RE: PD modeling of dataset with opposite values in the measurement effect
From: "Pereira, Luis" Luis.Pereira@bos.mcphs.edu
Subject: RE: [NMusers] PD modeling of dataset with opposite values in the measurement effect
Date: Fri, 27 Jan 2006 16:56:23 -0500
Dear LiPing
Some effect data can cross the baseline value over time giving the impression of a
negative effect not translatable into a 'negative' concentration. I suggest you look
at the E vs. C plot since you may have a case of short term tolerance (or rebound
effect) depicted by a clockwise hysteresis loop (or proteresis). In that case you
may minimize the hysteresis defining your PK in terms of the concentration at the
biophase, and then use an Emax, Sigmoid Emax or any other appropriate PD model.
Best luck
Luis
---------------------------------------------------------------
Luis M. Pereira, Ph.D.
Assistant Professor, Biopharmaceutics and Pharmacokinetics
Massachusetts College of Pharmacy and Health Sciences
179 Longwood Ave, Boston, MA 02115
Phone: (617) 732-2905
Fax: (617) 732-2228
Luis.Pereira@bos.mcphs.edu