Dear Karem,
The short answer is that it is possible to set up an useful PK model in
this circumstance. The focus however will be to describe the endogenous
substance with sufficient detail and quality. Only once you have done
that properly you can derive a meaningful PK model for the exogenous
substance.
An example can be found in the work of the Jusko group on cortisol,
which is both a non-steady state biomarker and a drug (but more
complicated because of feedback). See eg the Mager2013 paper:
https://doi.org/10.1177/0091270003258651
Hope this helps,
Jeroen
http://pd-value.com
jer...@pd-value.com
@PD_value
+31 6 23118438
-- More value out of your data!
On 05-10-2024 09:02, karam alali wrote:
Dear NONMEM users,
I encountered a case when an endogenous substance and an exogenous
substance were not separated by any analytical method or using
isotopes, which means we have a mix of both substances in the central
compartment.
1. What are the possible methods to predict their pharmacokinetics?
2. Is it valid to use the clearance and volume of distribution of the
total substance?
3. if I use the central compartment for the endogenous substance
DADTendo (which contains the total) and create a dummy compartment for
the exogenous substance DADTexo, would then be possible to account
separately for each of their pharmacokinetics (CL, V) when we set the
IPRED = A(endo) + A(exo)?
Note: the endogenous substances are not in a steady state
Regard
Karam Alali
PhD Candidate
Clinical Pharmacy Discipline
Universiti Sains Malaysia
