Clozapine N-oxide

Clozapine N-oxide (CNO) is a synthetic drug used mainly in biomedical research as a ligand to activate Designer Receptors Exclusively Activated by Designer Drugs (DREADDs),^[1] despite the initial belief that it was biologically inert. However, it has been shown to not enter the brain after administration^[2] and to reverse metabolize in peripheral tissues to form clozapine. Clozapine can bind to a number of different serotonergic, dopaminergic and adrenergic receptors within the brain.^[3] These off-target effects mean behavioral data using the CNO-DREADD system have to be interpreted with caution.^[4]

Clozapine N-oxide

Names
IUPAC name 3-chloro-6-(4-methyl-4-oxidopiperazin-4-ium-1-yl)-11H-benzo[b][1,4]benzodiazepine
Identifiers
CAS Number	34233-69-7
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL1688
ChemSpider	21169512
ECHA InfoCard	100.164.243
PubChem CID	135445691
UNII	MZA8BK588J
CompTox Dashboard (EPA)	DTXSID50955778
InChI InChI=1S/C18H19ClN4O/c1-23(24)10-8-22(9-11-23)18-14-4-2-3-5-15(14)20-16-7-6-13(19)12-17(16)21-18/h2-7,12,20H,8-11H2,1H3 Key: OGUCZBIQSYYWEF-UHFFFAOYSA-N
SMILES C[N+]1(CCN(CC1)C2=NC3=C(C=CC(=C3)Cl)NC4=CC=CC=C42)[O-]
Properties
Chemical formula	C18H19ClN4O
Molar mass	342.83 g·mol−1
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H315, H319, H335
Precautionary statements	P261, P264, P270, P271, P280, P301+P310, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Alternatives to CNO with more affinity, more inert character, and faster kinetics include Compound 21 (C21)^[5] and deschloroclozapine (DCZ).^[6]