›Maximum single dose 5 g
›Side effects and interference
›Red-brown discoloration of skin, urine, and mucous membranes — transient
›Interferes with colorimetric laboratory assays — co-oximetry, creatinine, bilirubin
›Indications
›All suspected severe cyanide poisoning
›Smoke inhalation with lactate >= 8 mmol/L or altered mental status
›Class I recommendation per 2023 AHA focused update
Antidote therapy — sodium nitrite and sodium thiosulfate (alternative)
›Sodium nitrite 3% solution — methemoglobin-forming agent
›Mechanism
›Induces methemoglobinemia — cyanide preferentially binds to methemoglobin
›Avoid or use with extreme caution in CO co-poisoning
›Adult dosing
›10 mL of 3% solution (300 mg) IV at 2.5-5 mL/minute
›Maximum 10 mL per dose
›Pediatric dosing — weight and hemoglobin-adjusted
›0.2 mL/kg of 3% solution — maximum 10 mL
›Adjust downward if hemoglobin < 120 g/L to prevent excessive methemoglobinemia
›Monitoring requirements
›Blood pressure every 2 minutes during infusion — hypotension common
›Methemoglobin target < 30%
›Sodium thiosulfate 25% solution — adjunctive agent
›Mechanism
›Sulfur donor enabling rhodanese enzyme to convert cyanide to thiocyanate
›Too slow for monotherapy in severe poisoning
›Adult dosing
›50 mL of 25% solution (12.5 g) IV over 10 minutes
›Administer after nitrite or as adjunct to hydroxocobalamin
›Pediatric dosing
›1 mL/kg of 25% solution — maximum 50 mL
›Separate IV line from hydroxocobalamin — chemically incompatible
›Redosing
›If symptoms recur — repeat half dose of both nitrite and thiosulfate
›Monitor for excessive methemoglobinemia with repeat nitrite
›Benzodiazepines for cyanide-induced seizures
›Lorazepam IV
›0.1 mg/kg IV — adult 2-4 mg IV
›Repeat every 5-10 minutes if seizures persist
›Diazepam IV
›5-10 mg IV adult dose
›Pediatric 0.2-0.3 mg/kg IV
›Phenobarbital for refractory seizures
›15-20 mg/kg IV loading dose
›Rate limit 60 mg/minute in adults
›Hemodynamic support
›Norepinephrine — first-line vasopressor
›0.1-0.5 mcg/kg/minute IV infusion
›Titrate to MAP >= 65 mmHg
›Epinephrine — if norepinephrine insufficient
›0.1-0.5 mcg/kg/minute IV infusion
›Consideration in cardiac arrest or peri-arrest states
›IV fluid resuscitation adjunct
›Isotonic crystalloid 20 mL/kg bolus
›Reassess fluid responsiveness before additional boluses
Methylene blue — experimental adjunct
›Methylene blue for cyanide cardiotoxicity
›Emerging evidence — not standard of care
›Counteracts cyanide cardiotoxicity at cellular level
›May depolarize resting membrane potential effects
›Not routinely recommended
›Consult toxicology before use
›Research context only outside toxicology guidance