Levofloxacin Injection Dosing Frequency
Levofloxacin injection should be administered once daily (OD), not twice daily (BD), for virtually all indications. 1, 2
Standard Dosing Regimen
The concentration-dependent bactericidal activity of fluoroquinolones like levofloxacin is optimized through once-daily dosing that maximizes peak drug plasma concentrations. 1
Recommended Doses by Indication
- Community-acquired pneumonia (CAP): 750 mg IV once daily for 5-14 days 1, 2, 3
- Nosocomial pneumonia: 750 mg IV once daily for 7-14 days 3, 4
- Complicated urinary tract infections/acute pyelonephritis: 750 mg IV once daily for 5 days or 250 mg once daily for 10 days 5, 6
- Complicated skin and skin structure infections: 750 mg IV once daily for 7-14 days 2, 3
- Sepsis and septic shock: 750 mg IV every 24 hours (assuming preserved renal function) 1, 2
Pharmacokinetic Rationale
Fluoroquinolones achieve optimal killing through concentration-dependent mechanisms, meaning higher peak concentrations correlate directly with superior clinical outcomes. 1 Once-daily dosing of 750 mg produces peak plasma concentrations of approximately 9-12 mg/L, which maximizes the peak:MIC ratio critical for bacterial eradication. 1, 7
The elimination half-life of levofloxacin is 6-8 hours in patients with normal renal function, which supports once-daily administration. 7
Critical Renal Dosing Adjustments
Before administering any dose, assess creatinine clearance, as levofloxacin is 80% renally eliminated. 2, 8
- CrCl 50-80 mL/min: Give 500 mg loading dose, then 250 mg every 24 hours 2
- CrCl <50 mL/min: Give 500 mg loading dose, then 250 mg every 48 hours 2
- Always give a full loading dose initially to rapidly achieve therapeutic levels, especially in critically ill patients with expanded extracellular volume from fluid resuscitation 1, 2
The Exception: Young Children Only
The only population requiring twice-daily dosing is children under 5 years of age (6 months to <5 years), who receive 10 mg/kg divided every 12 hours due to faster drug clearance in this age group. 2 This does not apply to injectable levofloxacin in typical adult hospital settings.
Common Pitfalls to Avoid
- Never use 500 mg when 750 mg is indicated for serious infections (CAP, nosocomial pneumonia, sepsis), as suboptimal peak concentrations lead to treatment failure 2
- Do not split the daily dose into twice-daily administration, as this defeats the concentration-dependent killing mechanism 1
- Failure to adjust for renal impairment leads to drug accumulation and increased toxicity risk, particularly tendon rupture and QT prolongation 2, 8
- Do not administer within 2 hours of antacids or medications containing divalent cations (calcium, magnesium, aluminum, iron), which markedly decrease absorption 8, 7
Guideline Consensus
Multiple international guidelines consistently recommend once-daily levofloxacin dosing. The Surviving Sepsis Campaign explicitly states "levofloxacin, 750 mg every 24 h" for optimizing pharmacokinetic/pharmacodynamic principles in sepsis. 1 The European guidelines for lower respiratory tract infections specify "levofloxacin 750 mg/24 h or 500 mg twice daily" only as an alternative for empirical coverage when treating Pseudomonas, but the 750 mg once-daily remains preferred. 1
The twice-daily option (500 mg BID) mentioned in some older literature is not standard practice and should not be used, as it provides no pharmacokinetic advantage and complicates dosing schedules without improving outcomes. 1