Recommended Dosages of Fluoroquinolones for Treating Infections
For most infections, ciprofloxacin should be dosed at 500 mg orally twice daily, while levofloxacin should be dosed at 750 mg orally once daily, with adjustments based on the specific infection type and severity. 1
General Dosing Guidelines for Common Fluoroquinolones
Ciprofloxacin
- For uncomplicated urinary tract infections: 250-500 mg orally twice daily for 3-7 days 1
- For complicated urinary tract infections and pyelonephritis: 500 mg orally twice daily for 7-14 days 1
- For respiratory tract infections: 500 mg orally twice daily for 7-14 days 2
- For skin and skin structure infections: 500 mg orally twice daily for 7-14 days 2
- For bone and joint infections: 500 mg orally twice daily for extended duration (typically 4-6 weeks) 2
- For gastrointestinal infections: 500 mg orally twice daily for 5-7 days 3
- For gonorrhea: 500 mg orally as a single dose 1
- For intravenous administration: 400 mg IV every 8-12 hours 1, 4
Levofloxacin
- For uncomplicated UTI: 250 mg orally once daily for 3 days 1
- For complicated UTI and pyelonephritis: 750 mg orally once daily for 5 days 1
- For respiratory infections: 750 mg orally once daily for 5-14 days (depending on severity) 1
- For intravenous administration: 250-750 mg IV once daily 1
Special Considerations for Specific Infections
Pyelonephritis
- Ciprofloxacin: 500 mg orally twice daily for 7 days, with or without an initial 400 mg IV dose 1
- Extended-release ciprofloxacin: 1000 mg orally once daily for 7 days 1
- Levofloxacin: 750 mg orally once daily for 5 days 1
- For patients requiring hospitalization: Start with IV therapy (ciprofloxacin 400 mg every 12 hours or levofloxacin 250-750 mg daily) 1
Gonorrhea
- Ciprofloxacin: 500 mg orally as a single dose (if susceptibility is known) 1
- Note: Due to increasing resistance, fluoroquinolones are no longer recommended as first-line therapy for gonorrhea in many regions 1
Disseminated Gonococcal Infection
- Ciprofloxacin: 400 mg IV every 12 hours initially, then switch to 500 mg orally twice daily to complete at least 1 week of therapy 1
- Levofloxacin: 250 mg IV daily initially, then switch to 500 mg orally once daily to complete at least 1 week of therapy 1
Dosing Considerations
Renal Impairment
- Dosage reduction is required for patients with creatinine clearance <30 ml/min 4
- For severe renal dysfunction, reduce the dose by up to 50% while maintaining the same dosing interval 4
Pharmacokinetic Considerations
- Fluoroquinolones exhibit concentration-dependent killing 1
- For aminoglycosides and fluoroquinolones, optimal dosing strategies involve optimizing peak drug plasma concentrations 1
- For ciprofloxacin, an approach that optimizes the dose within a nontoxic range (e.g., 600 mg every 12 hours with preserved renal function) provides the highest probability of favorable outcomes 1
Caveats and Pitfalls
- Always check local resistance patterns before prescribing fluoroquinolones, especially for empiric therapy 1
- If fluoroquinolone resistance exceeds 10% in the community, consider adding or substituting an initial dose of a long-acting parenteral antimicrobial (e.g., ceftriaxone 1g) 1
- Fluoroquinolones are contraindicated in pregnant or nursing women and in persons ≤17 years of age based on animal studies 1
- Quinolones are not active against Treponema pallidum and may not adequately treat incubating syphilis 1
- For complicated infections, always obtain cultures and susceptibility testing to guide therapy 1
By following these dosing guidelines and considering the specific infection type, patient factors, and local resistance patterns, clinicians can optimize the effectiveness of fluoroquinolone therapy while minimizing the risk of treatment failure and antimicrobial resistance.