levomethorphan levomethorphan levomethorphan (lvm) (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 racemethorphan are quite different, with dextromethorphan (dxm) being an antitussive at low doses and a dissociative hallucinogen at much higher doses. levomethorphan is about five times stronger than morphine. not to be confused with dextromethorphan, dextrorphan, or 3-methoxymorphinan. levomethorphanclinical dataatc codenonelegal statuslegal status au: s9 (prohibited substance) ca: schedule i de: anlage i (authorized scientific use only) uk: class a us: schedule ii pharmacokinetic dataelimination half-life3-6 hoursidentifiers iupac name (1r,9r,10r)-4-methoxy-17-methyl-17-azatetracycloheptadeca-2(7),3,5-triene cas number125-70-2 npubchem cid5362449chemspider4642423 yunii7zz22k9qe6chebichebi:146176 nchemblchembl1908323 ncomptox dashboard (epa)dtxsid20872403 echa infocard100.004.320 chemical and physical dataformulac18h25nomolar mass271.404 g·mol−13d model (jsmol)interactive image smiles coc1ccc2c34cccc4(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 ykey:mkxzasyaugddcj-cgtjxylnsa-n y ny (what is this?) (verify) 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 kappa opioid receptor, levomethorphan can produce dysphoria and psychotomimetic effects such as dissociation and hallucinations. 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 a 2014 annual aggregate manufacturing quota of 195 grams, up from 6 grams the year before. the salts in use are the tartrate (free base conversion ratio 0.644) and hydrobromide (0.958). at the current time, no levomethorphan pharmaceuticals are marketed in the united states.