PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: At least 28 days since prior intravesical therapy and recovered Endocrine therapy: Not specified Radiotherapy: At least 28 days since prior radiotherapy and recovered Surgery: Not specified Other: At least 3 months prior to cystoscopy since prior fluoroquinolones No concurrent fluoroquinolones No concurrent hemodialysis or peritoneal dialysis No concurrent probenecid or theophylline No concurrent antacids containing aluminum, magnesium or calcium, products containing iron or zinc, caffeine, cyclosporine, or warfarin