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Drugs Dictionary: Azithromycin

Azithromycin

Trade Name

Zithromax, Z-Pak (common brand names); generic azithromycin

Classification

Macrolide antibiotic

Dosage/Route

  • * Dosage:
    •      – Tablets: 250 mg, 500 mg, 600 mg
    •      – Suspension: 100 mg/5 mL, 200 mg/5 mL
    •      – IV: 500 mg vial
  • * Route: Oral (PO), intravenous (IV)

Usual Dosage

  • * Adults:
    •      – Community-acquired pneumonia (CAP): 500 mg PO day 1, then 250 mg PO daily days 2-5 (Z-Pak)
    •      – Chlamydia: 1 g PO single dose
    •      – IV (severe CAP): 500 mg IV daily for 1-2 days, then PO
  • * Children:
    •      – 10 mg/kg PO day 1, then 5 mg/kg PO daily days 2-5 (max 500 mg day 1, 250 mg thereafter)
  • * Duration: 3-5 days typically (shorter than other antibiotics)

Mechanism of Action

Binds to the 50S ribosomal subunit of bacterial RNA, inhibiting protein synthesis. Bacteriostatic (sometimes bactericidal at high doses) against gram-positive (e.g., Streptococcus), some gram-negative (e.g., H. influenzae), and atypical bacteria (e.g., Mycoplasma, Chlamydia)

Side Effects & Adverse Effects

  • * Side Effects: Nausea, diarrhea, abdominal pain, headache.
  • * Adverse Effects:
    •      – QT prolongation (arrhythmias, torsades de pointes; boxed warning).
    •      – Clostridioides difficile-associated diarrhea (CDAD).
    •      – Hepatotoxicity (rare; jaundice, elevated LFTs).
    •      – Hypersensitivity (rash, anaphylaxis, rare)

Nursing Management (Implications & Teachings)

  • * Implications:
    •      – Monitor ECG (QT interval) in patients with CV risk or on QT-prolonging drugs (e.g., amiodarone)
    •      – Assess for diarrhea (CDAD risk) and liver function (jaundice)
    •      – IV: Infuse 500 mg over 1-3 hours (1 mg/mL or 2 mg/mL dilution); avoid rapid push
    •      – PO: Give 1 hr before or 2 hr after meals (food delays absorption)
  • * Teachings:
    •      – Finish full course; take as prescribed
    •      – Report palpitations, severe diarrhea, or yellow skin
    •      – Avoid antacids (aluminum/magnesium) within 2 hours (reduce absorption)
    •      – Store suspension at room temp; shake well

Indication for This Patient

  • * Bacterial infections:
    •      – Respiratory (e.g., CAP, bronchitis, sinusitis)
    •      – STDs (e.g., Chlamydia)
    •      – Otitis media, pharyngitis (Streptococcus)
  • * Mycobacterium avium complex (MAC) prophylaxis/treatment (HIV patients)

Time

  • * Timing: PO: Once daily; IV: Daily (1-3 hr infusion)
  • * Onset: Symptom relief in 1-3 days
  • * Duration: 3-5 days (or single dose for Chlamydia)

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