Levofloxacin Dosing: Once Daily (OD)
Levofloxacin should be dosed once daily (OD), not twice daily (BD), for virtually all indications in adults and most pediatric patients. 1, 2
Standard Adult Dosing
The FDA-approved dosing for levofloxacin is once daily administration across all major indications 2:
- Community-acquired pneumonia: 500 mg once daily for 7-14 days, or high-dose 750 mg once daily for 5 days 1, 3, 4
- Complicated urinary tract infections/acute pyelonephritis: 750 mg once daily for 5 days, or 250 mg once daily for 10 days 2, 4
- Complicated skin infections: 750 mg once daily for 7-14 days 2, 5
- Drug-resistant tuberculosis: 750-1000 mg once daily (doses up to 1,250 mg have been used safely) 6
Pediatric Dosing Considerations
For children older than 5 years, levofloxacin is dosed once daily 6:
- Children ≥5 years: 10 mg/kg once daily (maximum 750 mg) 6
- Exception for young children (<5 years): 7.5-10 mg/kg divided twice daily (BD) is recommended due to faster drug clearance in this age group 6
The twice-daily dosing in young children is specifically noted: "For children younger than 5 yr of age, this dosage of levofloxacin should be given twice a day" 6. This reflects pharmacokinetic differences in younger children requiring split dosing to maintain therapeutic levels.
Pharmacokinetic Rationale for Once-Daily Dosing
The once-daily regimen is supported by levofloxacin's pharmacokinetic profile 4, 7, 8:
- Long half-life: 7-8 hours allows sustained therapeutic concentrations 8
- High bioavailability: Oral formulation is bioequivalent to IV, enabling seamless transitions 3, 4
- Concentration-dependent killing: Once-daily dosing maximizes peak concentration (Cmax), enhancing bactericidal activity 4, 5
- Extended mean residence time: 10.4-10.5 hours maintains adequate drug exposure 8
Clinical Advantages of Once-Daily Dosing
The once-daily regimen improves patient compliance and may reduce resistance development 3, 4:
- Better adherence with single daily dose versus multiple doses 4
- Maximizes concentration-dependent antibacterial activity 4, 5
- Shorter treatment courses (e.g., 5 days with 750 mg) maintain efficacy while reducing exposure duration 3, 4
Important Caveats
Renal dose adjustment is required for creatinine clearance <50 mL/min, though specific frequency may need modification rather than switching to twice-daily dosing 6, 1. The once-daily principle is generally maintained even with dose reductions.
The only exception to once-daily dosing is children under 5 years, where twice-daily administration accounts for developmental pharmacokinetic differences 6.