From: Leon J Aarons -
Subject: [NMusers] NONMEM and symbols
Date: 1/7/2004 1:38 PM

This is a suggestion/request from a journal editor. For the two 
journals that I am involved with - the British Journal of Clinical 
Pharmacology and the Journal of Pharmacokinetics and 
Pharmacodynamics - I frequently get papers to edit which are 
based on a NONMEM population analysis. The problem that I am 
concerned with can be illustrated with the two compartment open 
model which for NMTRAN is coded by ADVAN4, TRANS4. 
NONMEM uses V2 and V3 to denote the volume terms as well as 
other parameters such as F2 etc. The issue I have is that many 
authors are using these symbols, not only in tables, but in the 
body of the manuscript. Not only is the use of V2 and V3 
numerically illogical for a two compartment model - although I 
perfectly understand and accept why NONMEM uses this 
convention (it is actually a four compartment model) - these are 
above all pharmacokinetic parameters and should be understood 
outside the context of a NONMEM analysis.

I would recommend the article by Rowland and Tucker, 
J.Pharmacokin.Biopharm.(as was) 8: 497-507 (1980) 'Symbols in 
Pharmacokinetics' and in particular the quote from Humpty Dumpty 
aka Lewis Carroll
"When I use a symbol, it means just what I choose it to mean - 
neither more nor less"


Leon Aarons
School of Pharmacy and Pharmaceutical Sciences
University of Manchester
Manchester, M13 9PL, U.K.
tel +44-161-275-2357
fax +44-161-275-2396