Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CARDIZEM CD 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 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.
Dihydropyridine calcium channel blocker; inhibits calcium ion influx across cardiac and vascular smooth muscle cells, reducing peripheral vascular resistance and blood pressure.
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.
10-20 mg orally three times daily; extended-release: 30-60 mg orally once daily; maximum 120 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: 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.
Hepatic via CYP3A4; also undergoes deacetylation; substrate of P-glycoprotein.
Hepatic via CYP3A4; extensive first-pass metabolism; metabolites are inactive.
Renal: ~2-4% (unchanged), Hepatic metabolism to multiple metabolites; ~65% renal (metabolites), ~35% fecal/biliary. Total clearance: 5-7 m L/kg/min.
Renal: 70-80% as metabolites; Fecal: 15-20% as metabolites; <1% unchanged in urine
70-80% bound primarily to albumin (70%), also alpha-1 acid glycoprotein (10%). Binding saturable at high concentrations.
92-98% bound to plasma proteins (albumin and alpha-1-acid glycoprotein)
Approximately 5.3 L/kg. Meaning: Extensive tissue distribution (3-5 L/kg); reflects high lipophilicity and wide distribution beyond plasma.
0.8-1.2 L/kg. Clinical meaning: indicates extensive tissue distribution, consistent with high lipophilicity.
Extended-release (Cardizem CD): ~40% (range 35-45%) due to extensive first-pass metabolism. Immediate-release: ~40-50%. IV: 100%.
Oral immediate-release: 45-60% (due to first-pass metabolism); extended-release: 60-85% (due to slower release and reduced first-pass effect).
No specific GFR-based adjustment required, but use caution in severe renal impairment (Cr Cl <30 m L/min).
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: 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 Class A: no adjustment; Class B: reduce dose by 50%; Class C: avoid use or reduce by 75%.
Not approved for pediatric use; safety and efficacy not established.
0.25-0.5 mg/kg/dose orally every 6-8 hours; maximum 3 mg/kg/day. Extended-release not recommended.
Start at lower end of dosing range (120 mg once daily) due to increased risk of hypotension and bradycardia; titrate slowly.
Start at 10 mg orally twice daily; titrate slowly due to increased sensitivity and risk of hypotension.
None
None
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
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 in presence of functioning ventricular pacemaker),Hypotension (systolic < 90 mm Hg),Acute myocardial infarction with pulmonary congestion,Known hypersensitivity to diltiazem
Hypersensitivity to nifedipine,Cardiogenic shock,Significant aortic stenosis,Concurrent use with rifampin,Pregnancy (category C)
Grapefruit juice may increase diltiazem serum concentrations; avoid concurrent ingestion. Alcohol may enhance hypotensive effects. No significant food restrictions otherwise.
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.
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.
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 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.
Excreted in breast milk; M/P ratio ~0.85. Consider risks versus benefits; monitor infant for hypotension.
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.
No standard dose adjustment; monitor clinical response and blood pressure; may require lower doses due to vasodilation effects.
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).
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.
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 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 CARDIZEM CD vs ADALAT, 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.. 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 CARDIZEM CD 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 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 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 CARDIZEM CD 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. 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) . 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.