Levofloxacin Administration and Dosing
Levofloxacin can be taken with or without food, though food slightly delays absorption without affecting overall bioavailability 1.
Food Administration
Levofloxacin tablets may be taken with or without food 1. While a high-fat meal delays absorption by approximately 1 hour and slightly reduces peak concentration (Cmax reduced by about 14-21%), the total drug exposure (AUC) remains unchanged 2. This means the overall effectiveness is not compromised when taken with food.
Critical caveat: Avoid calcium-fortified orange juice and mineral-fortified cereals at the time of dosing, as these can reduce Cmax by 14-21% and may affect bioequivalence 3, 4. The mechanism appears to be competition for intestinal transport mechanisms rather than simple chelation.
Adult Dosing
The standard adult dosing varies by indication 5:
- Community-acquired pneumonia: 750 mg once daily for 5 days (high-dose short course) OR 500 mg once daily for 7-14 days
- Nosocomial pneumonia: 750 mg once daily for 7-14 days
- Complicated UTI/acute pyelonephritis: 750 mg once daily for 5 days OR 500 mg once daily for 7-14 days 6
- Uncomplicated UTI: 250 mg once daily
- Chronic bacterial prostatitis: 500 mg once daily for 28 days
- Skin infections: 500 mg once daily (uncomplicated) or 750 mg once daily (complicated)
The 750 mg dose was specifically designed to overcome fluoroquinolone resistance mechanisms through increased drug exposure 5.
Critical Drug Interactions and Timing
Separate levofloxacin by at least 2 hours before or after 1:
- Antacids containing magnesium or aluminum
- Iron supplements
- Multivitamins with zinc
- Sucralfate
- Didanosine
These agents significantly decrease levofloxacin absorption through chelation 7. However, when sucralfate is given 2 hours after levofloxacin, no interaction occurs 2.
Monitor closely when co-administered with:
- Warfarin (increased bleeding risk)
- NSAIDs (increased CNS effects and seizure risk)
- Corticosteroids (markedly increased tendon rupture risk, especially in patients >60 years)
- Antiarrhythmics (QT prolongation)
- Theophylline
- Oral antidiabetic agents or insulin (dysglycemia)
Administration Pearls
- Take at the same time each day 1
- Drink fluids liberally to prevent crystal formation in urine 1
- Bioavailability approaches 100% orally, making IV-to-oral conversion seamless 7
- Renal dose adjustment required when creatinine clearance <50 mL/min 7
Black Box Warnings to Communicate
Patients must immediately discontinue and contact you if they experience 1:
- Tendon pain, swelling, or inability to bear weight (tendinopathy/rupture risk)
- Muscle weakness or respiratory difficulty (myasthenia gravis exacerbation)
- Peripheral neuropathy symptoms (may be irreversible)
- Severe skin reactions or hypersensitivity
- CNS effects including seizures, confusion, or hallucinations
The tendon rupture risk is highest in patients >60 years, those on corticosteroids, and transplant recipients 1.