Ambroxol for the prevention of chronic bronchitis exacerbations: long-term multicenter trial. Protective effect of ambroxol against winter semester exacerbations: a double-blind study versus placebo.

In a 6-month, double-blind multicenter trial conducted over the winter, the effects of daily administration of ambroxol retard (75 mg) were compared with those of placebo in preventing exacerbations and improving symptoms and clinical signs in chronic bronchitis patients. The trial was completed by 110 patients in the ambroxol group and by 104 in the placebo group. Initially, there were no significant differences between the groups. By the end of the 2nd month of treatment, 67.2% of the ambroxol group had had no exacerbations compared to 50.4% in the placebo group. At the end of the 6-month trial, 45.5% of the treatment group had had no exacerbations, compared to only 14.4% of the control group. These differences were statistically significant. Patients in the treatment group lost significantly fewer days through illness (442) and had fewer days when they needed antibiotic therapy (371) compared to the placebo group patients (837 and 781). Ambroxol also produced statistically significant symptomatic improvement, measured as difficulty in expectoration, coughing, presence of dyspnea and the auscultatory signs as compared to controls. Since ambroxol was well tolerated and compliance was good, it appears like a drug of choice for pharmacological prophylaxis of chronic bronchitis.