A controlled study of slow-release theophylline and aminophylline in patients with chronic bronchitis

Twenty patients with chronic bronchitis who were also receiving beta-agonist inhalers entered a single-blind cross-over study comparing slow-release aminophylline (Phyllocontin) 325 mg twice daily and slow-release theophylline (Rona-slophyllin) 250 mg twice daily with placebo. 16 subjects who completed the study showed no objective or subjective benefit with either active preparation. Eight of the 16 patients achieved plasma theophylline levels of greater than 10 micrograms/ml on each of the drugs but no benefit was found when this group was analysed separately.