N-acetylcysteine reduces the exacerbation rate in patients with moderate to severe COPD. The National Mucolytic Study. Results of a randomized, double-blind, placebo-controlled study of iodinated glycerol in chronic obstructive bronchitis. Concomitant therapy with Cineole (Eucalyptole) reduces exacerbations in COPD: a placebo-controlled double-blind trial. Efficacy and tolerability of myrtol standardized in long-term treatment of chronic bronchitis. A double-blind, placebo-controlled study. Study Group Investigators. Prevention of acute exacerbations of chronic obstructive bronchitis with carbocysteine lysine salt monohydrate: a multicenter, double-blind, placebo-controlled trial. The effect of long-term treatment with erdosteine on chronic obstructive pulmonary disease: the EQUALIFE Study. N-isobutyrylcysteine, a donor of systemic thiols, does not reduce the exacerbation rate in chronic bronchitis. Efficacy and tolerability of oral acetylcysteine (Fabrol) in chronic bronchitis: a double-blind placebo controlled study. 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. Oral acetylcysteine reduces exacerbation rate in chronic bronchitis: report of a trial organized by the Swedish Society for Pulmonary Diseases. Long-term oral carbocisteine therapy in patients with chronic bronchitis. A double blind trial with placebo control. Effect of long-term treatment with sobrerol on the exacerbations of chronic bronchitis. Reduction in days of illness after long-term treatment with N-acetylcysteine controlled-release tablets in patients with chronic bronchitis. A controlled trial of intermittent oral acetylcysteine in the long-term treatment of chronic bronchitis. Oral Fabrol (oral N-acetyl-cysteine) in chronic bronchitis. Fluticasone and N-acetylcysteine in primary care patients with COPD or chronic bronchitis. [Drugs active on mucus in the primary treatment of chronic bronchitis. Controlled study of the activity of letosteine]. [Long-term therapy over 2 years with ambroxol (Mucosolvan) retard capsules in patients with chronic bronchitis. Results of a double-blind study of 180 patients]. Effects of N-acetylcysteine on outcomes in chronic obstructive pulmonary disease (Bronchitis Randomized on NAC Cost-Utility Study, BRONCUS): a randomised placebo-controlled trial. Orally administered N-acetylcysteine may improve general well-being in patients with mild chronic bronchitis. Effect of carbocisteine on acute exacerbation of chronic obstructive pulmonary disease (PEACE Study): a randomised placebo-controlled study. Oral N-acetylcysteine and exacerbation rates in patients with chronic bronchitis and severe airways obstruction. British Thoracic Society Research Committee.
This study was performed to confirm the efficacy of a 6-month therapy with a formulation of N-acetylcysteine (NAC; 600 mg/day p.o.) on frequency and severity of exacerbations in patients suffering from chronic obstructive pulmonary disease (COPD).
                One hundred sixty-nine patients attending five Italian centres were recruited in an open, randomized, controlled study. The patients were randomly allocated to standard therapy plus NAC 600 mg once a day or standard therapy alone over a 6-month period. At baseline, medical history was evaluated, and physical examination was performed; occurrence and severity of exacerbations and side effects of NAC were analyzed after 3 and 6 months.
                The results showed a decreased number of exacerbations (by 41%) in the group of patients treated with NAC and standard treatment: 46 patients had at least one exacerbation as compared with 63 patients of the group treated with standard therapy alone. Also the number of the patients with two or more exacerbations was lower in the NAC group (26%) than in the standard-therapy group (49%). The number of sick days was less (82) in the NAC group as compared with the standard-therapy group (155). There was a small but significant improvement in FEV(1) and MEF(50) in the NAC group. NAC once a day was well tolerated. There were no differences in the number of side effects reported in both groups.
                These data confirm results of previous studies which reported a reduction in the number of exacerbations in patients having moderate to severe COPD treated with the antioxidant NAC. Further, the once-daily formulation is well tolerated and is likely to improve patient compliance with the prescribed regimen.
