Efficacy and Safety of the Hexanic Extract of Serenoa repens vs. Watchful Waiting in Men with Moderate to Severe LUTS-BPH: Results of a Paired Matched Clinical Study

Serenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement

BACKGROUND

Benign prostatic hyperplasia (BPH) is a non-malignant enlargement of the prostate, which can lead to obstructive and irritative lower urinary tract symptoms (LUTS). The pharmacologic use of plants and herbs (phytotherapy) for the treatment of LUTS associated with BPH is common. The extract of the berry of the American saw palmetto or dwarf palm plant, Serenoa repens (SR), which is also known by its botanical name of Sabal serrulatum, is one of several phytotherapeutic agents available for the treatment of BPH.

OBJECTIVES

To assess the effects of Serenoa repens in the treatment of men with LUTS consistent with BPH.

SEARCH METHODS

We performed a comprehensive search of multiple databases (the Cochrane Library, MEDLINE, Embase, Scopus, Web of Science, and LILACS), trials registries, other sources of grey literature, and conference proceedings published up to 16 September 2022, with no restrictions on language or publication status.

SELECTION CRITERIA

We included randomized controlled trials of participants with BPH who were treated with Serenoa repens or placebo/no treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion at each stage and undertook data extraction and risk of bias assessment and GRADE assessment of the certainty of the evidence. We considered review outcomes measured up to 12 months after randomization as short term, and beyond 12 months as long term. Our main outcomes included urologic symptom scores, quality of life, and adverse events.

MAIN RESULTS

For this update, we narrowed the review question to only comparisons with placebo. We included 27 studies (of which 9 were new) involving a total of 4656 participants, 19 studies comparing Serenoa repens with placebo, and 8 studies comparing Serenoa repens in combination with other phytotherapeutic agents versus placebo. Most studies included men aged > 50 (mean age range 52 to 68) with moderate urologic symptoms (International Prostate Symptom Score [IPSS] range 8 to 19). Ten studies were funded by the pharmaceutical industry; two studies were funded by government agencies; and the remaining studies did not specify funding sources. Serenoa repens versus placebo or no intervention Results for this comparison are based on predefined sensitivity analyses limited to studies at low risk of bias. Serenoa repens results in little to no difference in urologic symptoms at short-term follow-up (3 to 6 months; IPSS score range 0 to 35, higher scores indicate worse symptoms; mean difference (MD) -0.90, 95% confidence interval (CI) -1.74 to -0.07; I2 = 68%; 9 studies, 1681 participants; high-certainty evidence). Serenoa repens results in little to no difference in the quality of life at short-term follow-up (3 to 6 months; IPSS quality of life domain range 0 to 6, higher scores indicate worse quality of life; MD -0.20, 95% CI -0.40 to -0.00; I2 = 39%; 5 studies, 1001 participants; high-certainty evidence). Serenoa repens probably results in little to no difference in adverse events (1 to 17 months; risk ratio (RR) 1.01, 95% CI 0.77 to 1.31; I2 = 18%; 12 studies, 2399 participants; moderate-certainty evidence). Based on 164 cases per 1000 men in the placebo group, this corresponds to 2 more (38 fewer to 51 more) per 1000 men in the Serenoa repens group. Serenoa repens results in little to no difference in urologic symptoms at long-term follow-up (12 to 17 months, IPSS score, MD 0.07, 95% CI -0.75 to 0.88; I2 = 34%; 3 studies, 898 participants; high-certainty evidence). Serenoa repens results in little to no difference in quality of life at long-term follow-up (12 to 17 months, IPSS quality of life, MD -0.11, 95% CI -0.41 to 0.19; I2 = 65%; 3 studies, 882 participants; high-certainty evidence). There were no data on long-term adverse events for this comparison. Serenoa repens in combination with other phytotherapy versus placebo or no intervention Different phytotherapeutic agents that include Serenoa repens may result in little to no difference in urologic symptoms compared to placebo at short-term follow-up (12 to 24 weeks, IPSS score, MD -2.41, 95% CI -4.54 to -0.29; I2 = 67%; 4 studies, 460 participants; low-certainty evidence). We are very uncertain about the effects of these agents on quality of life (very low-certainty evidence). These agents may result in little to no difference in the occurrence of adverse events; however, the CIs included substantial benefits and harms (12 to 48 weeks, RR 0.91, 95% CI 0.58 to 1.41; I2 = 0%; 4 studies, 481 participants; low-certainty evidence). Based on 132 cases per 1000 men in the placebo group, this corresponds to 12 fewer (55 fewer to 54 more) per 1000 men in the combined phytotherapeutic agents with Serenoa repens group.

AUTHORS' CONCLUSIONS

Serenoa repens alone provides little to no benefits for men with lower urinary tract symptoms due to benign prostatic enlargement. There is more uncertainty about the role of Serenoa repens in combination with other phytotherapeutic agents.

