Dicobalt edetate

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Related FACEM curriculum (2022) learning objectives:

• ME 3.8.1.6(e) Principles of management of toxicological presentations including: Indications for antidotes
• ME 3.8.2.4 Identify the appropriate antidote or antivenom.

Presentation

• aka cobalt edetate, cobalt EDTA, cobalt tetracemate
• 300mg/20mL vials

Toxicological indications

• Unequivocal cyanide poisoning

Contraindications

• Suspected cyanide poisoning

Pharmacodynamics and pharmacokinetics

• Inorganic cobalt salt, combines 1:6 with cyanide to form less toxic stable complexes
• Dicobalt edetate crosses the BBB
• Urinary excretion of cyanide-cobalt complex

Administration

• Only in resuscitation area with cardiac monitoring
• 300mg IV over 1 minute, chased with 50mL of 50% glucose (protects from toxicity)
• Repeat dose if no clinical response

Therapeutic Endpoints

• Improvement in:
  • Conscious state
  • Metabolic acidosis
  • Haemodynamics

Adverse Reactions

• Significant reactions especially if given when not indicated
• Due to direct toxicity of cobalt salt
  • Seizures
  • Face / neck / laryngeal oedema and urticaria
  • Chest pain
  • Dyspnoea
  • Hypotension

Specific considerations

• Limited data in pregnancy, but give if indicated.
• Paediatric dose 7.5mg/kg (max 300mg)

Practical points

• Only give if certain of cyanide poisoning - adverse effects minimised if given when indicated
• Ensure not giving Sodium calcium edetate (for lead poisoning) inadvertently
• Practically, there are probably better antidotes (relative efficacy unclear)