Nifedipine in asthma. Dose-related effect on resting bronchial tone.
In order to study the dose-related effect of nifedipine on expiratory flow rates, 15 asthmatic patients were given sublingually 10 mg and 20 mg of the drug on two different days and the FVC and FEV1 were measured during 90 minutes. Then they received 2.5 mg albuterol (Salbutamol) by inhalation, and the two parameters were measured again after 30 minutes. It was found that the drug has a dose-related effect on expiratory flow rates. Indeed, 20 mg nifedipine produced a mild (less than 10 percent) but significant improvement in FVC (p less than 0.01) and FEV1 (p less than 0.05), while the response to 10 mg was mild, not significant and manifested rather by a decrease in both parameters. In three patients, the forced expiratory flow rates markedly worsened. No correlation could be established between the effect of nifedipine and the severity of the disease. In contrast, the improvement produced by albuterol was strongly related to the degree of airway obstruction (p less than 0.001). Nifedipine in both doses did not potentiate the bronchodilatation induced by albuterol.