Dear, I’m having troubles calculating steady state parameters. To calculate the steady state parameters, I’ve used NCA. The parameters remain the same as for single dosing, except the dose interval is added (12 h) next to time of dose (0h, as then the first dose was administered). The problem is that WinNonLin calculates several parameter (e.g. Cmin, Cmax, Cavg) based on the first dosinginterval (0-12 h) instead of an average after reaching steady state. If I drop the first 3 intervals and start from 36 h, then he only gives the values calculated for the interval 36-48 h, instead of an average after reaching SS. Kind regards, Mathias
Mathias, I’m trying to follow what you want to achieve in your analysis, if I understand correctly th following should be helpful… NCA can only be used to calculate dose dependent parameters for a single dose event, in one of two states, naive first dose or steady state. When do you think steady-state was achieved in your study? (typically people assume it is within 5-7 half-lives) If you want to obtain average after reaching steady state; simply take each profile and assess the SS parameters for each profile (e.g. using Day as a sort) then send the final parameters to Descriptive stats to calculate the mean of those parameters of interest to you. Simon