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I am looking for examples in the literature where the precision of an
analytical method was extraordinarily large (50% or so) but the accuracy
was good (< 10% error) and that this was the only way to measure the
drug.
thanks
Peter L. Bonate, PhD
Senior Director
Global Head - Pharmacokinetics, Modeling, and Simulation
Global Clinical Pharmacology & Exploratory Development
Astellas Pharma Global Development
Three Parkway North
Deerfield, IL 60015
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Assays are governed by acceptance criteria for QC. In general these are
15 to 20% for instrumental techniques and 20 to 25% for ligand binding
assays. Ligand binding assays are moving towards an additional
requirement of total error TE which is the sum of cv and abs bias. That
being said, widening of the accuracy tolerance can happen with a
demonstration of due diligence. I have not however seen an assay
validated which suffers 50 %cv but returns 10% bias.
Something is wrong here which may be helped by increasing replicates?
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I don't have literature readily accessible, Peter, but recall that at
Crystal City II speakers from the major biotechs presented data from
cell-based assays that had these attributes. And as Ed O'Connor
mentions in his earlier reply, one way they attempted to deal with it
was by increasing the number of replicates - sample volume permitting.
--dean
Dean W. Knuth
President & CEO
Jasper Clinical Research & Development, Inc.
526 Jasper Street
Kalamazoo MI 49007
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