Effect of sodium cromoglycate and nifedipine on adenosine-induced bronchoconstriction

Inhaled adenosine causes bronchoconstriction in asthmatic patients. In 7 symptom-free asthmatics a study was performed to investigate the effect of sodium cromoglycate and nifedipine on adenosine-induced bronchoconstriction. All patients were challenged with increasing doses (from 0.03 to 2 mg) of nebulized adenosine to assess airway reactivity. The same procedure was repeated on different days at the same time each morning after administration of placebo and drugs in a randomized double-blind study. Airway response was measured as the forced expiratory volume in 1 s (FEV1). The PD20 value and the fall of FEV1 at the provocative dose were calculated. The PD20 data were modified in log values and the statistical analysis was performed by two-way analysis of variance. Mean decrease of FEV1 after adenosine challenge was 26.02 and 28.87% with placebo sodium cromoglycate and placebo nifedipine, respectively. Sodium cromoglycate and nifedipine gave a mean decrease of FEV1 of 6.44% (p less than 0.05) and 22.22%, respectively. PD20 values (geometric mean) after adenosine inhalation were 0.72 and 0.74 mg for placebo sodium cromoglycate and placebo nifedipine and 0.86 mg for nifedipine. Sodium cromoglycate gave a significant protection against adenosine in all subjects and in no case did the maximum dose used (2 mg) result in a fall in FEV1 value greater than 20%. Adenosine antagonism could be considered as a possible factor contributing to the pharmacologic efficacy of sodium cromoglycate in asthmatic patients. No protective effect was noticed with nifedipine.(ABSTRACT TRUNCATED AT 250 WORDS)