Lipid Profile and 5α-Reductase Inhibition Activity of Proprietary Ultrahigh-Pressure Supercritical Carbon Dioxide and Hexane Saw Palmetto Extracts

Inhibition of 5α-reductase (5αR), which blocks the conversion of testosterone to its active metabolite, dihydrotestosterone, has been shown to impact further prostate enlargement (benign prostatic hyperplasia, or BPH). Clinical trials of standardized lipidosterolic extracts of Serenoa repens (LSESr), also known as standardized extracts of saw palmetto, have demonstrated improvement in lower urinary tract symptoms (LUTS) and delayed progression of BPH. The aim of this preclinical study was to compare two standardized LSESr, a proprietary ultrahigh-pressure supercritical carbon dioxide extract of S. repens (UHP-sCESr) and the well-established hexanic extract of S. repens (HESr), for both 5αR inhibition activity and lipid profiles. UHP-sCESr and HESr had nearly identical inhibition curves and comparable IC50 values for 5αR-1 (9.25 ± 0.87 and 9.86 ± 0.11 μg/mL, respectively; p = 0.43) and 5αR-2 (7.47 ± 0.07 and 7.72 ± 0.05 μg/mL, respectively; p = 0.0544). UHP-sCESr and HESr also had comparable lipid profiles based on similar total fatty acid levels (87.7% and 91.5%, respectively), weight/weight comparisons of individual fatty acids, and individual fatty acid ratios to lauric acid. In addition, UHP-sCESr meets the standard set by the United States Pharmacopeia (USP) monograph for authenticity and purity for a supercritical carbon dioxide (SCCO2) extract of saw palmetto, whereas HESr meets the standard set by the European Medicines Agency (EMA) for a well-established medicinal product. In conclusion, based on enzyme inhibition curves and IC50 values, a standardized lipid profile is important to achieve comparable mechanisms of action for lipidosterolic extracts of saw palmetto. UHP-sCESr offers a comparable, standardized LSESr for men with LUTS/BPH in regions where the proprietary HESr is not available.

The Role of Combination Therapy with α-Blockers and Hexanic Extract of Serenoa repens in the Treatment of LUTS/BPH

The hexanic extract of Serenoa repens (HESr) has been in use for decades as an effective, safe and well-tolerated therapy for relieving bothersome lower urinary tract symptoms (LUTS) associated with benign prostate hyperplasia (BPH). This manuscript gives an overview of HESr as monotherapy for LUTS/BPH treatment and focuses on the currently available literature investigating the possible clinical benefits of HESr combination therapy with α-blockers. Combination therapy of HESr with α-blockers has been gaining significant interest in recent years, as an increasing body of evidence shows the beneficial pharmacological effects that HESr treatment can add to standard first-line treatment with α-blockers. By reducing persistent Prostatic Inflammatory Status (PIS), commonly present in LUTS/BPH patients, HESr complements the relaxation of prostate smooth muscle induced by α-blockers, thus providing additional symptom relief. Data suggest that patients harbouring PIS and having a specific clinical profile might especially benefit from the combination therapy. Future therapeutic efforts may take advantage of more personalised strategies for LUTS/BPH management.

Efficacy and Tolerability of 6-Month Treatment with Tamsulosin Plus the Hexanic Extract of Serenoa repens versus Tamsulosin Plus 5-Alpha-Reductase Inhibitors for Moderate-to-Severe LUTS-BPH Patients: Results of a Paired Matched Clinical Study

The objective of this subset analysis was to evaluate and compare the efficacy and tolerability of two combination treatments for men with moderate-to-severe lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS/BPH). Data were from a real-world, open-label, prospective, and multicenter study performed in outpatient urology clinics. Men with moderate-to-severe LUTS/BPH received 6-month treatment with tamsulosin (TAM) in combination with either the hexanic extract of S. repens (HESr) or a 5-alpha-reductase inhibitor (5ARI). Changes in urinary symptoms and quality of life were measured using the IPSS and BII questionnaires, respectively. Treatment tolerability was assessed by recording adverse effects (AEs). Patients in the two study groups were matched using iterative and propensity score matching approaches. After iterative matching, data were available from 136 patients (n = 68 treated with TAM + 5ARI, n = 68 with TAM + HESr). After 6 months of treatment, mean (SD) IPSS total score improved by 7.7 (6.3) and 6.7 (5.0) points in the TAM + 5ARI and TAM + HESr groups, respectively (p = 0.272); mean BII total scores improved by 3.1 (2.9) and 2.9 (2.4) points (p = 0.751), respectively. AEs were reported by 26.5% and 10.3% of patients in the same groups, mostly affecting sexual function (p < 0.027). When used in a real-world setting to treat patients with moderate-severe LUTS/BPH, 6-month treatment with TAM + HESr was as effective as TAM + 5ARI, but with better tolerability.