Flumexadol is an orally active non-narcotic analgesic. Flumexadol is a selective and affinity 5-HT2C receptor agonist with a Ki of 25 nM for the (+)-enantiomer of Flumexadol, and is 40-fold selective over the 5-HT2A receptor[1][2].

In rats and dogs dosed with 14C-Flumexadol (CERM1841), the 14C is excreted in the urine. The 14C eliminated in the faeces of dog is significantly higher than for rat. Conjugated metabolites, mostly glucuronides, accounted for the greater part of the urinary radioactivity in both species. Biotransformation products are predominantly acids in both species, follows by significant amounts of basic metabolites, with very little neutral substances. The major urinary metabolite in rats is 3-trifluoromethylbenzoic acid and 3-trifluoromethylhipuric acid. In the dog it is 3-trifluoromethylmandelic acid in addition to the benzoic acid and its conjugate. The basic products identified in the urine of both species are unchanged drug and 1-amino-2-hydroxy-2-(3-trifluoromethylphenyl)ethane, with the first predominating[3].

[1]. Hache J, et al. The pharmacology of 1841 CERM, a new analgesic. Arzneimittelforschung. 1978;28(4):642-5. [2]. Nilsson BM. 5-Hydroxytryptamine 2C (5-HT2C) receptor agonists as potential antiobesity agents. J Med Chem. 2006 Jul 13;49(14):4023-34. [3]. Kucharczyk N, et al. Metabolites of 2-(3-trifluoromethylphenyl)tetrahydro-1,4-oxazine (CERM) 1841) in rats and dogs. Xenobiotica. 1979 Nov;9(11):703-11.