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In Brief: Serenoa repens (Permixon ® ), an extract
of the dwarf American palm, has been available for several years for the
treatment of benign prostatic hypertrophy (BPH).
In men with BPH, oral administration of Serenoa repens 160mg twice daily for 1 to 3 months was generally superior to placebo in improving subjective and objective symptoms of BPH. The drug appears to have similar efficacy to finasteride as evidenced by data from over 1000 men. Few significant differences were demonstrated between Serenoa repens and a 1-adrenoceptor blockers in small comparative studies.
Gastrointestinal effects, such as nausea and abdominal pain, have been the most commonly reported adverse effects associated with Serenoa repens in clinical trials.
BPH is a heterogeneous disease, consequently no single agent or group of drugs is likely to be effective in all patients. Available data suggest that Serenoa repens may be useful as an alternative to the better established agents a 1-adrenoceptor blockers and finasteride. [Drugs & Therapy Perspectives 10(3):1-4, 1997. © 1997 Adis International Limited]
* (Permixon ® ) is currently available in some European and other countries (e.g. France, Germany and Spain) for the treatment of BPH. The drug is the n-hexane lipidosterolic extract of the pulp and seed of the dwarf American palm (also known as Serenoa repens). It is a complex mixture of various compounds. 
Like finasteride, Serenoa repens has inhibitory effects on 5a -reductase. Some of the features of these 2 agents are compared in the Differential Features Table. Various additional mechanisms for the efficacy of Serenoa repens in BPH have also been suggested, including inhibition of binding of dihydrotestosterone to cytosolic androgen receptors in prostate cells. 
TURP Is the Most Effective OptionFor those requiring therapy, transurethral resection of the prostate (TURP) has been the mainstay of treatment. Despite being very effective, TURP is associated with a high risk of complications and morbidity, including potential impotence.  Additionally, about 20 to 25% of patients do not have a long-term satisfactory outcome after TURP, and many men prefer to avoid the procedure and its potential complications.  Other methods may, therefore, be preferable for some individuals.
Rapid Relief with a -Blockers...Treatment with a 1-adrenoceptor blockers (such as alfuzosin+, doxazosin+, prazosin and terazosin+) can produce rapid relief of symptoms. However, results are not as good as with surgery and adverse effects such as orthostatic hypotension may be problematic. Long-term therapy is required to maintain the benefits. 
...But Not with FinasterideAlternative agents such as finasteride produce moderate reductions in prostate volume when given for a year or more, although this is not always associated with much symptomatic relief.  The drug has a slow onset of effect and beneficial effects may not become apparent until after at least 6 or possibly 12 months of therapy. 
Better than PlaceboImprovements in urinary frequency and peak urinary flow rates generally appear to be greater with Serenoa repens than placebo in patients with BPH. However, a large placebo effect is often seen in these individuals. In 3 studies (each evaluating >50 patients), Serenoa repens 160mg twice daily for 1 to 3 months was associated with: [11-13]
Similar to Finasteride...Serenoa repens and finasteride have been shown to reduce urinary symptoms to a similar extent (37 vs 39%). Serenoa repens 160mg twice daily was compared with finasteride 5mg once daily for 6 months in over 1000 men with BPH. Urinary symptoms were assessed by the International Prostate Symptom Score. Similar improvements in self-rated quality-of-life scores (69 vs 73%) were also noted between patient groups. 
Although both drugs improved peak urinary flow rates and reduced prostate volume, these changes were significantly greater with finasteride. However, a similar percentage of patients in each group had a 30% increase in peak urinary flow rate. Improvements in symptoms occurred rapidly, after 6 weeks of therapy in both groups.  Given the high placebo responses seen in these individuals, the inclusion of a placebo group would seem to be an important consideration in studies evaluating men with BPH.
...and Other ComparatorsAlthough there are few comparisons available, clinical efficacy tended to favour the a 1-adrenoceptor blockers, alfuzosin (2.5mg 3 times daily)  and prazosin (2mg every 12 hours)  over Serenoa repens (160mg twice daily) in 2 studies. However, few significant differences were observed between treatment groups for improvements in urinary frequency, urinary flow rate and postmicturition residual urine volume. These studies evaluated small patient numbers and were of short duration.
Serenoa repens should be taken with meals to minimise possible gastrointestinal disturbances. 
Key Points in the Overall Evaluation of Serenoa Repens in Benign Prostatic HypertrophyClinical Benefits
Although there was no significant difference between the 2 groups in the treatment options selected, patients in the SDP group were significantly better informed about BPH than control patients at 2 weeks after enrolment. The SDP group was also significantly more satisfied with the decision-making process at 3 and 12 months. General health and physical functioning remained stable among patients in the SDP group but deteriorated among control patients.
|Mechanism of action||Inhibition of 5a -reductase isoenzymes type 1 and 2 and other additional effects||Inhibition of 5a -reductase isoenzyme type 2|
|Efficacy in BPH|
|Prostate volume (% reduction)c||6||18|
|Risk of sexual dysfunction||Low||Low|
|Other adverse effects||Gastrointestinal||Breast tenderness and enlargement, hypersensitivity|
|Dosage (oral)||320 mg/day given bid||5mg daily|
|Acquisition cost d|
|In the UK (£)||NA||24.90|
|In the US ($)||NA||52.78|
|In France (FF)||199.55||201.40|
a Includes hesitancy, impairment of size or force of urinary stream, interruption of urinary stream and terminal dribbling. b Includes nocturia, sensation of incomplete voiding, urgency, dysuria and daytime frequency. c Data taken from large comparative study.  d For 28 days' treatment at usual maintenance dosage.
Abbreviations and symbol: bid = twice daily; NA = not available; § = drug provides relief from some or all of these symptoms.