What is the use of azithromycin (Zithromax)?

From the Guidelines

Azithromycin is recommended as a therapeutic option to prevent acute exacerbations of COPD in patients with a history of exacerbations, despite potential safety concerns, as it has been shown to reduce the frequency of acute exacerbations and improve lung function 1.

Key Points

• Azithromycin is a macrolide antibiotic that has been used to prevent acute exacerbations of COPD, with a dose of 250 mg daily for 1 year showing significant reduction in exacerbation rate 1.
• The use of azithromycin in COPD patients has been associated with a reduced risk of acute exacerbations, with a relative risk of 0.83 (95% CI, 0.72-0.95) compared to placebo 1.
• However, azithromycin therapy has also been linked to potential safety concerns, including the development of antibiotic resistance, hearing loss, and cardiovascular side effects, although these were not observed in the randomized trials reviewed for the guidelines 1.
• In patients with moderate to severe COPD, who have a history of one or more moderate or severe COPD exacerbations in the previous year despite optimal maintenance inhaler therapy, the use of a long-term macrolide such as azithromycin is suggested (Grade 2A) to prevent acute exacerbations of COPD 1.

Considerations

• The decision to use azithromycin should be based on a careful evaluation of the patient's individual risk factors and medical history, including the presence of QT prolongation or other conditions that may increase the risk of cardiovascular side effects 1.
• Patients should be monitored for potential adverse effects, including hearing loss and antibiotic resistance, and the duration and exact dosage of macrolide therapy should be tailored to the individual patient's needs 1.
• Azithromycin has also been shown to be effective in the treatment of other conditions, such as travelers' diarrhea and cystic fibrosis, with a single 1-gm dose or 500 mg daily for 3 days being effective in achieving clinical cure in travelers' diarrhea 1, and 250 mg daily or three times weekly being effective in improving lung function and reducing pulmonary exacerbations in cystic fibrosis patients 1.

From the FDA Drug Label

Azithromycin Tablets, USP are indicated for the treatment of patients with mild to moderate infections (pneumonia: see WARNINGS) caused by susceptible strains of the designated microorganisms in the specific conditions listed below Adults Acute bacterial exacerbations of chronic obstructive pulmonary disease due to Haemophilus influenzae, Moraxella catarrhalis or Streptococcus pneumoniae Acute bacterial sinusitis due to Haemophilus influenzae, Moraxella catarrhalis or Streptococcus pneumoniae. Community-acquired pneumonia due to Chlamydophila pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae or Streptococcus pneumoniae in patients appropriate for oral therapy Pharyngitis/tonsillitis caused by Streptococcus pyogenes as an alternative to first-line therapy in individuals who cannot use first-line therapy Uncomplicated skin and skin structure infections due to Staphylococcus aureus, Streptococcus pyogenes, or Streptococcus agalactiae Urethritis and cervicitis due to Chlamydia trachomatis or Neisseria gonorrhoeae. Genital ulcer disease in men due to Haemophilus ducreyi (chancroid).

Azithromycin is used to treat various bacterial infections, including:

• Acute bacterial exacerbations of chronic obstructive pulmonary disease
• Acute bacterial sinusitis
• Community-acquired pneumonia
• Pharyngitis/tonsillitis
• Uncomplicated skin and skin structure infections
• Urethritis and cervicitis
• Genital ulcer disease in men due to Haemophilus ducreyi (chancroid) 2

From the Research

Overview of Azithromycin

• Azithromycin is a macrolide antibiotic with an expanded spectrum of activity and improved tissue pharmacokinetic characteristics relative to erythromycin 3, 4.
• It is effective against some Gram-negative organisms associated with respiratory tract infections, particularly Haemophilus influenzae 3, 5.
• Azithromycin has similar activity to other macrolides against Streptococcus pneumoniae and Moraxella catarrhalis, and is active against atypical pathogens such as Legionella pneumophila, Chlamydia pneumoniae, and Mycoplasma pneumoniae 3.

Use in Respiratory Tract Infections

• Azithromycin is used to treat lower respiratory tract infections, including acute exacerbations of chronic bronchitis, community-acquired pneumonia, and cystic fibrosis 4, 5.
• A 3-day oral regimen of once-daily azithromycin has been shown to be as effective as 5- to 10-day courses of other antibacterial agents in patients with acute exacerbations of chronic bronchitis, pneumonia, sinusitis, pharyngitis, tonsillitis, and otitis media 3.
• Azithromycin tends to be more effective in terms of lower incidence of treatment failure and adverse events than amoxycillin or amoxyclav in patients with acute bronchitis of a suspected bacterial cause 5.

Safety and Effectiveness

• Azithromycin has been found to have high clinical effectiveness and a small number of adverse events in the treatment of lower respiratory tract infections 6.
• The most common adverse events associated with azithromycin are gastrointestinal in nature, such as abdominal pain, diarrhea, and vomiting 3, 6.
• Azithromycin may also have anti-inflammatory and immunomodulatory effects, which may be beneficial in the treatment of viral infections such as COVID-19 7.

Potential Use in Viral Infections

• Azithromycin may affect molecular pathways involved in inflammatory immunity upon viral infection, leading to a reduction of viral replication and a strong impairment of inflammatory pathways 7.
• The mechanism of action of azithromycin in viral infection may be dependent on a global amplification of interferon-dependent pathways mediating antiviral responses, together with a strong impairment of the inflammatory pathways relying on MAPK cascade inactivation 7.