Background: Although theophylline is recommended by current guidelines for the management of asthma in patients with persistent symptoms, theophylline has a narrow therapeutic index, requiring individual dose titration and regular monitoring of serum theophylline concentrations to avoid adverse effects.
Objective: To compare the inhaled long-acting bronchodilator, salmeterol, with the oral bronchodilator, theophylline, in the maintenance treatment of asthma.
Methods: In two multicenter, randomized, double-blind, double-dummy, placebo-controlled, parallel-group studies, patients received salmeterol aerosol 42 micrograms, extended-release theophylline capsules, or placebo twice daily for 12 weeks.
Results: Of 638 adult and adolescent patients with moderate asthma who entered the prebaseline theophylline titration period, 154 were withdrawn prior to randomization (71 due to theophylline-related adverse effects); 484 patients comprised the intent-to-treat population. The mean serum theophylline concentration measured approximately seven hours postdose during the titration period in the theophylline group was 12.7 mg/L (70 mumol/L). The same dose during the treatment period resulted in a mean serum theophylline concentration between 7.6 to 7.9 mg/L (42-44 mumol/L) when measured approximately 12 hours postdose. Salmeterol was significantly more effective than theophylline or placebo in improving mean morning PEF over the entire 12 weeks (P < or = .02). Mean predose FEV1 improved significantly with salmeterol compared with placebo (P < .001); there was no difference between theophylline and placebo. Salmeterol was also significantly more effective than theophylline or placebo (P < .02) in improving asthma symptoms, reducing nighttime awakenings, and reducing the daily use of albuterol. After 12 weeks of treatment, patients in the salmeterol group expressed significantly greater overall satisfaction with their asthma medication than did patients who received theophylline (P < .01). Patients in the theophylline group experienced more gastrointestinal adverse events than did patients in the salmeterol group (P < .05).
Conclusion: Salmeterol, 42 mg twice daily, was better tolerated and significantly more effective than extended-release theophylline twice daily in the maintenance treatment of asthma.