Responses to large doses of salbutamol and theophylline in patients with chronic obstructive pulmonary disease.

To assess additive effects of therapy with salbutamol and theophylline, we examined 16 patients (5 women, 11 men) with a mean age of 67.6 +/- 6.9 (SE) yr, long-standing chronic obstructive pulmonary disease, an FEV1 of 0.73 +/- 0.05 (SE) L, and a smoking history of 38.4 +/- 4.1 (SE) pack-years. On 2 consecutive days they were given large doses of either salbutamol followed by theophylline or vice versa. In the group as a whole, responses to salbutamol alone averaged 24% of the baseline FEV1 and responses to theophylline alone were 17% of baseline. Similar increases were observed when either drug was given after the other; responses to the 2 agents were additive. Responses to salbutamol were larger (p less than 0.05) than those to theophylline. Responses to salbutamol and theophylline were correlated. In 8 patients whose FEV1 increased after salbutamol by more than both 20% and 0.2 L, adding theophylline produced responses that were also large (32% baseline and 0.22 L). In the remaining 8 nonresponsive patients, salbutamol and theophylline were also additive, but the small (mean 10% or 0.06 L) increases in FEV1 with theophylline raised the question of the risk benefit ratio of high-dose theophylline therapy in such patients.