Levomethorphan

Levomethorphan
Clinical data


ATC code	None
Legal status
Legal status	AU: S9 (Prohibited) CA: Schedule I DE: Anlage I (Controlled) UK: Class A US: Schedule II
Pharmacokinetic data
Biological half-life	3-6 hours
Identifiers
IUPAC name (1R,9R,10R)-4-methoxy-17-methyl-17-azatetracyclo[7.5.3.0¹,¹⁰.0²,⁷]heptadeca-2(7),3,5-triene
CAS Number	125-70-2^N
PubChem (CID)	5362449
ChemSpider	4642423^Y
UNII	7ZZ22K9QE6^Y
ChEMBL	CHEMBL1908323^N
Chemical and physical data
Formula	C₁₈H₂₅NO
Molar mass	271.397 g/mol
3D model (Jmol)	Interactive image
SMILES COc1ccc2C[C@@H]3[C@@H]4CCCC[C@]4(CCN3C)c2c1
InChI InChI=1S/C18H25NO/c1-19-10-9-18-8-4-3-5-15(18)17(19)11-13-6-7-14(20-2)12-16(13)18/h6-7,12,15,17H,3-5,8-11H2,1-2H3/t15-,17+,18+/m0/s1^Y Key:MKXZASYAUGDDCJ-CGTJXYLNSA-N^Y
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Levomethorphan (INN, BAN) is an opioid analgesic of the morphinan family that has never been marketed. It is the L-stereoisomer of racemethorphan (methorphan). The effects of the two isomers of the racemethorphan are quite different, with dextromethorphan (DXM) contrarily being an antitussive at low doses and a dissociative hallucinogen at much higher doses. It is about five times stronger than morphine.

Levomethorphan is a prodrug to levorphanol, analogously to DXM acting as a prodrug to dextrorphan or codeine behaving as a prodrug to morphine. As such, levomethorphan has similar effects to levorphanol but is less potent as it must be demethylated to the active form by liver enzymes before being able to produce its effects. As a prodrug of levorphanol, levomethorphan functions as a potent agonist of all three of the opioid receptors, μ, κ (κ₁ and κ₃ but notably not κ₂), and δ, as an NMDA receptor antagonist, and as a serotonin-norepinephrine reuptake inhibitor. Via activation of the KOR, levomethorphan can produce dysphoria and psychotomimetic effects such as dissociation and hallucinations.