1. Pharmacology
        1.2. Analgesia
            1.2.1. Opioids
1.2.1.2. Opioid antagonist

Opioid antagonist

[Ref: SH(4)2:p114]

Naloxone

Nonselective antagonist
* Acts on all 3 opioid receptors

Pharmacokinetics

Short duration of action = 30-45 minutes
--> May require repeated doses

Clinical uses

Dosage

1-4 microgram/kg IV
--> Reverses opioid-induced analgesia and depression of ventilation

Neuraxial opioid

Continuous infusion of 5 microgram/kg/hour IV
--> Prevents depression of ventilation without altering analgesia due to neuraxial opioid

Side effect

Naltrexone

Highly effective orally
* Unlike naloxone (which is short-acting)
* Sustained antagonism for up to 24 hours

Used to treat addicts

Nalmefene

Pure opioid antagonist

Equipotent to naloxone

Longer duration than naloxone
--> Better protection for ventilatory depression

Opioid agonist-antagonists

[Ref: SH(H)2:p111]

Opioid agonist-antagonists bind to mu receptors
--> Limited response or no effect

 

 

Side effect profile is similar to opioid agonist, except:



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