Effects of withdrawal of sustained-release theophylline in patients with chronic obstructive lung disease.

In a double-blind, cross-over study, sustained-release theophylline was withdrawn to determine whether the drug was still effective after long-term treatment. Twenty adult out-patients with stable, chronic obstructive lung disease and who had been on continuous long-term treatment for at least 6 months, were studied. Lung function, plasma theophylline concentration, symptom score, number of nocturnal dyspnoea attacks, requirement for additional beta 2-stimulant aerosol, and side effects, were recorded before withdrawal, after withdrawal and after reinstitution of treatment. When theophylline was withdrawn, all parameters were significantly worsened, but after reinstitution of treatment they all improved significantly. The results show that sustained-release theophylline remains effective after at least 6 months' continuous treatment in adult patients.