Sodium Nitrite Drug Classification
Sodium nitrite is a cyanide antidote and methemoglobin-forming agent used specifically for the treatment of acute cyanide poisoning. 1
Primary Therapeutic Classification
Sodium nitrite functions as a cyanide antidote through its ability to induce methemoglobin formation, which has high affinity for cyanide ions and helps sequester them from critical cellular targets. 1, 2
The American Heart Association classifies sodium nitrite as a second-line cyanide antidote, recommended when hydroxocobalamin is unavailable. 1
Mechanism of Action
Sodium nitrite acts as an oxidizing agent that converts oxyhemoglobin to methemoglobin, creating a competitive binding site for cyanide ions that prevents cyanide from inhibiting cytochrome c oxidase in mitochondria. 3, 2
The drug also generates nitric oxide (NO) in the bloodstream, which may directly antagonize cyanide inhibition of cytochrome c oxidase—this NO-mediated effect may be equally or more important than the methemoglobin-forming action. 4
Clinical Context and Positioning
Sodium nitrite is positioned as an alternative to hydroxocobalamin, particularly when carbon monoxide poisoning is not a concern, since methemoglobin formation can further impair oxygen-carrying capacity in patients with concurrent carbon monoxide exposure. 1
The drug is typically administered in combination with sodium thiosulfate, which enhances cyanide elimination by serving as a substrate for enzymatic conversion of cyanide to thiocyanate. 1, 5
Important Safety Considerations
Sodium nitrite carries significant toxicity risks as a powerful oxidizing agent, capable of causing hypotension, excessive methemoglobin formation, hypoxia, altered consciousness, dysrhythmias, and death when overdosed. 3
Precise dosing is critical in children and patients with anemia to avoid excessive methemoglobin formation—the prescribing information provides specific weight-based and hemoglobin-adjusted dosing requirements. 1
Methylene blue serves as the antidote for sodium nitrite overdose, with dosing of 1-2 mg/kg IV for both adults and children, targeting methemoglobin levels below 30%. 6