Not to be confused with Dextromethorphan, Dextrorphan, or 3-Methoxymorphinan.
Clinical data
ATC code None
Legal status
Legal status
Pharmacokinetic data
Biological half-life 3-6 hours
CAS Number 125-70-2 N
PubChem (CID) 5362449
ChemSpider 4642423 YesY
Chemical and physical data
Formula C18H25NO
Molar mass 271.397 g/mol
3D model (Jmol) Interactive image
 NYesY (what is this?)  (verify)

Levomethorphan (INN, BAN) is an opioid analgesic of the morphinan family that has never been marketed.[1] It is the L-stereoisomer of racemethorphan (methorphan).[1] 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.[2]

Levomethorphan is a prodrug to levorphanol, analogously to DXM acting as a prodrug to dextrorphan or codeine behaving as a prodrug to morphine.[3] 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.[3] As a prodrug of levorphanol, levomethorphan functions as a potent agonist of all three of the opioid receptors, μ, κ1 and κ3 but notably not κ2), and δ, as an NMDA receptor antagonist, and as a serotonin-norepinephrine reuptake inhibitor.[3] Via activation of the KOR, levomethorphan can produce dysphoria and psychotomimetic effects such as dissociation and hallucinations.[4]

Levomethorphan is listed under the Single Convention on Narcotic Drugs 1961 and is regulated like morphine in most countries. In the United States it is a Schedule II Narcotic controlled substance with a DEA ACSCN of 9210 and 2014 annual aggregate manufacturing quota of 195 grammes, up from 6 grammes the year before. The salts in use are the tartrate (free base conversion ratio 0.644) and hydrobromide (0.958).[5] At the current time, no levomethorphan pharmaceuticals are marketed in the United States.

See also


  1. 1 2 J. Elks (14 November 2014). The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. pp. 656–. ISBN 978-1-4757-2085-3.
  2. Joseph M. Hornback (31 January 2005). Organic Chemistry. Cengage Learning. pp. 243–. ISBN 0-534-38951-1.
  3. 1 2 3 Gudin, Jeffrey; Fudin, Jeffrey; Nalamachu, Srinivas (2015). "Levorphanol use: past, present and future". Postgraduate Medicine. 128 (1): 46–53. doi:10.1080/00325481.2016.1128308. ISSN 0032-5481.
  4. Eduardo D. Bruera; Russell K. Portenoy (12 October 2009). Cancer Pain: Assessment and Management. Cambridge University Press. pp. 215–. ISBN 978-0-521-87927-9.
  5. http://www.deadiversion.usdoj.gov/quotas/conv_factor/index.html

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