Opioid toxicity

Question 1

Naloxone

Common indications

Answer 1

1. Treatment of opioid toxicity associated with respiratory and or neurological depression

Question 2

Naloxone

MOA

Answer 2

• Naloxone binds to opioid receptors (particularly the pharmacologically-important opioid u-receptors), where it acts as a competitive antagonist
• It has little to no effect in the absence of exogenous opioids
• However, if an opioid agonist naloxone displaces it from the receptors and in doing so, it reverses its effect
• In opioid toxicity, this is used to restore an adequate level of consciousness and respiratory rate

Question 3

Naloxone

Adverse effect

Answer 3

• Where naloxone is administered to reverse opioid toxicity in an opioid-dependant individual, an opioid withdrawal reaction may be precipitated
• This presents with pain (if the opioid was being taken for its analgesic effect), restlessness, N&V, dilated pupils and cold, dry and piloerection (Cold turkey)
• Naloxone has no other significant adverse effect

Question 4

Naloxone

Warnings

Answer 4

• There are no specific contraindications to the use of naloxone
• However caution should be exercised in patients who may have developed opioid dependence because of the risk of precipitating withdrawal
• Lower doses should be used in palliative care to reduce the risk of complete reversal of analgesia

Question 5

Naloxone

Interactions

Answer 5

• Naloxone has no clinically important drug interactions other that its interaction with opioids which is central to it’s pharmacological effect and practical use

Question 6

Naloxone

Administration

Answer 6

• 200-400mcg IV every 2-3 minutes, until satisfactory reversal achieved
• In patients who develop opioid toxicity in the context of chronic use (or palliative care), smaller incremental doses should be used