Azithromycin (Z-pack) Dosing Guidelines
The standard Z-pack (azithromycin) dosing regimen is 500 mg on day 1, followed by 250 mg once daily on days 2 through 5 for most common infections. 1
Adult Dosing Regimens
Standard 5-day Z-pack:
- Day 1: 500 mg as a single dose
- Days 2-5: 250 mg once daily
- Total dose: 1.5 grams
Alternative Regimens Based on Indication:
Acute Bacterial Exacerbations of COPD:
- Option 1: 500 mg once daily for 3 days
- Option 2: Standard 5-day regimen (500 mg day 1, then 250 mg days 2-5)
Acute Bacterial Sinusitis:
- 500 mg once daily for 3 days
Sexually Transmitted Infections:
- Non-gonococcal urethritis/cervicitis: 1 gram as a single dose
- Gonococcal urethritis/cervicitis: 2 grams as a single dose
- Chancroid: 1 gram as a single dose
Pediatric Dosing
Acute Otitis Media:
- Option 1: 30 mg/kg as a single dose
- Option 2: 10 mg/kg once daily for 3 days
- Option 3: 10 mg/kg on day 1, followed by 5 mg/kg/day on days 2-5
Acute Bacterial Sinusitis:
- 10 mg/kg once daily for 3 days
Community-Acquired Pneumonia:
- 10 mg/kg on day 1, followed by 5 mg/kg on days 2-5
Pharyngitis/Tonsillitis:
- 12 mg/kg once daily for 5 days (maximum 500 mg/day)
Special Considerations
Renal Impairment:
- No dosage adjustment needed for GFR 10-80 mL/min
- Use caution in severe renal impairment (GFR <10 mL/min)
Administration:
- Can be taken with or without food
- If taken with food, absorption may be reduced by up to 50%
Long-term Therapy (for conditions like bronchiectasis)
For chronic conditions requiring long-term therapy:
- 500 mg three times per week OR
- 250 mg daily OR
- 250 mg three times per week if side effects occur with higher dosing 2
Important Considerations
Advantages of Z-pack:
- Once-daily dosing improves compliance
- Short treatment duration (typically 3-5 days)
- Extensive tissue distribution with prolonged half-life
- Continues to be effective for several days after administration has ceased 3
Common Side Effects:
- Gastrointestinal: nausea, vomiting, abdominal pain, diarrhea
- Generally better tolerated than erythromycin 4
Monitoring for Long-term Use:
- ECG monitoring (baseline, 2 weeks, and after adding QT-prolonging medications)
- Periodic laboratory tests and audiometry for patients on extended therapy 2
The Z-pack's unique pharmacokinetics allow for short-duration therapy with excellent tissue penetration, making it an effective and convenient option for many common infections.