Naloxone
A pure opioid antagonist given by injection or nasal spray to reverse opioid overdose and opioid-induced breathing depression.
Drug card
- Class
- Opioid antagonist
- How it works
- Blocking opioid receptors, displacing opioids and reversing their effects
- Used for
- Opioid overdose and opioid-induced breathing depression
- Add-on to raise blood pressure in septic shock
- Known for
- Sudden opioid withdrawal in dependent people
- Its name
- nal- means an opioid antagonist (naloxone type)
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does naloxone work?
Naloxone competes with opioids for mu, kappa and sigma receptor sites, binding mu most strongly, and has no agonist activity of its own. Given without opioids it does essentially nothing and causes no tolerance or dependence. Its half-life is about an hour, shorter than that of most opioids.
Uses
What is naloxone used for?
- Opioid overdose and opioid-induced breathing depression
- Add-on to raise blood pressure in septic shock
Side effects
Side effects of naloxone
- Sudden opioid withdrawal in dependent peopleKnown forSerious
- Fast heart rate
- Raised blood pressure
- Nausea and vomiting
- Ventricular arrhythmias and cardiac arrestSerious
- Fluid in the lungs (pulmonary edema)Serious
- SeizuresSerious
- Headache
- Blocked or dry nose (nasal spray)
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Most opioids outlast it, so breathing depression can come back; keep the person watched and repeat doses as needed.
- In opioid-dependent people, and newborns of dependent mothers, it can precipitate abrupt and severe withdrawal.
- Reversal of buprenorphine or pentazocine may be incomplete and need larger or repeated doses.
Good to know: The nasal spray is made for immediate emergency use wherever opioids may be present, but it does not replace emergency medical care.
Remember it
A way to remember it
Naloxone knocks opioids off the receptor, but it leaves the party first.
It outcompetes opioids at mu receptors and reverses an overdose, but its half-life is about an hour, shorter than most opioids', so breathing depression can come back.
Written for biofideX
Its name
nal- means opioid antagonist (naloxone type)
Naloxone and naltrexone block opioid receptors. Nalbuphine, also nal-, is an opioid agonist-antagonist painkiller, and nalidixic acid, an old quinolone antibacterial, fits by chance.
- Every drug name stem
Its class
Opioid antagonists
Opioid antagonists bind opioid receptors, most strongly the mu receptor, without activating them, and displace opioids by competing for the same sites. This reverses respiratory depression, sedation and low blood pressure, but it also ends pain relief and can set off sudden withdrawal in people dependent on opioids.
Easily mixed up with opioid analgesics.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Naloxone hydrochloride nasal spray: label (DailyMed)
- Naloxone hydrochloride injection: label (DailyMed)
- Naloxone (NCI Thesaurus)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Pain, fever and inflammation
Naloxone is one of 15 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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