Role of thromboxane A2 synthetase inhibitors in the treatment of patients with bronchial asthma.

Asthma results from complex interactions among inflammatory cells, mediators, and the cells and tissues resident in the airways and is characterized by airway obstruction, airway inflammation, and airway hyperresponsiveness. Treatment of asthma should address not only the airway obstruction but also the chronic inflammation that may lead to hyperresponsiveness. In Japan, where the death rate from asthma has not increased despite increasing numbers of patients, treatment of bronchial asthma relies on the use of oral prophylactic antiasthma drugs, such as thromboxane synthetase inhibitors. Thromboxanes may facilitate the effect of acetylcholine on the airways and may be involved in hyperresponsiveness. Experiments using animal models have shown that thromboxane synthetase inhibitors have prevented increased airway reactivity after exposure to allergens and irritants. Double-blind clinical trials have shown that treatment with the thromboxane A2 synthetase inhibitor ozagrel hydrochloride significantly reduced the need for concomitant steroid therapy, compared with treatment with azelastine hydrochloride. This review discusses the role of thromboxane A2 synthetase inhibitors in the treatment of patients with bronchial asthma.