How to code vomit event as absorption lag and lost of amount in administration comp.

Dear all, Could someone please give me some tips coding vomitting event as an absorption lag and bioavailability decrease? It's a single dose oral solution with slow absorption. From data I noticed that the time of vomitting was at least 4 hour after dose. Some subjects had mutiple vomitting events. The exposure was noticed a delay after each vomitting compared with non-vomit subject. I have very limit data, and need a good fiitting for the plasma concentration to focus on the pd model. Is there any similar model reported in the literature? Much appreciate for your help! Best regards, Galadriel

Hi Gabriel, Is it possible that you do not need a PK model? Can you use a "nonparametric" (connect the dots) approach for the PK and just use that to drive the PD model? Just a thought. Susan Willavize, Ph.D. Pfizer Global Pharmacometrics Group

Galadriel, could you turn the dose compartment off with an other event (EVID = 2, CMT = -1), then given another dose after that. E.G, with emesis at four hours: #ID TIME CMT AMT EVID IND 1 0 1 100 1 1 1 4 -1 . 2 0 1 4 1 100 1 2 $PK IF(IND.EQ.1) THEN F1 = THETA(1) ; FRACTION NOT LOST ALAG1 = THETA(2) ; NORMAL LAG ELSE F1 = (1-THETA(1))*THETA(3) ; THETA(3) IS REDUCED BIOAVAILABILITY ALAG1 = THETA(4) ; LAG AFTER EMESIS END IF Other-Type Event: A positive value of CMT specifies a compartment to be turned on. A negative value of CMT specifies a compartment to be turned off. When CMT is 0, no change is made in the status of any compart- ment. PCMT is the same as for dose events.Mark (aka Golum) Mark Sale MD Next Level Solutions, LLC www.NextLevelSolns.com 919-846-9185 > -------- Original Message -------- Subject: [NMusers] How to code vomit event as absorption lag and lost of amount in administration comp. From: Galadriel <[EMAIL PROTECTED]> Date: Tue, July 22, 2008 7:13 am To: > > [email protected] > > Dear all, Could someone please give me some tips coding vomitting event as an absorption lag and bioavailability decrease? It's a single dose oral solution with slow absorption. From data I noticed that the time of vomitting was at least 4 hour after dose. Some subjects had mutiple vomitting events. The exposure was noticed a delay after each vomitting compared with non-vomit subject. I have very limit data, and need a good fiitting for the plasma concentration to focus on the pd model. Is there any similar model reported in the literature? Much appreciate for your help! Best regards, Galadriel