Interoccasion variability

Date: Fri, 17 Sep 1999 10:25:00 -0400 From: "Kevin Dykstra" <KDykstra@genetics.com> Subject: Interoccasion variability All, I have data for which PK was measured on multiple occasions for a number of patients. The drug in question obeys simple one-compartment kinetics and is administered as an IV infusion. I would like to obtain estimates of interoccasion variability as well as inter patient variability. In other words, we have Pij = Phat + Ei + Kij where Phat is the population typical parameter value, Ei is the interpatient error and Kij is the error for the jth occasion for the ith patient. It is not clear to me how to code this directly in NONMEM, although I have seen the problem addressed a couple times in the literature. I can imagine a two-stage approach where posthoc parameter estimates for each occasion are obtained and these then subjected to a linear mixed model analysis. Any other suggestions? Thanks in advance for your help. Kevin Dykstra