Inhibitory effect of DG-5128 on steroid-dependent asthma.

To study the possible role of alpha-2 receptors in intractable asthmatics, we investigated the ameliorative effects of 2-[2-(4,5-dihydro-1H-imidazol-2-yl)-1-phenylthyl]pyridine dihydrochloride sesquihydrate (DG-5128) on 10 steroid-dependent asthmatic patients. The forced expiratory volume in 1 second (FEV1) and the respiratory resistance (Rrs) were measured 1, 2, and 3 hours after oral administration of 200 mg DG-5128 and compared with the premedication measurements. Two hours after DG-5128 administration, the FEV1 rose significantly (p less than 0.01) and the Rrs decreased significantly (p less than 0.05). Asthmatic symptoms (cough, wheezing, dyspnea) also improved in 80% of the patients. This finding raises the possibility that alpha-2 adrenoceptors exist in human airways, that they play an important role in the pathophysiology of asthma, and that the overfunction of these alpha-2 adrenoceptors and/or Gi-protein cause intractable asthma.