NONMEM Users Network Archive

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modeling the circadian baseline

From: Ying HONG <yhong6>
Date: Thu, 26 Apr 2007 22:00:23 -0400

Dear NM users,

A biomarker, which shows clear circadian rhythm during placebo
treatment, was described by a turnover model with the introduction of a
periodic time-dependent production function KST with two harmonics. The
code in $DES is written as follows:

$DES

DPI = 3.14159
DPS1 = KOUT*A0
DPS2 = (KOUT*A1 + B1*DPI/12)*DCOS(DPI*T/12)
DPS3 = (KOUT*B1 - A1*DPI/12)*DSIN(DPI*T/12)
DPS4 = (KOUT*A2 + B2*DPI/6) *DCOS(DPI*T/6)
DPS5 = (KOUT*B2 - A2*DPI/6) *DSIN(DPI*T/6)

KST = DPS1 + DPS2 + DPS3 + DPS4 + DPS5

DADT(1) = KST - KOUT*A(1)

In the paper published by Hempel et al (CPT, 1998;64:622-35), a ETA was
introduced in the time T which accounts for the differences in wake-up
times between subjects (e.g. DCOS(DPI*(T+ETA)/12). Because ETA is
prohibited in the $DES, how can I code the interindividual variability
of time in the control stream?

Any suggestion is highly appreciated!


Kind Regards, Ying

--
Ying HONG, PhD
Department of Pharmaceutical Sciences
University at Buffalo, SUNY
C237 Cooke Hall, Buffalo, NY 14260

Tel: 716 645 2828 ext 275
Fax: 716 645 3693
E-mail: yhong6

Received on Thu Apr 26 2007 - 22:00:23 EDT

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