N-Desmethylclozapine-d₈is intended for use as an internal standard for the quantification of N-desmethylclozapine by GC- or LC-MS. N-Desmethylclozapine is an active metabolite of the atypical antipsychotic clozapine .¹It was originally described as an antagonist of serotonin (5-HT) receptor subtype 5-HT_2C(IC₅₀= 7.1 nM in rat choroid plexus) and later as an inverse agonist using human recombinant receptors.^2,3N-Desmethylclozapine is an antagonist at dopamine D₄receptors, an agonist at δ-opioid receptors, and a partial agonist at dopamine D₂and D₃, M₁muscarinic acetylcholine, and 5-HT_1Areceptors.^3,1,4N-Desmethylclozapine (30 mg/kg) decreases exploratory locomotor activity and increases prepulse inhibiton of the acoustic startle response in mice.⁵

1.Burstein, E.S., Ma, J., Wong, S., et al.Intrinsic efficacy of antipsychotics at human D2, D3, and D4 dopamine receptors: Identification of the clozapine metabolite N-desmethylclozapine as a D2/D3 partial agonistJ. Pharmacol. Exp. Ther.315(3)1278-1287(2005) 2.KuoppamÄki, M., SyvÄlahti, E., and Hietala, J.Clozapine and N-desmethylclozapine are potent 5-HT1C receptor antagonistsEur. J. Pharmacol.245(2)179-182(1993) 3.Lameh, J., Burstein, E.S., Taylor, E., et al.Pharmacology of N-desmethylclozapinePharmacol. Ther.115(2)223-231(2007) 4.Odagaki, Y., Kinoshita, M., and Ota, T.Comparative analysis of pharmacological properties of xanomeline and N-desmethylclozapine in rat brain membranesJ. Psychopharmacol.30(9)896-912(2016) 5.Maehara, S., Hikichi, H., and Ohta, H.Behavioral effects of N-desmethylclozapine on locomotor activity and sensorimotor gating function in mice-Possible involvement of muscarinic receptorsBrain Res.1418111-119(2011)