Pure MOP antagonist used for:
- Treatment of opioid overdose
- Reducing constipation
In combination with PO oxycodone.
|Class||μ-selective opioid receptor competitive antagonist|
|Uses||Opioid overdose, neuraxial opioid side effects (e.g. pruritus), prevention of constipation in combination with oral opioids|
|Presentation||Clear, colourless solution at 400mcg.ml-1|
|Route of Administration||IV, IM, PO|
|Dosing||0.1-0.4mg Q5min, 0.5mg.kg-1.hr-1 by infusion|
|Absorption||Very high first pass metabolism leading to ~2% PO bioavailability|
|Distribution||50% protein bound. VD 2L.kg-1, highly lipid soluble.|
|Metabolism||Rapid hepatic glucuronidation|
|Resp||Reversal of opioid-induced respiratory depression (↑ RR, ↑ VT)|
|CVS||↑ SVR & ↑ BP, arrhythmia due ↑ in SNS tone|
|CNS||↓ Analgesia, ↓ sedation, ↓ miosis. Antanalgesic in opioid naive patients. Precipitation of opioid withdrawal.|
|Other considerations||Duration of action is ~30-40 minutes is shorter than some opioids, which may lead to re-narcosis if not given subsequent doses or by infusion|
- Peck TE, Hill SA. Pharmacology for Anaesthesia and Intensive Care. 4th Ed. Cambridge University Press. 2014.
- Smith S, Scarth E, Sasada M. Drugs in Anaesthesia and Intensive Care. 4th Ed. Oxford University Press. 2011.