                Copyright 1999 S. Karger AG, Basel Seventy-four pulmonologists and one allergist were recruited to assess the efficacy and safety of iodinated glycerol (Organidin), 60 mg qid, vs placebo in patients with stable chronic obstructive bronchitis in a randomized, double-blind, placebo-controlled, parallel design. A total of 361 patients (180 to iodinated glycerol and 181 to placebo) who complained of cough and difficulty bringing up sputum entered the eight-week study. Evaluations were based upon eight primary symptom efficacy parameters (cough frequency, cough severity, chest discomfort, dyspnea, ease in bringing up sputum, patient and physician global assessments, and a derived patients' global assessment), and six secondary parameters (frequency of aerosol bronchodilator use, incidence and duration of acute exacerbations, frequency of concomitant medication use, incidences of adverse experiences and dropouts). Cough frequency, cough severity, chest discomfort, patients' ease in bringing up sputum, patients' overall condition, and a derived subject global assessment were significantly (p less than 0.05) improved by iodinated glycerol as compared with placebo within eight weeks of treatment. Dyspnea showed a trend toward improvement and the physicians' global evaluation showed no significant difference between groups. Similar findings were noted in a subgroup analysis of moderately-to-severely affected patients. The mean duration (days) of acute exacerbations and number of dropouts attributable to adverse experiences were significantly less (p less than 0.05) in the iodinated glycerol group.(ABSTRACT TRUNCATED AT 250 WORDS) The clinical effects of mucolytics in patients with chronic obstructive pulmonary disease (COPD) are discussed controversially. Cineole is the main constituent of eucalyptus oil and mainly used in inflammatory airway diseases as a mucolytic agent. We hypothesised that its known mucolytic, bronchodilating and anti-inflammatory effects as concomitant therapy would reduce the exacerbation rate and show benefits on pulmonary function tests as well as quality of life in patients with COPD.
                In this double-blind, placebo-controlled multi-center-study we randomly assigned 242 patients with stable COPD to receive 200 mg of cineole or placebo 3 times daily as concomitant therapy for 6 months during winter-time. The frequency, duration and severity of exacerbations were combined as primary outcome measures for testing as multiple criteria. Secondary outcome measures included changes of lung function, respiratory symptoms and quality of life as well as the single parameters of the exacerbations.
                Baseline demographics, lung function and standard medication of both groups were comparable. During the treatment period of 6 months the multiple criteria frequency, severity and duration of exacerbations were significantly lower in the group treated with cineole in comparison to placebo. Secondary outcome measures validated these findings. Improvement of lung function, dyspnea and quality of life as multiple criteria were statistically significant relative to placebo. Adverse events were comparable in both groups.
                Concomitant therapy with cineole reduces exacerbations as well as dyspnea and improves lung function and health status. This study further suggests cineole as an active controller of airway inflammation in COPD by intervening in the pathophysiology of airway inflammation of the mucus membrane.
                ISRCTN07600011. This multicenter, placebo-controlled, double-blind, randomized parallel-group trial was conducted to investigate the efficacy and tolerability of myrtol standardized (MYS, Gelomyrtol forte, 3 x 300 mg) in the long-term treatment of patients with chronic bronchitis during the winter. 246 patients received the investigational treatments (MYS: 122, placebo: 124) for at least 1 month; 215 subjects (110 under MYS and 105 under placebo) were evaluable in terms of efficacy (exacerbation rate, the need for antibiotics, symptom scores and general well-being) for the protocol-defined 6 months of treatment. Statistically significantly (p < 0.01) more patients remained without acute exacerbation in the myrtol standardized group (72%) compared to the placebo group (53%). In the placebo group, there was an evident peak in the incidence of exacerbations during the third month of treatment, which was not observed in the active treatment group. In the MYS group, 51.6% of the patients with an acute exacerbation required antibiotics vs. 61.2% under placebo. 