Lack of effect of 4 weeks of oral H1 antagonist on bronchial responsiveness.
Ten patients with stable chronic asthma completed a randomized double-blind placebo controlled crossover study examining the effect of 120mg terfenadine twice daily for 4 weeks on bronchial responsiveness. Bronchial responsiveness was measured by methacholine inhalation tests performed by the tidal breathing technique at 0, 2 and 4 weeks of active and placebo treatment periods separated by a one week washout period. There were no significant differences in mean baseline forced expired volume in 1 sec (FEV1) for placebo and terfenadine treatments (p greater than 0.05) and there were no differences between geometric mean provocative concentrations of methacholine to cause a 20% fall in FEV1 (PC20M) at 2 and 4 weeks of terfenadine (0.89 and 0.99 mg.ml.1) from placebo (0.94 and 0.84 mg.ml.1) (p greater than 0.05). Examination of individual PC20M values during terfenadine treatment showed that 5 patients had PC20M's outside their 95% confidence interval; 2 increased both 2 and 4 week values, 1 increased one value and 2 decreased one value each. It is concluded that terfenadine does not produce clinically significant changes in stable asthmatics.
Dept of Respiratory Medicine, Flinders Medical Centre, Bedford Park, South Australia.
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Ruffin
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Latimer
D000284:Administration, Oral; D000328:Adult; D001249:Asthma / Q000188:drug therapy*; D016084:Bronchoconstriction / Q000187:drug effects*; D002908:Chronic Disease; D004311:Double-Blind Method; D004341:Drug Evaluation; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006634:Histamine H1 Antagonists / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D016593:Terfenadine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*
D006634:Histamine H1 Antagonists; D016210:Methacholine Chloride; D016593:Terfenadine