Re: [NMusers] Estimation of Intake Time

From: Emmanuel Chigutsa <echigutsa_at_yahoo.com>
Date: Thu, 18 Jun 2015 15:42:09 +0000 (UTC)

Hi Andrej, You can try something along the following lines:-subtract 12 hou=
rs from the time of all doses in the dataset (create new time column)-add a=
 fixed ALAG of 12 hours and some variability on it. You¬†could also¬=
†fix the variability to a big number. You can also test covariates (patie=
nt subgroups) on this ALAG. Good luck, Mannie 
 
      From: Andrzej Bienczak <andrzej.bienczak_at_googlemail.com>
 To: nmusers_at_globomaxnm.com
 Sent: Thursday, June 18, 2015 9:35 AM
 Subject: [NMusers] Estimation of Intake Time
   
<!--#yiv0048360651 _filtered #yiv0048360651 {font-family:"Cambria Math";pan=
ose-1:2 4 5 3 5 4 6 3 2 4;} _filtered #yiv0048360651 {font-family:Calibri;p=
anose-1:2 15 5 2 2 2 4 3 2 4;}#yiv0048360651 #yiv0048360651 p.yiv0048360651=
MsoNormal, #yiv0048360651 li.yiv0048360651MsoNormal, #yiv0048360651 div.yiv=
0048360651MsoNormal {margin:0cm;margin-bottom:.0001pt;font-size:11.0pt;font=
-family:"Calibri", "sans-serif";}#yiv0048360651 a:link, #yiv0048360651 span=
.yiv0048360651MsoHyperlink {color:#0563C1;text-decoration:underline;}#yiv00=
48360651 a:visited, #yiv0048360651 span.yiv0048360651MsoHyperlinkFollowed {=
color:#954F72;text-decoration:underline;}#yiv0048360651 span.yiv0048360651E=
mailStyle17 {font-family:"Calibri", "sans-serif";color:windowtext;}#yiv0048=
360651 .yiv0048360651MsoChpDefault {font-family:"Calibri", "sans-serif";} _=
filtered #yiv0048360651 {margin:72.0pt 72.0pt 72.0pt 72.0pt;}#yiv0048360651=
 div.yiv0048360651WordSection1 {}-->Dear NMusers, ¬†I would like to pr=
esent you with a problem that some of you might have faced before. I am cur=
rently building a PK model for a drug with once daily oral administration. =
The drug has a long half-life and can be taken either in the morning or at =
night. Unfortunately due to lack of consistency in the recording of the adm=
inistration times by the study team part of the patients flagged to have ta=
ken the medication in the mornings were in fact taking it at night (i.e. 08=
:25 corresponds to 20:25 the previous day). At this stage there is no way o=
f tracking back what the correct intake times were.  The data consists=
 of 2 sparse measurements per patient and indeed looking at individual prof=
iles you can clearly see that some samples are from the elimination phase, =
indicating the drug was taken more than 12h prior. I could correct the data=
set based on an empirical judgement backed up by the visual analysis but I =
was hoping there would be a more robust way.  Is there any way to put=
 a THETA on the dosage time for those patients to let NONMEM estimate a cor=
rected administration time?  I tried simply adding an extra parameter =
on the intake time for those patients (placed the code in $PK): IF(FLAG_AM.=
EQ.1) TIME=TIME-THETA(17)  But received the following error message:=
 ¬†AN ERROR WAS FOUND IN THE CONTROL STATEMENTS. ¬†AN ERROR WAS FOU=
ND ON LINE  30 AT THE APPROXIMATE POSITION NOTED:    IF=
(FLAG_AM.EQ.1) TIME=TIME-THETA(17)¬†¬†¬†¬†¬†¬†¬=
†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬† ¬=
†¬†X¬†¬† ¬†THE CHARACTERS IN ERROR ARE: TIME 236¬† DA=
TA ITEM MAY NOT BE CHANGED WITH THIS VALUE OF ICALL.    I would b=
e grateful for some suggestions on how to deal with this issue.  Regar=
ds,  Andrzej    Andrzej Bienczak MSc, MPharm, DiplPharmPhar=
macometrics GroupDivision of Clinical PharmacologyDepartment of MedicineUni=
versity of Cape Town    

   

Received on Thu Jun 18 2015 - 11:42:09 EDT

This archive was generated by hypermail 2.3.0 : Fri Sep 27 2019 - 16:44:46 EDT