Book Review
`
`Pharmaceutical Dissolution Testing,
`edited by
`Jennifer Dressman (Johann Wolfgang Goether Univ., Frankfurt, Germany)
`and Johannes Krämer (Phast GmbH, Hamburg/Saar, Germany),
`published by Taylor & Francis Group, Boca Raton, FL
`ISBN 0-8427-5467-0
`
`e-mail: tahseen.mirza@novartis.com
`
`Tahseen Mirza, Ph.D.
`Assistant Director, Pharmaceutical and Analytical Development, Novartis Pharmaceutical Corporation,
`One Health Plaza, East Hanover, NJ 07936
`
`Ihappen to believe that the topic of dissolution is not
`
`taught rigorously in undergraduate colleges. It is taught
`mainly in pharmacy schools,but very rarely in chemistry
`departments. Consequently,chemists that obtain employ-
`ment in the pharmaceutical industry lack the necessary
`background and have to learn dissolution testing on the job.
`This is unfortunate because dissolution is one of the most
`critical tests that are performed in order to establish the
`quality of the dosage forms. Dissolution testing provides
`assurance that the dosage form disintegrates and de-aggre-
`gates,and the drug gets liberated and becomes available in
`solution at the site of absorption. It is,perhaps,the most
`important test from the perspective of a patient. Therefore,
`training students and pharmaceutical analysts in dissolution
`is a worthwhile investment. This new book edited by
`Jennifer Dressman and Johannes Kraemer is a welcome
`arrival and will be very helpful in training dissolution scien-
`tists.
`The book comprises 14 chapters. I started reading the
`first chapter (about 30 pages) entitled “Historical Develop-
`ment of Dissolution testing”and found it to be very
`insightful. Dr. Tim Grady,one of the co-authors,has partici-
`pated in the early evolution and growth of dissolution
`testing during his long and highly successful career at the
`USP. His insight on the historical perspective is quite inter-
`esting and invaluable. The authors explain that the dissolu-
`tion test was mainly developed because of the inadequacy
`of the disintegration test. They also rightly point out that
`“like disintegration testing,dissolution tests do not prove
`conclusively that the dosage form will release the drug in
`vivo in a specific manner,but dissolution does come one
`step closer….” The chapter provides an accurate insight into
`the early collaborative work that was performed primarily
`between USP and FDA in order to identify methodologies,
`
`equipment,specifications,and all the issues that a new tech-
`nique encounters. The authors have also provided a
`comprehensive account of the early steps that were taken
`to standardize the test so that the variability in results could
`be minimized. The effort of Dr. Bill Hanson in standardizing
`equipment is recognized. It is also a good chapter to read if
`inquiring minds want to know such things as why basket
`apparatus became official before paddle apparatus,why
`multiple calibrator tablets are used to establish equipment
`suitability,and so forth. It was difficult for me to not go back
`and read the chapter again. I think other readers will enjoy
`it,too.
`The next three chapters deal with the compendial and
`regulatory aspects of the dissolution test. The second
`chapter is entitled “Compendial Testing Equipment:Calibra-
`tion,Qualification,and Sources of Error”written by Vivian
`Gray. The chapter contains a good description of all
`compendial equipment. It provides useful information that
`can be applied to performing a successful calibration of
`compendial equipment. The role of calibrator tablets is
`described as a test of the dissolution system that provides
`assurance that the system is suitable for intended use. The
`chapter has many hints and useful remedies that can be
`used in overcoming errors during equipment calibration.
`Chapter 3,written by William Brown,who is a current liaison
`at the USP for the Biopharmaceutics Expert Committee,
`contains information about the role of the major pharma-
`copeias,viz.,USP,BP,JP,and EP. The main function of a phar-
`macopeia is to provide a uniform and public basis on which
`to evaluate therapeutic products that are used in the prac-
`tice of medicine and pharmacy. Ingredients and products
`that fall short of these specifications can be judged unsuit-
`able for use. The author does a good job of giving a compar-
`ative evaluation of the dissolution test in the major
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`pharmacopeias. The history of the pharmacopeias,their
`role,comparative differences,and the attempts to harmo-
`nize the pharmacopeias are other topics that a reader will
`find interesting.
