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Naloxone

Athanor · official

C19H21NO4 · 327.4 g/mol

IUPAC name: (4R,4aS,7aR,12bS)-4a,9-dihydroxy-3-prop-2-enyl-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one

Also called Narcan, opioid antagonist, N-allylnoroxymorphone, overdose reversal

Drugs
Open in Athanor
The structure of Naloxone
Drawn from its SMILES with RDKit
CorrosiveHarmful or irritantDangerHarmful if swallowed · Causes skin irritation · Causes serious eye damage · Causes serious eye irritation · May cause respiratory irritation

Names and identifiers

IUPAC name
(4R,4aS,7aR,12bS)-4a,9-dihydroxy-3-prop-2-enyl-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one
Synonyms
Narcan, opioid antagonist, N-allylnoroxymorphone
+ 39 more

overdose reversal, l-Naloxone, (-)-Naloxone, n-Allylnoroxymorphone, Naloxona, EN 1530 base, Naloxonum, Nalossone, N-Allyl-noroxymorphone, DBL Naloxone, 1-N-Allyl-14-hydroxynordihydromorphinone, Naloxone Nasal Spray, 17-Allyl-4,5alpha-epoxy-3,14-dihydroxymorphinan-6-one, DTXSID8023349, 1-N-Allyl-7,8-dihydro-14-hydroxynormorphinone, l-N-Allyl-14-hydroxynordihydromorphinone, NSC-70413, 17-Allyl-4,5-alpha-epoxy-3,14-dihydroxymorphinan-6-one, l-N-Allyl-7,8-dihydro-14-hydroxynormorphinone, 36B82AMQ7N, CHEBI:7459, N-Allyl-4,5alpha-epoxy-3,14-dihydroxy-6-morphinanon, 12-Allyl-7,7a,8,9-tetrahydro-3,7a-dihydroxy-4aH-8,9c-iminoethanophenanthro(4,5-bcd)furanone, Morphinan-6-one, 17-allyl-4,5alpha-epoxy-3,14-dihydroxy-, Morphinan-6-one, 4,5alpha-epoxy-3,14-dihydroxy-17-(2-propenyl)-, Morphinan-6-one, 4,5-epoxy-3,14-dihydroxy-17-(2-propenyl)-, (5alpha)-, 17-allyl-3,14-dihydroxy-4,5alpha-epoxymorphinan-6-one, Normorphinone, N-allyl-7,8-dihydro-14-hydroxy-, (-)-, DTXCID703349, (4R,4aS,7aR,12bS)-4a,9-dihydroxy-3-prop-2-enyl-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one, Morphinan-6-one, 4,5-alpha-epoxy-3,14-dihydroxy-17-(2-propenyl)-, (1S,5R,13R,17S)-10,17-dihydroxy-4-(prop-2-en-1-yl)-12-oxa-4-azapentacyclo[9.6.1.0^{1,13}.0^{5,17}.0^{7,18}]octadeca-7(18),8,10-trien-14-one, Abello, Naloxone, Curamed, Naloxon, Naloxon ratiopharm, (1S,5R,13R,17S)-10,17-dihydroxy-4-(prop-2-en-1-yl)-12-oxa-4-azapentacyclo(9.6.1.0^(1,13).0^(5,17).0^(7,18))octadeca-7(18),8,10-trien-14-one, (4R,4aS,7aR,12bS)-4a,9-dihydroxy-3-prop-2-enyl-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro(3,2-e)isoquinolin-7-one, naloxoni hydrochloridum, Hydrobromide, Naloxone

Molecular formula
C19H21NO4
Empirical formula
C19H21NO4
Molecular weight
327.4 g/mol
Exact mass
327.14706
CAS number
465-65-6
PubChem CID
5284596
Canonical SMILES
C=CCN1CCC23C4C(=O)CCC2(C1CC5=C3C(=C(C=C5)O)O4)O
Isomeric SMILES
C=CCN1CC[C@]23[C@@H]4C(=O)CC[C@]2([C@H]1CC5=C3C(=C(C=C5)O)O4)O
InChI
InChI=1S/C19H21NO4/c1-2-8-20-9-7-18-15-11-3-4-12(21)16(15)24-17(18)13(22)5-6-19(18,23)14(20)10-11/h2-4,14,17,21,23H,1,5-10H2/t14-,17+,18+,19-/m1/s1
InChIKey
UZHSEJADLWPNLE-GRGSLBFTSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

log P
log Kow = 2.09[1]
pKa
pKa2 (for the phenolic hydrogen) = 9.44 (naloxone hydrochloridel)[1]

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms
24
Rings
5
Aromatic rings
1
Fraction sp³ carbons (Fsp3)
0.53
H-bond donors
2
H-bond acceptors
5
Rotatable bonds
2
TPSA (Ų)
70
Formal charge
0
XLogP3
2.1 PubChem
Complexity
594 PubChem
Stereocenters
4 definedCIP: C7: S · C8: R · C17: R · C18: S
Double-bond geometry
None specified
Point group
C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C69.71%
  • H6.47%
  • N4.28%
  • O19.55%

Isotope pattern

100%327.14721%328.1503.0%329.153330.156

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P
1.3 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-2.74 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
5.18 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 327.38
  • log P ≤ 5 (Crippen): 1.3
  • H-bond donors ≤ 5: 2
  • H-bond acceptors ≤ 10: 5

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Danger

Most widely reported: 46 company reports to ECHA. Source [2].

  • Corrosive
  • Harmful or irritant
  • H302Harmful if swallowed
  • H315Causes skin irritation (87% of reports)
  • H318Causes serious eye damage (10.9% of reports)
  • H319Causes serious eye irritation (84.8% of reports)
  • H335May cause respiratory irritation (84.8% of reports)

Precautionary statements: P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P305+P354+P338, P317, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501

Storage

  • Store at 20 deg to 25 °C (68 deg to 77 °F). Protect from light. Store in carton until contents have been used.[1]

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. [1]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
  2. [2]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
  3. [3]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  4. [4]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
  5. [5]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
  6. [6]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  7. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  8. ·Literature on PubChem

Data last updated 2026-10-14.