Half-Life of Levofloxacin (Levaquin)
The half-life of levofloxacin (Levaquin) ranges from 6 to 8 hours in individuals with normal renal function. 1, 2
Pharmacokinetic Profile of Levofloxacin
Levofloxacin demonstrates predictable pharmacokinetic properties that are important to understand for optimal dosing:
- Elimination half-life: 6-8 hours in adults with normal renal function 2
- Extended half-life in special populations:
Excretion and Metabolism
Levofloxacin is primarily eliminated through renal mechanisms:
- Approximately 80% excreted unchanged in urine 1, 2
- Minimal metabolism occurs with no pharmacologically active metabolites 2
- Renal clearance involves both glomerular filtration and tubular secretion 1
- Mean apparent total body clearance: 144-226 mL/min 1
- Mean renal clearance: 96-142 mL/min 1
Clinical Implications of Half-Life
The 6-8 hour half-life supports once-daily dosing for most infections:
- For mild to moderate infections: Once-daily dosing (typically 500 mg) 3
- For more serious infections: Twice-daily dosing may be considered 3
- High-dose short-course therapy (750 mg once daily for 5 days) is effective for certain infections 4
Dosing Considerations in Special Populations
Renal Impairment
Dosage adjustment is required in patients with impaired renal function:
- Creatinine clearance <50 mL/min: Reduce dose to 750-1000 mg three times weekly 5
- Hemodialysis: Not removed by hemodialysis; supplemental doses after dialysis are not necessary 5
Elderly Patients
- No dosage adjustment based on age alone is necessary, but consider underlying renal function 1
Important Drug Interactions Affecting Half-Life
- Cimetidine: Reduces renal clearance by approximately 24% 1
- Probenecid: Reduces renal clearance by approximately 35% 1
- Antacids containing divalent cations: Significantly decrease absorption; administer at least 2 hours before or after levofloxacin 5
Clinical Relevance
Understanding levofloxacin's half-life is critical for:
- Proper dosing intervals: The 6-8 hour half-life allows for once-daily dosing in most cases
- Dose adjustments: Particularly important in patients with renal impairment
- Transitioning between IV and oral therapy: The high oral bioavailability (nearly 100%) allows for seamless transition without dosage adjustment 2
The predictable half-life and pharmacokinetics of levofloxacin make it a reliable option for treating various bacterial infections, with appropriate consideration of patient-specific factors that may affect drug clearance.