USDA Center for Veterinary Biologics Statistics Section Work Instructions Document: STATWI0005.01 Title: Logistic Curve Parameterizations in Commercial Software Author: Christopher Tong and Marie Vendettuoli Approved by: David Siev on 2017.03.23 This document approved for the indicated purposes Internal use Yes External distribution Yes CVB public web site Yes STATWI0005.01 Cover Page – page 0 2017.03.23 Source document: CVB Quality Manual Chapter 5 Parameterizations of the four-parameter logistic curve in software for estimating relative potency Christopher Tong∗ and Marie Vendettuoliy Statistics Section Center for Veterinary Biologics (CVB) U.S. Department of Agriculture Ames, Iowa, USA 23 March 2017 Contents 1 Introduction 3 2 Scope 3 3 Conventions 4 3.1 Concentration and dilution . 4 3.2 Assay response type . 5 3.3 4PL curve . 6 3.4 Graphing . 7 3.5 Suitability Criteria . 8 3.6 Procedure for estimating relative potency . 8 4 Examples 10 5 Software Implementation 13 5.1 SoftMax Pro 6.3 [10] . 14 5.2 Gen5 2.01 [1] . 15 6 An alternate parameterization of the 4PL curve 18 ∗
[email protected] [email protected] 1 STATWI0005.01 page 1 of 20 References 19 2 STATWI0005.01 page 2 of 20 1 Introduction In vitro enzyme immunoassays (eg, ELISAs) are often used as relative potency tests for lot release1 of biological products [2, 9]. In such assays, a single 96- well microtiter plate may contain serial dilution sequences of one or more test lots and a reference preparation. The measured response in each well is an Optical Density (OD) value.