Is lorazepam (1mg) contraindicated in a patient with myotonic dystrophy and respiratory failure in the UK?

Lorazepam is Contraindicated in Patients with Myotonic Dystrophy and Respiratory Failure

Lorazepam 1mg is contraindicated in patients with myotonic dystrophy who have respiratory failure due to the high risk of worsening respiratory depression that could be life-threatening. 1

Rationale for Contraindication

Respiratory Risks in Myotonic Dystrophy

• Myotonic dystrophy patients already have compromised respiratory function due to:
  • Progressive weakness of respiratory muscles leading to hypoventilation 2
  • Sleep-disordered breathing that can worsen respiratory function 2
  • Reduced ability to clear secretions due to expiratory muscle weakness 3
  • Increased sensitivity to respiratory depressant medications 4, 5

Specific Concerns with Lorazepam

• The FDA label explicitly states that lorazepam should be used with caution in patients with compromised respiratory function (e.g., COPD, sleep apnea) 1
• Benzodiazepines like lorazepam can cause potentially fatal respiratory depression, especially when respiratory function is already compromised 1
• Patients with myotonic dystrophy show increased sensitivity to central nervous system depressants 4, 5

Clinical Evidence Supporting Contraindication

• Case reports document respiratory arrest following benzodiazepine administration in myotonic dystrophy patients 4
• Even small doses of central nervous system depressants can cause severe respiratory depression in these patients 5
• The British Thoracic Society guidelines highlight that respiratory complications are a major cause of morbidity and the second most frequent cause of death in muscular dystrophy patients 2

Alternative Approaches

• For patients requiring anxiolysis or sedation:
  • Consider non-pharmacological approaches first
  • If medication is necessary, consult with a specialist respiratory team with experience in managing neuromuscular disorders 2
  • Any medication with respiratory depressant effects should be used with extreme caution and at reduced doses, with close monitoring 1
  • Have airway management equipment and ventilatory support immediately available

Monitoring Requirements if Use Cannot be Avoided

If, despite contraindications, a clinical decision is made that lorazepam is absolutely necessary:

1. Administer in a setting with continuous respiratory monitoring
2. Start with the lowest possible dose (less than 1mg)
3. Monitor CO2 levels continuously 2
4. Have non-invasive ventilation immediately available 2
5. Ensure oxygen therapy is available but remember that oxygen alone without ventilatory support can worsen hypercapnia 2

Important Considerations

• Patients with myotonic dystrophy may not display typical signs of respiratory distress despite significant compromise 2
• Even with normal or near-normal vital capacity measurements, patients may have chronic ventilatory failure 5
• The combination of myotonic dystrophy and respiratory failure represents a significant risk factor for adverse outcomes with any respiratory depressant medication 3

In conclusion, the risks of administering lorazepam to a patient with myotonic dystrophy and respiratory failure far outweigh any potential benefits, and alternative approaches should be strongly considered.