What is the recommended dosage of Azithromycin for bacterial infections?

Azithromycin Dosage Recommendations for Bacterial Infections

The recommended dosage of azithromycin for bacterial infections in adults is 500 mg on day 1 followed by 250 mg daily for days 2-5, or alternatively 500 mg daily for 3 days depending on the infection type. 1

Adult Dosing Regimens

Respiratory Tract Infections

• Community-acquired pneumonia (mild severity): 500 mg as a single dose on Day 1, followed by 250 mg once daily on Days 2 through 5 1
• Acute bacterial exacerbations of COPD (mild to moderate):
  • 500 mg daily for 3 days OR
  • 500 mg on Day 1, followed by 250 mg once daily on Days 2 through 5 1
• Acute bacterial sinusitis: 500 mg daily for 3 days 1

Skin and Soft Tissue Infections

• 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

Sexually Transmitted Infections

• Non-gonococcal urethritis and cervicitis: One single 1 gram dose 1
• Genital ulcer disease (chancroid): One single 1 gram dose 1
• Gonococcal urethritis and cervicitis: One single 2 gram dose 1

Pediatric Dosing Regimens

Otitis Media

• 5-day regimen: 10 mg/kg on day 1, then 5 mg/kg on days 2-5 1
• 3-day regimen: 10 mg/kg daily for 3 days 1
• 1-day regimen: 30 mg/kg as a single dose 1

Acute Bacterial Sinusitis

• 10 mg/kg once daily for 3 days 1

Community-Acquired Pneumonia

• 10 mg/kg on day 1, followed by 5 mg/kg on days 2-5 1

Pharyngitis/Tonsillitis

• 12 mg/kg once daily for 5 days 1
• Note: Higher dose than other pediatric indications due to potential for recurrence with lower dosing 2

Special Populations

Renal Impairment

• No dosage adjustment needed for GFR 10-80 mL/min
• Use caution in severe renal impairment (GFR <10 mL/min) as AUC increases by 35% 1

Hepatic Impairment

• No specific dosage recommendations available for hepatic impairment 1

Immunocompromised Patients

• Higher doses of azithromycin (600-1000 mg per day) may be used 3

Administration Considerations

• Can be taken with or without food 1
• Taking with a large meal may reduce absorption by up to 50% 4
• The large volume of distribution (23 L/kg) and intracellular accumulation contribute to its efficacy despite relatively low serum levels 4

Common Pitfalls and Caveats

1. Resistance concerns: Prolonged subinhibitory concentrations due to azithromycin's long half-life (up to 5 days) may promote development of resistant strains 3

2. Food interactions: While azithromycin can be taken with or without food, large meals may reduce absorption by up to 50% 4

3. Duration of therapy: Despite its long tissue half-life, shorter courses (3-day) have shown similar efficacy to 5-day courses for many infections 5

4. Gastrointestinal side effects: Though better tolerated than erythromycin, the most common adverse events are gastrointestinal (nausea, diarrhea, abdominal pain) 4

5. Pediatric dosing variation: Note that pharyngitis/tonsillitis requires a higher dose (12 mg/kg/day) than other pediatric indications (10 mg/kg/day) 1, 2

Azithromycin's unique pharmacokinetic profile allows for shorter treatment courses and once-daily dosing, with tissue concentrations remaining above MICs for common pathogens for up to 10 days after completion of therapy 6.