New Anti-Allergic Drugs for the Treatment of Allergic Rhinitis

Abstract

Many anti-allergic drugs for the treatment of allergic rhinitis are manufactured or available for sale in Japan. These include topical steroids, cromolyn sodium-like compounds (mast cell stabilizing agents), and non-sedative antihistamines. However, the mode of action and classification of these drugs are still contraversial. No definitive evidence has yet been presented supporting the assertion that mast cell stabilizing agents inhibit allergen induced chemical mediator release from the human nasal mucosal mast cell. Some mast cell stabilizing agents also have the antihistaminic effect that antihistamines do, and some anti-histamines inhibit chemical mediator release like mast cell stabilizing agents do. Further studies using human nasal mast cells are required to clarify the mode of action of each drug.
We have performed clinical trials of many anti-allergic drugs using a standardized double blind intergroup comparative method in patients with perennial allergic rhinitis. For general improvement of allergic symptoms, mast cell stabilizing agents such as tranilast, traxanox, and azelastine were superior to inactive placebo; ketotifen, oxatomide and tranilast were also superior to clemastine fumarate ; and, tranilast was comparable to amlexanox, tazanolast, traxanox and repirinast; topical amlexanox and ketotifen were also comparable to cromolyn sodium.
New anti-histamines such as terfenadine and astemizole were comparable to ketotifen, and loratazine was comparable to mequitazine for general improvement of allergic symptoms.