“…Theophylline is widely used as a maintenance treatment for moderately severe asthma and has been repeatedly shown to reduce day to day symptoms and to improve pulmonary function by bronchodilatation (Weinberger & Bronsky, 1974;Hambleton et al, 1977;Rachelefsy et al, 1978;. It has also been shown to block bronchoconstriction induced by exercise (Bierman et al, 1977) and inhaled allergens (Falliers, 1979), and to give a small degree of protection to bronchoconstriction induced by inhaled histamine in a small number of adults who were highly responsive (Cockroft et al, 1977a).…”