A substantial number of Americans have chronic obstructive pulmonary disease (COPD) in various stages of severity. Most of these patients have stage 1 disease, according to the American Thoracic Society, which means their forced expiratory volume in one second(FEV₁) is at least 50 percent of the predicted value. Stage 2 is defined as an FEV₁ value of 35to 49 percent of the predicted value, and stage3 is defined as an FEV₁ value of less than 35 percent of the predicted value. A problem common to all patients with COPD, regardless of disease severity, is acute exacerbation of chronic bronchitis, with some or all of the cardinal symptoms of increased dyspnea, increased sputum volume, and increased sputum purulence. Treatment for exacerbation remains controversial. Some authors suggest that acute exacerbation is noninfectious in nature and does not require treatment. Other studies have shown that treating acute exacerbations of chronic bronchitis with an antibiotic decreases the duration of illness and improves peak flow measurements. The selection of antibiotic is important because one study showed that second-line agents perform better than first-line agents. In addition, the advanced-generation macrolide and fluoroquinolone agents provide a broader spectrum of coverage and improved outcomes in patients with acute exacerbation of chronic bronchitis of bacterial origin. However, recent increases in Streptococcus pneumoniae resistance to macrolides have called this strategy into question. Amsden and associates compared the safety and efficacy of oral azithromycin and levofloxacin in the outpatient treatment of patients with acute bacterial exacerbation of chronic bronchitis.

The trial was a randomized, double-blind, double-dummy, multicenter trial. Patients included in the study were between 35 and 75 years of age with a history of chronic bronchitis, had purulent sputum that was positive for bacteria either by Gram stain or culture, and had at least two of the three cardinal symptoms of acute exacerbation of chronic bronchitis. Before enrollment, each participant's clinical findings, pulse oximetry values, arterial blood gas measurements, and FEV₁ values were recorded. The patients were randomized to receive azithromycin in a dosage of 500 mg on day 1 and 250 mg per day on days 2 through 5, or levofloxacin in a dosage of 500 mg daily for seven days. Patients were reassessed on day 4 of therapy for clinical and laboratory responses and for adverse reactions to the medication. This same assessment was repeated on day 24 after the initial screen.

Of the 235 patients enrolled in the study, 118 received azithromycin and 117 received levofloxacin. Both medications were well tolerated, with 21 patients (18 percent) in the azithromycin group and 23 patients (20 percent) in the levofloxacin group reporting mild to moderate adverse reactions. The majority of these reactions were gastrointestinal symptoms. By day 4 of therapy, 89 percent of the patients receiving azithromycin and 92 percent of those receiving levofloxacin had favorable clinical outcomes. At day 24, 82 percent and 86 percent had favorable responses to azithromycin and levofloxacin, respectively. Azithromycin and levofloxacin also had similar bacterial eradication rates.

The authors conclude that in the treatment of acute bacterial exacerbation of chronic bronchitis the standard five-day regimen of azithromycin results in outcomes similar to those resulting from a seven-day course of levofloxacin. These agents remain an effective and safe treatment option in patients with this condition, despite concerns about macrolide resistance.