Cumulative clinical experience from over a decade of use of levofloxacin in community-acquired pneumonia: critical appraisal and role in therapy Ayman M Noreddin1, Walid F Elkhatib2, Kenji M Cunnion3, George G Zhanel41Department of Pharmacy Practice, Hampton University, Hampton, VA, USA; 2Department of Microbiology and Immunology, Ain-Shams University, Cairo, Egypt; 3Department of Pediatrics, East Virginia Medical School, Norfolk, VA, USA; 4Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada Abstract: Levofloxacin is the synthetic L-isomer of the racemic fluoroquinolone, ofloxacin. It interferes with critical processes in the bacterial cell such as DNA replication, transcription, repair, and recombination by inhibiting bacterial topoisomerases. Levofloxacin has broad spectrum activity against several causative bacterial pathogens of community-acquired pneumonia (CAP). Oral levofloxacin is rapidly absorbed and is bioequivalent to the intravenous formulation such that patients can be conveniently transitioned between these formulations when moving from the inpatient to the outpatient setting. Furthermore, levofloxacin demonstrates excellent safety, and has good tissue penetration maintaining adequate concentrations at the site of infection. The efficacy and tolerability of levofloxacin 500 mg once daily for 10 days in patients with CAP are well established. Furthermore, a high-dose (750 mg) and short-course (5 days) of once-daily levofloxacin has been approved for use in the US in the treatment of CAP, acute bacterial sinusitis, acute pyelonephritis, and complicated urinary tract infections. The high-dose, short-course levofloxacin regimen maximizes its concentration-dependent antibacterial activity, decreases the potential for drug resistance, and has better patient compliance.Keywords: levofloxacin, community-acquired pneumonia, pharmacodynamics, resistance, pharmacokinetics, clinical use