Reviewed: Osmers R, Friede M, Liske E, et al. Efficacy and safety of isopropanolic black cohosh extract for climacteric symptoms. Obstet Gynecol. 2005;105:1074-1083.
Black cohosh (Actaea racemosa L., Ranunculaceae, syn. Cimicifuga racemosa [L.] Nutt) has a long history of medicinal use for a variety of gynecologic conditions, and numerous clinical trials suggest its efficacy in alleviating the climacteric (i.e., the period of time between the end of reproductive capacity in women and the completion of menopause) symptoms associated with menopause. Most of the clinical trials were conducted in the 1980s and 1990s, and, since that time, clinical research methods have continued to improve. Therefore, the present study was conducted to obtain new evidence of the safety and efficacy of black cohosh by evaluating the leading and most clinically tested product, a proprietary isopropanolic extract of black cohosh root stock and rhizome, Remifemin® (Remifemin is manufactured by Schaper & Brümer, Salzgitter, Germany). (At the time of the publication of this trial, Remifemin was imported and marketed in the United States by GlaxoSmithKline; as of June 20, 2005, the importation and marketing of Remifemin reverted to Enzymatic Therapy of Green Bay, WI, the company that initially introduced Remifemin to the US market.)
In this trial, 304 postmenopausal women (with either 6 months or more since the last regular menstruation) were randomly assigned to 1 of 2 treatments in a randomized, double-blind, placebo-controlled, multi-center trial. For 12 weeks, 1 group (n = 153) received 1 Remifemin tablet (2.5 mg isopropanolic extract of black cohosh [20 mg of root stock]) 2 times daily, and the other group (n = 151) received a placebo. Clinical examinations and interviews were conducted before treatment and at 4 and 12 weeks. Climacteric symptom intensity was evaluated on the basis of the Menopause Rating Scale (MRS)—a scale comprising 10 items, each of which is rated from 0 (no complaints) to 1 (severe symptoms) in increments of 0.1.
The primary outcome was the change from baseline in the MRS score. Secondary outcomes were safety (evaluated on the basis of adverse events and clinical measures) and changes in the 4 subscores of the MRS: hot flashes (hot flashes, sweating, and sleep disorders), psyche (depression, nervousness, irritability, and memory), soma (heart, joint, and muscle symptoms), and atrophy (sexual disorders, vaginal dryness, and urinary complaints).
The black cohosh extract was significantly more effective than was placebo in decreasing the MRS score (P < 0.001), and treatment had the greatest effect in women who had just begun menopause. The effect size was similar to that of conventional hormone replacement therapy and therefore clinically relevant. Four of the MRS subscores decreased significantly in the black cohosh group (relative to the placebo group): P = 0.007 for hot flashes, P = 0.012 for atrophy, and P = 0.019 for psyche. No significant treatment effect was observed for heart, joint, and muscle symptoms.
Adverse events were reported by 50 (32.7%) subjects in the black cohosh group and by 47 (31.1%) subjects in the placebo group; the difference in number of reported adverse events was not significantly different between groups. Most of the adverse effects in the black cohosh group were determined to be "mild and transient" and were deemed consistent with the data found in numerous other studies. A causal relation between black cohosh and adverse events was suspected to be "possible" in only 6 cases (3.9%) as compared to 7 cases (4.6%) in the placebo group. The researchers also evaluated the "putative hepatotoxic potential" of black cohosh in response to a few published case reports suggesting a possible relationship between ingestion of various black cohosh preparations (none have involved Remifemin) and hepatotoxicity, although these cases have been evaluated and deemed to lack evidence of causality. After monitoring liver enzymes during the trial, the authors wrote, "Our study does not show clinically relevant changes in the primarily important hepatic enzymes [GGT, AST, ALT] in comparison to placebo."
The results of this study confirm the findings of previous studies, which demonstrate the efficacy and tolerability of this particular proprietary black cohosh extract (Remifemin) in alleviating climacteric symptoms, especially hot flashes. Remifemin appears to be most effective during early menopausal years. The authors conclude that Remifemin has "a favorable benefit-risk ratio." The authors conclude that further randomized controlled trials to directly compare the effects of black cohosh preparations with those of conventional hormone replacement therapy would be valuable.
—Brenda Milot, ELS, and Mark Blumenthal