rac-Desethyl oxybutynin is an active metabolite of the muscarinic acetylcholine receptor (mAChR) antagonist oxybutynin .1,2,3 rac-Desethyl oxybutynin is formed from oxybutynin by the cytochrome P450 (CYP) isoform CYP3A4.2 It binds to mAChRs in isolated rat bladder, submaxillary gland, heart, and colon with Ki values of 5.38, 3.12, 16, and 5.59 nM, respectively. rac-Desethyl oxybutynin (0.4 and 0.8 mg/kg) reduces micturition pressure in rats.3
1.Lindeke, B., HallstrÖm, G., Johansson, C., et al.Metabolism of Oxybutynin: Establishment of desethyloxybutynin and oxybutynin N-oxide formation in rat liver preparation using deuterium substitution and gas chromatographic mass spectrometric analysisBiomed. Mass Spectrom.8(10)506-513(1981) 2.Oki, T., Kawashima, A., Uchida, M., et al.In vivo demonstration of muscarinic receptor binding activity of N-desethyl-oxybutynin, active metabolite of oxybutyninLife Sci.76(21)2445-2456(2005) 3.Mizushima, H., Kinoshita, K., Abe, K., et al.Pharmacokinetics/pharmacodynamics analysis of the relationship between the in vivo micturition pressure and receptor occupancy of (R)-oxybutynin and its metabolite in ratsBiol. Pharm. Bull.30(5)955-962(2007)