Aminophylline injection and theophylline tablets: Acute response in partially reversible chronic airway obstruction

Intravenous injections of aminophylline (250 mg) and tablets of theophylline (Neulin) (400 mg) were given, on separate occasions, to 10 patients with partially reversible severe airway obstruction. The dose of aminophylline was shown to be inadequate on the basis of the unsatisfactory plasma theophylline levels and a poor ventilatory response. Two hours after oral administration of theophylline, a mean plasma theophylline concentration in the optimal range (10 to 20 mug/ml) was reached, and a consistent improvement in the mean forced expiratory volume in one second (FEV1) occurred. A further large improvement in FEV1 after inhalation of salbutamol showed that the improvement in ventilation with the theophylline tablets, although consistent, was less than maximal.