PD modeling of dataset with opposite values in the measurement effect

From: "Li-Pin Kung" lpkung@aol.com Subject: [NMusers] PD modeling of dataset with opposite values in the measurement effect Date: Wed, 25 Jan 2006 14:19:35 -0500 Dear friends, When the population data of a pharmacological effect is distributed across zero, is it a variability or a dual effect or...? We don't accept the PK data when it is negative. However, we can not reject a PD data when it indicates a negative value of the desired effect. I believe the Hills eq holds when (E-E0 )/Emax is positive. Am I correct? I am working on a -blocker. I want to build a model for PKPD correlation. All the PK data are though concentrations. 20% of the corresponding PD data showed unfavorable to the pharmacological effect, i.e. the individual blood pressure at the though level was higher than its baseline. Is it reasonable to fit all the data to one Hills equation? What would be the base model do you suggest? Thanks, Liping