The 4PL Model in Bioassay

Who Should Attend


The course is intended for bioassayists and their trainers, statisticians, regulatory affairs personnel, quality control workers, and managers who need to understand how the 4PL model is used to estimate relative potency.


Graduates of the course will understand (and feel comfortable using) the 4PL model. The course strongly emphasizes the importance of good laboratory technique, especially volumetric transfers, to produce precise and accurate relative potency estimates.


The course is aimed at both beginning and experienced workers. The course assumes no previous knowledge of statistics.

Key Topics You Will Learn About


  • How to use the standard form of the 4PL model
  • How to work with the canonical 2PL form of the model
  • How to differentiate among drug substance, drug preparation, and drug product, and why it's important
  • How analytic dilution assays work
  • How to estimate relative potency
  • How to recognize non-similar (non-parallel) samples
  • Why averaging replicate columns can distort the data
  • Why many assay acceptance criteria can have unintended consequences
  • How to avoid "multiplicative mischief" from using too many assay acceptance criteria
  • Why true replicates have advantages over false replicates

How You Will Benefit From This Course


  • You will gain confidence in the use of the four-parameter logistic (4PL) model in bioassay
  • You will enhance your ability to extract meaningful information from your data sets
  • You will improve your decision-making abilities
  • You will learn new ways to look at data
  • You will understand the importance of careful pre-plate dilutions and careful transfers to the top well of the plate
  • You will understand how to achieve 5 %CV or less for your bioassays
  • You will consult with a seasoned expert about your data analysis challenges

Morning


The 4PL Model


  • The mathematical form of the 4PL
  • The canonical form of the 4PL (the 2PL)
  • The C parameter
  • The B parameter
  • Concentration vs. relative concentration
  • Plotting the 4PL against concentration, not log-concentration

Dose


  • Definition of drug substance, drug preparation, drug product, drug, dose
  • Dilution factor
  • Relative concentration
  • Standard presentation of information

Analytic Dilution Assays


  • Pioneers: Wood, Finney, Jerne
  • Theory of analytic dilution assays
  • Similarity ("parallelism")
  • Relative potency
  • How analytic dilution assays work

The 15-Parameter Logistic (15PL) Model


  • Randomization
  • Common parameters
  • The 15PL
  • Examples

Potency


  • Definition of potency
  • Absolute and relative potencies
  • A worked 4PL example


Afternoon


Software


  • The plate as the statistical unit
  • Full visual printout
  • Full text printout
  • Outlier removal

Some Plates for Class Discussion


  • Something about a mistake on the plate
  • Something about non-similarity
  • Something about pre-plate dilutions
  • Something about transfers to the top well

Acceptance Criteria


  • True non-similarity
  • Apparent non-similarity
  • Sample acceptance criteria
  • Acceptance criteria in general
  • Quality control sample

True Replicates and Pseudo Replicates


  • Pseudo replicates
  • True replicates
  • Bioassayists are responsible for precision

Assay Control Sample


  • Multiplicity, the experiment-wise alpha
  • ED50 values are not important here
  • Transitioning to a new ref std
  • Control charts
  • Final comments

Discussion


  • The "hook effect" and how to model it
  • Equivalence test vs. F-test
  • Participant questions

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