Question: Clss and AUCtau

[js3110]

Hi,

In the PK parameters there is no Clss (steady state clearance) or AUCtau. Are these not available,? or are they just named differently in the pk parameters? Thanks!

[billdenney]

AUCtau is a specific example of AUCint (AUC during an interval); Clss is similarly a variation on CLint (clearance during an interval). Please use those.

[js3110]

Hi Bill,

Just to follow up, could you clarify which parameter is Clss? I don't see CLint in the list of available parameters.

[js3110]

Which aucint? there are lots of different ones, I would assume aucint.last?
And do we have to then manually set the interval (aka Tau), or is it automatically calculated?
Same question for Clint (although I can't seem to find that one?) I am using the table from https://billdenney.github.io/pknca/articles/Selection-of-Calculation-Intervals.html#parameters-available-for-calculation-in-an-interval as a reference, so maybe its not up to date?

[billdenney]

The challenge of answering your question is that AUCtau (and the CDISC definition) is not specific.

Most likely, you would want aucint.inf.pred or aucint.inf.obs. If the next concentration after the interval is BLQ, then you would likely want to extrapolate to the end of the interval using the half-life. If the next concentration after the interval is not BLQ, then all of the estimates should be the same since it's interpolation.

[js3110]

ok, thanks! yes, there are a lot of parameters where the CDISC version is very vague, and you have 5 or 6 different parameters for 1 CDISC version.

And what about CLss?