nalorphine nalorphine nalorphine (inn) (brand names lethidrone, nalline), also known as n-allylnormorphine, is a mixed opioid agonist–antagonist with opioid antagonist and analgesic properties. it was introduced in 1954 and was used as an antidote to reverse opioid overdose and in a challenge test to determine opioid dependence. not to be confused with nalbuphine. nalorphineclinical datatrade nameslethidrone, nallineother namesn-allylnormorphineahfs/drugs.cominternational drug namesatc codev03ab02 (who) legal statuslegal status au: s4 (prescription only) ca: schedule i us: schedule iii identifiers iupac name 17-allyl-7,8-didehydro-4,5α-epoxymorphinan-3,6α-diol cas number62-67-9 ypubchem cid5284595iuphar/bps1629drugbankdb11490 ychemspider4447643 yuniiu59wb2wry2keggd08247chebichebi:7458chemblchembl415284 ycomptox dashboard (epa)dtxsid3023348 echa infocard100.000.497 chemical and physical dataformulac19h21no3molar mass311.381 g·mol−13d model (jsmol)interactive image smiles o2\c=c/54n(cc51c3c(o12)c(o)ccc3c4)c\c=c inchi inchi=1s/c19h21no3/c1-2-8-20-9-7-19-12-4-6-15(22)18(19)23-17-14(21)5-3-11(16(17)19)10-13(12)20/h2-6,12-13,15,18,21-22h,1,7-10h2/t12-,13+,15-,18-,19-/m0/s1 ykey:uiqmveyfgzjhcz-sstwwwiqsa-n y (verify) nalorphine was the second opioid antagonist to be introduced, preceded by nalodeine (n-allylnorcodeine) in 1915 and followed by naloxone in 1960 and naltrexone in 1963. due to potent activation of the κ-opioid receptor, nalorphine produces side effects such as dysphoria, anxiety, confusion, and hallucinations, and for this reason, is no longer used medically. pharmacology pharmacodynamics nalorphine acts at two opioid receptors — the μ-opioid receptor (mor) where it has antagonistic effects, and at the κ-opioid receptor (kor) (ki = 1.6 nm; ec50 = 483 nm; emax = 95%) where it exerts high-efficacy partial agonist/near-full agonist characteristics. chemistry analogues nalorphine has a number of analogues including niconalorphine (the nicomorphine analogue), diacetylnalorphine (heroin analogue), dihydronalorphine (dihydromorphine), and a number of others as well as a number of codeine-based analogues. synthesis nalorphine synthesis: amended procedure: more recently, it has become much more commonplace to use ethyl chloroformate instead of cyanogen bromide for the von braun degradation demethylation step. see for example the list of phenyltropanes or the synthesis of paroxetine for further examples of this.