Weight normailized doses in modeling

From: "TKT (Thomas Klitgaard Tygesen)" <tkt@novonordisk.com> Subject: [NMusers] Weight normailized doses in modeling Date: Fri, 26 Oct 2001 22:19:24 +0200 Dear nmusers: Could some of you enlighten me with some considerations on dose normalizations (by weight) in PK/PD modeling? I'm in the process of setting up a dose dependant one-compartment model on insulin and have all my dose in weigh normalized units. Moreover, I have a number of covariates which I'd like to investigate, as to their influence on model parameters (by looking at the eta's and the individual parameters estimates, plotted against these covariates). However, it may be that my model should be expressed in absolute doses (e.g. by multiplying a dose of, say, 0.3 U/kg by each subjects weight) before running the estimation. Otherwise, my final parameters will in some way be expressed in per kg units. Does the per kg estimation present any particular problems (e.g. by masking covariate effect) or is more a matter of practice? Thanks in advance. Thomas K Tygesen Civil engineer Direct +45 44424960 Fax +45 44421940 tkt@novonordisk.com