GSK-1004723 is a dual histamine H(1) and H(3) receptor antagonist with a long duration of action that has been investigated for the treatment of allergic rhinitis. GSK-1004723 was designed for intranasal administration as a suspension or solution. Clinical trials (phase 1 and 2) showed that GSK-1004723 is well tolerated and demonstrates clinically significant attenuation of symptoms (tested in an environmental allergen challenge chamber). However, attenuation of symptoms was less than seen for treatment with cetirizine (a commonly used over-the-counter antihistamine).