Re: PD modeling question
From:LSheiner
Subject:Re: [NMusers] PD modeling question
Date:Wed, February 27, 2002 11:58 am
The simplest approach is to model the receptor's dynamics shifting between
active (R*) and inactive (R) states:
(1) dR*/dt = kon R C - koff R*,
where C is observed drug conc. or Ce,
and subject to the constraint R + R* = Rtot.
Then, if
(2) E/Emax = R*/Rtot,
dividing (1) by Rtot and substituting E/Emax for
R*/Rtot and rearranging yields
dE/dt = Emax kon C - (kon C + koff)E,
which has onset as rapid as you wish (controlled by C),
and offset as slow as you wish (controlled by koff).
A more complex relationship than the linear one (2) between E and R*
is also possible.
To identify this model and distinguish it from "effect compartment model",
especially when experiment is undertaken in
saturable effect range, requires EXQUISITE data.
LBS.