Azatadine dimaleate (SCH10649) is an inhibitor for histamine（IC50=6.5 nM） and cholinergic（IC50=10 nM）.

95% of Azatadine is biotransformed in Sabouraud dextrose broth within 72 hours treatment with two major metabolites, 7-hydroxyazatadine (25%) and 8-hydroxyazatadine (50%), and two minor metabolites, N-desmethylazatadine and 9-hydroxyazatadine. [2]

Azatadine delays the onset of dyspnea-induced by aerosolized histamine, acetylcholine and serotonin in the conscious guinea-pig with PD50 of 0.01 mg/kg, 0.739 mg/kg and 0.86 mg/kg. Azatadine protects conscious guinea-pigs against death induced by the intravenous injection of histamine with oral PD50 of 0.009 mg/kg in guinea-pig and 0.22 mg/kg in mice. [1] Following a single oral dose of Azatadine (4 mg) in fasted volunteers, a Cmax of 3 μg/L has been measured by RIA 4.2 hours after administration. Azatadine is almost completely metabolised by hydroxylation, demethylation and formation of zwitterion isomers by oxidative ring opening. Azatadine (8.8 mg oral) in healthy volunteers results in a Csub>max of 5.9 μg/L at 5.3 hours after treatment and bioavailability of 80%. [3] Azatadine (1 mg twice daily for 14 days) is effective in relieving the histamine-mediated symptoms of seasonal allergic rhinitis. [4]