Pharmacokinetic considerations on the amiloride-dose The peak plasma levels 3-4 hours after intake of 10 or 20 mg amiloride are 20 μg/L (32) and 38-40 μg/L respectively(33). These concentrations are well below the half maximal inhibitory concentration (IC50) of amiloride for Na+/H+ and Na+/Ca2+-transporters and the α1-receptor, but well above the IC50 for ENaC(34). Using the pharmacokinetic characteristics of amiloride(35) we calculated the required amiloride infusion in order to reach a steady-state concentration between 30-45 μg/L.