62.5% of the patients treated with antibiotics in the MYS group required them for < or = 7 days, whereas 76.7% of the patients in the placebo group treated with antibiotics for exacerbation needed antibiotics for > 7 days. Well-being (assessed in terms of general health and health impairment by cough and expectoration) was significantly better under treatment with MYS. The overall therapeutic efficacy evaluation scored higher for MYS. Therefore, it is concluded that long-term treatment with MYS is equally well tolerated as placebo but is clearly superior in efficacy in terms of protecting against acute exacerbations in patients with chronic bronchitis: it reduces the frequency and intensity of acute exacerbations, the need of antibiotics for them and the health impairment by cough and expectoration. The efficacy and safety of carbocysteine lysine salt monohydrate (SCMC-Lys) in the prevention of acute exacerbations associated with chronic obstructive bronchitis were evaluated in a multicenter double-blind, placebo-controlled, parallel group trial in 662 outpatients. After a 1-month run-in period, patients were randomized to three groups and assigned to receive one of the following oral treatments: continuous SCMC-Lys 2.7 g once daily, intermittent SCMC-Lys at the same dosage (1-week courses alternating with 1-week intervals on placebo) or placebo. Each treatment lasted for 6 months and spanned the cooler months of the year. Evaluation was based on a daily recording of relevant clinical symptoms and signs and subsequent evaluation of the collected data by three blinded independent physicians. A total of 146 patients (23%) failed to complete the 6-month treatment (mostly due to difficulties in complying with protocol requirements), without clear-cut differences in the dropout rate in the three groups. An intention-to-treat analysis revealed that the incidence of patients without exacerbations in the group assigned to continuous SCMC-Lys treatment was significantly higher than in the placebo-treated group (p < 0.001). The total number of patients with at least one exacerbation was 66 (29.6%) in the group treated with continuous SCMC-Lys compared with 100 (45.9%) with placebo. In the former group the time between initiation of treatment and first exacerbation was significantly prolonged. The average number of days with acute respiratory illness was significantly decreased in the group receiving continuous SCMC-Lys compared with the group receiving placebo, and this was associated with a significant reduction in the antibiotic consumption during the trial period. In patients assigned to intermittent treatment, results of the assessed endpoints did not differ significantly from those observed in the placebo group. No serious adverse effects were reported. It is concluded that continuous administration of SCMC-Lys throughout the winter season is effective in preventing acute exacerbations in patients with chronic obstructive bronchitis and it is well tolerated. Erdosteine is a new thiol compound with effects on bacterial adhesiveness as well as antioxidant and mucoactive properties. The EQUALIFE study, a fully randomized, double-blind, placebo-controlled, parallel-group, multicenter study, was designed to assets the effectiveness of long-term treatment with erdosteine in patients with moderate chronic obstructive pulmonary disease (COPD). One hundred and fifty-five patients received oral erdosteine, 300 mg b.i.d., or placebo for 8 months during the winter season to assess the effect of treatments on exacerbation rate, hospitalization, lung function and quality of life, assessed using the Short Form 36 and the St. George's Respiratory Questionnaire. A pharmacoeconomic analysis was also conducted to compare the two treatments. One hundred and twenty-four patients completed the study with erdosteine (n = 63) or placebo (n = 61). The group of COPD patients who received 8 months of continuous treatment with erdosteine had significantly fewer exacerbations and spent fewer days in the hospital than did the placebo group; furthermore, they had no loss of lung function. Patients in the erdosteine group also showed a significant improvement in health-related quality of life. The mean total COPD-related disease costs per patient were lower in the erdosteine group than in the placebo group over the study period. The results indicate that 8 months of treatment with erdosteine is effective in reducing exacerbation and hospitalization rates and in improving health status. The study suggests that erdosteine is likely to provide an important contribution to the therapy of patients with symptomatic COPD. N-isobutyrylcysteine (NIC), a new thiol compound that is not rapidly hydrolysed to give higher levels of free thiols in the body than N-acetylcysteine (NAC), was used to test if the effect of NAC on exacerbations in chronic bronchitis was an effect of the unhydrolysed thiol compound. Smokers or exsmokers with chronic bronchitis forced expiratory volume in one second (FEV1) >40% and reversibility < or = 10% predicted were treated with oral NIC 300 mg b.i.d. or placebo for 24 weeks. Steroids, NAC, antibiotics, and nonsteroid