Pharmacologic bronchodilation response to salbutamol in COPD patients

BACKGROUND: Airway hyperresponsiveness (AHR) is the most characteristic feature of asthma, which is reported in COPD patients and smokers. Increased airway responsiveness to ß-agonists is also demonstrated in asthmatics as well as smokers. However, there is no report regarding AHR to ß-agonist drugs in COPD patients. Therefore, in this study pharmacologic bronchodilation response to salbutamol in COPD patients was examined. MATERIALS AND METHODS: The threshold concentrations of inhaled salbutamol required for a 20% change in forced expiratory flow in 1 sec (FEV1) as PC20, or a 35% change in specific airway conductance (sGaw) as PC35 was measured in 14 COPD patients and 14 normal subjects. RESULTS: Airway responsiveness to salbutamol in COPD patients (PC20 = 14.14 ± 1.62 and PC35 = 9.70 ± 1.48 mg/l) was significantly lower than normal subjects (PC20 = 224.57 ± 16.62 and PC35 = 81.87 ± 8.16 mg/l, P < 0.001 for both cases). The values of FEV1 and sGaw in COPD patients (56.43 ± 14.45 and 0.081 ± 0.120 respectively) were significantly lower than those of normal subjects (104.07 ± 5.72 and 0.194 ± 0.041 respectively), (P < 0.001 for FEV1 and P < 0.005 for sGaw). There was a significant correlation between FEV1 with PC20 salbutamol (r = 0.862, P < 0.001). The correlations between PC20 and PC35 was also statistically significant (r = 0.862, P < 0.001). CONCLUSION: These results showed increased airway responsiveness of most COPD patients to salbutamol which was highly correlated to airway caliber. Key words: Airway caliber, airway responsiveness, COPD, salbutamol, smoker.