Irdabisant (CEP-26401) (CEP-26401) is a selective, orally active and blood-brain barrier (BBB) penetrant antagonist/inverse agonist of histamine H3 receptor (H3R) (rat H3R Ki= 7.2 nM, human H3R Ki= 2.0 nM). Irdabisant exhibits relatively low inhibitory activity against hERG current (IC50= 13.8 μM). Irdabisant exhibits cognition-enhancing and wake-promoting activities in the rat social recognition model. Irdabisant can be used for research on schizophrenia or cognitive impairment.

Irdabisant exhibits inverse agonist activity with EC50 values of 2.0 nM and 1.1 nM for rat H3R and human H3R, respectively; exhibits antagonist activity with Kb, app values of 1.0 nM and 0.4 nM for rat H3R and human H3R, respectively. Irdabisant exhibits moderate activity at Muscarinic M2 (Ki = 3.7 ± 0.0 μM) and Adrenergic α1A (Ki = 9.8 ± 0.3 μM) receptors, Norepinephrine transporters (Ki = 10 ± 1 μM), Dopamine transporters (Ki = 11 ± 2 μM), and phosphodiesterase PDE3 (IC50 = 15 ± 1 μM). Irdabisant inhibits the cytochrome P450 enzymes CYP1A2, 2C9, 2C19, 2D6, and 3A4 with IC50 values of greater than 30 μM, indicating less potential for drug-drug interactions[1].

Irdabisant (0.0001-0.1 mg/kg; i.v. or p.o.; single dosage) improves performance in the rat social recognition model of short-term memory. Irdabisant (0.01-0.3 mg/kg; p.o.; single dosage) dose-dependently inhibits H3R agonist RAMH-induced dipsogenia. Irdabisant (1 mg/kg for i.v. and 3 mg/kg for p.o.; single dosage) is rapidly absorbed with high oral bioavailability in rat and monkey, and exhibits a moderate clearance in monkey and dog compared to the rat[1]. Irdabisant (3-30 mg/kg; p.o.; single dosage) exhibits wake-promoting activity in rat. Irdabisant (3-30 mg/kg; i.p.) increases prepulse inhibition (PPI) in DBA/2NCrl mice[2].