anti-inflammatory drugs use were restricted. Exacerbations were recorded by a respiratory symptom diary card and the time to onset of the first exacerbation after the start of treatment was measured using life-table analysis. Spirometry was performed at each visit. Six hundred and thirty-seven patients were randomized to treatment with NIC (n=316) or placebo (n=321). NIC did not prolong the time to first exacerbation (life-table analysis, p=0.59) and no increase in FEV1 or forced vital capacity was observed. Altered taste perception, taste loss and anosmia occurred more often in the NIC group (p<0.001). In conclusion, N-isobutyrylcysteine, a N-acetylcysteine-like drug with a greater bioavailability has, contrary to N-acetylcysteine, no effect on exacerbations in chronic bronchitis. This suggests that the effect of N-acetylcysteine on exacerbations in chronic bronchitis is not due to the relatively low free thiol levels (other than glutathione) produced by N-acetylcysteine therapy. This multicentre, double-blind, placebo controlled, between-patient study in general practice in the United Kingdom examined the effect of oral N-acetylcysteine (Fabrol) on the symptomatology of patients with chronic bronchitis over a 3-month period. Although improvement in subjective symptoms (sputum viscosity and character, difficulty in expectoration and cough severity) occurred in both treatment groups over the trial period, improvements in difficulty in expectoration and cough severity were greater in patients receiving N-acetylcysteine compared to matching placebo. Trial medication was well tolerated, with a greater number of side-effects attributed to therapy occurring in patients receiving 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. This multicentre trial was undertaken to confirm previous results indicating that long-term treatment with oral acetylcysteine reduces the exacerbation rate in patients with chronic bronchitis. Two hundred and eighty-five patients, smokers or ex-smokers, with chronic bronchitis started a pre-trial placebo-period of 1 month. After this run-in period 259 patients were included in the trial and randomized into two parallel groups. The patients were treated in a double-blind way either with acetylcysteine 200 mg b.i.d. or placebo b.i.d. for 6 months. The trial was completed by 98 patients in the acetylcysteine group and by 105 patients in the placebo group. Initially, there were no significant differences between the groups. Twice weekly, the patients filled in a diary card concerning symptoms. The number of exacerbations was assessed from these cards and at visits 2, 4 and 6 months after institution of therapy. The exacerbation rate was significantly lower in the acetylcysteine group in which 40% of the patients remained free from exacerbations compared to 19% in the placebo group. Sick-leave due to acute exacerbation was significantly less common in the acetylcysteine group. The drug was well tolerated. nan 706 chronic bronchitic patients were admitted to a double-blind controlled multicenter study to evaluate the effect of the prolonged administration of sobrerol on exacerbations, clinical signs and respiratory function indexes. Patients were treated at random with sobrerol 300 mg b.i.d. or placebo b.i.d. for 3 consecutive months during the winter of 1983/1984. At the beginning of the study, sex, body surface, smoking habits, environment, anti-influenzal vaccination, concomitant pathologies and therapies, respiratory anamnesis, clinical condition and spirometric indexes were equivalent in the two groups. Among the patients admitted to the study, 76% of the sobrerol group did not complain of any exacerbations compared to 58% of the placebo group (p less than 0.001), moreover the risk of exacerbation was about twice higher than with the drug. The use of antibiotics was equivalent in the two groups, whilst the consumption of bronchodilators/theophyllines was markedly lower in the sobrerol group. The response of the clinical signs (dyspnea and auscultatory semeiotics) and of the spirometric indexes (RV, VC and FEV1) to therapy, was significantly higher in the patients treated with sobrerol compared to the placebo group. The opinion expressed by the experimenter and by the patient at the end of each month of treatment was again in favor of sobrerol. Side effects, which were minor and no different from those claimed by the patients treated with placebo, and the hematological and hematochemical assessments, carried out before and after treatment, support the good tolerance of sobrerol. These results let us hope for a more appropriate use of the mucus-regulating agents, particularly in the chronic bronchopulmonary pathologies for which these drugs seem to represent the most rational care. The clinical effect of N-acetylcysteine (NAC) controlled-release tablets, 300 mg b.i.d., and placebo, in chronic