Naltrexone

Athanor · official

C₂₀H₂₃NO₄ · 341.4 g/mol

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

Also called Revia, Vivitrol, opioid antagonist, alcohol use disorder

Drugs

Open in Athanor

Drawn from its SMILES with RDKit

DangerHarmful if swallowed · Harmful in contact with skin · May cause an allergic skin reaction · Harmful if inhaled · May cause allergy or asthma symptoms or breathing difficulties if inhaled · Suspected of causing genetic defects · Very toxic to aquatic life

Names and identifiers

IUPAC name: (4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a,9-dihydroxy-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one
Synonyms: Revia, Vivitrol, opioid antagonist
+ 38 more
alcohol use disorder, Vivitrex, Celupan, Naltrexona, N-Cyclopropylmethylnoroxymorphone, Naltrexonum, Nemexin, N-Cyclopropylmethyl-14-hydroxydihydromorphinone, DTXSID4046313, 17-(Cyclopropylmethyl)-4,5alpha-epoxy-3,14-dihydroxymorphinan-6-one, 17-(Cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxymorphinan-6-one, UM-792, 5S6W795CQM, CHEBI:7465, EN-1639A FREE BASE, (4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a,9-dihydroxy-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one, NSC-758439, DTXCID2026313, Nalorex, Morphinan-6-one, 17-(cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxy-, (5alpha)-, (1S,5R,13R,17S)-4-(cyclopropylmethyl)-10,17-dihydroxy-12-oxa-4-azapentacyclo[9.6.1.0^{1,13}.0^{5,17}.0^{7,18}]octadeca-7(18),8,10-trien-14-one, Adepend, Opizone, Trexal, (1S,5R,13R,17S)-4-(cyclopropylmethyl)-10,17-dihydroxy-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)-3-(Cyclopropylmethyl)-4a,9-dihydroxy-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro(3,2-e)isoquinolin-7-one, RefChem:56739, EN1639A, N07BB04, (1S,5R,13R,17S)-4-(cyclopropylmethyl)-10,17-dihydroxy-12-oxa-4-azapentacyclo(9.6.1.01,13.05,17.07,18)octadeca-7(18),8,10-trien-14-one, 240-649-9, ReVia, (-)-Naltrexone, Naltrexonum [INN-Latin], (4R,4As,7aR)-3-(cyclopropylmethyl)-4a,9-dihydroxy-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one, Naltrexona [INN-Spanish], Naltrexone (1.0 mg/mL in Methanol), Morphinan-6-one, 17-(cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxy-, (5.alpha.)-
Molecular formula: C₂₀H₂₃NO₄
Empirical formula: C₂₀H₂₃NO₄
Molecular weight: 341.4 g/mol
Exact mass: 341.16271
CAS number: 16590-41-3
PubChem CID: 5360515
Canonical SMILES: C1CC1CN2CCC34C5C(=O)CCC3(C2CC6=C4C(=C(C=C6)O)O5)O
Isomeric SMILES: C1CC1CN2CC[C@]34[C@@H]5C(=O)CC[C@]3([C@H]2CC6=C4C(=C(C=C6)O)O5)O
InChI: InChI=1S/C20H23NO4/c22-13-4-3-12-9-15-20(24)6-5-14(23)18-19(20,16(12)17(13)25-18)7-8-21(15)10-11-1-2-11/h3-4,11,15,18,22,24H,1-2,5-10H2/t15-,18+,19+,20-/m1/s1
InChIKey: DQCKKXVULJGBQN-XFWGSAIBSA-N
Molfile

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

Physical properties

Solubility in water: Solubility of 100 mg/mL in water at 25 °C (naltrexone hydrochloride)[1]
log P: log Kow = 1.92[1]
pKa: pKa1 (for the proton on the nitrogen) = 8.38[1]
2 values
Only one source reports it.
Value As written Source
–shown pKa1 (for the proton on the nitrogen) = 8.38 [1] Hazardous Substances Data Bank (HSDB)cites PMID:239235 Kaufmann JJ et al; J Med Chem 18: 647-55 (1975)
– pKa2 (for the phenolic hydrogen) = 9.93, at 20 °C /Naltrexone hydrochloride/ [1] Hazardous Substances Data Bank (HSDB)cites PMID:239235 Kaufmann JJ et al; J Med Chem 18: 647-55 (1975)

Value	As written	Source
–shown	pKa1 (for the proton on the nitrogen) = 8.38	[1] Hazardous Substances Data Bank (HSDB)cites PMID:239235 Kaufmann JJ et al; J Med Chem 18: 647-55 (1975)
–	pKa2 (for the phenolic hydrogen) = 9.93, at 20 °C /Naltrexone hydrochloride/	[1] Hazardous Substances Data Bank (HSDB)cites PMID:239235 Kaufmann JJ et al; J Med Chem 18: 647-55 (1975)

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: 25
Rings: 6
Aromatic rings: 1
Fraction sp³ carbons (Fsp3): 0.65
H-bond donors: 2
H-bond acceptors: 5
Rotatable bonds: 2
TPSA (Å²): 70
Formal charge: 0
XLogP3: 1.9 PubChem
Complexity: 621 PubChem
Stereocenters: 4 definedCIP: C8: S · C9: R · C18: R · C19: 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

C70.36%
H6.79%
N4.10%
O18.74%

Isotope pattern

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: 1.53 Crippen (Wildman and Crippen 1999)
log S (water solubility): -2.96 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 5.07 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 341.41
log P ≤ 5 (Crippen): 1.53
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: 76 company reports to ECHA. Source [2].

Harmful or irritant
Health hazard
Environmental hazard

H302Harmful if swallowed (50% of reports)
H312Harmful in contact with skin (23.7% of reports)
H317May cause an allergic skin reaction (35.5% of reports)
H332Harmful if inhaled (26.3% of reports)
H334May cause allergy or asthma symptoms or breathing difficulties if inhaled (23.7% of reports)
H341Suspected of causing genetic defects (11.8% of reports)
H400Very toxic to aquatic life (50% of reports)

Precautionary statements: P203, P233, P260, P261, P264, P270, P271, P272, P273, P280, P284, P301+P317, P302+P352, P304+P340, P317, P318, P321, P330, P333+P317, P342+P316, P362+P364, P391, P403, P405, P501

View all classifications (2)

[2] European Chemicals Agency (ECHA) · 76 reports · DangerH302, H312, H317, H332, H334, H341, H400
[1] Hazardous Substances Data Bank (HSDB) · WarningH302

Storage

Keep container tightly closed in a dry and well-ventilated place. Recommended storage temperature 2 - 8 °C. Light sensitive. Keep in a dry place. (naltrexone hydrochloride)[1]
Naltrexone hydrochloride tablets should be stored in well-closed containers at 15-30 °C.[1]
The entire dose pack containing naltrexone for extended-release injectable suspension should be refrigerated at 2-8 °C; the dose pack can be stored at room temperature (ie, room temperatures not exceeding 25 °C) for up to 7 days. Storage at temperatures above 25 °C or freezing should be avoided.[1]
Store in a tightly sealed container, protected from light, and at room temperature.[1]

Incompatibilities

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

Data last updated 2026-10-14.