Pyroxamine (INN), also known as pyroxamine maleate (USAN) (developmental code names AHR-224, NSC-64540), is an antihistamine and anticholinergic related to diphenylpyraline. Pyroxamine (INN), also known as pyroxamine maleate (USAN) (developmental code names AHR-224, NSC-64540), is an antihistamine and anticholinergic related to diphenylpyraline.