NBME 22 Naloxone (NBME Answers)

Retired NBME 22 Answers

nbme22/Block 1/Question#5 (reveal difficulty score)
A 10-month-old girl is brought to the ...
Naloxone 🔍 / 📺 / 🌳 / 📖
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submitted by ∗d_holles(218)

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This question confused me bc I thought loperamide could not cross the BBB and therefore could not cause respiratory depression (mu-opioid agonism at the brainstem results in CNS/respiratory depression, 1). But @dr.xx is correct in noting that ↓ RR and CNS depression in the Pt should call for an mu-opioid antagonist rather than bethanchol (cholinomimetic) to treat constipation.

https://anesthesiology.pubs.asahq.org/article.aspx?articleid=2675905

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nwinkelmann http://medresearch.in/index.php/IJPR/article/view/782/1271 This explains a case in an infant. "Respiratory depression and coma after overdosage have been shown to be reversible by injection of naloxone [6]. Owing to its structural similarity to opioid, loperamide toxicity can be reversed by using Nalaxone which is a specific opioid antagonist acts competitively at opioid receptors. Naloxone hydrochloride is usually given intravenously for a rapid onset of action which occurs within 2 minutes." +4

yb_26 FA 2019: "Loperamide has poor CNS penetration" - so it still penetrates => can cause respiratory depression +5

whoissaad Also maybe because the blood brain barrier in a baby is not developed as well as in an adult. +5

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submitted by ∗pingra(6)

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I looked at it this way:

A ten month girl receiving adult doses of a mu agonist (which has POOR CNS penetration not zero) could probably have some adverse effects

I then read that the kid has a decreased RR (10/min) and marked abdominal dissension (prob due to the fact that opioids slow peristalsis; sketchy pharm also says opioids can lead to biliary colic)

Figured naloxone would reverse these symptoms

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submitted by ∗syoung07(58)

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Loperamide is a Mu opioid agonist that can be used to tx diarrhea. It doesn't cross the BBB so theres no chance of addiction but you can still see the effects of opioid overdose I believe. So tx opioid overdose with naloxone.

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submitted by ∗dr.xx(176)

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Normal respiratory rate for a 10 month old > 50 breaths per minute.

Naloxone should be given in the presence of respiratory depression and may require repeated dosing.

https://www.ncbi.nlm.nih.gov/pubmed/28506439

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