methorphan methorphan methorphan comes in two isomeric forms, each with differing pharmacology and effects: dextromethorphan - an over-the-counter cough suppressant, as well as dissociative hallucinogen. levomethorphan - a potent opioid analgesic that was never clinically developed; a prodrug of the powerful opioid agonist analgesic levorphanol (levo-dromoran). racemethorphan levomethorphan (l), dextromethorphan (r)clinical dataatc codenonelegal statuslegal status au: s9 (prohibited substance) ca: schedule i de: anlage i (authorized scientific use only) uk: class a us: schedule ii un: psychotropic schedule i identifiers iupac name 3-methoxy-17-methylmorphinan cas number510-53-2 npubchem cid3008chemspider2901 nunii8yb8f78wm1chebichebi:146177chemblchembl22207 nchemical and physical dataformulac18h25nomolar mass271.404 g·mol−13d model (jsmol)interactive image smiles cn1ccc23ccccc2c1cc4=c3c=c(c=c4)oc 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 nkey:mkxzasyaugddcj-uhfffaoysa-n n ny (what is this?) (verify) racemethorphan is the racemic mixture of both of these stereoisomers. it is listed under the single convention on narcotic drugs 1961 and is therefore listed in the united states as a controlled substance, specifically as a narcotic in schedule ii with an acscn of 9732 and an annual aggregate manufacturing quota of 3 grams in 2014. the salts in use are the hydrobromide (free base conversion ratio 0.770) and the tartrate (0.644)