Levofloxacin Bioavailability
Levofloxacin has virtually 100% oral bioavailability, making oral and intravenous formulations completely interchangeable at equivalent doses. 1
Pharmacokinetic Profile
The absolute bioavailability of levofloxacin from both 500 mg and 750 mg tablets is approximately 99%, demonstrating complete oral absorption 1
Oral absorption is very rapid and complete, with little difference in serum concentration-time profiles between 500 mg oral and intravenous doses (infused over 60 minutes) 2
Peak plasma concentrations are reached within 1-2 hours after oral administration 1, 2
Clinical Implications of High Bioavailability
The oral and intravenous routes of administration can be considered completely interchangeable, with equal doses (mg/mg) producing similar plasma concentration profiles and equivalent extent of exposure (AUC) 1
This bioequivalence allows seamless transition between IV and oral formulations without dosage adjustment, providing flexibility in treatment settings and enabling step-down therapy as patient condition improves 3
Total drug exposure is equivalent between intravenous and oral formulations at the same milligram-per-kilogram dose 4
Effect of Food on Absorption
Food administration prolongs time to peak concentration by approximately 1 hour and decreases peak concentration by approximately 14% following tablet administration 1
Despite these minor effects, levofloxacin tablets can be administered without regard to food, as the overall bioavailability remains essentially complete 1
Important Absorption Interactions
Antacids and medications containing divalent cations (aluminum, magnesium, calcium, iron) markedly decrease levofloxacin absorption and must not be administered within 2 hours of levofloxacin 4, 5
This interaction is critical to avoid, as concurrent administration can significantly compromise the therapeutic efficacy of levofloxacin 2, 6