Systematic (IUPAC) name
(1S,5R,13R,17S)- 10,17-dihydroxy- 4-(prop-2-en-1-yl)- 12-oxa- 4-azapentacyclo [,13.05,17.07,18] octadeca- 7(18),8,10-trien- 14-one
Clinical data
AHFS/ monograph
Pregnancy cat. B (USA)
B1 (Aus)
Legal status Prescription Only (S4) (AU)
Routes IV, IM
Pharmacokinetic data
Bioavailability 2% (90% absorption but high first-pass metabolism)
Metabolism Liver
Half-life 1-1.5 h
Excretion Urine, Biliary
CAS number 465-65-6 YesY
ATC code V03AB15
PubChem CID 5284596
DrugBank DB01183
ChemSpider 4447644 YesY
KEGG D08249 YesY
Synonyms 17-allyl- 4,5α-epoxy- 3,14-dihydroxymorphinan- 6-one
Chemical data
Formula C19H21NO4 
Mol. mass 327.37 g/mol
SMILES eMolecules & PubChem
 N(what is this?)  (verify)

Naloxone is an opioid antagonist drug developed by Sankyo in the 1960s.[1] Naloxone is a drug used to counter the effects of opiate overdose, for example heroin or morphine overdose. Naloxone is specifically used to counteract life-threatening depression of the central nervous system and respiratory system. Naloxone is also experimentally used in the treatment for congenital insensitivity to pain with anhidrosis (CIPA), an extremely rare disorder (1 in 125 million) that renders one unable to feel pain. It is marketed under various trademarks including Narcan, Nalone, and Narcanti, and has sometimes been mistakenly called "naltrexate." It is not to be confused with naltrexone, an opioid receptor antagonist with qualitatively different effects, used for dependence treatment rather than emergency overdose treatment.



Naloxone has an extremely high affinity for μ-opioid receptors in the central nervous system. Naloxone is a μ-opioid receptor competitive antagonist, and its rapid blockade of those receptors often produces rapid onset of withdrawal symptoms. Naloxone also has an antagonist action, though with a lower affinity, at κ- and δ-opioid receptors.


Naloxone is synthesized from thebaine. The chemical structure of naloxone resembles that of oxymorphone, the only difference being the substitution of the N-methyl group with an allyl (prop-2-enyl) group. The name naloxone has been derived from N-allyl and oxymorphone.


Naloxone is most commonly injected intravenously for fastest action. The drug generally acts within a minute, and its effects may last up to 45 minutes. It can also be administered via intramuscular or subcutaneous injection. Use of a wedge device (nasal atomizer) attached to a syringe to create a mist delivering the drug to the nasal mucosa[2] may also be utilized, although this solution is more likely utilized outside of a clinical facility.


Counteracting opiate overdose and addiction

Naloxone has been distributed as part of emergency kits to heroin users, and this has been shown to reduce rates of fatal overdose. Projects of this type are under way in San Francisco, New Mexico, Philadelphia, New York State, Baltimore, Boston, Los Angeles, Milwaukee, and Chicago, with pilot projects started in Scotland in 2006[citation needed]. Also in the UK, in December 2008 the Welsh Assembly Government announced intention to establish demonstration sites for ‘take home’ Naloxone.[3] While naloxone is still often used in emergency treatments for opioid overdose, its clinical use in the long-term treatment of opioid addiction is being increasingly superseded by naltrexone. Naltrexone is structurally similar but has a slightly increased affinity for κ-opioid receptors over naloxone, can be administered orally, and has a longer duration of action.

Enteral naloxone has been successfully used in the reduction of gastritis and esophagitis associated with opioid therapy in mechanically-ventilated acute care patients.

The combination oxycodone/naloxone is used for the prophylaxis of opioid-induced constipation in patients requiring strong opioid therapy under the trade name Targin and in the Netherlands under Targinact.[4]

Preventing opioid abuse

Naloxone is used as a secondary chemical in the drug Suboxone. Suboxone and Subutex were created to help opiate-addicted patients detox. Suboxone contains four parts buprenorphine and one part naloxone, while Subutex contains only buprenorphrine. Naloxone was added to Suboxone in an effort to dissuade patients from grinding it up for abuse in combination with opiates. Intravenously administered naloxone is supposed to block the effects of any opiates and cause the user to go into immediate withdrawal. Oral or sublingual administration affects only the gastrointestinal tract, and has the added benefit of helping to reverse constipation and lowered bowel motility caused by chronic medical use, or abuse, of a variety of opioids. Because of possible side effects of naloxone in some patients, chemical detox is often begun with Suboxone's sister drug, Subutex, which does not contain naloxone.

