As the foreword says, drug delivery technology has played an important role in the development of the animal health industry since the 1980s.

This report provides a review of what is happening now in several important sectors of veterinary medicine and animal health. The take-up of drug delivery innovations has been most marked in one single sector, that of control of internal parasitic worms and external insect and mite parasites in cattle and sheep. The total value of this sector is more than 2000 m USD, about 12% of the total animal health and nutrition market. Over the past 15-20 years, a number of products utilising plastics, polymers and erodible metals have been developed, containing various active parasiticidal ingredients, sometimes as a series of tablets released through physical or electrochemical changes in the carrier, sometimes formulated in polymer or other complex matrices or retained within a semi-permeable membrane. Ear tags for fly control, collars for flea control and pour-on products for treatment of pigs, cattle and sheep have been developed.

The technology used in veterinary products often seems primitive by comparison with the biomaterials and devices R&D for human products, including as it does, hardware for administration of medicines and relatively simple formulation advances that provide longer-lasting release of actives, taste-masking, rapid-dissolution for tablets, or skin penetration. Into this class fall recent developments involving antibiotic-containing polymer formulations for periodontal disease, and mucosal-adhesive polymer patches containing chlorhexidine and nicotinamide for oral hygiene in dogs after dental treatment.

However, some products and technologies have been extremely innovative, including complex device engineering and polymer chemistry for dependable prolonged or repeat-releasing products in cattle and sheep, management of the sub-microscopic structure of antigens using novel surfactants and adjuvants for vaccines in horses, a pour-on product containing a notoriously insoluble anti-worm agent for sheep, that contains wax-coated microparticles given a positive charge to assist retention in the lanolin and migration through the skin, and shampoos for pet animals sold by a French company, containing surfactants in multilamellar vesicles developed by CNRS. A novel delivery system that uses microchips and batteries has been launched in New Zealand that improves breeding success for cattle, called the ‘intelligent breeding device’. The product is implanted and releases specific hormones in a timed sequence over defined periods. The US company Alza has been quite active in innovating delivery systems for animals, or adapting existing products for humans, utilising its expertise in the management of polymer-membrane systems that act as osmotic pumps. There are other drug delivery companies that have sought veterinary uses of developments primarily for humans.

This report is a useful summary of existing products and near-future trends. It does not go deeply into what current research in human biomaterials might do for veterinary drug delivery in the longer term. It might have some relevance for companies interested in the potential of the animal health market as an ‘add-on’ to human medical business, indeed part of Chapter 4 deals with generic issues in licensing delivery technology into the animal health area. The final chapter provides quite-detailed profiles of companies involved in developing drug delivery technologies, adjuvants and vaccine systems, including Aquila Biopharmaceuticals, CollaGenex Corp, Emisphere Technologies, Fuisz Technologies, PowderJect, Scherer DDS Ltd, and VRI.

Frontiers in Tissue Engineering Eds. Charles W Patrick Jr, Antonios G Mikos and Larry V McIntire, Pergamon (Elsevier Science Ltd) 1998 (ISBN 0 08 042689 1, hardback xvi + 700 pages)

This is a blockbuster, designed to take on ‘the enormous task of providing a comprehensive overview of this emerging field [of Tissue Engineering] and communicating the excitement felt by many of its participants’, in the words of the American pioneers in this area, Joseph Vacanti and Bob Langer, who provide the preface and contribute to the chapters. There are over 80 authors involved, 77 from the USA, 3 from Canada and one each from Korea and Japan. One question that immediately arises is how far the book can be said to represent the cutting edge of world R&D if it does not include European authors. Certainly, papers by European authors active in relevant fields seem under-represented in some chapters (see chapter III.4 Tissue engineered tendon, compared with chapters IV.7 Tissue engineered skin or IV.8 Engineering a bioartificial liver system).

The subject range is certainly broad. Just over half the book deals in a broad and authoritative way with the basics of tissue engineering – understanding cells, cell-cell interaction and cell-material interactions. Published in 1998 with the most recent references in 1997 and ‘in press’, it is as up-to-date as such a large multi-author volume can be. The references themselves are extremely useful for further reading. The index is rather sketchy and not very thorough, so that it is easier to navigate using chapter titles. There are useful chapters on ethical considerations and regulatory issues, the latter written by FDA CDRH and CBER staff involved in day-to-day regulation of biomaterials and devices. The remainder of the book deals with organ and tissue systems and the work underway, for example with tendons, peripheral nervous system, muscles, small intestine, heart and skin. Each chapter discussed the clinical problem, the normal physiology, form and function of the tissue or organ, the natural repair processes, current medical or surgical interventions, current work on tissue engineering and prospects for future development.

