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HerbClip
Densie Webb, PhD Christina Chase, MS, RD Michele Schuman Editor - Mark Blumenthal Editorial Coordinator - Jan Veenstra
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Heather S Oliff, PhD Jill Hoppe Alondra Oubré, PhD
Writers Risa N Schulman, PhD Carolyn Orlando, AM Mariann Garner-Wizard
Underwriting - Wayne Silverman Production Coordinator - Susan McFarland
File: § Herb-Drug Interactions § Evidence-based Herbal Medicine HC 042210-197 Date: RE: July 6, 2001 Assessing A Rational Basis for Clinically Relevant Herb-Drug Interactions
Hardy ML. Herb-drug interactions: An evidence-based table. Alternative Medicine Alert. 2000; Vol. June, pp. 64-69. As the patients use of herbal products increases, so do the physicians’ concerns of herb-drug interactions. The literature consists mainly of case reports and most pharmacological data has not been assessed for clinical relevance. This paper is a table of the interactions of commonly used herbs and commonly prescribed drugs. The table is a work in progress because it is not exhaustive and new data will probably come available. The table is designed to provide the clinician with easy to use guidance in assessing the potential for interactions. The mechanism of actions for the interactions is listed when known or postulated. The table is organized alphabetically by drug category. It is very simple to look up the prescription drug category and see which herbs may cause potentially harmful interactions with the drug. The table includes such drug categories as: antiarrhythmics, which when given with cathartic laxatives such as aloe and cascara may actually increase the arrhythimia by increased potassium loss; benzodiazepines, which when given in conjunction with St. John's wort or kava may cause a decreased therapeutic efficacy, potentiation of common side effects, and increased sedation caused by the herbs binding to the GABA receptor site; barbiturates, which when given with valerian may increase the therapeutic effect and may prolong barbiturateinduced sleep; diuretics, an example is when Lasix® is combined with panax ginseng there may be a decreased therapeutic effect because ginseng may cause diuretic resistance; hypoglucemic agents, an example is when insulin is combined with garlic, panax ginseng, or fenugreek the herbs may cause an enhanced therapeutic effect by direct hypoglycemic activity or decreased glucose absorption; another category is minerals, which when given with fibercontaining herbs like flax or psyllium may cause decreased bioavailability of the mineral; nonsteroidal anti-inflammatory drugs (NSAIDs), which when given with nettles cause an increased therapeutic effect by potentiating the antiinflammatory activity of the NSAIDs; or opioids, when combined with panax ginseng may cause a decreased therapeutic effect by blunting the analgesic effect. The entire list of potential interactions, including the aforementioned, is over four pages long.
The author provides the level of evidence for the interaction (i.e. controlled trial, case report, animal study). Interestingly, most of the interactions are based on case reports or theory. The evidence from controlled trials is limited. This is probably the best paper available, in terms of ease of use, describing drug-herb interactions. Both the clinician and consumer would benefit by keeping this paper handy as a desk reference. —Heather S. Oliff, Ph.D.
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