bronchitis was investigated. The study was performed as a double-blind six month comparison between active drug and placebo in two parallel groups, with statistical evaluation after four and six months. The patients were chosen from nine centres. One hundred and sixteen out-patients were included and ninety one of them completed the six month study. The acetylcysteine-treated group had a significantly reduced number of sick-leave days caused by exacerbations of chronic bronchitis after the four winter months December-March compared with the control group (NAC 173, placebo 456). The number of exacerbation days was also very much reduced, however, not significantly (NAC 204, placebo 399). At the end of the six month trial, including also two spring months, the absolute numbers of sick-leave days and exacerbation days were still fewer in the acetylcysteine-treated group, (NAC 260, placebo 739) and (NAC 378, placebo 557) respectively. This study demonstrates a significant reduction in sick-leave days after four months of NAC-treatment. A constant tendency to reduction in the number of exacerbations and exacerbation days was also registered after four and six months. The differences in these parameters were, however, not statistically significant. This was probably due to the small number of patients participating. In 69 out-patients with chronic bronchitis in 6 centres the effects of acetylcysteine 600 mg daily, 3 days a week for 6 months, and a placebo have been compared in a double-blind controlled trial. Thirty-five patients were treated with the mucolytic and 34 with the dummy preparation. In the former the clinical course of the chronic bronchitis improved to a greater extent and a significantly lower number of exacerbations was observed. The advantages of long-term oral treatment with the mucolytic in chronic bronchitis suggest that it may be useful as an alternative to long-term antibiotic prophylaxis, or to complement brief courses of antibiotics, in addition to the usual physiotherapy. Five hundred and twenty-six patients suffering from chronic bronchitis were randomized to receive either N-acetylcysteine (NAC) or placebo during a 6-month period. The aim was to compare the number of acute exacerbations in the two groups. General practitioners were asked to enter patients with a diagnosis of chronic bronchitis, based on the MRC criteria. We failed to find any statistically significant difference in the number of exacerbations between the two treatment groups although there was a slight trend towards improvement in the NAC group during the first 3 months of the trial. The tolerability was similar for both treatments. Patients taking NAC showed a reduction in number of days on which they were incapacitated and this result was statistically significant. Increased oxidative stress and bronchial inflammation are important mechanisms in the pathophysiology of COPD.
                To investigate whether treatment with the inhaled corticosteroid fluticasone propionate (FP) or the anti-oxidative agent N-acetylcysteine (NAC) are effective in primary care patients.
                The study was a 3-year placebo-controlled randomised controlled trial preceded by a 3-month washout and 2-week prednisolone pre-treatment. Patients were (ex-)smokers with chronic bronchitis or COPD. Interventions were inhaled FP 500microg b.i.d., oral NAC 600mg o.d., or placebo. Exacerbation rate and quality of life measured with the Chronic Respiratory Questionnaire (CRQ) were the primary outcomes, FEV(1) decline and respiratory symptoms secondary outcomes.
                286 patients recruited from 44 general practices were randomised. Exacerbation rate was 1.35 times higher for NAC (p=0.054) and 1.30 times higher for FP (p=0.095) compared with placebo. CRQ total scores did not differ between NAC (p=0.306) or FP (p=0.581) treatment compared to placebo. Annual postbronchodilator FEV(1) decline was 64mL [SD 5.4] for NAC [p=0.569 versus placebo], 59mL [SD 5.7] for FP [p=0.935], and 60mL [SD 5.4] for placebo.
                No beneficial treatment effects for either high-dosed inhaled fluticasone propionate or oral N-acetylcysteine were observed in our study population of patients with COPD or chronic bronchitis. nan nan Increased oxidative stress is important in the pathogenesis of chronic obstructive pulmonary disease (COPD). We postulated that treatment with the antioxidant N-acetylcysteine would reduce the rate of lung-function decline, reduce yearly exacerbation rate, and improve outcomes.
                In a randomised placebo-controlled study in 50 centres, 523 patients with COPD were randomly assigned to 600 mg daily N-acetylcysteine or placebo. Patients were followed for 3 years. Primary outcomes were yearly reduction in forced expiratory volume in 1 s (FEV1) and the number of exacerbations per year. Analysis was by intention to treat.