The price was not available at the time of writing this review. It is difficult not to recommend this book, however, because of its integrated approach to the anatomy, function, pathology and bioengineering possibilities. Even if we feel that it has not spotlighted what is happening in Europe, it gives a welcome window onto current activities in the USA against which EU R&D can be benchmarked. As a reference book and a volume for academic use, it is likely to be well-used and will provide a foundation for knowledge that can then be supplemented by proceedings of the ESAO, for example, to provide a fully up-to-date picture of progress.

Design Engineering of Biomaterials for Medical Devices. David Hill. John Wiley & Sons Ltd, Chichester UK, New York USA. 1998. Hardback £95.00 (xii + 468 pp, ISBN 0 471 96708 4)

This book is an extraordinary tour de force written by an intensely practical materials engineer, employed by Rocket Medical plc of the UK. The text, created by one person, speaks with a coherent voice, thus overcoming one of the problems facing a multi-authored book, no matter how well edited. But what a voice! Each chapter approaches its topic from the fundamental aspects, as if it were a practical lecture and demonstration. This reader was impressed by this pragmatic approach. However, it often seems too occupied with the comprehensive engineering and design approach to materials per se, seeming to neglect or perhaps not adequately bias the text towards those aspects that are really important for biomedical materials or biomedical applications. Lists of materials and their characteristics mention non-medical applications far more than medical ones. For example, Chapter 13, dealing with batteries in a descriptive and comprehensive way, gives one absolutely no idea of which type of battery might be used in a pacemaker or defibrillator, and why. The chapter on polymers mentions many that are used in non-medical applications but few that are used in devices, omitting for example polylactic and polycaprolactone polymers already in use for solid systems. These are serious shortcoming in a book that contains ‘Biomaterials’ and ‘medical devices’ in its title, since it gives the impression that the author has cobbled together a series of lectures he gives to local college students, rather than selecting material carefully to correspond with the title.

Yet there is something compelling about this encyclopaedic and down-to-earth approach. The book is targeted by the author firmly at students and engineers but it also provides the non-expert with valuable insights into all sorts of aspects of materials selection, behaviour and use. The systematic approach (see Chapter 15 on Design process and factors for some excellent figures and tables) and the general atmosphere of ‘Questions that should be asked’ is very valuable. The book is clearly the prelude to more detailed texts that will take the advanced reader as well as the student through specific biomaterials or devices issues, well-prepared by this volume. Since the scope is ‘medical devices’, it would have been useful to have had a chapter entitled ‘What are medical devices?’, because we would then see the vast range of products for healthcare that are included in this phrase, in USA and in EU, as defined by the FDA and the European Commission.

Scattered throughout the book there are small niggling typographic errors that should have been picked up (‘you’ for ‘your’, ‘phosphorous’ for ‘phosphorus’, ‘doe’ for ‘does’, ‘dosimety’ instead of ‘dosimetry’, for example). The index appears undiscriminating. There are too many entries that lead to mere words or phrases rather than explanatory sections (try ultrasonic welding and weight-to-strength ratio) and there are inaccuracies (ultrasonic welding on page 64 not page 63 as indexed, and weight-to-strength ratio does not appear on page 6, rather it is strength-to-weight ratio). But somehow, despite the caveats above, I feel that this is a book to recommend. Its approach is bracing, it will underpin the necessary understanding of materials for students who then go on to specific design and engineering tasks for devices and materials, and it is relatively good value-for-money.

Metals as Biomaterials Eds. Jef A Helsen and H Jürgen Breme. John Wiley & Sons Ltd, Chichester UK, New York USA. 1998. Hardback £120.00 (xii + 510 pp, ISBN 0 471 96935 4)

This book comprises 15 chapters by 20 authors, all from Europe (Germany, Belgium, the Netherlands, France and Portugal) covering a satisfyingly broad scope, from the materials themselves to retrieval analysis via the nature and manipulation of the material-material and material-tissue interfaces and measurement techniques for material integrity, characteristics and structure. The authors come from recognised centres of excellence such as INEB Portugal, University of the Saarland Saarbrucken, Institute of Materials Science Dresden, Catholic University of Leuven and Memory Metal Holland, the only industrial representative. The book is avowedly aimed as a handbook and reference book for professionals in industry, clinics and research, and as a fundamental textbook for all biomaterials students.

