Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
NITRO-DUR vs ISMO
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Nitroglycerin is a prodrug that is converted to nitric oxide (NO) in vascular smooth muscle, activating guanylyl cyclase, increasing c GMP, leading to vasodilation primarily in veins and arteries.
Isosorbide mononitrate is a nitrate that dilates coronary arteries and peripheral veins. It acts by releasing nitric oxide, which activates guanylate cyclase, increasing c GMP levels, leading to smooth muscle relaxation and vasodilation.
Prophylaxis and treatment of angina pectoris due to coronary artery disease,Heart failure (IV formulation),Hypertensive crisis (IV formulation),Anal fissures (topical ointment)
Prevention of angina pectoris due to coronary artery disease,Off-label: Treatment of acute angina (immediate-release forms)
Transdermal: Initial 0.2-0.4 mg/h applied once daily, titrate to 0.4-0.8 mg/h; maximum 0.8 mg/h. Remove for 10-12 hours daily to prevent tolerance.
20 mg orally twice daily, 7 hours apart (e.g., 8 AM and 3 PM) to minimize nitrate tolerance.
2–3 minutes (nitroglycerin); prolonged to ~30 minutes for active metabolites. Clinical context: Requires frequent dosing or continuous administration for sustained effect.
Terminal elimination half-life is approximately 5-6 hours. In elderly patients or those with hepatic impairment, half-life may be prolonged (up to 8-10 hours), warranting dose adjustment.
Metabolized by glutathione S-transferases (GSTs) in the liver and erythrocytes, producing glycerol dinitrate and nitrite ions.
Primarily metabolized in the liver by denitration; minor metabolism via glucuronidation. Metabolites are inactive.
Primarily renal (>80% as inactive metabolites; <1% unchanged nitroglycerin). Minor biliary/fecal elimination.
Primarily renal; 80-90% of the dose is excreted as inactive metabolites (isosorbide mononitrate and isosorbide dinitrate) in urine. Less than 1% is excreted unchanged. Fecal excretion is minimal.
~60% (mainly to albumin).
Approximately 30% bound to plasma proteins, primarily albumin.
~3 L/kg (extensive tissue distribution).
Vd is 0.6-0.9 L/kg, indicating distribution into total body water. Higher Vd may be observed in patients with heart failure.
Transdermal: ~70% (relative to IV). Oral: <10% (extensive first-pass metabolism).
Oral: 90-100% (sustained-release formulations). Sublingual: high but variable; generally effective due to extensive absorption.
No dose adjustment needed for any degree of renal impairment.
No dose adjustment required for GFR ≥30 m L/min. For GFR <30 m L/min, consider reducing dose to 10 mg twice daily due to potential accumulation of active metabolite.
Child-Pugh Class A: No adjustment. Child-Pugh Class B: Use with caution, consider dose reduction by 25-50% due to reduced metabolism. Child-Pugh Class C: Avoid use or use minimal effective dose (e.g., 0.2 mg/h) with close monitoring.
No dose adjustment in Child-Pugh A or B. For Child-Pugh C, reduce dose to 10 mg twice daily and monitor for hypotension.
Safety and efficacy not established in pediatric patients; no standard dosing guidelines.
Safety and efficacy not established; no standard dosing recommendations.
Start at low end of dosing range (0.2 mg/h), titrate slowly, monitor for hypotension and dizziness. Increased sensitivity due to age-related vascular changes; may require extended nitrate-free interval (e.g., 12-14 hours).
Start at 10 mg twice daily with gradual titration based on tolerance and renal function. Monitor for hypotension and dizziness.
Do not use with phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil) due to risk of severe hypotension.
Do not use with phosphodiesterase-5 (PDE-5) inhibitors (e.g., sildenafil, tadalafil) due to risk of severe hypotension.
Hypotension, especially in hypovolemic patients; tolerance with chronic use; paradoxical bradycardia and increased angina; exacerbate hypertrophic cardiomyopathy; avoid abrupt discontinuation.
Hypotension and reflex tachycardia may occur,Caution in patients with volume depletion or hypotension,May cause headaches; tolerance may develop with prolonged use,Abrupt withdrawal may increase angina frequency
Concomitant use with PDE-5 inhibitors; severe anemia; increased intracranial pressure; hypersensitivity to nitroglycerin; acute circulatory failure; constrictive pericarditis; pericardial tamponade.
Concurrent use of PDE-5 inhibitors,Severe anemia,Closed-angle glaucoma,Hypersensitivity to isosorbide mononitrate or nitrates,Acute myocardial infarction with low filling pressures
Avoid alcohol, as it can enhance hypotensive effects. No specific food restrictions, but high-fat meals may delay absorption of nitroglycerin if administered orally; transdermal route is less affected.
Alcohol may enhance hypotension risk. Avoid high-fat meals if extended-release formulation, as they may affect absorption. No other significant food interactions.
FDA Pregnancy Category C. First trimester: Animal studies show fetal harm, but no adequate human studies; potential risk cannot be ruled out. Second and third trimesters: Possible fetal bradycardia, hypotension, and reduced placental perfusion; avoid near term due to risk of maternal hypotension and fetal distress.
ISMO (isosorbide mononitrate) is categorized as FDA Pregnancy Category C. In animal studies, reduced fetal survival and growth retardation were observed at high doses. No adequate human studies exist. Use only if potential benefit justifies risk. First trimester: Theoretical risk of hemodynamic effects; avoid unless necessary. Second/third trimester: May cause fetal hypoxia due to maternal hypotension; monitor fetal heart rate. Peripartum: May exacerbate uterine relaxation and postpartum hemorrhage if used near delivery.
