What are the consequences of a 70-year-old man ingesting 60ml of dextromethorphan?

Consequences of 60ml Dextromethorphan Ingestion in a 70-Year-Old Man

A 70-year-old man who has ingested 60ml of dextromethorphan is at high risk for severe toxicity including altered mental status, seizures, serotonin syndrome, and potentially life-threatening complications requiring immediate medical attention. 1

Immediate Clinical Effects

The consequences of this large dextromethorphan overdose in an elderly patient include:

• Central Nervous System Effects:

  • Altered mental status ranging from confusion to coma
  • Hallucinations and psychosis
  • Seizures, potentially progressing to status epilepticus
  • Loss of cranial nerve reflexes in severe cases 2

• Cardiovascular Effects:

  • Tachycardia
  • Hypertension or hypotension
  • Cardiac arrhythmias

• Respiratory Effects:

  • Respiratory depression
  • Potential need for mechanical ventilation

• Other Effects:

  • Serotonin syndrome (hyperthermia, neuromuscular hyperactivity, autonomic instability) 3
  • Nausea and vomiting
  • Dizziness

Severity Assessment

The severity of dextromethorphan toxicity is dose-dependent. Guidelines indicate that ingestion exceeding 7.5 mg/kg requires emergency department evaluation 1. For a 70-year-old man:

• 60ml of dextromethorphan likely contains approximately 900-1800mg (depending on formulation)
• This far exceeds the 7.5 mg/kg threshold (approximately 525mg for a 70kg individual)
• Elderly patients are at higher risk due to:
  • Decreased drug clearance
  • Potential polypharmacy interactions
  • Age-related changes in metabolism 4

Age-Related Considerations

The patient's advanced age (70 years) significantly increases the risk of severe toxicity:

• Elderly patients have reduced hepatic clearance of dextromethorphan
• CYP2D6 metabolism may be slower in geriatric patients
• Higher susceptibility to CNS effects including psychosis 4
• Increased risk of falls and injuries due to CNS depression

Potential Complications

This overdose may lead to several serious complications:

• Refractory Status Epilepticus:

  • Seizures that do not respond to standard anticonvulsant therapy 2
  • May require intensive care management with propofol or midazolam infusion

• Serotonin Syndrome:

  • Particularly if the patient is taking other serotonergic medications
  • Presents with hyperthermia, neuromuscular abnormalities, and autonomic instability
  • Can be life-threatening if severe 3

• Respiratory Failure:

  • May require intubation and mechanical ventilation
  • Particularly concerning in elderly patients with underlying respiratory conditions

Management Considerations

While not directly asked in the question, it's important to note that management would include:

• Immediate medical attention in an emergency department
• Supportive care with airway management
• Benzodiazepines for seizures
• Naloxone may be considered for respiratory depression
• Cooling measures for hyperthermia
• Intensive monitoring of vital signs and neurological status 1

Special Concerns in Elderly Patients

The consequences may be more pronounced in elderly patients due to:

• Potential for drug interactions with medications commonly used by older adults
• Reduced physiological reserve to compensate for toxic effects
• Higher risk of falls and subsequent injuries due to CNS depression
• Increased sensitivity to anticholinergic effects 4

This overdose represents a medical emergency requiring immediate intervention to prevent potentially fatal outcomes, especially given the patient's advanced age and the large amount ingested.