SODIUM NITRITE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SODIUM NITRITE (SODIUM NITRITE).
Sodium nitrite is a vasodilator that acts by relaxing vascular smooth muscle, primarily through the generation of nitric oxide (NO). It also converts hemoglobin to methemoglobin, which binds cyanide, thereby acting as an antidote for cyanide poisoning.
| Metabolism | Sodium nitrite is rapidly metabolized to nitric oxide and other nitrogen oxides. It is also converted to methemoglobin. The exact metabolic enzymes are not well-defined, but it is thought to involve interactions with hemoglobin and other heme-containing proteins. |
| Excretion | Primarily renal; 60-70% as nitrate and unchanged nitrite; minor biliary (<5%) and fecal (<2%) elimination. |
| Half-life | Terminal half-life: 0.5–1 hour (nitrite); due to rapid oxidation to nitrate, which has a half-life of 5–8 hours. Clinically, methemoglobin reduction requires monitoring for 2–4 hours. |
| Protein binding | Minimal (<10%); no specific binding proteins; primarily free in plasma. |
| Volume of Distribution | 0.2–0.4 L/kg; distributes into extracellular fluid and erythrocytes; larger Vd reflects tissue uptake. |
| Bioavailability | IV: 100%; oral: not clinically used (rapid conversion to nitrate, ~50% bioavailability, but therapeutic levels unattainable). |
| Onset of Action | IV administration: 30–60 seconds to onset of methemoglobin formation; maximum effect within 5–10 minutes. |
| Duration of Action | Methemoglobin levels peak at 5–10 minutes and persist for 30–60 minutes, with clinical effect lasting 1–2 hours; may require repeat dosing. |
300 mg (10 mL of a 30 mg/mL solution) intravenously over 2-4 minutes, followed immediately by sodium thiosulfate. May repeat once after 30-60 minutes if needed.
| Dosage form | SOLUTION |
| Renal impairment | Use with caution in renal impairment; no specific GFR-based dose adjustment established. Monitor for methemoglobinemia and hypotension. |
| Liver impairment | No specific Child-Pugh-based adjustment; use with caution in severe hepatic impairment due to potential for reduced metabolism. |
| Pediatric use | 0.2 mL/kg (6 mg/kg) of a 30 mg/mL solution intravenously over 2-4 minutes; maximum 10 mL (300 mg). Follow with sodium thiosulfate. |
| Geriatric use | Consider lower initial dose (e.g., 150 mg IV) and monitor for hypotension and methemoglobin levels due to age-related physiological changes. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SODIUM NITRITE (SODIUM NITRITE).
| Breastfeeding | No data on excretion into breast milk or M/P ratio are available. Sodium nitrite's short half-life and rapid metabolic clearance suggest minimal infant exposure. However, due to risk of methemoglobinemia in infants, breastfeeding should be avoided during administration and for at least 24 hours after the last dose. Consult a toxicologist for acute poisoning scenarios. |
| Teratogenic Risk | Sodium nitrite is not known to be teratogenic in humans. In animal studies, no teratogenic effects were observed at clinically relevant doses. However, due to the potential for methemoglobinemia and subsequent fetal hypoxia, use during pregnancy should be limited to acute cyanide poisoning where benefits outweigh risks. There is no evidence of specific fetal malformations across trimesters. |
■ FDA Black Box Warning
WARNING: Sodium nitrite can cause severe hypotension and methemoglobinemia. Monitor blood pressure and methemoglobin levels closely. Use with caution in patients with anemia, cardiovascular disease, or respiratory compromise.
| Serious Effects |
Absolute: Known hypersensitivity to sodium nitrite or any component of the formulation. Relative: Severe hypotension, severe anemia, G6PD deficiency, congenital methemoglobin reductase deficiency.
| Precautions | May cause severe hypotension; administer under close medical supervision. Risk of methemoglobinemia, especially in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Use with caution in patients with cardiovascular disease, renal impairment, or respiratory disease. Monitor methemoglobin levels. Avoid in patients with known hypersensitivity to nitrites. |
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| Fetal Monitoring | Maternal: Continuous pulse oximetry (note: methemoglobinemia may cause SpO2 artifact), arterial blood gases with co-oximetry (methemoglobin level), vital signs, and ECG. Fetal: Continuous fetal heart rate monitoring if viable fetus. Monitor for maternal and fetal hypoxia. Check methemoglobin levels at baseline and after each dose; maintain methemoglobin <30%. |
| Fertility Effects | No human data on fertility effects. Animal studies have not reported adverse effects on fertility. Sodium nitrite is not suspected to impair male or female reproductive function at therapeutic doses. Chronic high-dose exposure may theoretically affect fertility via hypoxic stress, but not relevant for acute use. |