Odapipam (NNC 756) is a selective, high affinity and benzazepine dopamine D1 receptor antagonist with a Kd of 0.18 nM. Odapipam is also a superior positron emission tomography (PET) radiotracer[1][2].
The metabolism of Odapipam has been studied with phenobarbital-induced rat liver microsomes. During the incubation of Odapipam, five different metabolites are formed. The electron-ionization (EI+) mass spectra of the metabolites indicated the formation of N-desmethyl-Odapipam, 1-hydroxy-Odapipam, the two isomers of 3′-hydroxy-Odapipam and a metabolite which is dehydrogenated in the dihydrobenzofuran moiety[3].
[1]. Abi-Dargham A, et al. PET studies of binding competition between endogenous dopamine and the D1 radiotracer [11C]NNC 756. Synapse. 1999 May;32(2):93-109. [2]. Nielsen EB, et al. Dopamine receptor occupancy in vivo: behavioral correlates using NNC-112, NNC-687 and NNC-756, new selective dopamine D1 receptor antagonists. Eur J Pharmacol. 1992 Aug 14;219(1):35-44. [3]. J. VANGGAARD ANDERSEN, et al. Normal-phase liquid chromatography-particle-beam mass spectrometry in drug metabolism studies of the dopamine receptor antagonist Odapipam and the muscarine M1 receptor agonist Xanomeline. Xenobiotica. 1997, 27: 901-912.