NITRO IV
Clinical safety rating
cautionComprehensive clinical and safety monograph for NITRO IV (NITRO IV).
Nitroglycerin is a vasodilator that primarily acts by relaxing vascular smooth muscle via the release of nitric oxide (NO), which activates guanylate cyclase to increase cGMP, leading to venodilation and, at higher doses, arterial dilation. This reduces preload and afterload, decreasing myocardial oxygen demand.
| Metabolism | Nitroglycerin is extensively metabolized in the liver by glutathione S-transferases and, to a lesser extent, by arterial walls. It undergoes denitration to form 1,2- and 1,3-glyceryl dinitrate, which have weaker vasodilatory activity. |
| Excretion | Renal (minimal, <1% unchanged) and hepatic metabolism; metabolites excreted renally. |
| Half-life | 1-4 minutes (rapidly cleared from blood); terminal half-life ~2-3 minutes due to rapid biotransformation in RBCs and vascular tissue. |
| Protein binding | 60% bound to albumin. |
| Volume of Distribution | 3-4 L/kg (high, due to extensive tissue uptake, especially vascular smooth muscle). |
| Bioavailability | IV: 100% (not administered via other routes due to extensive first-pass metabolism). |
| Onset of Action | IV: 1-2 minutes. |
| Duration of Action | 3-5 minutes (rapid tolerance with continuous infusion; effects dissipate quickly after cessation). |
| Molecular Weight | 101.1 |
Initial infusion rate 5 mcg/min via continuous IV infusion, titrate by 5 mcg/min every 3-5 minutes until response; usual maintenance dose 10-20 mcg/min; maximum 200 mcg/min.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for GFR ≥30 mL/min; for GFR <30 mL/min, consider dose reduction due to risk of methemoglobinemia and cyanide toxicity, monitor closely. |
| Liver impairment | Child-Pugh class A: no adjustment; Child-Pugh class B: reduce dose by 50%; Child-Pugh class C: avoid use or use with extreme caution, reduce dose by 75%. |
| Pediatric use | 0.25-0.5 mcg/kg/min IV continuous infusion, titrate by 0.5-1 mcg/kg/min every 3-5 minutes; maximum 5 mcg/kg/min for children. |
| Geriatric use | Initiate at lower end of dosing range (5 mcg/min) due to increased sensitivity; titrate slowly with careful hemodynamic monitoring. |
| 1st trimester | Avoid due to risk of fetal hypoxia and potential teratogenicity; use only if clearly needed. |
| 2nd trimester | Use with caution; may cause fetal bradycardia or hypotension. |
| 3rd trimester | Avoid near term; may cause uterine relaxation and interfere with labor. |
Clinical note
Comprehensive clinical and safety monograph for NITRO IV (NITRO IV).
| Placental transfer | Rapidly crosses the placenta; fetal levels approximate maternal levels. |
| Breastfeeding | Excretion into breast milk is minimal; however, due to risk of methemoglobinemia in infants, avoid use in breastfeeding women. |
| Lactation Rating | L4 (Possibly Hazardous) |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: Limited human data; animal studies show fetal harm at high doses. Second/third trimester: Potential risk of fetal bradycardia and hypotension; use only if clearly needed. Avoid near term due to risk of uterine relaxation and hemorrhage. |
| Fetal Monitoring | Continuous fetal heart rate monitoring during infusion, maternal blood pressure, heart rate, and oxygen saturation. Monitor for signs of uterine hemorrhage near term. |
| Fertility Effects | No human data on fertility impairment. Animal studies show no adverse effects on fertility at therapeutic doses. |
■ FDA Black Box Warning
Nitroglycerin is contraindicated in patients with severe anemia, increased intracranial pressure, or those using phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil) due to risk of severe hypotension.
| Serious Effects |
Severe hypotensionHypovolemiaCardiac tamponadeConstrictive pericarditisCerebral hemorrhageGlaucoma
| Precautions | Hypotension and reflex tachycardia may occur; monitor blood pressure, May exacerbate angina from abrupt discontinuation (tolerance and rebound), Caution in patients with hypovolemia, right ventricular infarction, or hypertrophic cardiomyopathy, Avoid in patients with constrictive pericarditis or pericardial tamponade, May cause methemoglobinemia, especially with high doses or prolonged use |
| Food/Dietary | No specific food restrictions. Avoid alcohol as it may enhance vasodilation and hypotension. |
| Clinical Pearls | Use non-PVC infusion sets to minimize drug adsorption. Monitor for hypotension, especially with concurrent PDE-5 inhibitor use. Tolerance can develop with prolonged infusion; use lowest effective dose. Do not abruptly discontinue after prolonged use to avoid rebound ischemia. Avoid in patients with right ventricular infarction or severe aortic stenosis. |
| Patient Advice | Report any severe headaches, dizziness, or fainting during infusion. · Avoid taking erectile dysfunction medications like sildenafil or tadalafil while on this treatment. · Notify your healthcare provider if you have a history of low blood pressure or recent heart attack. · The medication will be given by a healthcare professional and vital signs will be monitored closely. · Do not stop the infusion suddenly without medical advice. |
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