Levofloxacin Dosing in Adults with Normal Renal Function
For adults with normal renal function (creatinine clearance ≥50 mL/min), levofloxacin should be dosed at 250 mg, 500 mg, or 750 mg orally once daily for 24 hours, with the specific dose and duration determined by the type and severity of infection being treated. 1
Standard Dosing by Infection Type
The FDA-approved dosing regimens for adults with creatinine clearance ≥50 mL/min are infection-specific 1:
Respiratory Tract Infections
- Community-acquired pneumonia: 750 mg once daily for 5 days provides optimal efficacy while minimizing treatment duration 1, 2
- Acute bacterial sinusitis: 750 mg once daily for 5 days 3
- Acute exacerbations of chronic bronchitis: 500 mg once daily for 7 days 3
Urinary Tract Infections
- Uncomplicated UTIs: 250 mg once daily for 3 days is highly effective 4
- Complicated UTIs and acute pyelonephritis: 250 mg once daily for 7-10 days, or 750 mg once daily for 5 days 1, 4
Skin and Soft Tissue Infections
- Complicated skin and skin structure infections: 750 mg once daily 5
Pharmacokinetic Rationale for Once-Daily Dosing
The high bioavailability (approaching 100%) and concentration-dependent bactericidal activity of levofloxacin support once-daily administration. 6 Key pharmacokinetic properties include:
- Peak plasma concentrations (Cmax) of approximately 2.8 mg/L and 5.2 mg/L are achieved within 1-2 hours after 250 mg and 500 mg oral doses, respectively 6
- Elimination half-life ranges from 6-8 hours in patients with normal renal function 6
- Approximately 80% is eliminated unchanged in urine through glomerular filtration and tubular secretion 6
- Oral absorption is rapid and complete, with oral bioavailability equivalent to intravenous administration 2, 6
High-Dose, Short-Course Strategy
The 750 mg once-daily regimen for 5 days maximizes concentration-dependent bacterial killing and may reduce resistance development while improving compliance. 2 This approach has demonstrated non-inferiority to traditional 10-day regimens of 500 mg daily in community-acquired pneumonia and acute bacterial sinusitis 2.
Critical Administration Instructions
Drug Interactions with Chelating Agents
Levofloxacin must be administered at least 2 hours before or 2 hours after antacids containing magnesium or aluminum, sucralfate, metal cations (iron), multivitamins with zinc, or didanosine preparations. 1 These agents significantly decrease levofloxacin absorption through chelation 6.
Food and Hydration
- Levofloxacin can be taken without regard to food, as absorption is minimally affected 1, 6
- Adequate hydration should be maintained to prevent crystalluria and cylindruria 1
Common Pitfalls to Avoid
Do not reduce the dose in normal renal function based on patient age alone—elderly patients with preserved renal function (creatinine clearance ≥50 mL/min) require standard dosing 1. Age-related pharmacokinetic differences are primarily attributable to declining renal function rather than age itself 6.
Avoid using levofloxacin as first-line therapy for routine community-acquired infections where beta-lactams or macrolides remain effective, as this practice may drive fluoroquinolone resistance in pneumococci and other pathogens 7. Reserve levofloxacin for infections with beta-lactam or macrolide-resistant pathogens, severe infections, or patients with risk factors for complications 7.
Do not assume all fluoroquinolones have equivalent dosing—levofloxacin is the L-isomer of ofloxacin and is significantly more active than the R-isomer, requiring specific dosing distinct from racemic ofloxacin 6, 5.