects. The manufacturer recommends discontinuing breastfeeding or the drug, considering the importance of the drug to the mother.
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.
Pregnancy-induced increases in plasma volume and hepatic metabolism may reduce diltiazem concentrations, potentially requiring dose adjustments. However, specific pharmacokinetic studies in pregnant women are lacking. Clinical monitoring of therapeutic effect (e.g., blood pressure control) should guide dosing; gradual titration is recommended, and doses may need to be increased based on response. Avoid abrupt discontinuation.
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.
Diltiazem (Cardizem CD) is a nondihydropyridine calcium channel blocker; use with caution in patients with systolic heart failure (HFr EF) due to negative inotropic effects. Avoid concurrent use with beta-blockers due to risk of bradycardia and heart block. May increase dugoxin levels; monitor digoxin levels. Contraindicated in sick sinus syndrome or second/third-degree AV block without pacemaker. Also inhibits CYP3A4; monitor for interactions with statins (e.g., simvastatin dose limit 10 mg).
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 capsule whole; do not crush or chew. May be taken without regard to meals.,Do not stop abruptly; gradual taper advised to avoid rebound hypertension or ischemia.,Report symptoms of bradycardia (dizziness, fainting) or heart failure (swelling, shortness of breath).,Avoid grapefruit juice as it may increase drug levels and risk of side effects.,Use sunscreen and protective clothing due to possible photosensitivity.
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 CD vs AFEDITAB CR, answered by our medical review team.
CARDIZEM CD is a Calcium Channel Blocker that works by Diltiazem is a calcium channel blocker that inhibits calcium ion influx across cardiac and vascular smooth muscle cell membranes, resulting in dilation of coronary arteries and peripheral arterioles, and decreased myocardial contractility and conduction velocity.. 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 CD 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 CD is: Hypertension: 180-360 mg once daily orally. Angina: 120-360 mg once daily orally. Maximum dose: 480 mg/day.. 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 CD 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 CD is classified as Category C. Diltiazem, the active ingredient in Cardizem CD, is classified as Pregnancy Category C. Animal studies have demonstrated embryotoxicity and teratogenicity (skeletal abnormalities) . 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.