Medical brain notes 47

  Herbal Medicine Herbal therapies have become an integral part of the American health care scene. Since 1991, public use of herbal products has increased quite markedly, with over $5 billion spent annually. This does not include the many (up to 25%) pharmaceutical products used in conventional practice that originally were, and in some cases still are, derived from plants (Table 69.1). The perennial appeal of herbs may stem from their “natu-ral” origin, giving them the reputation of being some-how safer and better tolerated than prescription drugs. In addition, they are available without prescription, of-ten at much lower cost. For much of the world’s popu-lation, herbal treatments remain the first and some-times the only available treatment. Proponents of herbal therapy also state that the multiple compounds found in most herbal preparations have the advantage of acting  synergistically;  that is, they act in concert to produce a more enhanced effect than would a single...

  HERBAL MEDICINE TRADITIONS   Chinese traditional medicine, Ayurvedic  (Indian), and  Tibetan  traditions use complex herbal recipes and nutrition to achieve “balance” in the ill pa-tient. Although these practices are most commonly found in ethnic populations, they are also becoming popular in some western complementary and alternative circles.   Homeopathic  treatments frequently bear herbal   names and are often confused with allopathic herbal  preparations. The difference is that homeopathic reme-dies are serially diluted and shaken until they may lack any molecule of the original herb ingredient. Therefore, there is no risk of pharmacological toxicity from a homeopathic preparation.  Bach’s Flower Remedies  are a homeopathic variation in which flower essences are created by floating flowers in sunlit water. These essences are usually intended as remedies for emotional and spiritual rather than specific physical complaints. ...

  POTENTIAL CONCERNS   Detractors of herbal medicine use have legitimate con-cerns about dosage variability, possible toxicity and adulteration, herb–drug interactions, and above all, lack of FDA regulation. Far from being intrinsically harm-less, many pharmacologically active plant alkaloids and other compounds are natural defensive poisons; their very effectiveness may be an unanticipated conse-quence of their adaptive toxicity to grazing animals and insects. Thus, herbal products like digitalis, while quite “natural,” may also be dangerous or even fatal in over-dose. Other herbs may not be superior to better-researched pharmaceuticals, or they may delay the use of more effective therapy. While herbal research has un-derstandably lagged far behind that of patented med-ications, a surprising number of clinical trials exist, al-though some of them are fraught with methodological problems and much of the data is foreign and therefore not readily accessible to U. S. physicians. ...

  REGULATORY ISSUES   The explosion in popularity of herbs dates to the  Dietary Supplement Health and Education Act of 1994  ( DSHEA ), in which the FDA recognized herbal prepa-rations as dietary supplements outside of its direct reg-ulatory control. The act was a compromise between the FDA and manufacturing lobbies brought about in large measure by increased public demand for herbal prod-ucts. Instead of FDA regulation, these products now fall under the far less stringent Current Good Manu-facturing Practice in Manufacturing, Packaging or Holding Human Food regulations. Unlike prescription pharmaceuticals, which must be proved safe and effec-tive before being marketed, supplements do not have to be either safe or effective as long as they avoid thera-peutic claims on the label. Neither are they policed in regard to delivering accurate doses, although some consumer-oriented organizations, such as  Consumer   Lab  (www.ConsumerLab.com), are starting to...

  HERBAL PREPARATIONS   Echinacea   The purple coneflower  Echinacea purpura,  and its close relatives,  E. angustifolia  and  E. pallida,  are the source of the herb Echinacea, which is widely popular as a non-specific immune stimulant. These perennials are native to the prairies of North America and are now widely grown garden ornamentals. The root and aerial parts of the plant are the portions used, and the preparation’s potency can be verified by the transient tingling sensa-tion produced when it is tasted. Echinacea contains alkamides, caffeic acid esters (echinacoside, cichoric acid, caftaric acid), polysaccharides (heteroxylan), and an essential oil. Some echinacea products are standard-ized for their  echinacoside  content. In the past, adulter-ation with American feverfew ( Parthenium integri-folium ) was common. Echinacea is now sold either by   itself or in combination with golden seal or zinc for the treatment of co...

  Feverfew   Feverfew ( Tanacetum parthenium ) is a common European composite herb with daisylike white flowers now widely naturalized in the United States. While its name (a corrupted version of the Latin  febrifugia ) indi-cates a long history in herb lore, feverfew’s current pop-ularity is due to its use in the prevention and treatment of migraines. Feverfew has also been used for rheuma-toid arthritis and numerous other conditions with far less substantiation. The leaves contain sesquiterpene lactones, including  parthenolide,  which is thought to be the most active and important ingredient. Feverfew preparations are frequently standardized for partheno-lide content, which can vary substantially depending on time of harvest (levels drop after seeds form) and other factors. Most studies have used feverfew standardized to 0.6 to 0.7% parthenolide; the value of leaves con-taining less than 0.2% parthenolide is questionable.   Mechanism of Action   Par...

  Ginkgo Biloba Leaf Extract   Ginkgo, or maidenhair tree ( Ginkgo biloba ), is thought to be the most ancient of living tree species, and it is now also one of the top selling herbs in Europe and the United States because of its reputed ability to improve cognitive function.  Ginkgo leaf extract  is prepared from ginkgo leaf by a complex process that removes toxic  ginkgolic acid.  This reduces the risk of allergic reactions   to the leaves if they are consumed directly. Ginkgo leaf extract contains  24% flavone glycosides  (including the antioxidant  rutin,  which improves capillary fragility) and  6% terpene lactones.   Mechanism of Action   Ginkgo leaf extract appears to act primarily as a mild  cerebral vasodilator  that increases cerebral blood flow   and reduces blood viscosity.  Ginkgolides  inhibit platelet activating factor, and this may improve microcircula-tory blood flow in athero...

  Ginseng   Panax  ginseng describes the root from two species of   plants,  Asian  ginseng ( Panax ginseng ) and  American  gin-seng ( Panax quinquefolius ), popularly used for improv-ing stamina and providing a sense of well-being. The terms red and white ginseng refer to how the root is processed, not the species of origin.  Red  ginseng roots are steam-cured prior to drying, while  white  ginseng is bleached and dried. Panax ginsengs contain triterpenoid saponins called  ginsenosides  (also called  panaxosides ), of which up to 18 types are recognized as having differing and sometimes opposing pharmacological properties.   Siberian ginseng ( Eleutherococcus senticosus ) should not be confused with Panax ginseng. Although it belongs to the same plant family (Araliaceae), it is a much larger, more abundant, and consequently less ex-pensive plant. Like Panax ginseng, however, it is used as a tonic and adapt...

  Kava   Kava-kava ( Piper methysticum ) is a South Pacific island shrub the rhizome or root of which was used in the past as a ceremonial beverage and that today is popular as an  anxiolytic.  Historically, women prepared the kava by pounding and then chewing it. After being allowed to ferment in bowls, the kava was drunk by male islanders to mark a special event. The herb would induce a pleas-ant euphoric tranquility and contribute to the group’s social cohesion. The active ingredients are thought to be  kavapyrones  (also known as kavalactones), a family of   related synergistically active compounds that include  kawain  and  methysticin.   Mechanism of Action   The exact mechanism of action is unclear, but it is thought that kavapyrones may act in the amygdala, pro-ducing a tranquilizing and muscle relaxant effect. Despite inducing mild sedation and euphoria, there is usually no cognitive or memory impairment at typical dos...