NITROMIST
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NITROMIST (NITROMIST).
Nitroglycerin is a prodrug that releases nitric oxide (NO) which activates guanylyl cyclase, increasing cGMP in smooth muscle cells, leading to vasodilation primarily of venous capacitance vessels and coronary arteries.
| Metabolism | Primarily hepatic via glutathione S-transferases (GST) and possibly cytochrome P450 (CYP3A4) to inactive metabolites. |
| Excretion | Renal excretion of inactive metabolites accounts for >80% of elimination; biliary/fecal excretion is minimal (<15%). |
| Half-life | 2–3 minutes for nitroglycerin; rapid metabolism results in short terminal half-life. Clinically, effects dissipate within 30 minutes of discontinuation. |
| Protein binding | Approximately 60% bound to plasma proteins (albumin). |
| Volume of Distribution | 3.3 L/kg; large Vd indicates extensive tissue distribution, especially to vascular smooth muscle. |
| Bioavailability | Sublingual: ~40% (due to first-pass metabolism); transdermal: variable (~10–30%); intravenous: 100%. |
| Onset of Action | Sublingual spray: 1–3 minutes; intravenous: immediate (1–2 minutes); transdermal: 30–60 minutes. |
| Duration of Action | Sublingual spray: 30–60 minutes; intravenous: 3–5 minutes after infusion stop; transdermal: 8–12 hours with patch removal. Tolerance develops with continuous exposure. |
1-2 sprays (0.4-0.8 mg) sublingually or intraorally at onset of angina, may repeat every 5 minutes up to 3 doses. Prophylaxis: 1 spray (0.4 mg) 5-10 minutes before activity.
| Dosage form | AEROSOL, METERED |
| Renal impairment | No dose adjustment required for renal impairment. |
| Liver impairment | Use with caution in severe hepatic impairment (Child-Pugh C); consider dose reduction due to increased bioavailability. |
| Pediatric use | Not recommended for use in pediatric patients due to lack of safety and efficacy data. |
| Geriatric use | Initiate with lower doses (e.g., 1 spray = 0.4 mg) due to increased sensitivity and higher risk of hypotension. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for NITROMIST (NITROMIST).
| Breastfeeding | Nitroglycerin is excreted into breast milk in small amounts; M/P ratio is approximately 0.55. American Academy of Pediatrics considers it compatible with breastfeeding. However, use caution in nursing mothers due to potential for infant hypotension. |
| Teratogenic Risk | FDA Pregnancy Category X. Nitroglycerin is contraindicated in pregnancy due to risk of fetal bradycardia and hypotension. First trimester: Risk cannot be ruled out; use only if clearly needed. Second and third trimesters: Increased risk of maternal hypotension leading to decreased placental perfusion. Not recommended. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to nitroglycerin","Severe hypotension (SBP <90 mmHg)","Cardiac tamponade","Constrictive pericarditis","Hypertrophic cardiomyopathy with left ventricular outflow tract obstruction","Concurrent use with phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil)","Increased intracranial pressure (e.g., head trauma, cerebral hemorrhage)","Severe anemia"]
| Precautions | ["Hypotension","Hypovolemia","Increased intracranial pressure","Hypertrophic cardiomyopathy","Severe anemia","Tolerance with continuous use","Contraindicated use with phosphodiesterase-5 inhibitors (e.g., sildenafil)"] |
Loading safety data…
| Fetal Monitoring | Monitor maternal blood pressure and heart rate continuously during infusion. Assess fetal heart rate and uterine activity if used near term. Monitor for signs of maternal hypotension and fetal distress. |
| Fertility Effects | No evidence of impaired fertility from animal studies. In humans, no specific studies on fertility effects. Nitroglycerin may affect uterine blood flow; theoretical risk but not well studied. |