Basic and clinical studies on fleroxacin (FLRX)

We carried out basic and clinical studies on fleroxacin (FLRX), a new antimicrobial agent, with the following results. 1. Antibacterial activity: the in vitro activity of fleroxacin was determined against 30 standard strains and 567 clinical isolates of 16 different species by a microbroth dilution method and compared with those of norfloxacin (NFLX), ofloxacin (OFLX), enoxacin (ENX), ciprofloxacin (CPFX), and pipemidic acid (PPA). Fleroxacin showed excellent activity against Gram-positive cocci and Gram-negative bacilli of standard strains. Furthermore, it was 8 to 512 times more effective than PPA and almost the same as NFLX, ENX, OFLX, but 2 to 16 times less effective than CPFX. 2. Serum and sputum levels in chronic respiratory infections: four patients with chronic respiratory infection were given various doses of fleroxacin (150-300mg) orally, and its concentrations in serum and sputum were measured by HPLC. Peak levels of fleroxacin in serum (2.06-7.74 μ;g/ml) were higher than those of OFLX, and high concentrations were observed even 8 h after administration (1.58-4.94 μg/ml). Furthermore, since the sputum levels were higher than serum levels in all patients, fleroxacin seems to transfer easily into lung tissue and sputum. Our results suggest that fleroxacin should be useful in patients with acute and chronic respiratory infection. 3. Clinical effects and adverse reactions: twenty-one patients with respiratory infection were tested with fleroxacin. The overall efficacy rate was 84.2% (excellent 3, good 13, fair O, poor 3, unevaluable 2). As side effects, auditory hallucinations, dizziness and a heat sensation were observed in one patient each. Transient slight elevation of BUN was observed in one patient.