Levofloxacin Adult Dosing
For adults with normal renal function (creatinine clearance ≥50 mL/min), levofloxacin is dosed at 250 mg, 500 mg, or 750 mg orally once every 24 hours, depending on the specific infection being treated. 1
Standard Dosing by Indication
Respiratory Tract Infections
- Community-acquired pneumonia (CAP): 750 mg once daily for 5 days (high-dose short-course) or 500 mg once daily for 7-14 days 2, 1, 3
- Acute bacterial sinusitis: 750 mg once daily for 5 days or 500 mg once daily for 10-14 days 4, 1
- Acute exacerbations of chronic bronchitis: 500 mg once daily for 7 days 4, 1
Urinary Tract Infections
- Complicated UTI and acute pyelonephritis: 750 mg once daily for 5 days or 250 mg once daily for 10 days 1, 3
- Uncomplicated UTI: 250 mg once daily for 3 days 1
Skin and Soft Tissue Infections
- Uncomplicated skin infections: 500 mg once daily for 7-10 days 1, 5
- Complicated skin and skin structure infections: 750 mg once daily for 7-14 days 2, 1
Severe/Resistant Infections
- Drug-resistant tuberculosis: 750-1,000 mg once daily, with 1,000 mg representing the optimal balance between efficacy and tolerability 4
- Anthrax post-exposure prophylaxis: 500 mg once daily for 60 days 6
Renal Dose Adjustments
Dose adjustment is mandatory when creatinine clearance falls below 50 mL/min, as levofloxacin is 80% renally eliminated unchanged. 2, 4, 1
- CrCl 50-80 mL/min: 500 mg loading dose, then 250 mg every 24 hours 2
- CrCl 20-49 mL/min: Adjust based on initial dose (see FDA label for specific adjustments) 1
- CrCl 10-19 mL/min: Further reduction required 1
- Hemodialysis patients: 750-1,000 mg three times weekly, administered after dialysis 2
Administration Considerations
Timing with Other Medications
Administer levofloxacin at least 2 hours before or 2 hours after antacids containing magnesium or aluminum, sucralfate, metal cations (iron), multivitamins with zinc, or didanosine, as these agents markedly decrease fluoroquinolone absorption. 4, 1, 7
Food and Hydration
- Levofloxacin can be taken without regard to food, as bioavailability approaches 100% and is minimally affected by food 1, 7
- Maintain adequate hydration to prevent crystalluria, particularly in patients with history of kidney stones 2, 1
High-Dose Short-Course Rationale
The 750 mg once-daily regimen maximizes concentration-dependent bactericidal activity, optimizes the peak:MIC ratio critical for bacterial eradication, and may reduce potential for resistance emergence. 2, 3, 8 This regimen produces peak plasma concentrations of approximately 9-12 mg/L, which is critical for efficacy against serious infections 2.
Critical Warnings and Monitoring
Cardiac Monitoring
- Obtain baseline ECG in elderly patients or those with risk factors for QT prolongation 4
- Monitor ECG at baseline, 2 weeks, and after adding any QT-prolonging medication 4
Blood Glucose
- Monitor blood glucose regularly in diabetic patients, as fluoroquinolones carry risk of hypoglycemia 4
Contraindications
- Avoid in pregnancy due to teratogenic effects 2, 4
- Use cautiously in patients with history of tendon disorders, particularly if on concurrent corticosteroids 4
Common Pitfalls to Avoid
- Do not use 500 mg when 750 mg is indicated for severe infections, as suboptimal peak concentrations can lead to treatment failure with concentration-dependent killing 2
- Do not forget renal dose adjustment in elderly patients, who commonly have reduced renal function even with normal serum creatinine 2, 4
- Do not use as monotherapy for intra-abdominal infections—must combine with metronidazole 500 mg every 8-12 hours for anaerobic coverage 2