Lecture Notes: Cyanide Poisoning

Introduction

• Channel: Medicosis Perfectionalis
• Previous topic: Methemoglobinemia
• Current topic: Cyanide Poisoning

Historical Context and Examples

• 2013 Brazilian nightclub fire: cyanide poisoning caused 156 deaths.
• Story of Rasputin: survived cyanide poisoning from food and drink.

Forms and Exposure

• Cyanide exists in gas, liquid, and solid forms.
• Exposure through inhalation, ingestion, or skin absorption.
• Common cause in the U.S.: smoke inhalation.
• Other causes: suicidal ingestion, certain medications (e.g., sodium nitroprusside), industrial exposure, and certain wrapping materials.

Physiology and Mechanism

• Electron Transport Chain: Involves complexes 1-5; focus on complex 4.

  • Cytochrome C oxidase (complex 4) involves cytochrome A, A3, and contains ferric iron (Fe3+).

• Cyanide Binding:

  • Cyanide preferentially binds to ferric iron (Fe3+).
  • Targets include methemoglobin (forming cyanomethemoglobin) or cytochrome C oxidase in mitochondria.
  • Binding to cytochrome C oxidase inhibits complex 4, halting ATP production.

Effects of Inhibition

• Mitochondria cannot utilize oxygen due to inhibited electron transport chain.
• Results in reliance on anaerobic glycolysis, leading to lactic acidosis and high anion gap metabolic acidosis.

Treatment and Prevention

• Inducing methemoglobinemia can divert cyanide binding away from cytochrome C oxidase, thus "curing" cyanide poisoning.
• Sodium thiosulfate used to excrete cyanide.

Additional Information

• Anecdotal Claims: Unproven cancer cure claims involving cyanide.
• Exam Tip: Cyanide poisoning scenarios with healthcare professionals due to access.

Conclusion

• Cyanide poisoning is a critical area with both historical and modern significance.
• Understanding cyanide's preference for ferric iron (Fe3+) is crucial for diagnosing and treating exposure.
• Emphasis on the importance of evidence-based science over anecdotal claims.

Additional Resources

• Patreon: Support at patreon.com/medicosis

Personal Advice

• Be safe, stay happy, and study hard.