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Philip D Hansten, John R Horn. (Pp 176; $14.95.) H&H Publications, 2003. ISBN 0-9674718-4-2.
Drug interactions account for up to 20% of all adverse drug reactions. The elderly are most susceptible to adverse drug interactions, partly because of age related changes in pharmacokinetics, but largely because of polypharmacy. The 2001 UK census data show that there almost seven million individuals over the age of 70 years, representing more than 10% of the population. Given this increase, it is likely that the potential for adverse drug interactions is going to increase, and it is therefore important for all prescribers to be aware of possible adverse drug interactions, and minimise the risk.
The authors of this pocketbook have a distinguished track record of producing excellent textbooks in this area. The 2003 edition of the book packs a lot of information in its 134 pages, in fact most of the information that one is likely to need about possible interactions. The main section covers the top 100 drug interactions listed alphabetically, the interactions for each drug presented as a table, followed by a text section on management. The authors then include three appendices covering the effects of antibiotics and warfarin, drug interactions that prolong the QTC interval, genetic polymorphisms of the cytochrome P450 enzymes (new for the 2003 edition), and drug interactions with herbal products. The book ends with a table of drugs known to modulate the activity of cytochrome P450 enzymes, and the efflux transporter P-glycoprotein.
Many of the interactions are covered in a great deal of detail. However as with any book, it is easy to find omissions—for example, the lack of any mention of the interaction between the cerivastatin and gemfibrozil, which lead to the withdrawal of cerivastatin, or the interactions with mibefradil, which also lead to its withdrawal. In addition one may come across drug names such as colesevelam, which are not commonly used in the UK. Nevertheless, this book is useful, and gives more detail than the British National Formulary in the types of interactions and their mechanisms. I note that a PDA version will soon be available, which I think will be an invaluable aid to clinical care; this will also allow more rapid updating as our knowledge of serious interactions increases.