Theophylline mitigates the bronchoconstrictor effects of sulfur dioxide in subjects with asthma

Abstract

The objective of the study was to investigate the ability of a sustained-release (SR) theophylline tablet (Uniphyl; Purdue Frederick Co., Norwalk, Conn.) to block or mitigate sulfur dioxide (SO 2)—induced bronchoconstriction in adult subjects with asthma. Eight subjects participated in a double-blind, crossover study with a 400 mg theophylline tablet or placebo once a day for a week before a 10-minute SO 2 challenge. FEV 1 and total respiratory resistance (R T) were measured before and after the SO 2 challenge and on a different day before and after an air exposure. After exposure to SO 2, average values of FEV 1 dropped 16% after placebo treatment and 7% after theophylline treatment. The corresponding percentages for R T were a 37% increase after placebo and a 7% increase after theophylline treatment. Analysis of variance demonstrated a significant difference between the SO 2-induced decrease in FEV 1 and increase in R T after SR theophylline treatment compared with that of placebo treatment. Thus, we conclude that SR theophylline tablets, taken at this concentration for 1 week, mitigate SO 2-induced bronchoconstriction.