Basic and clinical studies of balofloxacin in the field of internal medicine

A new quinolone drug for oral use, balofloxacin (BLFX), was investigated basically and clinically. The following results were obtained: (1) Minimum inhibitory concentration (MIC) of BLFX for the gram-positive bacteria; Staphylococcus aureus and Enterococcus faecalis, among 247 strains of 11 species isolated from inpatients of the First Department of Internal Medicine, Faculty of Medicine, Kyushu University, was approximately equivalent to that of a control drug, tosufloxacin, and superior to those of ofloxacin and ciprofloxacin by at least two test tubes. The concentration of BLFX needed for gram-negative rods such as Escherichia coli. Citrobacter freundii, Klebsiella pneumoniae, Enterobacter spp. and Proteus spp. was slightly inferior to that of the control drugs, the minimum 90% inhibitory concentration (MIC₉₀) being lower than 3.13 μg/ml for all of these rods. The MIC₅₀ and MIC₉₀ for Pseudomonas aeruginosa were 6.25 and 50 μg/ml, respectively, showing BLFX to be slightly inferior to the controls. (2) BLFX was orally administered at a dose of 100~200 mg, twice a day, for 4~21 days to 10 patients (2 of whom were the same person). The clinical efficacy was rated as excellent in one, good in five and fair in one of 7 patients with respiratory infections diseases. The clinical efficacy was effective for one with colitis, and excellent and good in each one of the patients with cystitis. Neither side effects nor abnormal changes in clinical laboratory test values, likely to be attributable to the drug, were observed in any of the patients.