Over-the-counter herbals and drug interactions: getting the (right) message across.
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Biomedical subjects
Publications and source records attributed to Alyson Huntley.
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Herbal medicine is one of most popular choices of complementary therapies for women, particularly as an alternative treatment for menopausal symptoms. The most commonly used herbal medicines for the menopause is probably black cohosh (Actaea/Cimcifuga racemosa); other preparations used include red clover (Trifolium pratense), dong quai (Angelica sinesis) and evening primrose (Oenothera biennis). Some of these herbal medicines have a very good safety profile with little or no suggestion of interaction with conventional drugs. For others, there are many and significant drug-herb interactions. This article outlines the major known and theoretical drug-herb interactions of herbal medicines thought to be of benefit for menopausal symptoms, as well as discussing the implications for the medical profession.
Black cohosh (Actaea racemosa/Cimicifuga racemosa) is a North American perennial plant that has been used for traditional medicinal purposes by the native Indian population. Its modern day application is the treatment of menopausal symptoms. Unlike conventional non-herbal medications, herbal preparations have not been systematically evaluated for their safety. However, the evidence from in vitro, animal and clinical studies all suggest that black cohosh is a safe herbal therapy for menopausal women if taken for a limited period. More research is needed to evaluate the safety of this herb over longer periods of time, and also to further investigate its mechanism of action.
This paper systematically reviews the clinical evidence relating to the safety of extracts of the herbal anxiolytic kava (Piper methysticum). Literature searches were conducted in four electronic databases and the reference lists of all papers located were checked for further relevant publications. Information was also sought from the spontaneous reporting schemes of the WHO and national drug safety bodies and ten manufacturers of kava preparations were contacted. Data from short-term post-marketing surveillance studies and clinical trials suggest that adverse events are, in general, rare, mild and reversible. However, published case reports indicate that serious adverse events are possible including dermatological reactions, neurological complications and, of greatest concern, liver damage. Spontaneous reporting schemes also suggest that the most common adverse events are mild, but that serious ones occur. Controlled trials suggest that kava extracts do not impair cognitive performance and vigilance or potentiate the effects of central nervous system depressants. However, a possible interaction with benzodiazepines has been reported. It is concluded that when taken as a short-term monotherapy at recommended doses, kava extracts appear to be well tolerated by most users. Serious adverse events have been reported and further research is required to determine the nature and frequency of such events.
OBJECTIVE: To systematically review the available data relating to the safety of medicinal extracts of black cohosh (Actaea racemosa). DESIGN: Systematic literature searches were conducted in seven electronic databases, and the reference lists of all papers located were checked for further relevant publications. Information was also sought from the spontaneous reporting programs of the World Health Organization and national drug safety bodies. Sixteen manufacturers of black cohosh preparations were contacted and asked for data held on file. Finally, our own departmental files were searched. No language restrictions were imposed. Combination products and homeopathic preparations were excluded. RESULTS: Data from clinical studies and spontaneous reporting programs suggest that adverse events (AEs) with black cohosh are rare, mild, and reversible. Gastrointestinal upsets and rashes are the most common AEs. The spontaneous reporting programs do contain a few serious AEs, including hepatic and circulatory conditions, but causality cannot be determined. Although there is large amount of data investigating the efficacy of black cohosh, in particular the product Remifemin, safety issues and the monitoring of AEs have not been the focus. CONCLUSION: If black cohosh products are taken for a limited length of time, there seems to be a slight risk of mild, transient AEs. More serious AEs seem to be rare, and it is impossible to ascertain causality with black cohosh with the limited data available. Thus, although definitive evidence is not available, it would seem that black cohosh is a safe herbal medicine.