NITRO IV

Clinical safety rating: caution

Comprehensive clinical and safety monograph for NITRO IV (NITRO IV).

How it works

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.

What the body does with it

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).

Classification & Brands

Dosing & administration

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.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for NITRO IV (NITRO IV).

Breastfeeding	Unknown excretion in human milk. M/P ratio not established. Short half-life suggests minimal exposure; however, use with caution and consider risk of infant hypotension.
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

Warnings & precautions

■ 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.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Allergy to nitroglycerin or nitrates","Severe anemia","Increased intracranial pressure (e.g., head trauma, cerebral hemorrhage)","Concomitant use of phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)","Hypotension (systolic BP < 90 mmHg)","Right ventricular infarction","Constrictive pericarditis","Pericardial tamponade"]

Clinical Precautions

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"]

Clinical Tips & Counseling

Drug interactions

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NITRO IV

Clinical safety rating: caution

Comprehensive clinical and safety monograph for NITRO IV (NITRO IV).

How it works

What the body does with it

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).

Classification & Brands

Dosing & administration

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.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for NITRO IV (NITRO IV).

Breastfeeding	Unknown excretion in human milk. M/P ratio not established. Short half-life suggests minimal exposure; however, use with caution and consider risk of infant hypotension.
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