Cyanokit (Hydroxocobalamin) for Non-Cyanide Toxicity
Cyanokit (hydroxocobalamin) is NOT recommended for non-cyanide toxicity and should be restricted exclusively to confirmed or highly suspected cyanide poisoning. 1, 2
Evidence-Based Restrictions
The most recent and authoritative guidelines explicitly limit hydroxocobalamin use:
The 2023 American Heart Association guidelines recommend hydroxocobalamin only for cyanide poisoning, specifically in patients with cardiac arrest, cardiovascular instability, metabolic acidosis, or altered mental status from known or suspected cyanide exposure 1
Routine administration after smoke inhalation is NOT recommended unless there is high suspicion of severe cyanide poisoning based on clinical criteria 2
The American Society of Anesthesiologists explicitly states that hydroxocobalamin should not be routinely administered after smoke inhalation, reserving it only for cases with high suspicion of severe cyanide poisoning 2
Specific Clinical Indications for Use
Hydroxocobalamin should ONLY be administered when the following criteria are met:
Adults 1, 3
- Suspected cyanide exposure (fire smoke, industrial exposure, intentional poisoning) AND
- Severe manifestations: cardiac arrest, cardiovascular collapse, shock, coma, or severe metabolic acidosis
- Plasma lactate ≥8-10 mmol/L in the appropriate clinical context 2, 3
Pediatric Patients 2, 3
- Smoke inhalation AND
- Signs of moderate or severe cyanide poisoning (altered consciousness, cardiovascular instability)
Why Not for Non-Cyanide Toxicity?
Mechanism Specificity
Hydroxocobalamin works by directly binding cyanide ions to form cyanocobalamin (vitamin B12), which is then renally excreted 4, 5. This mechanism is entirely specific to cyanide and provides no therapeutic benefit for other toxins.
Potential Harms
- Oxalate nephropathy can occur with hydroxocobalamin administration 3
- Chromaturia and pink skin discoloration complicate clinical assessment 6
- False elevation of laboratory values can interfere with diagnostic testing
- Resource misallocation in mass casualty events if used inappropriately
Common Pitfalls to Avoid
Do NOT administer hydroxocobalamin for:
- Carbon monoxide poisoning alone (without cyanide co-exposure) 2
- General smoke inhalation without specific cyanide toxicity indicators 2
- Other toxidromes (tricyclic antidepressants, cocaine, opioids, etc.) 1
- Metabolic acidosis from non-cyanide causes
- Empiric use in all fire victims 7
Critical Decision Point
The key distinguishing feature is severe metabolic acidosis (pH <7.20) or elevated lactate (≥8-10 mmol/L) in the context of potential cyanide exposure 8, 2. Without this context, hydroxocobalamin has no role.
Antidote Stocking Considerations
Hospital formularies stock hydroxocobalamin specifically for cyanide emergencies, not for broad toxicological use:
- Immediate availability is recommended for emergency departments that accept poisoned patients 1
- Hydroxocobalamin is preferred over sodium nitrite/sodium thiosulfate for cyanide poisoning due to superior safety profile 1
- This preference is based on ease of use, wider indications, and lack of methemoglobin formation 1
Alternative Toxin-Specific Antidotes
For non-cyanide toxicities, use appropriate evidence-based antidotes 1:
- Opioids: naloxone
- Benzodiazepines: flumazenil (with caution)
- Cardiac glycosides: digoxin-specific antibody fragments
- Toxic alcohols: fomepizole
- Cocaine cardiotoxicity: benzodiazepines, sodium bicarbonate for wide-complex dysrhythmias 1