1st Edition
Microbiological Assay for Pharmaceutical Analysis A Rational Approach
A user-friendly guide for the evaluation of microbiological assays, Microbiological Assay for Pharmaceutical Analysis: A Rational Approach provides a lucid explanation of the sources of error in microbiological assay and helps analysts choose efficient assay designs that will minimize those sources of error. Beginning with a review of the theoretical basis for the quantitative aspects, the author discusses microbiological assay as a branch of pharmaceutical analysis and distinguishes it from biological assay in general. He draws attention to the microbiological aspects that may not be so obvious to the chemical analyst and to the analytical aspects that may not be so obvious to the microbiologist.
The book contains detailed evaluations of assays that illustrate typical experimental designs and addresses how to present a realistic assessment of the best potency estimate from a series of assays. Although there are other valuable books available in this area, they do not address evaluation. Microbiological Assay for Pharmaceutical Analysis: A Rational Approach expands on the guidance given in pharmacopoeias and helps you choose the assay design most appropriate for the purpose of your assay.
Biological Assays in General
The Different Sorts of Microbiological Assay
The Basis of Calculation of Potency Estimates
Which Mathematical Model?
THE AGAR DIFFUSION ASSAY - ITS QUANTITATIVE BASIS
Historical Introduction
The Theory of Zone Formation
Principle of Calculation of Potency Estimate
THE THEORY AND PRACTICE OF TUBE ASSAYS FOR GROWTH PROMOTING SUBSTANCES
Introduction
The Mode of Action
Critical Factors in the Assay of Growth-Promoting Substances
Other Sources of Error
THE THEORY AND PRACTICE OF TUBE ASSAYS FOR GROWTH INHIBITING SUBSTANCES
Historical Introduction
Measurement of Response
The Form of Response Line
Historical Development of the Turbidimetric Method
Linearization of Sigmoid Curves
The Quantitative Theory of Microbial Inhibition
A Practically Determined Log Dose-Response Curve
Factors Affecting Final Cell Count
Summary and Conclusions
WHAT DO WE WANT OF AN ASSAY? HOW DO WE ATTAIN OUR GOAL?
Introduction
Pharmacopoeial Intention
Control of Antibiotic Bulk Materials
Control in Routine Manufacture
Research and Development
GENERAL PRACTICAL ASPECTS OF MICROBIOLOGICAL ASSAYS
Introduction
Inoculum
Test Solutions
Weighing
The Assay Medium
Selection of Latin Squares and the Plating Routine
Aseptic Techniques
Measuring Responses
Calculation of Potency Estimates and Confidence Limits
STANDARD REFERENCE MATERIALS
Historical Introduction
"Official" Reference Materials
National and Regional Reference Materials
In-House Standards
PRELIMINARY EVALUATION OF DATA
Introduction
Common Sense Inspection
Specific Tests for Abnormality
Detection of Outliers
Replacement of Missing Values
Summary and Conclusions
PARALLEL LINES ASSAYS - SOME DESIGNS AND THEIR EVALUATION
Introduction
A 3-Dose Level Assay Using Petri Dishes
A 3-Dose Level Assay for One Unknown Using a Large Plate and Latin Square Design
A 2-Dose Level Assay for Four Preparations [three unknowns] Using a Large Plate and 8 x 8 Latin Square Design
A 2-Dose Level Assay for Two Preparations [one unknown] Using a Large Plate and 8 x 8 Latin Square Design with Two Weighings of Each Preparation
A 4-Dose Level Turbidimetric Assay for One Unknown
A Small Plate Assay Using a 5-Dose Level Standard Curve
SLOPE RATIO ASSAYS, SOME DESIGNS AND THEIR EVALUATION
Introduction
Some Possible Designs
Preliminary Evaluation
General Statistical Procedures
The Procedure of Bliss
Evaluation of a 2-Dose Level Assay (1) Using the Bliss Procedure (2) The Procedure of the European Pharmacopoeia
CHOICE OF EXPERIMENTAL DESIGN
Introduction
Available Experimental Designs for Agar Diffusion Assays
Regulations and Options
Factors Influencing Width of Confidence Limits
Bias Due to Curvature of the Response Line
Non-Paralellism Due to Curvature
Choosing a Design for a Turbidimetric Growth Inhibiting Substance Assay
Choosing a Design for Turbidimetric Assay of Growth Promoting Substance
Summary and Conclusions
CONCLUDING THOUGHTS
Introduction
Calculation of a Weighted Mean Based on Internal Assay Variation
Comparison of the European and International Pharmacopoeia Methods
Application of the Various Formulae to Some Practical Results
Biography
William Hewitt studied pharmacy at the University of Nottingham. Later he studied chemistry at the University of London. He worked in the pharmaceutical industry for several years as a quality control analyst; this included the antibiotic sector, where he was introduced to and became fascinated by the microbiological potency testing of antibiotics. This was followed by work overseas as an advisor in quality control of pharmaceuticals. It was overseas that William recognized that the quantitative/mathematical principles of microbiological assay were not well understood. He prepared notes for use in his own laboratory explaining these principles. These were then expanded substantially and published in 1977 by Academic Press as: Microbiological Assay: An Introduction to Quantitative Principles and Evaluation. Few books have been written on the subject of microbiological assay, and the need was perceived for a book with more emphasis on the practical and microbiological aspects of the subject. A second book was produced in 1989, written in collaboration with Stephen Vincent, whose meticulous approach to practical detail and staff training made him an ideal partner. Theory and Application of Microbiological Assay was published by Academic Press. William has been active in promoting the understanding of microbiological assay through technology transfer in several Asian countries. He has also directed several short training courses in the U.K. and the U.S. and has acted as consultant to laboratories in Australia, Belgium, Ireland, Slovenia, and the U.K. Now retired from active laboratory work, William continues to write and produce software for assay evaluation, Hewitt Bioassays. He lives in a delightful rural part of West Wales with his wife and three cats. He has a passion for traditional jazz and plays clarinet.