                The yearly rate of decline in FEV1 did not differ between patients assigned N-acetylcysteine and those assigned placebo (54 mL [SE 6] vs 47 mL [6]; difference in slope between groups 8 mL [9]; 95% CI -25 to 10). The number of exacerbations per year did not differ between groups (1.25 [SD 1.35] vs 1.29 [SD 1.46]; hazard ratio 0.99 [95% CI 0.89-1.10, p=0.85]). Subgroup analysis suggested that the exacerbation rate might be reduced with N acetylcysteine in patients not treated with inhaled corticosteroids and secondary analysis was suggestive of an effect on hyperinflation.
                N-acetylcysteine is ineffective at prevention of deterioration in lung function and prevention of exacerbations in patients with COPD. Oral N-acetylcysteine (NAC) exerts a beneficial action in chronic bronchitis by reducing the number of exacerbations. There have been few studies of the effect of NAC (or of any other drug) on general well-being in chronic bronchitis. We used an established psychiatric instrument (General Health Questionnaire; GHQ) and a visual analogue scale (VAS) to measure well-being in a 22-week, placebo-controlled, double-blind, parallel-group study of NAC administered as sustained release tablets 600 mg b.i.d., including during the winter months, to patients with mild chronic bronchitis. One hundred and fifty-three patients were accepted for randomized treatment, 129 finished the study (59 NAC, 70 placebo), and well-being was measured in 105 (46 NAC, 59 placebo). The number of observed exacerbations was unexpectedly low in both groups. The number was lowest in the NAC group, however, the difference did not reach statistical significance in the present study (P = 0.08). There were no statistically significant differences between NAC and placebo in subjective symptom scores, FEV1 or FVC. The distribution of GHQ score at baseline was uneven, but NAC was significantly superior to placebo in terms of a favourable effect on GHQ score. GHQ score correlated with the number of exacerbations, and VAS correlated with GHQ score. This study therefore demonstrates the validity of measuring general well-being in patients with mild chronic bronchitis. Future studies of the treatment of chronic bronchitis should use a battery of more specifically adapted instruments which are now becoming available to measure well-being. Chronic obstructive pulmonary disease (COPD) is characterised by airflow limitation, and has many components including mucus hypersecretion, oxidative stress, and airway inflammation. We aimed to assess whether carbocisteine, a mucolytic agent with anti-inflammatory and antioxidation activities, could reduce the yearly exacerbation rate in patients with COPD.
                We did a randomised, double-blind, placebo-controlled study of 709 patients from 22 centres in China. Participants were eligible if they were diagnosed as having COPD with a postbronchodilator forced expiratory volume in 1 s (FEV(1)) to forced vital capacity (FVC) ratio (FEV(1)/FVC) of less than 0.7 and an FEV(1) between 25% and 79% of the predicted value, were aged between 40 and 80 years, had a history of at least two COPD exacerbations within the previous 2 years, and had remained clinically stable for over 4 weeks before the study. Patients were randomly assigned to receive 1500 mg carbocisteine or placebo per day for a year. The primary endpoint was exacerbation rate over 1 year, and analysis was by intention to treat. This trial is registered with the Japan Clinical Trials Registry (http://umin.ac.jp/ctr/index/htm) number UMIN-CRT C000000233.
                354 patients were assigned to the carbocisteine group and 355 to the placebo group. Numbers of exacerbations per patient per year declined significantly in the carbocisteine group compared with the placebo group (1.01 [SE 0.06] vs 1.35 [SE 0.06]), risk ratio 0.75 (95% CI 0.62-0.92, p=0.004). Non-significant interactions were found between the preventive effects and COPD severity, smoking, as well as concomitant use of inhaled corticosteroids. Carbocisteine was well tolerated.
                Mucolytics, such as carbocisteine, should be recognised as a worthwhile treatment for prevention of exacerbations in Chinese patients with COPD. 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.
In participants with chronic bronchitis or COPD, treatment with a mucolytic may produce a small reduction in acute exacerbations, but may have little or no effect on the overall quality of life. The effects on exacerbations shown in early trials were larger than those found in the more recent studies. This may be because the earlier smaller trials were at higher risk of selection or publication bias, so the benefits of treatment may not be as large as suggested by the previous evidence.