Z-Pack (Azithromycin) Dosing for Bacterial Infections
The typical Z-pack (azithromycin) dosage for treating most bacterial infections in adults is 500 mg on day 1, followed by 250 mg once daily for days 2 through 5, for a total of 1.5 grams. 1
Standard Dosing Regimens for Adults
For community-acquired pneumonia (mild severity), pharyngitis/tonsillitis (second-line therapy), and uncomplicated skin/skin structure infections: 500 mg as a single dose on day 1, followed by 250 mg once daily on days 2 through 5 1
For acute bacterial exacerbations of chronic obstructive pulmonary disease (mild to moderate) and acute bacterial sinusitis: Either 500 mg daily for 3 days OR 500 mg on day 1 followed by 250 mg daily for days 2-5 1
For genital ulcer disease (chancroid) and non-gonococcal urethritis/cervicitis: One single 1-gram dose 1
For gonococcal urethritis and cervicitis: One single 2-gram dose 1
Alternative Regimens for Specific Conditions
For upper respiratory infections: 500 mg daily for 3 days OR 500 mg on day 1 followed by 250 mg daily for 4 days 2
For travelers' diarrhea with dysentery: Single 1-gram dose OR 500 mg daily for 3 days 3
Administration Guidelines
- Azithromycin tablets can be taken with or without food 1
- Taking with food may reduce gastrointestinal side effects, although large meals may reduce absorption by up to 50% 4
- For optimal effectiveness, complete the full course of therapy even if symptoms improve before completion 1
Special Populations
Renal Impairment
- No dosage adjustment is recommended for patients with GFR >10 mL/min 1
- Use caution in patients with severe renal impairment (GFR <10 mL/min) as AUC may increase by 35% 1
Hepatic Impairment
- No specific dose adjustment recommendations are available for patients with hepatic impairment 1
- Monitor for side effects in patients with liver disease 1
Pediatric Dosing
- For acute otitis media: 30 mg/kg as a single dose OR 10 mg/kg once daily for 3 days OR 10 mg/kg on day 1 followed by 5 mg/kg/day on days 2-5 1
- For acute bacterial sinusitis: 10 mg/kg once daily for 3 days 1
- For community-acquired pneumonia: 10 mg/kg on day 1 followed by 5 mg/kg on days 2-5 1
- For pharyngitis/tonsillitis: 12 mg/kg once daily for 5 days (for children 2 years and above) 1
Safety Considerations
- Before initiating therapy in patients with cardiac risk factors, an ECG should be performed to assess QTc interval 2
- Avoid azithromycin if QTc is >450 ms for men and >470 ms for women 2
- Most common adverse effects are gastrointestinal (nausea, diarrhea, abdominal pain) 4
- Gastrointestinal tolerance is better than that of erythromycin 4
- Incident or worsening nausea or vomiting occur in approximately 3% of patients with gastrointestinal infections 3
Clinical Efficacy
- Clinical studies show high cure rates (>80%) for respiratory tract infections, skin and soft tissue infections, and sexually transmitted infections 4, 5
- Most patients with respiratory infections become afebrile within 48 hours of starting treatment 6
- The unique pharmacokinetics of azithromycin are characterized by high, sustained tissue concentrations, allowing for shorter treatment courses than many other antibiotics 7
- Three-day and five-day regimens have shown equivalent efficacy in the treatment of atypical pneumonia 6
Antimicrobial Stewardship Considerations
- Limit antibiotic exposure whenever possible to minimize development of resistance 2
- Consider viral etiology of many respiratory infections before prescribing antibiotics 2
- Treatment with the shortest effective duration will minimize exposure of both pathogens and normal microbiota to antimicrobials 2
- Assess response to therapy at days 5-7 (improvement of symptoms) 2