Thermochemical studies on the quantity-antibacterial effect relationship of fluoroquinolones

Using LKB - 2277 bioactivity monitor, the inhibitory action of three fluoro quinolones on Escherichia coli growth was investigated at 37 degreesC. The three fluoroquinolones were Lomefloxacin, Norfloxacin and Pefloxacin. In ac cordance with thermokinetic model, the relationships of the drugs, such as k similar to c, P-max similar to k and I% similar to c, were obtained. Half inhibitory concentrations of the drugs, Ic(50), were obtained by quantitat ive analysis. From the view of thermodynamics, the relationship between qua ntity and effect of fluoroquinolones was investigated, which showed paradio xical effect (PE) situation. The action mechanism of paradioxical effect wa s also studied.