moleculefinder

Naltrexone

C20H23NO4341.4 g/mol Calculated

Also called Celupan, Nemexin, Vivitrex and Vivitrol.

An opioid antagonist used in alcohol and opioid use disorder. It occupies the same receptors opioids use and blocks them for a day at a time.

Sources and notes
  • The introductionfrom sourceMoleculeFinder curated
  • Other namesfrom sourcePubChem / Wikidata
  • Formula and weightcomputedPubChem
  • 2D drawingcomputedPubChem structure, drawn by RDKit
  • 3D modelfrom sourcePubChem 3D conformerLoaded after the page has painted, and on a phone only when you ask for it; the 2D drawing shows until it arrives.

Where you encounter it

Dispensed on prescription, not sold on a shelf. Naltrexone on the product labels we hold.

Medicines

VivitrolAdded by the makerActive ingredient

Every product and list we hold

Sources and notes
  • The product labels and their strengthsfrom sourceDailyMed (FDA label)Each label lists the molecule as an ingredient, and an active ingredient at the strength shown.
  • How it gets therefrom sourceMoleculeFinder curatedEach mark is set by hand on our lists, never inferred; a label's ingredient is added by the maker. A row with no mark data says Not marked.
  • The line abovefrom sourceMoleculeFinder curatedFrom the group the molecule belongs to.

Explore its structure

Choose a part to light it up.

A C=O with a carbon on each side. Its oxygen accepts hydrogen bonds but has no hydrogen to give, and it resists oxidation better than an aldehyde.

From: standard chemistry.

Sources and notes
  • The drawingcomputedPubChem structure, drawn by RDKitThe page's one shipped drawing, with the chosen part lit in amber under it.
  • The partscomputedFound by ruleEach part is found by a chemical pattern, never picked by hand atom by atom; its words say where they come from.

Compare a related molecule

Naloxone

Naltrexone

Naloxone reverses an opioid overdose within minutes, while naltrexone survives the gut and lasts many hours; both block the same opioid receptor.

Naloxone vs Naltrexone, side by side
Sources and notes
  • The sentencefrom sourceMoleculeFinder comparison notesThe pair's answer line.
  • The two drawingscomputedPubChem structures, drawn by RDKitThe two drawings side by side.

Properties and sources

Calculated by PubChem

Molecular formula
C20H23NO4
Molecular weight
341.4 g/mol
XLogP3octanol/water, log units
1.9
Polar surface areatopological
70 Ų
H-bond donors
2
H-bond acceptors
5
Rotatable bonds
2
Complexity
621

Measured LD50, HSDB via PubChem

1,450 mg/kg pure naltrexone, rat, oral

An LD50 is an animal study measurement, not a dose for a person.

Reported Hazard label (GHS), ECHA, HSDB via PubChem

Danger Irritant pictogram (GHS07), Health hazard pictogram (GHS08) and Environmental pictogram (GHS09); hazard statements H302, H312, H317, H332, H334, H341, H400

Reported Licence

The US Food and Drug Administration licenses Naltrexone for human use (NDA 021897, authorized April 13, 2006), as Vivitrol. Drugs@FDA

Groups it belongs to

Category
Prescription medicine
Chemical groups
Alcohols, Aromatics, Ketones, Phenols, Ethers
Elements
Nitrogen
Hazard classes
Irritant, Health hazard, Environmental hazard, GHS Danger
SMILESC1CC1CN2CC[C@]34[C@@H]5C(=O)CC[C@]3([C@H]2CC6=C4C(=C(C=C6)O)O5)O

PubChem CID 5360515 · Wikidata Q409587 · InChIKey DQCKKXVULJGBQN-XFWGSAIBSA-N · Data refreshed

How MoleculeFinder sources and labels its data

Questions
What is Naltrexone?
An opioid antagonist used in alcohol and opioid use disorder. It occupies the same receptors opioids use and blocks them for a day at a time.
How toxic is Naltrexone?
The reported LD50 of Naltrexone is 1,450 mg/kg (rat, oral). An LD50 is an animal study measurement, not a dose for a person. Its GHS hazard label carries the signal word Danger and the hazard pictograms Irritant, Health hazard and Environmental. from sourcefrom source
What kind of molecule is Naltrexone?
Naltrexone has the formula C20H23NO4 and a molecular weight of 341.4 g/mol. MoleculeFinder files it under opioid antagonist, in the prescription medicine group. from sourcefrom sourcefrom sourcefrom source
Who licenses Naltrexone as a medicine?
The US Food and Drug Administration licenses Naltrexone for human use (NDA 021897, authorized April 13, 2006), as Vivitrol. from source
Sources and notes
  • Calculated valuescomputedPubChemComputed from the structure, so no laboratory conditions apply; complexity is PubChem's own structural score.
  • LD50from sourceHSDB via PubChemOther values the sources report: guinea pig, oral, 1,490 mg/kg; monkey, oral, 3,000 mg/kg. The page shows the one LD50 the site uses everywhere.
  • Hazard labelfrom sourceECHA, HSDB via PubChemThe label combines these classifications.
  • ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
  • Licencefrom sourceDrugs@FDARead 2026-10-21.
  • Data refreshedfrom sourceMoleculeFinder2026-11-09

Keep exploring

Compared side by side with naltrexoneNaloxoneC19H21NO4Both carry an alcohol, an ether and a ketone group.OxycodoneC18H21NO4Both carry a phenol, an alcohol and an ether group.BuprenorphineC29H41NO4Both carry a phenol, an ether and a ketone group.HydromorphoneC17H19NO3
Sources and notes
  • Compared side by sidefrom sourceMoleculeFinder comparison notesA molecule we compare it with on its own page.
  • Similar in shapecomputedRDKit Morgan/TanimotoNeighbours by structural fingerprint; the sentence names the chemical groups the two share.
  • The drawingscomputedPubChem structures, drawn by RDKit