Pharm

Azithromycin

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Azithromycin, Zithromax

  • See also
  1. Macrolide
  2. Erythromycin
  • Indications
  1. Activity Spectrum
    1. Spectrum includes organisms covered by Erythromycin
    2. Increasing Macrolide resistance for most indications
    3. HaemophilusInfluenzae
    4. Moraxella catarrhalis
    5. Toxoplasmosis gondii
    6. Mycobacterium Avium Complex (Clarithromycin better)
    7. Borrelia Burgdorferi
  2. Conditions
    1. Single dose Chlamydia trachomatis treatment
    2. Non-tuberculous Mycobacterial infections
    3. Helicobacter infections
    4. Community Acquired Pneumonia
      1. Limit to suspected Mycoplasma pneumonia or Legionella pneumonia
      2. Macrolide resistant pneumococcus is common
      3. Consider Doxycycline as alternative
    5. Streptococcal Pharyngitis (second line agent)
      1. Macrolides are only indicated in significant allergy to beta-lactams
    6. Original indications that have fallen out of favor due to Antibiotic Resistance
      1. Otitis Media
        1. Not recommended due to increased resistance rates
      2. Acute Sinusitis
        1. Not recommended due to growing resistance rates
  3. References
    1. (2013) Presc Lett 20(8): 44
  • Medications
  1. Intravenous
  2. Tablets: 250, 500, 600 mg
  3. Oral suspension: 100 ro 200 mg per 5 ml
    1. Take on an empty Stomach
  4. Packs
    1. Z-Pak: 500 mg day 1, 250 mg days 2 to 5
    2. Tri-Pak: 500 mg tabs x3
    3. Packet containing 1000 mg
  • Dosing
  1. See Pertussis
  2. See Chlamydia trachomatis
  3. Take more than 1 hour before or 2 hours after food
  4. General Dosing
    1. Adult
      1. Day 1: 500 mg orally daily
      2. Day 2 to 5: 250 mg orally daily
    2. Child
      1. Day 1: 10 mg/kg orally daily (maximum: 500 mg)
      2. Day 2 to 5: 5 mg/kg orally daily (maximum: 250 mg)
    3. Infant under age 6 months
      1. 10 mg/kg/day for 5 days
  5. Group A Streptococcal Pharyngitis (second line agent in beta lactam allergy)
    1. Take 12 mg/kg up to 500 mg orally daily for 5 days
  6. Acute Exacerbation of Chronic Bronchitis
    1. Adult: Take 500 mg orally daily for 3 days
  7. Chlamydia, Chancroid or Nongonococcal Urethritis
    1. Adult: Take 1 gram orally once
    2. Doxycycline for 7 days is preferred
  8. Mycobacterium Avium Complex Disease (e.g. AIDS)
    1. Adult: Take 1200 mg orally once weekly
    2. Active disease is treated with at least 2 drugs
  • Pharmacokinetics
  1. Half Life: 68 hours
  • Adverse Effects
  1. See Macrolide
  2. Hypertrophic Pyloric Stenosis
    1. Infants age <45 days
  3. QT Prolongation with Azithromycin
    1. Class effect with Macrolides
    2. Three fold increased risk of Sudden Cardiac Death while on Azithromycin
    3. Higher risk with known QTc Prolongation, Hypokalemia, Hypomagnesemia, Class IA or III Antiarrhythmics
    4. Ray (2013) N Engl J Med 366(20): 1881-90 [PubMed]
  • Safety
  1. Considered safe in Lactation
  2. Pregnancy Category C
    1. Macrolides in general (including Azithromycin) may increase heart defects with first trimester exposure of 5-7 days
    2. Previously only Clarithromycin was considered a potential Teratogen (Cleft Lip association)
    3. Fan (2020) BMJ 368: m331 +PMID:32075790 [PubMed]
  • Drug Interactions
  1. Drug-Induced QTc Prolongation
    1. Avoid combining with other agents that prolong QTc
  2. Warfarin
    1. May increase INR
  3. Aluminum or MagnesiumAntacids
    1. May interfere with Azithromycin absorption
  • Resources
  1. Azithromycin Tablet (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d470695c-c0d7-4361-8783-45f58a932ac4