A double-blind, placebo-controlled evaluation of (dl)-3,7-dihydro-1,8-dimethyl-3-(2-methylbutyl)-1H-purine-2,6-dione in exercise-induced bronchospasm.

The investigational drug, (dl)-3, 7-dihydro-1, 8-dimethyl-3-(2-methylbutyl)-1 H-purine-2, 6-dione, has been proven to be an active bronchodilator and antiallergic compound in animal and clinical studies. Adult asthmatic patients who demonstrated greater than or equal to 20% improvement in FEV1 after inhalation of aerosolized isoproterenol or its equivalent and greater than or equal to 20% reduction in FEV1 after a graded treadmill exercise received theophylline (3, 6 mg/Kg, every 6 h) for 4 days. Further selection of patients was made by demonstrating that theophylline effectively blocked exercise-induced reduction in FEV1 and was effective in increasing FEV1 by 20% when measured 2 h after oral administration. Thus, these adult asthmatics entered a double-blind, placebo-controlled, two-dose cross-over study with the investigational drug at dosage 0.075 mg/kg twice daily and 0.125 mg/kg twice daily. At both dosages studied the investigational drug was found to be an effective bronchodilator in blocking exercise-induced reduction in FEV1 by improving asthma disability scores and increasing FEV1 2 h after oral administration. The incidence and severity of the side effects observed were less than those observed with theophylline.