From these in vitro data, we would expect to observe 50 to 90% anti-HCV effects in humans at serum drug concentrations of 2 to 10 μM, respectively. Moreover, we compiled the drug concentration results from several previously-reported clinical data on the level of steady-state concentrations in patients who took repeat daily doses of mifepristone (>4 days). For instance, repeated oral administration of 100 and 200-mg mifepristone daily for 4 days achieved maximum plasma levels of 4.5 and 5.4 μM, respectively (9).