Religious debate [Regulatives / Guidelines]

posted by nobody – 2016-02-12 18:26 (2966 d 22:06 ago) – Posting: # 15986
Views: 16,118

❝ parameterization of models in terms of rate constants or clearances


For models I don't care. I care for the discussions deduced from these parameters. And often the "half-life" discussions are... ehmmm... undercomplex... :-D

❝ What I definitely don’t like is that PK software in evaluating data of an extravascular dose spit out CL/ƒ, V/ƒ, etc. Since ƒ is unknown, this kind of “information” is meaningless


Nope. Sometimes this is as close to "reality" as you can get (if you lack the info on f for example). There are other cases you simply can not get closer to the information you want. Take metabolite pk in the central compartment. In your logic it's all trash, as you will normally not know Vd. And amounts are usually what's interesting (where does the drug go? Sometimes you have urine data, rarely fecal data, and even if, for non-iv application without iv data: how did it end up in feces?), concentrations without Vd normally are of limited value (you can assume Vd metabolite to be smaller than Vd parent, but that doesn't bring you that far, huh?).

There are other cases where you can not obtain all parameters you might want. Deal with it and take as much info out of your data as you can get (on a scientific basis). Better than a lot of (NONMEM) models overparameterized ad nauseam, months of runtime, highly correlated parameters, in the end completely meaningless nonsense. But 6 or 8 compartments, most of them without any meaningful datasets to determine the related parameters...

Kindest regards, nobody

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