NONMEM Users Network Archive

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RE: Time-varying input/flexibility to change input rate on the fly

From: Bill Denney <wdenney>
Date: Fri, 6 Aug 2021 16:15:42 -0400

Hi Robin,

I don't think that I've seen an update. That said, the need I had then was
for a very specific need for an unusual drug. I've only seen this type of
issue once where it seemed to need time-dependent effects. Generally,
effects similar-- but not identical-- to what I was experiencing at the time
are better-modeled with simpler systems. For example, adsorption to
infusion sets can almost always be modeled as a decrease in bioavailability
and/or a lag time (it's not typically time-dependent behavior).

I would assume that loss of part of a tablet or detachment of a patch could
be simply modeled as random variability (or a fixed effect) on
bioavailability. Random pump malfunction would depend on how it
malfunctioned, but I would be wary of trying to model random effects as this
more complex time-dependent bioavailability unless you had data on the
malfunction method-- in which case I would suggest putting it into the
dataset as a different dosing record.

Thanks,

Bill

-----Original Message-----
From: owner-nmusers
Of Robin Michelet
Sent: Friday, August 6, 2021 3:38 PM
To: nmusers
Subject: [NMusers] Time-varying input/flexibility to change input rate on
the fly

Dear all,

I was wondering if any progress has been made on the topic raised originally
by Bill Denney in 2018:

https://www.mail-archive.com/nmusers

Are there any simpler ways in NM 7.5 to adapt input (e.g. infusion
rates) in $DES during the integration step without adapting the dataset
itself? I.e. to model the malfunctioning of an infusion pump (at random),
the loss of part of a tablet, or the detachment of a patch?

Thank you! I could not answer to the original topic which is why I just
linked to it.

--
Dr. ir. Robin Michelet
Senior scientist

Freie Universitaet Berlin
Institute of Pharmacy
Dept. of Clinical Pharmacy & Biochemistry Kelchstr. 31
12169 Berlin
Germany
Phone: + 49 30 838 50659
Fax: + 49 30 838 4 50656
Email: robin.michelet
www.clinical-pharmacy.eu
https://fair-flagellin.eu/
Received on Fri Aug 06 2021 - 16:15:42 EDT

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