Effects of the calcium antagonist tiapamil on pulmonary gas exchange in patients with chronic obstructive pulmonary disease who receive salbutamol.
Patients with chronic obstructive pulmonary disease (COPD) and cardiovascular diseases are frequently given combination therapy with a beta 2-agonist and a calcium antagonist. Each drug is known to increase ventilation-perfusion inequalities. It was our aim to define the effects of their combination on lung function and on pulmonary gas exchange in eight subjects with COPD but partially reversible airway obstruction. Sixty minutes after placebo or 450 mg tiapamil, subjects inhaled 0.2 mg salbutamol. There was no significant effect of tiapamil on specific airway conductance and the forced expiratory volume in 1 second before or after the inhalation of salbutamol. Blood was drawn 30, 55, 80, and 100 minutes after placebo or tiapamil dosing. After placebo the mean (+/- SD) arterial oxygen tension (Pao2) fell from 67.1 +/- 7.3 to 64.4 +/- 5.5 mm Hg and the mean alveolar-arterial oxygen tension difference (AaDo2) rose from 34.6 +/- 8.4 to 40.5 +/- 6.8 mm Hg. After tiapamil the mean Pao2 fell from 68.7 +/- 7.3 to 66.4 +/- 5.8 mm Hg and the mean AaDo2 rose from 35.1 +/- 6.8 to 38.7 +/- 7.4 mm Hg. The changes in Pao2 were not significant. The increase in AaDo2 after placebo was significant, but that after tiapamil was not. We conclude that the combination of the calcium antagonist tiapamil and the bronchodilator salbutamol is safe with respect to lung function in COPD. There is no evidence that tiapamil increases beta 2-agonist-induced impairment in pulmonary gas exchange.
D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000188:drug therapy; D000420:Albuterol / Q000627:therapeutic use*; D004311:Double-Blind Method; D004341:Drug Evaluation; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000188:drug therapy*; D008297:Male; D008448:Maximal Expiratory Flow Rate; D008875:Middle Aged; D011437:Propylamines / Q000097:blood / Q000378:metabolism / Q000627:therapeutic use*; D011659:Pulmonary Gas Exchange / Q000187:drug effects*; D011897:Random Allocation; D013976:Tiapamil Hydrochloride
D011437:Propylamines; D000420:Albuterol; D013976:Tiapamil Hydrochloride