• Clinical response rate (a reduction in signs and symptoms, and stabilization/improvement of sinus x-ray results) at post-therapy visit, 2 - 5 days after the last dose of study drug
  

• Incidence of adverse events; change in physical examination, and laboratory tests from the start of the study to after treatment
  

Levofloxacin is an antibacterial agent used for the treatment of many types of severe infections with rapid onset and brief duration in adults. This is a randomized, open-label, parallel group, multicenter study to determine the safety and effectiveness of levofloxacin (500 mg tablets once daily by mouth for 10 - 14 days) compared with amoxicillin/clavulanate (500 mg/125 mg tablets by mouth every 8 hours for 10 - 14 days) in adults with rapid onset of severe inflammation/infection of the sinuses. The study consists of 4 visits: one visit for screening and enrollment, and three visits to assess the safety and effectiveness of treatment (one telephone contact during Days 3 - 6 of the study [if no significant improvement in symptoms has occurred by that time, a visit is scheduled]; one visit [post-therapy] 2 - 5 days after the last dose of the study drug; and one visit [post-study] 28 - 32 days after the last dose of the study drug). The total duration of patient participation in the study is approximately 6 weeks. The primary measure of effectiveness is assessed by the clinical response rate after the completion of treatment (a reduction in the signs and symptoms, and by stabilization or improvement in x-ray findings). Safety evaluations (incidence of adverse events, physical examination, and laboratory tests) are performed throughout the study. The study hypothesis is that treatment with levofloxacin is at least as effective and as well tolerated as treatment with amoxicillin/clavulanate potassium in adults with rapid onset of severe inflammation/infection of the sinuses. 500 mg tablets of levofloxacin by mouth once daily, or 500 mg/125 mg amoxicillin/clavulanate tablets by mouth every 8 hours. The duration of treatment is 10 - 14 days.