nortilidine nortilidine nortilidine is the major active metabolite of tilidine. it is formed from tilidine by demethylation in the liver. the racemate has opioid analgesic effects roughly equivalent in potency to that of morphine. the (1r,2s) isomer has nmda antagonist activity. the drug also acts as a dopamine reuptake inhibitor. the reversed-ester of nortilidine is also known, as is the corresponding analogue with the cyclohexene ring replaced by cyclopentane, which have almost identical properties to nortilidine. nortilidineidentifiers iupac name ethyl (1r,2s)-2-(methylamino)-1-phenylcyclohex-3-ene-1-carboxylate cas number38677-94-0pubchem cid162321chemspider142535unii7145g6817jchebichebi:77839 ychemblchembl1614654comptox dashboard (epa)dtxsid10191256 chemical and physical dataformulac16h21no2molar mass259.349 g·mol−13d model (jsmol)interactive image smiles ccoc(=o)1(ccc=c1nc)c2=cc=cc=c2 inchi inchi=1s/c16h21no2/c1-3-19-15(18)16(13-9-5-4-6-10-13)12-8-7-11-14(16)17-2/h4-7,9-11,14,17h,3,8,12h2,1-2h3/t14-,16+/m0/s1key:pdjzpnkvldweki-goeboniosa-n use nortilidine has been sold as a designer drug, first being identified in poland in may 2020.