Naloxone

This is a specific opioid antagonist.The elimination half-life is 60–90 min, with a duration of action between 30 and 45 min.

Uses
Reversal of opioid adverse effects – respiratory depression, sedation, pruritus and urinary retention As a diagnostic test of opioid overdose in an unconscious patient

Contraindications
Patients physically dependent on opioids

Administration
• Reversal of opioid overdose: 200 μg IV bolus, repeat every 2–3 min until desired response, up to a total of 2mg
• Infusion may be required in patients with renal impairment or those who had taken longacting opioids, e.g. MST
• Reversal of spinal opioid-induced pruritus: dilute 200 μg in 10 ml

WFI. Give 20-μg boluses every 5 min until symptoms resolve Titrate dose carefully in postoperative patients to avoid sudden return
of severe pain

How not to use naloxone
Large doses given quickly

Adverse effects
Arrhythmias
Hypertension

Cautions
Withdrawal reactions in patients on long-term opioid for medical reasons or in addicts
Postoperative patients – return of pain and severe haemodynamic disturbances (hypertension,VT/VF, pulmonary oedema)

Organ failure
Hepatic: delayed elimination