moleculefinder

Naloxone

C19H21NO4327.4 g/mol Calculated

Also called N-Allyl-noroxymorphone and n-Allylnoroxymorphone.

The opioid antagonist sold as Narcan, which reverses an opioid overdose in minutes and is now sold over the counter in the United States.

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

Sold over the counter, without a prescription. Naloxone on the product labels we hold.

Medicines

NarcanAdded by the makerActive ingredient, 4 mg
SuboxoneAdded 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
C19H21NO4
Molecular weight
327.4 g/mol
XLogP3octanol/water, log units
2.1
Polar surface areatopological
70 Ų
H-bond donors
2
H-bond acceptors
5
Rotatable bonds
2
Complexity
594

Measured LD50, HSDB via PubChem

90 mg/kg pure naloxone, mouse, intravenous

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

Reported Hazard label (GHS), ECHA via PubChem

Danger Corrosive pictogram (GHS05) and Irritant pictogram (GHS07); hazard statements H302, H315, H318, H319, H335

Reported Licence

The US Food and Drug Administration licenses Naloxone for human use (NDA 208411, authorized November 18, 2015). Drugs@FDA

Groups it belongs to

Category
OTC medicine
Chemical groups
Alcohols, Aromatics, Ketones, Phenols, Ethers
Elements
Nitrogen
Hazard classes
Corrosive, Irritant, GHS Danger
SMILESC=CCN1CC[C@]23[C@@H]4C(=O)CC[C@]2([C@H]1CC5=C3C(=C(C=C5)O)O4)O

PubChem CID 5284596 · Wikidata Q282902 · InChIKey UZHSEJADLWPNLE-GRGSLBFTSA-N · Data refreshed

How MoleculeFinder sources and labels its data

Questions
What is Naloxone?
The opioid antagonist sold as Narcan, which reverses an opioid overdose in minutes and is now sold over the counter in the United States.
How toxic is Naloxone?
The reported LD50 of Naloxone is 90 mg/kg (mouse, iv). 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 Corrosive and Irritant. from sourcefrom source
What kind of molecule is Naloxone?
Naloxone has the formula C19H21NO4 and a molecular weight of 327.4 g/mol. MoleculeFinder files it under opioid antagonist, in the OTC medicine group. from sourcefrom sourcefrom sourcefrom source
Who licenses Naloxone as a medicine?
The US Food and Drug Administration licenses Naloxone for human use (NDA 208411, authorized November 18, 2015). 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: rat, intravenous, 107 mg/kg; rat, another route, 239 mg/kg; mouse, another route, 286 mg/kg; rat, another route, 500 mg/kg. The page shows the one LD50 the site uses everywhere.
  • Hazard labelfrom sourceECHA 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 naloxoneNaltrexoneC20H23NO4Both carry an alcohol, an ether and a ketone group.OxycodoneC18H21NO4Both carry a phenol, an ether and a ketone group.HydromorphoneC17H19NO3Both carry a phenol, an alcohol and an ether group.BuprenorphineC29H41NO4
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