From the Guidelines
Morphine is not contraindicated in paracetamol overdose, but its use should be cautious and not delay the administration of N-acetylcysteine (NAC) as an antidote. The primary concern in paracetamol overdose is hepatotoxicity, and morphine can mask its symptoms. However, morphine can be used for pain management in patients who have overdosed on paracetamol, particularly when pain is a significant symptom. The standard dose of morphine for pain would apply: 0.1 mg/kg IV or 5-10 mg for adults, titrated to effect 1.
Key Considerations
- Morphine dosing may need to be reduced if the patient has developed liver failure from the overdose, as the liver is involved in its metabolism.
- Close monitoring of the patient's respiratory status is essential when administering morphine, especially if the patient has taken other central nervous system depressants alongside paracetamol.
- The priority in paracetamol overdose remains administering the antidote N-acetylcysteine (NAC) promptly, typically with a loading dose of 150 mg/kg over 1 hour, followed by maintenance doses 1.
- Acetaminophen levels should be drawn in all patients presenting with acute liver failure (ALF), as acetaminophen is the leading cause of ALF and there is an available antidote.
Administration of NAC
- NAC should be given as early as possible, but may still be of value 48 hours or more after ingestion 1.
- NAC may be given orally (140 mg/kg by mouth or nasogastric tube diluted to 5% solution, followed by 70 mg/kg by mouth q 4 h 17 doses) and has few side effects (occasional nausea, vomiting, rare urticaria or bronchospasm) 1.
From the Research
Morphine and Paracetamol Overdose
- There is no direct evidence in the provided studies that morphine is contraindicated in paracetamol overdose 2, 3, 4, 5.
- The studies primarily focus on the use of N-acetylcysteine (NAC) as an antidote for acetaminophen (paracetamol) overdose 2, 3, 4, 5.
- One study compares intravenous morphine and paracetamol for managing pain in patients with isolated limb trauma, but it does not discuss the use of morphine in paracetamol overdose 6.
- The provided studies do not address the specific question of whether morphine is contraindicated in paracetamol overdose, suggesting that there may not be sufficient evidence to provide a definitive answer.