Stockley's Herbal Medicines Interactions

Herbal products have gained substantial public acceptance. They are currently used by an estimated 5–20% of the population, resulting in global annual sales of £35 billion (€50 billion, US$60 billion). In part, this is because the general public perceives medicines from a natural source to be safer and more effective than those derived from synthetic chemicals. Importantly, herbal products are federally categorized as dietary supplements, foods and nutrients and regulated much less stringently than standard pharmaceuticals. This has enabled herbal products to have less than specific indications and variable quality control. They can be stocked in a variety of commercial outlets without much cautionary labelling, displayed with relatively innocuous substances like vitamins and minerals implying equivalent therapeutic benefit and purchased without consultation with a licensed healthcare professional. The net result is that many patients are unlikely to consider that self-medication with a herbal medicine carries risks. However, there is ample evidence that certain herbals can cause adverse consequences particularly when administered with standard drug therapy. Since up to 43% of patients taking herbals also receive a prescription or an over-the-counter drug, unwanted herbal medicine–drug interactions have the potential to be broad in scope. Healthcare professionals confess lack of knowledge in this area. A wealth of new experimental data now exists on this topic and regulations for traditional medicines are changing in many countries. This has provided the basis for the first edition of Stockley's Herbal Medicines Interactions with the primary purpose to be an easily accessible guide for healthcare professionals that would enable unbiased and useful counsel for patients wanting to take a herbal product with standard medicines. The current best available published information has been critically reviewed and presented in a familiar format for rapid access and application to the clinical circumstance. The introductory section provides an excellent referenced orientation. Subsequently, 150 monographs of herbal medicines, nutraceuticals and dietary supplements are summarized under the headings of synonyms, pharmacopoeias, constituents, use and indication, pharmacokinetics and interactions overview. Then, interactions between each and specific drugs are described in a standardized layout (single statement of outcome, clinical evidence, experimental evidence, mechanism, importance and management, references). The data are presented for more than 550 interactions. Although the best information comes from controlled clinical studies, these are relatively few with herbal medicines. In this book, much is derived from animal and in vitro data which makes the translation of it directly to the clinical environment not readily apparent. However, a helpful rating system incorporates this shortcoming into one of five readily understandable symbols (life-threatening, significant hazard requiring dosage adjustment or close monitoring, potentially hazardous but where data are inconclusive, doubt about outcome requiring guidance about possible adverse effects and some monitoring, not considered of clinical importance). Overall, Stockley's Herbal Medicines Interactions is a unique, well thought out and needed publication in the area of natural products–drug interactions that approaches the specified goals set for it.