Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
TIAZAC 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 cell membranes, resulting in coronary vasodilation, peripheral vasodilation, decreased myocardial contractility, and decreased AV nodal 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 pectoris,Atrial fibrillation or atrial flutter (rate control),Paroxysmal supraventricular tachycardia (PSVT)
Hypertension,Chronic stable angina,Vasospastic angina (Prinzmetal's angina)
Oral: 120-360 mg once daily; maximum 540 mg daily.
30-60 mg orally once daily, extended-release; maximum 90 mg/day.
Terminal elimination half-life is 5-7 hours for immediate-release; for TIAZAC (extended-release), effective half-life is approximately 6-9 hours due to prolonged absorption
Terminal elimination half-life is 6-11 hours; prolonged in hepatic impairment and elderly due to reduced clearance
Hepatic via CYP3A4 isoenzyme; extensive first-pass metabolism; metabolites include N-desmethyl diltiazem (active) and others.
Primarily hepatic via CYP3A4; undergoes extensive first-pass metabolism.
Renal (2-4% unchanged, 60% as inactive metabolites); Fecal (30%); Biliary (minor)
Renal (80% as inactive metabolites), fecal (15% as metabolites), unchanged drug (<1%)
70-80% bound to plasma proteins (albumin)
92-98% bound to plasma proteins (primarily albumin)
Approximately 1.7 L/kg; suggests extensive tissue distribution
0.5-0.9 L/kg; high distribution indicates extensive tissue binding
Approximately 40% for oral immediate-release; extended-release formulation has comparable bioavailability with reduced peak-to-trough fluctuations
Oral extended-release: approximately 50-60% due to first-pass metabolism; absolute bioavailability is 45-60%
No specific adjustment required; use with 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: no adjustment; Child-Pugh Class B: reduce total dose by 50%; Child-Pugh Class C: reduce total dose by 60-70%.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated.
Not established; use in children <18 years is not recommended.
Not recommended for use in pediatric patients; safety and efficacy not established.
Start at lower end of dosing range (120 mg daily); titrate slowly due to increased sensitivity and potential for 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.
Bradycardia and heart block (risk increased with beta-blockers or digoxin),Heart failure with reduced ejection fraction (may worsen in acute MI or pulmonary congestion),Hypotension,Increased risk of gastrointestinal bleeding in elderly,Hepatic impairment (dose adjustment may be required),Abrupt withdrawal may exacerbate angina or cause rebound hypertension,Concurrent use with CYP3A4 inhibitors (e.g., clarithromycin, itraconazole) increases diltiazem levels
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 (unless paced),Second- or third-degree AV block (unless paced),Hypotension (systolic < 90 mm Hg),Cardiogenic shock,Atrial fibrillation/flutter with accessory bypass tract (e.g., Wolff-Parkinson-White syndrome, Lown-Ganong-Levine syndrome),Acute myocardial infarction with pulmonary congestion,Hypersensitivity to diltiazem
Hypersensitivity to nifedipine or any component,Cardiogenic shock,Concomitant use with strong CYP3A4 inducers (e.g., rifampin),Kock pouch (ileostomy)
Avoid grapefruit juice and grapefruit products due to CYP3A4 inhibition, which can increase diltiazem levels. Limit sodium intake as part of hypertension management. No significant interaction with other foods.
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.
TIAZAC (diltiazem) is classified as FDA Pregnancy Category C. First trimester: Limited human data; animal studies have shown embryotoxic and teratogenic effects at high doses. Second and third trimesters: No well-controlled studies; risk of fetal bradycardia, hypotension, and hypocalcemia due to calcium channel blockade. 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 into human breast milk at low concentrations. The milk-to-plasma ratio is approximately 0.4 to 0.8. Relative infant dose is estimated to be <1% of maternal weight-adjusted dose; considered compatible with breastfeeding. Monitor infant for potential adverse effects such as bradycardia, hypotension, or sedation.
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 may alter the pharmacokinetics of diltiazem due to increased plasma volume, renal clearance, and hepatic metabolism. Dose adjustments may be necessary; titrate to clinical effect. No specific dosing guidelines; use the lowest effective dose and monitor blood pressure and heart rate 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.
TIAZAC (diltiazem extended-release) is a nondihydropyridine calcium channel blocker used for hypertension and stable angina. Avoid use in patients with sick sinus syndrome or second/third-degree AV block without a pacemaker. It is a substrate of CYP3A4; monitor for interactions with strong inhibitors (e.g., ketoconazole) or inducers (e.g., rifampin). In hepatic impairment, start at lowest dose. Use with beta-blockers increases risk of bradycardia and heart failure. May cause gingival hyperplasia; stress good oral hygiene.
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 TIAZAC exactly as prescribed, usually once daily. Swallow the capsule whole; do not crush, chew, or open.,Do not stop taking this medication abruptly, as it may worsen chest pain or blood pressure.,Avoid drinking grapefruit juice or eating grapefruit while on this drug, as it can increase side effects.,Common side effects include dizziness, headache, swelling in the ankles/feet, and constipation. Contact your doctor if you experience very slow heartbeat, fainting, or shortness of breath.,Inform your doctor about all other medications, especially beta-blockers, digoxin, or other blood pressure drugs.
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 TIAZAC vs AFEDITAB CR, answered by our medical review team.
TIAZAC is a Calcium Channel Blocker that works by Diltiazem, a benzothiazepine calcium channel blocker, inhibits calcium ion influx across cardiac and vascular smooth muscle cell membranes, resulting in coronary vasodilation, peripheral vasodilation, decreased myocardial contractility, and decreased AV nodal 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 TIAZAC 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 TIAZAC is: Oral: 120-360 mg once daily; maximum 540 mg daily.. 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 TIAZAC 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. TIAZAC is classified as Category C. TIAZAC (diltiazem) is classified as FDA Pregnancy Category C. First trimester: Limited human data; animal studies have shown embryotoxic and teratogenic effects at high doses. Seco. 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.