Oral N-acetylcysteine and exacerbation rates in patients with chronic bronchitis and severe airways obstruction. British Thoracic Society Research Committee.

The influence of oral N-acetylcysteine on the exacerbation rate in patients with chronic bronchitis and severe airways obstruction has been studied. Two hundred and forty four patients entered the study during October and November 1983 and took placebo sachets for a run in month. One hundred and eighty one who completed this month satisfactorily were randomised to receive either active (acetylcysteine 200 mg three times a day) or matching placebo sachets for five months in a double blind parallel group study. The two groups were well matched. Patients kept detailed daily symptom diaries and were assessed monthly. At the end of the five months' study the outcome in the group taking acetylcysteine appeared a little better, but the differences did not reach conventional levels of statistical significance for the mean (SD) number of exacerbations (2.1 (0.2) for acetylcysteine, 2.6 (0.2) for placebo; p = 0.08); total days taking an antibiotic (13.5 (1.7), 18.0 (2.8); p = 0.17); total days spent in bed (4.8 (0.8), 5.1 (1.1); p = 0.9); number of withdrawals (13 (15%), 20 (21%); p = 0.4); incidence of side effects (which were few); drug compliance (which was good); and the patients' assessment of the treatment.