Hi all.
I have a question regarding Volume of distribution at steady state, Vss.
My understanding is that Vss is measured at the phase of the profile in which drug is at steady state between central and peripheral compartments – i.e. drug leaves the central compartment at the same rate at which it enters the central compartment from peripheral compartment(s).
If my understanding is correct (which it may not be), then why is it that WinNonlin will only produce a value for Vss using AUCtau and not AUC0-t? The fact that it only uses AUCtau implies that Vss is only relevant following repeat dosing and that steady state may actually refer to steady state following repeat dosing. Does this mean that in a repeat dose study, I should not report Vss following a single, first dose?
I would be very grateful for any clarification on this, and any corrections to my assumptions.