Abstract
A new quinolone antimicrobial drug, grepafloxacin (GPFX), was studied basically and clinically.
Its antimicrobial activity (50% minimum inhibitory concentration: MIC50) against major respiratory pathogens was 0.39 μg/ml against Staphylococcus aureus, 0.39 μg/ml against Streptococcus pneumoniae, less than 0.003 μg/ml against Haemophilus influenzae, 0.025 μg/ml against Branhamella catarrhalis, and 0.78 μg/ml against Pseudomonas aeruginosa.
In one of the 2 patients with respiratory infectious disease, the maximum sputum and serum levels of GPFX after a single administration of 100 mg were 1.56 μg/ml and 0.85 μg/ml, and the peak ratio (maximum sputum level/maximum blood level × 100) was 183.5%. In the other patient, the maximum sputum and serum levels of GPFX after a single administration of 200 mg were 1.68 μg/ml and 1.13 μg/ml, respectively, and the peak ratio was 148.7%.
Fifteen patients with respiratory tract infections were studied for the clinical evaluation of GPFX. The rate of clinical efficacy was 100%(13/13; unknown in 2 patients). Although 2 strains of P. aeruginosa were not eradicated, all other bacteria (2 strains of S. pneumoniae, 5 strains of H. influenzae, and 3 strains of B. catarrhalis) were eradicated. The rate of bacterial elimination in sputum samples was 83.3%. No reversed effect was observed.
The results suggest that GPFX can be expected to exert excellent clinical effects on respiratory infectious diseases due to bacteria including S. pneumoniae, when it is administered once or twice a day.
