Bioequivalence and Bioavailability Forum

Dear Naresh!

❝ I have to perform Steady state analysis in WinNonlin, but I am not sure

❝ about the method which I supposed to be used will give correct results or

❝ not,

Any specific questions? Which version of WinNonlin are you using (WinNonlin 5.x, Phoenix 6.x)?
I guess you have read the User's Guide (WNL v5.2.1 page 172, Phoenix 6.0 page 280, Phoenix 6.1 page 277).

❝ If any one can provide data with results then I can crosscheck with my

❝ method.

Critical are only time deviations of samples scheduled at t=tau. WinNonlin estimates AUC_TAU based on lambda_z; therefore if the last sampling time point deviates from tau you should get an AUC_TAU # AUClast.
Open WinNonlin's 'Exp1.pwo':
in 'Dosing Regimen' check ☑ 'Steady state', Dose 1, Time of Last Dose 0, Tau 24
in 'Model Options' > 'NCA Settings' > 'Calculation Method' > Linear Trapezoidal (Linear/Log Interpolation)
You should get
  Lambda_z 0.0646
  AUClast 69.7739
  AUC_TAU 69.7739 (AUC_tau=AUC_last, because t_last=tau)
Change the last time point in 'Exp1.pwo' from 24 h to 23.5 h > in 'NCA Workbook' > right click > Refresh
  Lambda_z 0.0677
  AUClast 68.8564
  AUC_TAU 69.4879 (AUC_tau>AUC_last, because t_last<tau)
Change the last time point in 'Exp1.pwo' from 24 h to 24.5 h > in'NCA Workbook' > right click > Refresh
  Lambda_z 0.0596
  AUClast 70.7462
  AUC_TAU 70.0202 (AUC_tau<AUC_last, because t_last>tau)

Does this example answer your question?