The combined effect of theophylline and terbutaline in patients with chronic obstructive airway diseases.

Using a double-blind, cross-over design the acute bronchodilating effect of 375 mg microcrystalline theophylline, 5 mg terbutaline, a combination of both drugs and placebo was studied in 11 patients suffering from moderate to severe chronic obstructive lung disease with partially reversible airway obstruction. Plasma concentrations both theophylline and terbutaline were measured. The bronchodilation produced by oral intake of 5 mg terbutaline and 375 mg theophylline was comparable. The maximal median value of terbutaline in plasma was 4.6 ng/ml 2 h after intake of medication, followed by a decline with a double peak in some patients. The maximal median increase of FEV1 was 37% 3 h after intake of medication. The maximal median plasma level of theophylline reached 12.5 ng/ml 30 min after intake of the medication. The median maximal increase of FEV1 was 24%. One hour after intake of medication and throughout the whole test period up to 7 h, the combination of 5 mg terbutaline and 375 mg theophylline produced a significantly greater bronchodilation than each drug alone. It is concluded that 375 mg microcrystalline theophylline produced a significantly greater bronchodilation than each drug alone. It is concluded that 375 mg microcrystalline theophylline and 5 mg terbutaline produces almost equal bronchodilating activity: a combination of both drugs, however, results in further bronchodilation.