When you look up dosing for levofloxacin for community acquired pneumonia (CAP), you will find that both of the following options are approved:
Levofloxacin 500 mg IV/PO daily x 7-14 days
Levofloxacin 750 mg IV/PO daily x 5 days
This is based on a multicenter, randomized, double-blind, active treatment trial comparing these two regimens in CAP (mild to severe). This non-inferiority trial shows that the 750 mg dose of levofloxacin for 5 days is "at least as effective and well tolerated" as the 500 mg dose of levofloxacin for 10 days.
So why should you choose the 750 mg daily x 5 day regimen?
Higher doses maximize the concentration-dependent pharmacokinetic profile of the drug
Higher doses and shorter duration may be associated with less drug resistance
Patients subjectively report feeling better at day 3 with the higher dose regimen
As alway with levofloxacin, don't forget to renally dose adjust subsequent doses when writting a script or scheduled inpatient order for patients with reduced creatinine clearance!
Additional Information
References
Dunbar LM, Wunderink RG, Habib MP, et al. High-dose, short-course levofloxacin for community-acquired pneumonia: A new treatment paradigm. Clin Infect Dis. 2003;37:752-60.
