Azyben

Approved Indications:

• Respiratory Tract Infections:
• Community-acquired pneumonia (mild to moderate) caused by susceptible organisms.
• Acute bacterial exacerbations of chronic bronchitis.
• Pharyngitis and tonsillitis due to Streptococcus pyogenes.
• Acute bacterial sinusitis.
• Skin and Soft Tissue Infections:
• Uncomplicated skin and skin structure infections caused by susceptible strains of Staphylococcus aureus and Streptococcus pyogenes.
• Sexually Transmitted Infections:
• Uncomplicated Chlamydia trachomatis infections of the cervix and urethra.
• Urethritis and cervicitis caused by Neisseria gonorrhoeae (in combination therapy).
• Non-gonococcal urethritis (NGU) and cervicitis.
• Ear Infections:
• Acute otitis media caused by susceptible bacteria.
• Other Clinically Accepted Uses (Off-label):
• Prevention of Mycobacterium avium complex (MAC) infections in HIV-infected patients.
• Traveler’s diarrhea caused by Campylobacter jejuni or Shigella.
• Some atypical infections caused by Mycoplasma pneumoniae and Legionella pneumophila.

Route: Oral and intravenous.

Adults:

• Respiratory Tract Infections:
• 500 mg once daily for 3 days, or
• 500 mg on day 1 followed by 250 mg once daily on days 2 through 5.
• Skin and Soft Tissue Infections:
• 500 mg once daily for 5 days.
• Sexually Transmitted Infections:
• Single 1 gram oral dose for uncomplicated Chlamydia infection.
• Mycobacterium avium complex prophylaxis:
• 1200 mg once weekly.

Pediatrics:

• Dosage based on body weight (generally 10 mg/kg once daily for 3 days).
• For specific infections, dosing regimens may vary; consult pediatric guidelines.

Elderly:

• No specific dose adjustment required; monitor renal function.

Renal Impairment:

• No dose adjustment needed for mild to moderate impairment; use with caution in severe impairment.

Hepatic Impairment:

• Use with caution; no specific dosing recommendations available.

Administration Notes:

• Oral tablets or suspension can be taken with or without food.
• Intravenous administration for patients unable to take oral medication; followed by oral therapy as clinically indicated.

Azithromycin is a macrolide antibiotic that inhibits bacterial protein synthesis by binding reversibly to the 50S ribosomal subunit of susceptible bacteria. This binding blocks the translocation of peptides during translation, inhibiting bacterial growth (bacteriostatic effect) and, at higher concentrations, may be bactericidal. Its broad spectrum covers many gram-positive, gram-negative, and atypical pathogens, providing effective treatment against respiratory, skin, and sexually transmitted infections.

• Absorption:
  Oral bioavailability ~37%; peak plasma concentrations achieved 2–3 hours post-dose.
• Distribution:
  Extensive tissue penetration; high intracellular concentrations in phagocytes and fibroblasts.
  Large volume of distribution (~31 L/kg).
• Metabolism:
  Minimal hepatic metabolism; largely unmetabolized.
• Elimination Half-life:
  Approximately 68 hours, supporting once-daily dosing and short-course therapy.
• Excretion:
  Primarily biliary excretion; less than 6% excreted unchanged in urine.

• Pregnancy:
  Classified as Category B by FDA. Animal studies show no evidence of harm to fetus; no well-controlled human studies but generally considered safe when clearly needed.
• Lactation:
  Excreted in breast milk in low concentrations; caution advised during breastfeeding.

• Primary Therapeutic Class: Antibiotic
• Subclass: Macrolide antibiotic

• Known hypersensitivity to azithromycin, erythromycin, or other macrolides.
• History of cholestatic jaundice or hepatic dysfunction associated with prior macrolide use.

• May cause QT prolongation; use with caution in patients with cardiac conduction abnormalities or on other QT-prolonging drugs.
• Rare reports of hepatotoxicity, including fatal hepatic failure.
• Monitor for Clostridioides difficile-associated diarrhea.
• Use caution in patients with myasthenia gravis due to risk of exacerbation.
• Allergic reactions, including anaphylaxis, have been reported.

Common:

• Gastrointestinal: Diarrhea, nausea, abdominal pain, vomiting.
• Headache.

Serious but Rare:

• QT interval prolongation, arrhythmias.
• Hepatotoxicity (including cholestatic hepatitis).
• Severe allergic reactions (anaphylaxis, Stevens-Johnson syndrome).
• Clostridioides difficile-associated diarrhea.

• May increase plasma concentrations of drugs metabolized by CYP3A4 (e.g., warfarin, theophylline, carbamazepine).
• Caution with other QT-prolonging agents (e.g., amiodarone, quinidine).
• Antacids containing aluminum or magnesium may reduce azithromycin absorption; separate dosing by at least 2 hours.
• Potential interaction with ciclosporin increasing nephrotoxicity risk.

• Recommended as first-line treatment for certain respiratory tract infections and chlamydial infections in recent clinical guidelines.
• Increasing awareness of QT prolongation risk leading to more cautious use in at-risk populations.
• Ongoing surveillance for macrolide resistance in pathogens.

• Store at 20°C to 25°C (68°F to 77°F).
• Protect from moisture and light.
• Keep suspension formulations refrigerated (2°C to 8°C) and discard after 10 days.
• Tablets should be kept in a dry place away from excessive heat.