Azatadine is an histamine and cholinergic inhibitor with IC50 of 6.5 nM and 10 nM, respectively.Target: Histamine ReceptorAzatadine, a new antihistamine, was evaluated for its efficacy in 20 patients with chronic allergic rhinitis. Eighty percent of patients had symptomatic relief with a twice daily dosage of 2 mg. Sedation was volunteered as a side effect by six of the patients and was admitted by two further patients after specific questioning. A choice reaction time test gave slowing of motor function in these sedated patients. Four of the previously sedated patients experienced good symptomatic control with minimal sedation when the azatadine dose was reduced to 1 mg twice daily; slowing of motor function was not observed at this, the normal recommended dose.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.