Sodium nitrite

Renal Impairment Sodium nitrite is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

Important Dosage and Administration Instructions If clinical suspicion of cyanide poisoning is high, administer Sodium Nitrite Injection without delay. Comprehensive treatment of acute cyanide intoxication requires support of vital functions. Administration of sodium nitrite and sodium thiosulfate should be considered adjunctive to appropriate supportive therapies.

Airway, ventilatory and circulatory support, and oxygen administration should not be delayed in order to administer sodium nitrite and sodium thiosulfate [ see Warnings and Precautions ]. The expert advice of a regional poison control center may be obtained by calling 1-800-222-1222. Identifying Patients with Cyanide Poisoning Cyanide poisoning may result from inhalation, ingestion, or dermal exposure to various cyanide-containing compounds, including smoke from closed-space fires.

Sources of cyanide poisoning include hydrogen cyanide and its salts, cyanogenic plants, aliphatic nitriles, and prolonged exposure to sodium nitroprusside.. The presence and extent of cyanide poisoning are often initially unknown. There is no widely available, rapid, confirmatory cyanide blood test. Treatment decisions must be made on the basis of clinical history and signs and symptoms of cyanide intoxication Table 1.

Common Signs and Symptoms of Cyanide Poisoning Symptoms Headache Confusion Dyspnea Chest Tightness Nausea Signs Altered Mental Status (e.g., confusion, disorientation) Seizures or Coma Mydriasis Tachypnea/Hyperpnea (early) Bradypnea/Apnea (late) Hypertension (early)/ Hypotension (late) Cardiovascular Collapse Vomiting Plasma Lactate Concentration ≥ 8 mmol/L In some settings, panic symptoms including tachypnea and vomiting may mimic early cyanide poisoning signs.

The presence of altered mental status (e.g., confusion and disorientation) and/or mydriasis is suggestive of true cyanide poisoning although these signs can occur with other toxic exposures as well. Smoke Inhalation Not all smoke inhalation victims will have cyanide poisoning and may present with burns, trauma, and exposure to other toxic substances making a diagnosis of cyanide poisoning particularly difficult.

Prior to administration of Sodium Nitrite Injection, smoke-inhalation victims should be assessed for the following: Exposure to fire or smoke in an enclosed area Presence of soot around the mouth, nose, or oropharynx Altered mental status Although hypotension is highly suggestive of cyanide poisoning, it is only present in a small percentage of cyanide-poisoned smoke inhalation victims.

Also indicative of cyanide poisoning is a plasma lactate concentration greater than or equal to 10 mmol/L (a value higher than that typically listed in the table of signs and symptoms of isolated cyanide poisoning because carbon monoxide associated with smoke inhalation also contributes to lactic acidemia). If cyanide poisoning is suspected, treatment should not be delayed in order to obtain a plasma lactate concentration.

Use with Other Cyanide Antidotes The safety of administering other cyanide antidotes simultaneously with Sodium Nitrite Injection has not been established. If a decision is made to administer another cyanide antidote with Sodium Nitrite Injection, these drugs should not be administered concurrently in the same intravenous (IV) line. [ see Dosage and Administration ]

Recommended Monitoring Monitor patients for at least 24-48 hours after Sodium Nitrite Injection administration for adequacy of oxygenation and perfusion and for recurrent signs and symptoms of cyanide toxicity. When possible, obtain hemoglobin/hematocrit when treatment is initiated. Measurements of oxygen saturation using standard pulse oximetry and calculated oxygen saturation values based on measured PO 2 are unreliable in the presence of methemoglobinemia.

Methemoglobin level : Administrations of sodium nitrite solely to achieve an arbitrary level of methemoglobinemia may be unnecessary and potentially hazardous. The therapeutic effects of sodium nitrite do not appear to be mediated by methemoglobin formation alone [see Clinical Pharmacology ] and clinical responses to sodium nitrite administration have been reported in association with methemoglobin levels of less than 10%.

Administration of sodium nitrite beyond the initial dose should be guided primarily by clinical response to treatment (i.e., a second dose should be considered only if there is inadequate clinical response to the first dose). It is generally recommended that methemoglobin concentrations be closely monitored and kept below 30%.

Monitor serum methemoglobin levels during treatment using co-oximetry, and discontinue administration of sodium nitrite when methemoglobin levels exceed 30%. Intravenous methylene blue and exchange transfusion have been reported in the literature as treatments for life-threatening methemoglobinemia.

Incompatibility Information Chemical incompatibility has been reported between sodium nitrite and hydroxocobalamin and these drugs should not be administered simultaneously through the same IV line. No chemical incompatibility has been reported between sodium thiosulfate and sodium nitrite, when administered sequentially through the same IV line as described in Dosage and Administration.

Simultaneous administration of sodium nitrite and blood products (whole blood, packed red cells, platelet concentrate and/or fresh frozen plasma) through the same intravenous line is not recommended. However, blood products and sodium nitrite can be administered simultaneously using separate intravenous lines (preferably on contralateral extremities, if peripheral lines are being used).