Bioequivalence and Bioavailability Forum

Hi PKPDFX, nice nick

OK, just to stay inline with WinNonlin’s nomenclature:

• Classification variables or factors are categorical independent variables, e.g., formulation, treatment, and gender.
  
• Regressor variables or covariates are continuous independent variables, e.g., temperature or body weight.

IMHO your model specification ‘subject+period+sequence+sex+bw’ is correct.
I just reproduced your results with both WinNonlin 4.1 and the current version, 5.0.1: no difference in results.

I remember that I’ve tried to include covariates in BE a couple of years ago and failed as well.
I put it on my ‘to-do-list’, and left it there until today…

Sorry, no better news, consider contacting Pharsight’s support—and post the answer to the forum (I’m curious as well).