The 3 Me analog of fentanyl 3 MeF was first introduced by Paul Janssen J Med Chem 1974 17 10 1047 1051 which has been recently revisited by Slavic researchers J Serb Chem 2004 69 7 511 526 QSAR reveals that the OH was first incorporated into 3 MeF because this pharmacophore had previously been shown to raise the potency of closely related piperidine based narcotics J Med Chem 1962 5 5 913 919 such as phenoperidine for example AFAIK ohmefentanyl was first reported by Chinese chemists in 1979 Scienta Sinica Vol XXIV No 5 pp 710 721 May 1981 Since that time both Chinese and also American scientists submitted the first elaborate evaluations on OMF isomer variations in 1995 in the JMC J Med Chem 1995 38 18 3652 3659 J Med Chem 1995 38 9 1547 1557