title: Theophylline in maintenance treatment of chronic asthma: concentration-dependent additional effect to beta 2-agonist therapy.
abstract: The effect of long-term treatment with theophylline was studied in 20 chronic asthmatic patients receiving oral and inhaled beta 2-agonists. In a double-blind, randomized cross-over fashion during three consecutive 6-week periods, the patients received theophylline in individually adjusted dosages or placebo to obtain plasma concentrations of 25-45 mumol/l, 50-85 mumol/l and 0, respectively. PEF, beta 2-aerosol consumption, symptom scores and side-effects were recorded daily. The addition of theophylline caused a significant further bronchodilating effect. There was, however, a large interindividual variation in response to additional theophylline and only half of the subjects were responders. Those responding had increased therapeutic efficacy from a steady-state concentration in the range of 50-85 mumol/l compared to the lower concentration. The responders had, on average, more pronounced air-flow obstruction. The incidence of adverse reactions increased with increasing concentrations of theophylline.
mesh_terms: D000318:Adrenergic beta-Agonists / Q000097:blood / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000420:Albuterol / Q000008:administration & dosage / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology; D002908:Chronic Disease; D002986:Clinical Trials as Topic; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004357:Drug Synergism; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D011897:Random Allocation; D013726:Terbutaline / Q000008:administration & dosage / Q000627:therapeutic use; D013806:Theophylline / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*
chemical_list: D000318:Adrenergic beta-Agonists; D013806:Theophylline; D013726:Terbutaline; D000420:Albuterol