Hi Yaming,
This simplifies things significantly. The first dose will (hopefully fully) define the PK of drug 1. The dose of drug 2 will be modeled as the sum of the two.
Since you have only drug 1 at the beginning, you should be able to model the full time course with:
F=A(2)/V2 + A(3)/V3
Then for the first few days, A(3)/V3 (concentration of drug 2) will be zero.
Thanks,
Bill
Quoted reply history
From: owner-nmusers users
Sent: Wednesday, April 25, 2012 10:43 AM
To: Retsilisitsoe Moholisa; nmusers
Subject: RE: [NMusers] modeling of total concentration of two drugs with different kinetics in NONMEM
Hi Retsilisitsoe,
The two drugs are given at different time (a few days apart). The first drug is a maintenance drug without dosing history, but subjects are assumed to wash out the drug sufficiently. In period 1, subjects were given a single IV infusion of first drug, a few days later, subjects were given the second drug (IV infusion again), where the first drug is not necessarily completely cleared.
Thanks,
Yaming
From: Retsilisitsoe Moholisa [mailto:Retsilisitsoe.Moholisa
Sent: Wednesday, April 25, 2012 10:23 AM
To: Yaming Hang; nmusers
Subject: Re: [NMusers] modeling of total concentration of two drugs with different kinetics in NONMEM
Dear Yaming
I have two questions.
1.Were the drugs given at the same time as a fixed dose combination?
2. Do you have PK when the drugs are give separately?
>>> Yaming Hang <Yaming.Hang m<mailto:Yaming.Hang
Dear All,
I’m trying to model in NONMEM the kinetics of two drug entities co-existing in the blood. Since the assay cannot differentiate these two entities, I only have the total concentration of these two in the blood. Does anyone has similar experience? Can you please share the NONMEM code?
Thanks,
Yaming
Yaming Hang, Ph.D.
Pharmacometrics
Biogen Idec
14 Cambridge Center
Cambridge, MA 02142
Office: 781-464-1741
Fax: 617-679-3463
Email: Yaming.Hang biogenidec.com>
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