NONMEM Users Network Archive

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Re: Scaling for pediatric study planning

From: Paul Hutson <prhutson>
Date: Fri, 19 Sep 2008 12:07:40 -0500
Dear Leonid:
Regarding d): I would not expect to need to scale the KM at all unless the affinity of the substrate (drug) is known to be different between species.  Size alone would not be expected to affect the KM of elimination.  It could clearly affect the KM of a passive or active gut absorption process due to the surface area of the intestine.
my $0.02

Leonid Gibiansky wrote:

Leonid Gibiansky, Ph.D.
President, QuantPharm LLC
e-mail: LGibiansky at
tel:    (301) 767 5566

Dear NM_Users,

we have all been good students and listened to Nick when he told us again and again the rock-solid truths of allometry:

Volume: *(WT/70)

CL: *(WT/70)**0.75

any rate constant related to distribution or elimination: *(WT/70)**(-0.25)

Here my questions:
a) how do we allometrically scale a first-order rate constant of absorption after oral dosing?

b) how do we allometrically scale a first-order rate constant of absorption from a subcutaneous injection site?

Thank you for your thoughts,


Joachim GREVEL, Ph.D.
MERCK SERONO International S.A.
Exploratory Medicine
1202 Geneva
Tel: +41.22.414.4751
Fax: +41.22.414.3059
Paul R

Paul R. Hutson, Pharm.D.

Associate Professor

UW School of Pharmacy

777 Highland Avenue

Madison WI 53705-2222

Tel  608.263.2496

Fax 608.265.5421

Pager 608.265.7000, p7856

Received on Fri Sep 19 2008 - 13:07:40 EDT

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