NITRO-DUR
Clinical safety rating
cautionComprehensive clinical and safety monograph for NITRO-DUR (NITRO-DUR).
Nitroglycerin is a prodrug that is converted to nitric oxide (NO) in vascular smooth muscle, activating guanylyl cyclase, increasing cGMP, leading to vasodilation primarily in veins and arteries.
| Metabolism | Metabolized by glutathione S-transferases (GSTs) in the liver and erythrocytes, producing glycerol dinitrate and nitrite ions. |
| Excretion | Primarily renal (>80% as inactive metabolites; <1% unchanged nitroglycerin). Minor biliary/fecal elimination. |
| Half-life | 2–3 minutes (nitroglycerin); prolonged to ~30 minutes for active metabolites. Clinical context: Requires frequent dosing or continuous administration for sustained effect. |
| Protein binding | ~60% (mainly to albumin). |
| Volume of Distribution | ~3 L/kg (extensive tissue distribution). |
| Bioavailability | Transdermal: ~70% (relative to IV). Oral: <10% (extensive first-pass metabolism). |
| Onset of Action | Transdermal: 30–60 minutes (plasma levels); 60–120 minutes for hemodynamic effects. |
| Duration of Action | Transdermal: 8–12 hours (therapeutic effect); tolerance develops with continuous use; requires 10–12 hour nitrate-free interval. |
| Molecular Weight | 62.1 |
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.
| Dosage form | FILM, EXTENDED RELEASE |
| Renal impairment | No dose adjustment needed for any degree of renal impairment. |
| Liver impairment | 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. |
| Pediatric use | Safety and efficacy not established in pediatric patients; no standard dosing guidelines. |
| Geriatric use | 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). |
| 1st trimester | Limited human data; animal studies show no consistent teratogenic effects. Use only if clearly needed. |
| 2nd trimester | May cause maternal hypotension and decrease uterine blood flow. Use with caution. |
| 3rd trimester | May cause fetal bradycardia and hypotension. Avoid near term due to risk of uterine relaxation and postpartum hemorrhage. |
Clinical note
Comprehensive clinical and safety monograph for NITRO-DUR (NITRO-DUR).
| Placental transfer | Crosses placenta; detected in fetal circulation. |
| Breastfeeding | Excretion into breast milk is minimal; however, use with caution due to potential for hypotension in infant. |
| Lactation Rating | L2 |
| Teratogenic Risk | 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. |
| Fetal Monitoring | Monitor maternal blood pressure and heart rate; fetal heart rate monitoring during prolonged use; assess uterine tone and contractions; watch for signs of methemoglobinemia. |
| Fertility Effects | No adequate studies; animal data suggest no significant impairment of fertility at clinically relevant doses. |
■ FDA Black Box Warning
Do not use with phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil) due to risk of severe hypotension.
| Serious Effects |
Hypersensitivity to nitroglycerin or any componentSevere anemiaIncreased intracranial pressure (e.g., head trauma, cerebral hemorrhage)Concomitant use with phosphodiesterase-5 inhibitors (e.g., sildenafil) or soluble guanylate cyclase stimulators (e.g., riociguat)
| Precautions | Hypotension, especially in hypovolemic patients; tolerance with chronic use; paradoxical bradycardia and increased angina; exacerbate hypertrophic cardiomyopathy; avoid abrupt discontinuation. |
| Food/Dietary | 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. |
| Clinical Pearls | 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. |
| Patient Advice | 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. |
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