From the FDA Drug Label
The absolute bioavailability of levofloxacin from a 500 mg tablet and a 750 mg tablet of levofloxacin are both approximately 99%, demonstrating complete oral absorption of levofloxacin. The bioavailability of levofloxacin is approximately 99% for both 500 mg and 750 mg oral tablets, indicating complete oral absorption 1.
- The absolute bioavailability is given as F = 0.99 ± 0.08 for a 500 mg tablet and F = 0.99 ± 0.06 for a 750 mg tablet.
From the Research
Levofloxacin has excellent bioavailability of approximately 100% when taken orally, meaning almost all of the drug reaches systemic circulation unchanged. This high bioavailability allows for equivalent dosing between oral and intravenous administration, typically 500-750 mg once daily for most infections. The bioavailability of oral levofloxacin is little affected by the administration with food, as stated in the study by 2. According to 2, oral absorption is very rapid and complete, with little difference in the serum concentration-time profiles following 500mg oral or intravenous (infused over 60 minutes) doses.
The high bioavailability of levofloxacin results from its chemical structure as a fluoroquinolone antibiotic with good solubility and permeability characteristics, as mentioned in 3. It undergoes minimal first-pass metabolism in the liver, with approximately 80% of the dose excreted unchanged in urine, as reported in 2. For patients with renal impairment (creatinine clearance <50 mL/min), dose adjustments are necessary despite the high bioavailability, as the drug's elimination is primarily renal, as noted in 2 and 4.
Key points to consider when prescribing levofloxacin include:
- High bioavailability of approximately 100% when taken orally
- Equivalent dosing between oral and intravenous administration
- Minimal effect of food on absorption
- Rapid and complete oral absorption
- Minimal first-pass metabolism in the liver
- Primarily renal elimination
- Necessary dose adjustments for patients with renal impairment
Overall, levofloxacin's high bioavailability and favorable pharmacokinetic profile make it a valuable option for the treatment of various bacterial infections, as discussed in 5, 4, and 6.