Some Useful Things I Didn’t Know About Opioids

From a talk on sedating the critical patient by Dr H. Nicole Trenholme

• The nausea that we see with pure mu opioids is WORSE when they’re given intramuscularly. Hydromorphone specifically, when given IM, is much more likely to induce vomiting than when it is given IV. (Also useful to know for when you DO want to make them vomit.) 

• Pure mu opioids decrease urine production by causing increased ADH production. They can also cause urinary retention by reducing elimination. Useful to keep in mind for that hospital patient that just won’t pee.

• You know that you can fully reverse an opioid with naloxone or naltrexone, but keep in mind that this will also remove any analgesia associated with the opioid. And if you don’t have naloxone and you need to reduce the effect of your full mu you can achieve partial reversal with low doses of butorphanol (0.05-0.1 mg/kg) or buprenorphine.

• On the topic of the partials: buprenorphine binds stronger to the receptor than pure mu agonists or mu antagonists, meaning that they are more challenging to reverse if adverse events occur, or to over-ride if the patient needs stronger analgesia through mu receptor agonism. 

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