Depersonalization disorder

A 2001 Russian study has shown that naloxone can be used to treat depersonalization disorder. According to the study: "In three of 14 patients, depersonalization symptoms disappeared entirely and seven patients showed a marked improvement. The therapeutic effect of naloxone provides evidence for the role of the endogenous opioid system in the pathogenesis of depersonalization."[5]


Possible side effects include: change in mood, increased sweating, nausea, nervousness, restlessness, trembling, vomiting, allergic reactions such as rash or swelling, dizziness, fainting, fast or irregular pulse, flushing, headache, heart rhythm changes, seizures, sudden chest pain.[6]

Naloxone has been shown to block the action of pain-lowering endorphins which the body produces naturally. The likely reason for this is that these endorphins operate on the same opioid receptors that Naloxone blocks. Naloxone is capable of blocking a placebo pain-lowering response, both in clinical and experimental pain, if the placebo is administered together with a hidden or blind injection of naloxone.[7] Other studies have found that placebo alone can activate the body's μ-opioid endorphin system, delivering pain relief via the same receptor mechanism as morphine.[8]

Legal status

The patent for naloxone has expired. It is available in generic forms.


The CAS number of naloxone is 465-65-6; the anhydrous hydrochloride salt has CAS 357-08-4 and the hydrochloride salt with 2 molecules of water, hydrochloride dihydrate, has CAS 51481-60-8.

See also


  1. ^ US Patent 3254088 - Morphine Derivative
  2. ^ "Journal of Emergency Nursing". 
  3. ^ "IHRA 21st International Conference Liverpool, 26th April 2010 - Introducing 'take home' Naloxone in Wales". Retrieved 9 March 2011. 
  4. ^ Simpson K, et al. (2008 Dec). "Fixed-ratio combination oxycodone/naloxone compared with oxycodone alone for the relief of opioid-induced constipation in moderate-to-severe noncancer pain". Curr Med Res Opin 24 (12): 3503–3512. doi:10.1185/03007990802584454. PMID 19032132. Retrieved 2009-04-09. 
  5. ^ Nuller YL, Morozova MG, Kushnir ON, Hamper N (June 2001). "Effect of naloxone therapy on depersonalization: a pilot study". J. Psychopharmacol. (Oxford) 15 (2): 93–5. doi:10.1177/026988110101500205. PMID 11448093. 
  6. ^
  7. ^ Sauro, Marie D; Greenberg, Roger P. (Feb 2005), "Endogenous opiates and the placebo effect: A meta-analytic review", Journal of Psychosomatic Research 58 (2): 115–120, PMID 15820838, 
  8. ^

External links

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Look at other dictionaries:

  • (+)-Naloxone — Systematic (IUPAC) name (1R,5S,13S,17R) 10,17 dihydroxy 4 (prop 2 en 1 yl) 12 oxa 4 azapentacyclo [,13.05,17.07,18] octadeca 7(18),8,10 trien 14 one …   Wikipedia

  • Naloxone — Structure de la naloxone Général Nom IUPAC 17 allyl 4,5α époxy 3,14 dihydroxymorphinan 6 one …   Wikipédia en Français

  • naloxone — ☆ naloxone [nal′ək sōn΄ ] n. [< N al(lylnor)ox(ymorph)one] a white, crystalline, nonaddictive, synthetic drug, C19H21NO4·HCl, used to counteract the effects of narcotic overdoses: in full naloxone hydrochloride …   English World dictionary

  • naloxone — ● naloxone nom féminin Antidote des opiacés (substances dérivées de l opium) …   Encyclopédie Universelle

  • naloxone — noun Etymology: N allyl + hydroxy + one Date: 1964 a synthetic potent antagonist C19H21NO4 of narcotic drugs and especially morphine that is administered especially in the form of its hydrochloride …   New Collegiate Dictionary

  • naloxone — An alkaloid antagonist of morphine and of the opiate peptides …   Dictionary of molecular biology

  • naloxone — /neuh lok sohn, nal euhk sohn /, n. Pharm. a narcotic analgesic antagonist, C19H21NO4, used in the reversal of acute narcotic analgesic respiratory depression. [1960 65; by shortening and rearrangement of dihydroxy , morphinan , and one,… …   Universalium

  • naloxone — noun A drug used to counter the effects of an overdose on opioids (such as heroin or morphine) …   Wiktionary

  • naloxone — nal·ox·one nal äk .sōn, nal ək .sōn n a potent synthetic antagonist of narcotic drugs and esp. morphine that is administered in the form of its hydrochloride C19H21NO4·HCl see NARCAN * * * n. a drug that is a specific antidote to morphine and… …   Medical dictionary

  • naloxone — na·lo·xó·ne s.m. TS farm. sostanza antagonista degli stupefacenti naturali e di sintesi, priva di effetti analoghi a quelli della morfina, usata nelle intossicazioni acute da oppiacei {{line}} {{/line}} DATA: sec. XX. ETIMO: nome commerciale …   Dizionario italiano

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