1-Methyl-1,4-diazepane in which the hydrogen attached to the nitrogen at position 4 is substituted by a 1-(2-ethoxyethyl)-1H-benzimidazol-2-yl group. A relatively selective histamine H1 antagonist, it is used as the difumatate salt for allergic rhinitis, urticaria, and pruritic skin disorders, and in eyedrops for the symptomatic relief of allergic conjuntivitis.