Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CARDIZEM SR 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 cell membranes during depolarization, leading to negative inotropic, chronotropic, and dromotropic effects, and vasodilation.
Dihydropyridine calcium channel blocker; inhibits calcium ion influx across cardiac and vascular smooth muscle cells, reducing peripheral vascular resistance and blood pressure.
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.
10-20 mg orally three times daily; extended-release: 30-60 mg orally once daily; maximum 120 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: 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.
Primarily hepatic via CYP3A4; undergoes extensive first-pass metabolism.
Hepatic via CYP3A4; extensive first-pass metabolism; metabolites are inactive.
Renal: 2-4% unchanged; hepatic metabolism: ~60-70% (including active metabolites); fecal: ~30-40%.
Renal: 70-80% as metabolites; Fecal: 15-20% as metabolites; <1% unchanged in urine
Approximately 70-80%, primarily to albumin and alpha-1-acid glycoprotein.
92-98% bound to plasma proteins (albumin and alpha-1-acid glycoprotein)
3.1-5.1 L/kg; large Vd indicates extensive tissue distribution (e.g., myocardium, vascular smooth muscle).
0.8-1.2 L/kg. Clinical meaning: indicates extensive tissue distribution, consistent with high lipophilicity.
Oral (sustained-release): approximately 40-50% due to first-pass metabolism; variable among formulations.
Oral immediate-release: 45-60% (due to first-pass metabolism); extended-release: 60-85% (due to slower release and reduced first-pass effect).
For GFR < 10 m L/min: Use with caution and reduce dose by 25-50%; consider extended dosing interval.
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 B: Reduce dose by 50%; Child-Pugh Class C: Use not recommended.
Child-Pugh Class A: no adjustment; Class B: reduce dose by 50%; Class C: avoid use or reduce by 75%.
Safety and efficacy not established; no specific weight-based dosing guidelines available.
0.25-0.5 mg/kg/dose orally every 6-8 hours; maximum 3 mg/kg/day. Extended-release not recommended.
Initial dose 60 mg twice daily; titrate slowly due to increased risk of bradycardia and hypotension.
Start at 10 mg orally twice daily; titrate slowly due to increased sensitivity and risk of hypotension.
None.
None
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
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 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,Cardiogenic shock,Significant aortic stenosis,Concurrent use with rifampin,Pregnancy (category C)
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.
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.
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.
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 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.
Excreted in breast milk; M/P ratio ~0.85. Consider risks versus benefits; monitor infant for hypotension.
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.
No standard dose adjustment; monitor clinical response and blood pressure; may require lower doses due to vasodilation effects.
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.
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 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 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 SR vs ADALAT, 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.. 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 SR 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 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 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 SR 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 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. 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.