`Chapter 4 deals with the topic of the role of dissolution in
`the regulation of pharmaceuticals. The author of this
`chapter is Vinod Shah,who has played a very active and
`important role in the development of industry guidances
`while working at the U.S. Food and Drug Administration
`(CDER). The chapter gives an overview of the FDA guid-
`ances that utilize dissolution in justifying pre- or post-
`approval manufacturing changes and in applying for
`bio-waivers on the basis of BCS system. The section on
`dissolution profile comparison is very clear and concise. The
`author points out that these guidances have increased our
`reliance on the dissolution test,and it is to be expected that
`dissolution will continue to play a vital role in assessing both
`pharmaceutical as well as biopharmaceutical aspects of
`dosage forms.
`In Chapter 5,Clive Wilson and Kilian Kelly provide an
`overview of the various aspects of the role of GI transit in
`drug absorption. This knowledge was gathered mainly from
`the application of modern investigative tools such as MRI,
`gamma scintigraphy,and magnetic moment imaging. The
`chapter deals with the practical aspects such as the effect of
`gastric emptying and transit time on drug delivery and
`absorption. It is useful information for entry-level formula-
`tors and analytical chemists and serves as a good reference
`for those who are more experienced in the area of drug
`delivery. Chapter 6,entitled “Physiological Parameters Rele-
`vant to Dissolution Testing:Hydrodynamic Consideration”by
`Steffen Diebold,is well written. This can be a difficult topic,
`but the author has done a good job of explaining the
`concepts in a clear and concise manner. The author high-
`lights the fact that dissolution is a hydrodynamics-depen-
`dant process. Therefore,in order to control the variability in
`dissolution testing,one must understand how to maintain
`steady hydrodynamic conditions during the test. The
`chapter is a good reference for concepts such as Reynolds
`numbers,flow patterns (laminar to turbulent flow),the role of
`diffusion boundary layer,and also hydrodynamics in the GI.
`Chapter 7,written by Jennifer Dressman et al.,is entitled
`“Development of Dissolution Test on the Basis of Gastroin-
`testinal Physiology.” It provides logical,systematic,and
`scientifically sound strategies for the development of disso-
`
`lution methods. The main focus of the chapter is on the
`proper selection of the media. The authors write,“This is not
`a trivial question,since the outcome of the test can be
`greatly dependent on the dissolution medium,especially if
`the drug itself and/or key excipients are poorly soluble
`and/or ionizable.” I particularly like the strategy in which
`drugs are classified on the basis of solubility. For high solu-
`bility drugs,a simple test could be developed using buffer at
`pH 6.8 instead of acidic medium. Several good reasons for
`using the higher pH are presented,most importantly the
`fact that the gastric pH varies significantly in different indi-
`viduals and populations. Also,some drugs may not be as
`stable in acidic medium. Finally,the strategy for using
`biorelevent media in dissolution testing is very well
`explained.
`The next three chapters provide good background on the
`theory and modeling of in vitro–in vivo correlations,study
`design,and interpretation of in vitro–in vivo data. In
`Chapter 11,Johannes Kraemer et al. look at the dissolution
`test as a test of quality control. The chapter describes strate-
`gies for the development of dissolution methods,taking
`advantage of the regulatory guidances and pharmacopeial
`chapters. In Chapter 12,Cynthia Brown provides dissolution
`method development strategies from an industrial perspec-
`tive. The author emphasizes that dissolution methods not
`only assess quality of the product but also play a big role in
`the characterization of formulations during product devel-
`opment. The next chapter by Dale VonBeheren and
`Stephen Dobro is entitled “Design and Qualification of Auto-
`mated Dissolution Systems.” The chapter is concise and the
`authors discuss different aspects of dissolution automation
`including the rationale for extent of automation,regulatory
`considerations,21CFR11 compliance,equipment qualifica-
`tion,and maintenance. In the last chapter,V. Srini Srinivasan
`describes the role of dissolution in the assessment of
`bioavailability of ingredients in dietary supplements.
`The main aim of the authors was to write and edit a book
`covering all the aspects of dissolution utilizing experts from
`the entire international arena. I believe that the book
`certainly meets the objective. In conclusion,the book is a
`useful addition both as a text book for teaching new dissolu-
`tion scientists and as a reference book for all practitioners of
`dissolution.
`[Note:This book may be purchased at www.dissolutiontech.
`com.]
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