The scope would certainly satisfy that aim. The chapters are supported in most cases by a profusion of tables, graphs, figures and illustrations. The index is less satisfactory, being a combination of single-page entries for subjects, which are sometimes the start page of a relevant section, and sometimes just an individual mention, and page-ranges to sub-chapters or sections dealing with the referenced topic. It is not complete or, always, accurate – the subject of stents is referenced pages 87-9 but page 89 is illustrations of dental springs; cobalt is referenced to pages 269 and 274 but also appears in text on pages 275-279, 282 and 284 and in tables and figures on pages 278, 281, 283-285. In the text, most spelling mistakes and usage errors have been picked up and corrected, but there are some remaining, such as T1 for Ti, polyethelene for polyethylene, particular for particulate, tissular for tissue, granulated tissue for granulation tissue. All chapters include a nomenclature section at the end, a glossary of abbreviations used, which is very helpful. The reference sections as usual are a good guide to background research and reading – for students and PhDs, a consolidated reference list might also be useful.

The first chapter gives an aide memoire for the characteristics that need to be borne in mind when choosing or designing a material for use as an orthopaedic implant, and good flow diagrams for designing and executing the manufacture. The considerations are of course somewhat different when a soft tissue replacement such as contact lens, ligament or skin is considered, but this is understandably outside the scope of the book. The text integrates in a very easy and impressive way the physical aspects of the material and the physiological, biological and surgical aspects of the eventual device in use (see pp 23-25 for example). The book is indeed useful for reference – Chapter 2 contains physical data on most metallic biomaterials in use and the corresponding biological materials they replace or supplement, in tabulated form.

The chemical bases for corrosion phenomena are fully-c9vered in Chapter 4. Chapters 5-8 concern surfaces and surface modification, including organic, polymeric and ceramic coatings. Chapter 6 on organic coatings is perhaps too simple and generalised in its approach to structure and characteristics of proteins and amino-acids, and spends too little time discussing the current advances in glycopeptides, growth factors and integrin-like surface attachment molecules that are now being developed as coating components for better osteointegration of prostheses. Chapter 7 on polymers provides a detailed introduction to polymer structure and molecular behaviour that enables the reader to visualise why polymers behave as they do when used as biomaterials in vivo. Chapter 8 provides similar useful detail on ceramic coatings and surface-hardening.

Chapters 3 (shape memory metals), 5-8 (surfaces and coatings) and 9-11 (biological responses) are of great relevance to the biomaterials projects in Brite-EuRam. Chapter 9 is another very useful reference, to the known toxicological effects of the metals used in implants. The other two chapters describe the electrochemical and biological bases of material-cell interaction respectively. Chapters 12-14 certainly provide detailed information on three analytical methods, enough for the reader to pass an examination; but they would be little use to people using techniques other than X-ray photoelectron spectroscopy, atomic force microscopy and electrochemical impedance spectroscopy.

Perhaps the most interesting chapter from the practical and clinical point of view is the final one, dealing with retrieval analysis. In the current harsh climate of reimbursement justification and cost-benefit analysis, the future of many new developments will depend, paradoxically, on an adequate bank of high-quality reliable historic data relating to long-term performance of materials and devices in vivo. The reports reviewed in this chapter certainly suggest that we will be seeing more problems in future, rather than less. The behaviour of hip replacements made using Ti stems and CoCr alloy heads was not predicted from in vitro work, with increasing cases of galvanic crevice corrosion at the head-neck junction and local tissue necrosis due to metal particles. It is also clear that patients carrying implants of Ni, Cr, Co alloys have unphysiologically-high levels of the metal ions in their blood and urine. The toxicological outcomes are not yet clear, though it is known that these three metals are highly allergenic, cobalt is associated with pulmonary fibrosis and nickel salts are carcinogenic. The adverse effects of most importance in relation to implants are bone resorption due to metal and polyethylene particles and granulomatous or necrotic soft-tissue reactions due to particles or leached ions. It is of increasing concern that a few cases of bone and connective tissue cancers seem definitely associated with fracture fixation or implantation of metals.