Re: Data Construct / ADVAN selection
From: LSheiner <lewis@c255.ucsf.edu>
Subject: Re: Data Construct / ADVAN selection
Date: Tue, 03 Apr 2001 09:34:36 -0700
Off the top of my head ...
1. Your very first record should have EVID=1, not 0. But, why don't you just drop the EVID column completely; it's not needed with this simple data (e.g. use $INPUT ID AMT TIME DV RATE IDUR MDV DROP.
2. Why are you modeling the infusion duration if you know it is 2 hours? More logically, for individual 1, for example, the first record should read
ID AMT TIME DV RATE IDUR MDV EVID
1 150 0 0 75 2 1 1
Note the '75' rate means the infusion will last 2 hours to deliver the total dose (AMT) of 150. For the second individual, the AMT = 340, and the RATE = 170, etc.
With this set-up you can drop the last 3 columns (IDUR MDV EVID),
$INPUT ID AMT TIME DV RATE DROP DROP DROP
as none of them are needed, and also your code simplifies to.
$PK
V=THETA(1)+ETA(1)
CL=THETA(2)+ETA(2)
S1=V/1000 ;where Dose is in mg and DV is in ng/ml
3. The additive etas may give you trouble in the posthoc step; it's probably safer to use
$PK
V=THETA(1)*EXP(ETA(1))
CL=THETA(2)*EXP(ETA(2))
4. You should probably start with a fuill OMEGA, nota diagonal one; you can then see if a diagonal one su7ffices. Thus you might start with
$OMEGA BLOCK(2) 0.25 .1 0.25
LBS.
--
_/ _/ _/_/ _/_/_/ _/_/_/ Lewis B Sheiner, MD (lewis@c255.ucsf.edu)
_/ _/ _/ _/_ _/_/ Professor: Lab. Med., Bioph. Sci., Med.
_/ _/ _/ _/ _/ Box 0626, UCSF, SF, CA, 94143-0626
_/_/ _/_/ _/_/_/ _/ 415-476-1965 (v), 415-476-2796 (fax)