Major
Haloperidol × Morphine
First-generation antipsychotics. Butyrophenone derivatives×Natural opium alkaloids
Mechanism
Additive CNS depression and sedation. Severe hypotension and respiratory depression have been reported, especially in older patients.
Symptoms
Drowsiness, slowed breathing (rate below 12/min), cyanosis of lips. Severe cases include respiratory arrest. Older patients: fall risk.
Management
Avoid the combination in older patients. For opioid-induced nausea, use ondansetron (no QT issue in short courses in older patients) or metoclopramide. For acute delirium, dexmedetomidine (no respiratory depression).