Is there a scientific basis for the therapeutic effects of serenoa repens in benign prostatic hyperplasia? Mechanisms of action.

PURPOSE: The huge resurgence of interest in herbal remedies has spawned a global industry that now competes with conventional drugs as adjuncts and/or alternatives for various conditions. The medical treatment of benign prostatic hyperplasia (BPH) is no exception. Along with alpha-blockers and 5alpha-reductase inhibitors the extract of the American dwarf palm, Serenoa repens, is unquestionably the most widely used. Together with Pygeum africanum, an extract from the bark of the African plum tree, it is licensed in Germany, France and other European countries for symptomatic BPH. This review was done to analyze the large number of in vivo and in vitro laboratory studies that have been performed with extracts of Serenoa repens to elucidate mechanism(s) of action.

MATERIALS AND METHODS: A literature search (MEDLINE) revealed more than 30 publications relating to laboratory studies with extracts of Serenoa repens, addressing the question of a mechanism of action. It would appear that the n-hexane lipidosterolic extract of Serenoa repens, namely Permixon (Pierre Fabre Medicament, Boulogne, France), is a product that has uniquely been subjected to more scientific investigation than any other such preparation.

RESULTS: Placebo controlled and comparative clinical studies of Permixon indicate its efficacy for BPH/lower urinary tract symptoms. Numerous mechanisms of action have been proposed, including an antiandrogenic action, an anti-inflammatory effect and an antiproliferative influence through the inhibition of growth factors.

CONCLUSIONS: Set against the background of our current knowledge of the pathophysiology of the aging prostate, the results of these studies suggest a wide spectrum of activity. However, precise mechanism(s) of action remain obscure. Balance and caution are needed when extrapolating the results of in vitro laboratory studies to the complex human situation.