Effects of fluoroquinolones on HERG currents.

We have investigated the effects of four fluoroquinolones on the human ether-à-go-go-related gene (HERG) mediated K(+) currents to evaluate their potential to induce QT-prolongation. HERG currents were measured from stably transfected Chinese hamster ovary (CHO) cells by means of the patch-clamp technique. Bath application of sparfloxacin, moxifloxacin and grepafloxacin produced an inhibition of HERG outward currents at -40 mV with EC(50) of 13.5+/-0.8, 41. 2+/-2.0 and 37.5+/-3.3 microg/ml, respectively. Current inhibitions were reversible after washout of the compounds. By contrast, ciprofloxacin at concentrations of up to 100 microg/ml did not effect HERG outward currents.