Synergism between ipratropium and theophylline in asthma

Ipratropium bromide is a bronchodilator whose effect has been compared with beta agonists but not with theophylline. Twelve asthmatics were given four two-week courses of the different combinations of ipratropium (40 micrograms in two puffs), theophylline capsules, and their corresponding placebos in a random, double-blind fashion. There was a significant increase in FEV1 and MMFR 60 minutes after theophylline was administered (p less than 0.05) when measured after one and two weeks of therapy. FEV1 and MMFR were significantly increased (p less than 0.05) 30 and 60 minutes after ipratropium inhalation and this increase was significantly greater when the patient had also been taking theophylline compared with placebo capsules (p less than 0.05). There was no toxicity associated with this combination. The synergism demonstrated may be related to the time sequence of drug administration, mechanical or cellular factors.