Most clinical research has tested the commercial preparation of black cohosh known as Remifemin, which is standardised to contain triterpene glycosides (0.8-1.2 mg/tablet), but recently there has been some investigation of BNO 1055, an aqueous ethanolic extract (58% vol/vol), sold as Klimadynon and Menofem (Bionorica AG, Neumarkt, Germany).
A review of eight clinical trials published in 1998 found that black cohosh (Remifemin) is a safe and effective alternative to HRT for menopausal patients in whom HRT is contraindicated (Lieberman 1998). Symptoms responding to treatment with black cohosh include hot flushes, vaginal thinning and drying, night sweats, sleep disturbances, anxiety and depression.
Two clinical studies have been conducted in recent years with the BNO 1055 black cohosh extract. A double-blind, randomised, multicentre study compared the effects of BNO 1055 (40 mg/day) to conjugated oestrogens (0.6 mg/day) and placebo on climacteric complaints, bone metabolism and endometrium (Wuttke et al 2003). The study involved 62 postmenopausal women who took their allocated treatment for 3 months. BNO 1055 proved to be equipotent to conjugated oestrogens and superior to placebo in reducing climacteric symptoms and both active treatments produced beneficial effects on bone metabolism. Vaginal superficial cells increased with both active treatments; however, BNO 1055 had no effect on endometrial thickness, which was significantly increased by conjugated oestrogens.
A randomised study (Hernandez & Pluchino 2003) was also performed with 136 young premenopausal breast cancer survivors experiencing hot flushes as a result of tamoxifen therapy. When BNO 1055 (Menofem/Klimadynon, corresponding to 20 mg of herbal drug) was used together with tamoxifen for 12 months, the number and severity of hot flushes were reduced, with almost 50% of subjects becoming free of hot flushes, and severe hot flushes were reported by only 24% compared with 74% for those using tamoxifen alone.
In contrast, a previous double-blind, placebo controlled study (n = 85) failed to detect significant improvements with black cohosh for hot flush frequency or severity when used by patients with breast cancer for 2 months and who were also taking tamoxifen (Jacobson et al 2001). Unfortunately, the authors of that study did not specify which black cohosh product was being used or the dosage, making a comparison with the previous study difficult.
Recently, a Swiss multicentre, randomised, placebo-controlled, double-blind study (Frei-Kleiner et al 2005) was conducted with 122 menopausal women and found that daily black cohosh root extract Cr 99 (6.5 mg dried rhizome extract, drug/extract ratio 4.5-8.5:1 corresponding to 29-55 mg with an average of 42 mg crude drug, extraction solvent 60% ethanol v/v) had a significant effect in women with menopausal disorders of moderate intensity according to a Kupperman Index >20. Concerning the Menopause Rating Scale, active treatment decreased score values by 48% in the A. racemosa group compared with 14% for placebo. Herbal combination studies One study has investigated the effects of a fixed combination of isopropanolic black cohosh (Remifemin; standardised to 1 mg triterpene glycosides) and ethanolic St John's wort (standardised to 0.25 mg total hypericine) in women with menopausal symptoms with pronounced psychological symptoms (Uebelhack et al 2006). The double-blind, randomised study of 301 women found that 16 weeks of herbal treatment produced a significant 50% reduction in the Menopause Rating Scale score compared with 20% with placebo and a significant 42% reduction in the Hamilton Depression Rating Scale compared with only 13% in the placebo group. Each treatment tablet contained black cohosh extract (corresponding on average to 3.75 mg native extract and 22.5-41.25 mg rootstock) and St John's wort extract (corresponding to 70 mg native extract and 245-350 mg herb). Patients took two tablets twice daily for 8 weeks then reduced to one tablet twice daily for the remainder of the study. There were no relevant group differences regarding adverse events, laboratory values, or tolerability.
A combination of soy isoflavones, black cohosh and nutritional supplements failed to have a significant effect on menopausal symptoms in a 12-week randomised,
placebo-controlled, double-blind study of 124 women (Verhoeven et al 2005). Women in the supplement group received 125 mg soy extract daily (providing 50 mg isoflavones including 24 mg genistein and 21.5 mg daidzein), 1,500 mg evening primrose oil extract (providing 1 50 mg gamma linoleic acid), 100 mg Actaea racemosa L. extract (providing 8 mg deoxyacetein), 200 mg calcium, 1.25 fjg vitamin D, and 10 IU vitamin E, whereas the women in the placebo group received 2000 mg olive oil daily.
Commission E has approved the use of this herb as a treatment for menopausal symptoms (Blumenthal et al 2000). Similarly, the World Health Organization (WHO) recognises its use for the 'treatment of climacteric symptoms such as hot flushes, profuse sweating, sleeping disorders and nervous irritability'. The North American Menopause Society recommends black cohosh, in conjunction with lifestyle approaches, as a treatment option for women with mild menopause-related symptoms (2004).
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