Wednesday, 6 October 2010

Self Study - Herbs and Herbal Medicine

Bauer, B A "Herbal therapy: what a clinician needs to know to counsel patients effectively", Mayo Clinic Proceedings (2000), 75(8): 835-841

"The use of herbal medicine in the United States has been increasing at a steady pace over the past decade. Most recent estimates suggest that the US population spends $5 billion per year for herbal supplements alone."
"Interest in herbal medicine has been facilitated by multiple factors, including the perception that pharmaceutical medications are expensive, overprescribed, and often dagnerous. Alternatively, herbal medicine is often perceived as being 'natural' and is therefore considered safe."
"By strict botanical definition, a herb is 'a seed-producing annual, biennial, or perennial that does not develop persistent woody tissue but dies down at the end of a growing season'."
"Another definition for a herb is a 'plant or plant part valued for its medicinal, savory or aromatic qualities'."
"To avoid semantic confusion, some experts prefer the term botanical, which encompasses any plant-derived product used for a medicinal or health purpose. Others use the term phytomedicine or phytotherapeutics to denote the plant-derived products used for medicinal purposes."

Fugh-Berman, A "Herb-drug interactions", The Lancet (2000), 355(9198):134-138

"Concurrent use of herbs may mimic, magnify, or oppose the effect of drugs. Plausible cases of herb-drug interactions include:
- bleeding when warfarin is combined with ginkgo (Ginkgo biloba), garlic (Allium sativum), dong qual (Angelica sinensis), or danshen (Salvia miltiorrhiza)
- mild serotonin syndrome in patients who mix St John's wort (Hypericum perforatum) with serotonin-reuptake inhibitors
- decreased bioavailability of digoxin, theophylline, cyclosporin, and phenprocoumon when these drugs are combined with St John's wort
- induction of mania in depressed patients who mix antidepressants and Panax ginseng
- exacerbation of extrapyramidal effects with neuroleptic drugs and betel nut (Areca catechu)
- increased risk of hypertension when tricyclic antidepressants are combined with yohimbine (Pausinystalla yohimbe)
- potentiation of oral and topical corticosteroids by liquorice (Glycyrrihiza glabra)
- decreased blood concentrations of prednisolone when taken with the Chinese herbal product xaio chai hu tang (including senna [Cassia senna] and cascara [Rhamnus purshiana]) and soluble fibres (including guar gum and psyllium) can decrease the absorption of drugs.
Many reports of herb-drug interactions are sketchy and lack laboratory analysis of suspect preparations. Health-care practitioners should caution patients against mixing herbs and pharamceutical drugs."

What is the definition of a "herb"?

"A herb is a plant that is valued for flavour, scent, medicinal or other qualities other than its food value."
"Herbs have a variety of uses including culinary, medicinal, or in some cases even spiritual usage. In medicinal or spiritual use any of the parts of the plant might be considered 'herbs', including leaves, roots, flowers, seeds, resin, root bark, inner bark (cambium), berries and sometimes the pericarp or other portions of the plant"
"Culinary use of the term 'herb' typically distinguishes between herbs, from the leafy green parts of a plant, and spices, from other parts of the plant, including seeds, berries, bark, root and fruit. Culinary herbs are distinguished from vegetables in that, like spices, they are used in small amounts and provide flavour rather than substance to food."
"Botanical herbs by definition cannot be woody plants"
"There may be some medicinal effects when [herbs are] consumed in the small levels that typify culinary 'spicing', and some herbs are toxic in larger quantities."
"Herbs have long been used as the basis of traditional Chinese herbal medicine, with usage dating as far back as the first century CE and far before."
"Medicinal use of herbs in Western cultures has its roots in the Hippocratic (Greek) elemental healing system, based on a 4-fold elements healing metaphor."
"Modern pharmaceuticals had their origins in crude herbal medicines, and to this day, many drugs are still extracted as fractionare/isolate compounds from raw herbs and then purified to meet pharmaceutical standards."

American Botanical Council: Terminology

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