Post treatment effect

3 messages 3 people Latest: Oct 10, 2001

Post treatment effect

From: Atul Bhattaram Venkatesh Date: October 10, 2001 technical
From: "atul" <bvatul@ufl.edu> Subject: Post treatment effect Date: Tue, 9 Oct 2001 23:44:39 -0700 Hello All Could somebody share ideas on how to incorporate a POST TREATMENT EFFECT ie., we have a new baseline parameter (nontoxic levels) at the end of a study which is much lower than the observed baseline (toxic levels) initially in PKPD models. Any references in this direction? Thanks Atul

Re: Post treatment effect

From: Nick Holford Date: October 10, 2001 technical
From: Nick Holford <n.holford@auckland.ac.nz> Subject: Re: Post treatment effect Date: Wed, 10 Oct 2001 16:58:56 +1300 Atul, If I understand you correctly you are wanting to describe the situation where the response after treatment is different from the starting response. The response (what you call "levels") may have its own time course independent of drug treatment or the time course may be affected by the treatment. This sounds like you might want to consider a disease progress model that accounts for the changing response over time. This review may help: Chan PLS, Holford NHG. Drug treatment effects on disease progression. Ann Rev Pharmacol 2001;41:625-59 Nick -- Nick Holford, Divn Pharmacology & Clinical Pharmacology University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x6730 fax:373-7556 http://www.phm.auckland.ac.nz/Staff/NHolford/nholford.htm

RE: Post treatment effect

From: Stephen Duffull Date: October 10, 2001 technical
From: "Stephen Duffull" <sduffull@pharmacy.uq.edu.au> Subject: RE: Post treatment effect Date: Thu, 11 Oct 2001 08:32:58 +1000 Atul In addition to Nick's comment about the changing underlying disease process you might also consider that the temporal nature of the "drug on" model is not the same as the "drug off" model, eg the time for maximum effect of a proton pump inhibitor is a few hours but the time to loss of effect is a few days. There are also examples where the off is faster than the on. In addition some feedback mechanisms may take longer to return to "normal" than the length of your experiment and therefore apparently altering the baseline... etc etc ... Regards Steve ================= Stephen Duffull School of Pharmacy University of Queensland Brisbane, QLD 4072 Australia Ph +61 7 3365 8808 Fax +61 7 3365 1688 http://www.uq.edu.au/pharmacy/duffull.htm