Abstract
Nifesipine, a potent calcium antagonist, was given to 33 asthmatic patients, in order to investigate its possible effect on bronchoconstriction. 10 mg of nifedipine with a bronchodilator, i.e., 4mg of terbutaline, was given orally to group A(9 cases); placebo of nifedipine and terbutaline to group B(8 cases); nifedipine with placebo of terbutaline to group C(8 cases); and placebos of both drugs to group D(8 cases). Medication of the subjects was carried out using a double blind method, and all other drugs were washed out the subjects 16 hours or more before the medication. In order to confirm the effect on pulmonary function, forced expiratory spirograms and maximal expiratory flow volume curves were examined before, and after 15 min, 30 min and 60 min of the medication. The results were as follows: 1. In group D, in which placebos were given, parameters of ventilatory function gradually and significantly decreased from the baseline values following the time course. 2. However, in group C, nifedipine apparently inhibited this decrease in ventilatory function. 3. In groups A and B, i.e., those in which terbutaline or terbutaline with nifedipine were given, parameters of ventilatory function significantly increased in comparison with the baseline values, although there was no apparent advantage of combination of the two drugs over use of terbutaline alone. 4. In group D, pulse rate significantly decreased from baseline value; it remained unchanged in both groups A and B, and increased in group C. Blood pressure apparently fell from baseline value in both groups A and C. The above results suggest that the calcium antagonist nifedipine inhibits bronchoconstriction in asthmatics, probably due to vagotony induced through repeated deep inspiration and expiration. This would also support the reported effect of the drug on exercise-induced asthma.
