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:


DPI = 3.14159
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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