Naloxone

Question 1

What is the generic name of naloxone?

Answer 1

Naloxone hydrochloride dihydrate

Question 2

What type of medication is naloxone?

Answer 2

An Opioid antagonist

Question 3

What is the mechanism of action of naloxone?

Answer 3

• Reverses the following symptoms caused by opioid analgesics:
  
  • Respiratory depression
  • Sedation
  • Hypotension

Naloxone antagonizes the opioid effects by competing for the same opioid receptor sites (mu, kappa and gamma). The strongest binding is to the mu-opioid receptors.

The exact mechanism of action is not fully understood.

Question 4

What are the adverse effects of naloxone?

Answer 4

• Opioid withdrawl (nausea, vomiting, sweating, tachycardia, hypertension & combative behaviour)
• Pulmonary oedema in patients with pre-existing cardiac disease
• Dysrhythmias (VF, VT)

Question 5

What are the contraindications of naloxone?

Answer 5

Cannot be given to neonates born to opioid addicted mothers due to risk of inducing opioid withdrawl

Question 6

What is the preparation and dosage of naloxone?

Answer 6

• Preparation: 400mcg (1mL) ampoule
  
  • Dilution: 400mcg (1mL) ampoule diluted to 4mL with 3mL NaCl (100mcg:1mL)
• Dose (opioid overdose)
  
  • <16yo: 5mcg/kg diluted bolus (max 100mcg)
    
    • Repeat: 2min
    • Max Total Dose: 2mg
  • 16+yo:
    
    • IM: 400mcg undiluted bolus
      
      • Repeat: 2min
      • Max Total Dose: 2mg
    • IV: 100mcg diluted bolus
      
      • Repeat: 2min
      • Max Total Dose: 2mg
• Dose (Etorphine or Buprenorphine overdose)
  
  • <16yo: 10mcg/kg diluted bolus (max 2mg)
    
    • Repeat: 5min
    • Max Total Dose: Nil max
  • 16+yo: 2mg undiluted bolus
    
    • Repeat: 5min
    • Max Total Dose: Nil max

Notes:

• Opioid effects may exceed that of naloxone and renarcotisation is possible. Therefore repeat doses may be required.
• Hypoventilating newborns, due to maternal opiate use, will be hypercapnoeic and naloxone may provoke dysrhythmias, seizures and pulmonary oedema.