Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
TIAZAC vs ADALAT CC
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, a dihydropyridine calcium channel blocker, inhibits calcium ion influx across cardiac and smooth muscle cell membranes, leading to vasodilation and decreased 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 mg orally once daily; may titrate to 60 mg or 90 mg once daily based on response and tolerability.
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: 7-10 hours; clinical context: sustained-release formulation provides therapeutic concentrations over 24 hours with once-daily dosing, but half-life does not directly reflect drug effect duration due to slow absorption.
Hepatic via CYP3A4 isoenzyme; extensive first-pass metabolism; metabolites include N-desmethyl diltiazem (active) and others.
Hepatic metabolism via CYP3A4; nifedipine is converted to inactive metabolites.
Renal (2-4% unchanged, 60% as inactive metabolites); Fecal (30%); Biliary (minor)
Renal: 70-80% as metabolites, fecal: 15-20% as metabolites, biliary: minimal (<5% unchanged).
70-80% bound to plasma proteins (albumin)
92-98% bound primarily to albumin.
Approximately 1.7 L/kg; suggests extensive tissue distribution
1.2-1.6 L/kg; clinical meaning: indicates extensive tissue distribution, with higher concentrations in organs such as liver and kidney, and lower in brain due to P-glycoprotein efflux.
Approximately 40% for oral immediate-release; extended-release formulation has comparable bioavailability with reduced peak-to-trough fluctuations
65-90% after oral administration; absolute bioavailability of nifedipine in ADALAT CC: approximately 65% due to first-pass metabolism in liver and gut wall.
No specific adjustment required; use with caution in severe renal impairment (Cr Cl <30 m L/min).
No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (Cr Cl <30 m L/min), start at 30 mg once daily and titrate cautiously.
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%.
For mild to moderate hepatic impairment (Child-Pugh A or B), reduce initial dose to 30 mg once daily; for severe impairment (Child-Pugh C), contraindicated or use with extreme caution.
Not established; use in children <18 years is not recommended.
Safety and efficacy not established; use is not recommended in pediatric patients.
Start at lower end of dosing range (120 mg daily); titrate slowly due to increased sensitivity and potential for hypotension.
Initiate at 30 mg once daily; titrate slowly due to increased risk of hypotension and higher drug exposure. Monitor closely.
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
Beta-blocker withdrawal: taper if discontinuing; exacerbation of angina,Heart failure: use caution in patients with severe left ventricular dysfunction,Hepatic impairment: reduce dose,Peripheral edema: may occur; differentiate from worsening heart failure,Monitor blood pressure during initiation and titration
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,Concurrent use with strong CYP3A4 inducers (e.g., rifampin)
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.
Avoid grapefruit and grapefruit juice as they inhibit CYP3A4 metabolism, raising nifedipine levels and risk of toxicity. High-fat meals may increase absorption; take consistently with respect to meals. Avoid alcohol as it may exacerbate 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.
Adalat CC (nifedipine) is an extended-release formulation of nifedipine, a dihydropyridine calcium channel blocker. In animal studies, nifedipine has been associated with embryotoxicity, fetotoxicity, and teratogenicity (e.g., digital anomalies, cleft palate) at doses several times the maximum recommended human dose. In humans, data are limited but there is no clear evidence of a significant increase in major congenital malformations. First trimester exposure is not strongly associated with major defects; however, some studies suggest a possible small increase in oral clefts. Second and third trimester use may cause maternal hypotension and subsequent fetal distress (e.g., reduced uteroplacental perfusion). Use near term may theoretically inhibit labor, but nifedipine is used as a tocolytic for preterm labor. Overall, the risk is considered low; however, fetal monitoring is recommended if used in pregnancy. FDA Pregnancy Category C (prior to 2015 categorization).
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 is excreted into human breast milk in small amounts. The milk-to-plasma (M/P) ratio is approximately 0.56 to 1.0 based on limited data. The estimated daily infant dose via milk is less than 5% of the maternal weight-adjusted dose, which is considered clinically insignificant. No adverse effects have been reported in breastfed infants. However, caution is advised, especially with high maternal doses or prolonged use. The American Academy of Pediatrics considers nifedipine compatible with 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.
Pregnancy may alter the pharmacokinetics of nifedipine due to increased plasma volume and altered hepatic metabolism. However, specific dosing adjustments for Adalat CC in pregnancy are not well established. In clinical practice, dosing for hypertension in pregnancy (e.g., preeclampsia) often uses immediate-release nifedipine, not extended-release. For Adalat CC, the same dosing as in non-pregnant adults (30-90 mg once daily) is typically used, but titration should be cautious to avoid maternal hypotension. No formal dose adjustment is recommended, but careful monitoring and individualized titration are advised.
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.
Adalat CC (nifedipine extended-release) is a dihydropyridine calcium channel blocker used primarily for hypertension. Avoid in patients with unstable angina or within 4 weeks of myocardial infarction due to reflex tachycardia risk. May cause peripheral edema, especially in higher doses; consider adding an ACE inhibitor if edema is problematic. CYP3A4 inhibitors (e.g., grapefruit juice, macrolides, azole antifungals) significantly increase nifedipine levels; avoid coadministration. Tablet shell may appear intact in stool; this is normal.
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 or chew.,Do not consume grapefruit or grapefruit juice while taking this medication.,May cause dizziness or lightheadedness; avoid driving if affected.,Notify your doctor if you experience rapid heartbeat, swelling in the ankles or feet, or prolonged erections.,Take exactly as prescribed; do not skip doses or stop abruptly without consulting your doctor.
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 ADALAT CC, 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.. ADALAT CC is a Calcium Channel Blocker that works by Nifedipine, a dihydropyridine calcium channel blocker, inhibits calcium ion influx across cardiac and smooth muscle cell membranes, leading to vasodilation and decreased myocardial contractility.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between TIAZAC and ADALAT CC 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 ADALAT CC is: 30 mg orally once daily; may titrate to 60 mg or 90 mg once daily based on response and tolerability.. 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 ADALAT CC 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. ADALAT CC is classified as Category C. Adalat CC (nifedipine) is an extended-release formulation of nifedipine, a dihydropyridine calcium channel blocker. In animal studies, nifedipine has been associated with embryotox. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.