Effect of verapamil inhalation on bronchial asthma

The effect of inhaled verapamil 20 mg on pulmonary functions and arterial blood gases in 15 patients with extrinsic bronchial asthma was studied in single-blind fashion. A significant decrease (p less than 0.05) in airway resistance and a significant increase (p less than 0.01) in specific conductance was observed after verapamil inhalation. A small increase (p less than 0.1) was observed in forced vital capacity and peak expiratory flow rate after verapamil inhalation; however, this was not statistically significant. None of the parameters of pulmonary function tests showed a significant change after normal saline inhalation. A significant fall in PaO2 (p less than 0.05) and PaCO2 (p less than 0.05) was noted after normal saline inhalation. PaCO2 showed a significant fall (p less than 0.01) after verapamil inhalation. Alveolar arterial oxygen gradient P(A-a)O2 widened significantly (p less than 0.001) after normal saline inhalation. A larger dose (20 mg) of verapamil inhalation produces a significant bronchodilator effect on large airways, but does not produce a significant change in arterial oxygen tension from the baseline value in patients with bronchial asthma.