Excreted in breast milk; M/P ratio not established. Use with caution, monitor infant for hypotension or methemoglobinemia; consider pump and discard if high doses used.
Excretion into human milk is unknown. Due to risk of infant methemoglobinemia and hypotension, caution is advised. M/P ratio: Not available. American Academy of Pediatrics considers nitrate derivatives compatible with breastfeeding, but monitor infant for cyanosis and lethargy.
No specific dose adjustments recommended; however, increased plasma volume may reduce drug concentrations; titrate to effect, avoid hypotension to maintain placental perfusion.
No specific dose adjustments for ISMO in pregnancy are established due to lack of pharmacokinetic studies. However, pregnancy-induced hemodynamic changes (increased plasma volume, cardiac output) may reduce efficacy; consider dose titration based on clinical response. Avoid doses >60 mg/day to minimize hypotensive risk. Use immediate-release formulations for flexible dosing if needed.
NITRO-DUR (nitroglycerin) transdermal patch is used for angina prophylaxis, not acute attacks. Apply to hairless area, avoid chest if possible to prevent interference with defibrillation. Rotate sites daily to prevent tolerance; remove patch for 10-12 hours daily to maintain nitrate-free interval. Contraindicated with PDE5 inhibitors (sildenafil, tadalafil, vardenafil) due to risk of severe hypotension. Monitor for hypotension, reflex tachycardia, headache.
ISMO (isosorbide mononitrate) is a nitrate used for angina prophylaxis, not for acute attacks. Tolerance develops with sustained use; maintain a 10-12 hour nitrate-free interval to prevent tolerance. Do not use with phosphodiesterase-5 inhibitors (e.g., sildenafil) due to risk of profound hypotension. Contraindicated in severe anemia, increased intracranial pressure, or hypertrophic obstructive cardiomyopathy. Discontinue if blurred vision or dry mouth occurs.
Apply patch once daily to clean, dry, hairless skin on upper arm, chest, or back.,Remove old patch before applying new one.,Keep patch on for 12-14 hours then remove for 10-12 hours to prevent tolerance.,Do not use during acute angina attack; use sublingual nitroglycerin instead.,Avoid alcohol and erectile dysfunction drugs (Viagra, Cialis, Levitra) while using this patch.,Common side effects: headache, dizziness, flushing. Report severe headache or fainting.,Do not stop abruptly; may cause rebound angina.
Take as prescribed to prevent angina; do not use for acute attacks.,May cause headache, dizziness, or hypotension; rise slowly from sitting.,Avoid taking erectile dysfunction drugs (e.g., sildenafil, tadalafil) as severe blood pressure drop can occur.,Do not stop abruptly to avoid rebound angina.,Store in original container away from light and moisture.
No interactions on record
"Bosentan, a dual endothelin receptor antagonist and an inducer of CYP3A4 and CYP2C9, reduces systemic exposure to vismodegib, a Hedgehog pathway inhibitor primarily metabolized by CYP3A4. This interaction leads to decreased serum concentrations of vismodegib, potentially diminishing its antitumor efficacy in patients with advanced basal cell carcinoma. Concomitant use may require vismodegib dose adjustment or alternative therapies to avoid therapeutic failure."
"Vismodegib inhibits CYP3A4, which is the primary enzyme responsible for metabolizing nilotinib. Concomitant administration may lead to increased nilotinib plasma concentrations, elevating the risk of QT interval prolongation, torsades de pointes, hepatotoxicity, and myelosuppression. Clinical vigilance is warranted due to the narrow therapeutic index of nilotinib."
"Vismodegib, a hedgehog pathway inhibitor, is a moderate inhibitor of CYP2C9, the primary enzyme responsible for metabolizing tolbutamide. Concomitant use can significantly decrease tolbutamide clearance, leading to elevated plasma concentrations and prolonged hypoglycemic effects. This increases the risk of severe hypoglycemia, especially in diabetic patients, and may require dose adjustment of tolbutamide."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about NITRO-DUR vs ISMO, answered by our medical review team.
NITRO-DUR is a Nitrate Vasodilator that works by Nitroglycerin is a prodrug that is converted to nitric oxide (NO) in vascular smooth muscle, activating guanylyl cyclase, increasing c GMP, leading to vasodilation primarily in veins and arteries.. ISMO is a Nitrate Vasodilator that works by Isosorbide mononitrate is a nitrate that dilates coronary arteries and peripheral veins. It acts by releasing nitric oxide, which activates guanylate cyclase, increasing c GMP levels, leading to smooth muscle relaxation and vasodilation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between NITRO-DUR and ISMO depend on the specific clinical indication. These are both Nitrate Vasodilator agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of NITRO-DUR is: Transdermal: Initial 0.2-0.4 mg/h applied once daily, titrate to 0.4-0.8 mg/h; maximum 0.8 mg/h. Remove for 10-12 hours daily to prevent tolerance.. The standard adult dose of ISMO is: 20 mg orally twice daily, 7 hours apart (e.g., 8 AM and 3 PM) to minimize nitrate tolerance.. 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 NITRO-DUR and ISMO 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. NITRO-DUR is classified as Category C. FDA Pregnancy Category C. First trimester: Animal studies show fetal harm, but no adequate human studies; potential risk cannot be ruled out. Second and third trimesters: Possible . ISMO is classified as Category C. ISMO (isosorbide mononitrate) is categorized as FDA Pregnancy Category C. In animal studies, reduced fetal survival and growth retardation were observed at high doses. No adequate . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.