Clozapine N-oxide is the major metabolite of Clozapine and is blood-brain barrier permeable. Clozapine N-oxide is an agonist of DREADDs and activates the DREADD receptors hM3Dq and hM4Di. Clozapine N-oxide is also a dopamine antagonist and selective muscarinic M4 receptor agonist.

METHODS: hM4Di-transduced primary embryonic rat neuronal cultures were treated with Clozapine N-oxide (0.01-1000 nM), and activity on hM4Di receptors was detected by FLIPR assay.
RESULTS: The EC50 value for Clozapine N-oxide was 8.1 nM. [1]
METHODS: WT and hM3Dq-transfected mouse embryoma cells ATDC5 were treated with Clozapine N-oxide (750 nM) to detect intracellular calcium signaling.
RESULTS: Administration of Clozapine N-oxide resulted in immediate coordinated induction of single [Ca2+]i spines in hM3Dq-ATDC5 cells, and only spontaneous [Ca2+]i signaling was observed in Clozapine N-oxide-treated WT controls. [2]

METHODS: To investigate potential effects on sleep, Clozapine N-oxide (1-10 mg/kg) was injected intraperitoneally into C57BL/6J mice.
RESULTS: Clozapine N-oxide altered sleep in mice. Sleep was analyzed using electroencephalography (EEG) and electromyography (EMG), revealing dose-dependent suppression of rapid eye movement (REM) sleep, changes in EEG spectral power during non-rapid eye movement (NREM) sleep, and alterations in sleep structure. [3]
METHODS: To investigate the effects on reward-seeking behavior, Clozapine N-oxide (0.1-10 mg/kg) was administered intraperitoneally to C57BL6/JJcl mice.
RESULTS: The off-target effects of commonly used doses of Clozapine N-oxide on motivated reward seeking were negligible. [4]