- On 25 Dec 2005 at 14:10:25, "Samtani, Mahesh [PRDUS]" (MSamtani.at.prdus.jnj.com) sent the message

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Dear PharmPK readers,

I am trying to deconvolute an extravascular profile of a drug whose

IV curve can be described by the triexponential equation: Conc(pg/mL)

= 450*exp(-2*t)+ 40*exp(-0.2*t)+ 5*exp(0.02*t) after a dose of

40000000 pg.

In trying to figure out the unit impulse response I divide the three

coefficients (450, 40, 5) by the dose, which produces ridiculously

small numbers. Is it OK to put these small numbers as different

values of the A term into WinNonlin during the deconvolution process?

I am also assuming that it is OK to put in the three exponents as

different values of alpha into WinNonlin.

Furthermore, the extravascular dose is not the same as the IV dose.

Is there a correction needed in WinNonlin to account for a different

doses.

Kindly advice,

M Samtani - On 27 Dec 2005 at 09:49:09, "Teuscher, Nathan" (Nathan.Teuscher.-a-.mdsinc.com) sent the message

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The following message was posted to: PharmPK

In my experience with the deconvolution engine within WinNonlin, you

must scale the IV coefficients (A and B) to be dose equivalent to the

extravascular dose. For example, if you have a 10 mg IV dose and a 50 mg

oral dose, multiply A and B by 5 and use those values in the WinNonlin

input sheet.

This is different from other software such as PCDCON or spreadsheets

where the unit dose can be used for the IV parameters.

Nathan Teuscher

--

Nathan S. Teuscher, Ph.D.

Associate Director, PK/PD and Pharmacometrics

MDS Pharma Services

Tel: (402) 437-6332

Cell: (402) 617-7207

Fax: (402) 476-7598

Email: Nathan.Teuscher.at.mdsinc.com

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