Description
A histamine H1 receptor antagonist (Ki = 0.001 µM); selective for histamine H1 over histamine H2 and H3 receptors (Kis = >100 µM for both), as well as 5-HT1A, 5-HT1B, 5-HT1C, 5-HT1D, 5-HT2, and 5-HT3, dopamine D1 and D2, α1- and α2-adrenergic, adenosine, and muscarinic receptors in radioligand binding assays (Kis = >1 µM for all); reduces histamine release from bronchial mast cells in ovalbumin-sensitized guinea pigs at 0.1, 0.3, and 1 mg/kg; reduces histamine-induced paw edema in rats, skin edema in dogs, and bronchoconstriction in guinea pigs (ED50s = 0.5, 0.07, and 0.03 mg/kg, respectively); inhibits passive cutaneous anaphylaxis, as well as compound 48/80-induced lethal shock in rats (ED50s = 1.6 and 0.07 mg/kg, respectively)