Re: Placebo in indirect PD models

From: Nick Holford n.holford@auckland.ac.nz Subject: Re: [NMusers] Placebo in indirect PD models Date: Thu, 27 Apr 2006 17:16:19 +1200 Ivan, Mark, I broadly agree with Mark's suggestion for a placebo response based on the 'Bateman' function as an empirical description. But there is a related class of models which describe disease progression that can be intepreted as having a biological basis e.g. the rate of bone resorption changes with time; growth of tumour cells (see Holford et al 2001). These models are extensions to the turnover (aka indirect effect) model family which incorporate time varying changes in either input or loss which are independent of drug. Whether or not one can estimates the model parameters is a question of the design of the study but with suitable designs the structural and randome effects parameters should be estimable. Best wishes, Nick Holford NHG, Mould DR, Peck CC. Disease Progress Models. In: Atkinson A, editor. Principles of Clinical Pharmacology. San Diego: Academic Press; 2001. p. 253-62. -- Nick Holford, Dept Pharmacology & Clinical Pharmacology University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x86730 fax:373-7556 http://www.health.auckland.ac.nz/pharmacology/staff/nholford/