[Sobrerol as expectorant in patients with stable chronic respiratory tract infections. A controlled study]

A randomized double-blind crossover study compared the clinical effectiveness of 14-day treatment with 400 mg/day of sobrerol and placebo in 23 patients with stable chronic bronchial disease. In a further open trial phase all patients received 2.0 g glyceringuaiacol per day. During the 9-week trial, subjective symptoms and findings were recorded by numerical code, side-effects listed, pulmonary function tests performed and sputum physical characteristics determined on a weekly basis. Data was statistically analyzed using an analysis of variance adapted from HILLS and ARMITAGE, the Wilcoxon matched-pairs signed-ranks test, the paired t-test and the %2 test. Both subjective assessment of overall clinical efficacy and statistical analysis of the above factors failed to show any significant advantage of sobrerol over placebo. Sputum physical characteristics failed to reveal a significant difference between sobrerol and placebo, with the exception of a temporary reduction in sputum volume (p less than 0.05) on the fourth day of therapy with sobrerol. Similarly, 2.0 g glyceringuaiacol for 14 days failed to influence subjective symptoms, pulmonary function tests or sputum physical characteristics. In conclusion, sobrerol is a further example of an expectorant lacking evidence of clinical effectiveness in the management of bronchial secretions in patients with stable chronic bronchial disease.