Rapid Efficacy of the Highly Selective α 1A -Adrenoceptor Antagonist Silodosin in Men With Signs and Symptoms of Benign Prostatic Hyperplasia: Pooled Results of 2 Phase 3 Studies

Effect of alpha-adrenoceptor antagonists on sexual function. A systematic review and meta-analysis

BACKGROUND

Alpha-adrenoreceptor antagonists or alpha-blockers are used in the treatment of hypertension, in the therapy of benign prostatic hyperplasia and in medical expulsive treatment of ureteral stones. These agents may affect the sexual function, with differences between drugs within the same class, depending on their selectivity for receptor subtypes. The aim of this review was to analyze the effects of alpha-blockers on sexual function.

MATERIALS AND METHODS

We conducted a systematic review and meta-analysis by searching PubMed, EMBASE and other databases for randomized controlled trials (RCTs) reporting sexual adverse effects in patients treated with alpha-blockers. Odds ratios for sexual dysfunction were calculated using random effects Mantel-Haenszel statistics.

RESULTS

Out of 608 records retrieved, 75 eligible RCTs were included in the meta-analysis. Compared with placebo, alphablockers were associated with increased odds of ejaculatory disorders both in patients with lower urinary tract symptoms (LUTS) associated to benign prostatic hyperplasia (BPH) (OR: 7.53, 95% CI: 3.77-15.02, Z = 5.73, p < 0.00001, I2 = 55%) and in patients with ureteral stones (OR: 2.88, 95% CI: 1.50-5.44, Z = 3.19, p < 0.001, I2 = 31%). Uroselective alpha-blockers showed higher odds of ejaculatory disorders. Conversely, nonselective alpha-blockers were not associated with higher odds of ejaculatory dysfunction. Silodosin was associated with increased odds of ejaculatory dysfunction compared with tamsulosin (OR: 3.52, 95% CI: 2.18-5.68, 15 series, 1512 participants, Z = 5.15, p < 0.00001, I2 = 0%). Naftopidil and alfuzosin showed lower odds of ejaculatory dysfunction compared to uroselective alpha-blockers.No statistically significant differences in the odds of erectile dysfunction were observed when alpha-blockers were compared to placebo.

Efficacy and Side Effects of Drugs Commonly Used for the Treatment of Lower Urinary Tract Symptoms Associated With Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is the most common benign disease of the prostate gland and is caused by benign hyperplasia of the smooth muscle cells and stromal cells in this important gland. BPH is also the most common disease underlying lower urinary tract symptoms (LUTS). The incidence of BPH increases with age and affects more than half of all men 50 years or older. BPH mainly exerts effects on urinary function and can seriously reduce a patient's quality of life. At present, treatment for BPH aims primarily to improve the quality of life and reduce the risk of BPH-related complications. Pharmacological therapy is recommended for moderate-to-severe cases of LUTS that are suggestive of BPH. A range of drugs is currently available to treat this condition, including α1-adrenoceptor antagonists, 5α-reductase inhibitors (5-ARIs), phosphodiesterase type 5 inhibitors (PDE5Is), muscarinic receptor antagonists (MRAs), β3-adrenoceptor agonists, and plant extracts. Of these, the most commonly used drugs in the clinic are α1-adrenoceptor antagonists, 5-ARIs, and combination therapy. However, these drugs exert their effects via various mechanisms and are associated with adverse reactions. The purpose of this review is to provide current comprehensive perspectives on the mechanisms of action, efficacy, and adverse reactions associated with the drugs most commonly used for the treatment of BPH.

Silodosin for the treatment of lower urinary tract symptoms in men with benign prostatic hyperplasia

BACKGROUND

A variety of alpha-blockers are used for treating lower urinary tract symptoms (LUTS) in men with benign prostatic hyperplasia (BPH). Silodosin is a novel, more selective alpha-blocker, which is specific to the lower urinary tract and may have fewer side effects than other alpha-blockers.

OBJECTIVES

To assess the effects of silodosin for the treatment of LUTS in men with BPH.

SEARCH METHODS

We performed a comprehensive search using multiple databases (Cochrane Library, MEDLINE, EMBASE, Scopus, Google Scholar, and Web of Science), trials registries, other sources of grey literature, and conference proceedings with no restrictions on the language of publication or publication status up until 13 June 2017.

SELECTION CRITERIA

We included all parallel, randomized controlled trials. We also included cross-over designs.

DATA COLLECTION AND ANALYSIS

Two review authors independently classified studies and abstracted data from the included studies. We performed statistical analyses using a random-effects model and interpreted them according to the Cochrane Handbook for Systematic Reviews of Interventions. We rated the quality of evidence according to the GRADE approach.

MAIN RESULTS

We included 19 unique studies with 4295 randomized participants across four comparisons for short-term follow-up. The mean age, prostate volume, and International Prostate Symptom Score were 66.5 years, 38.2 mL, and 19.1, respectively. Silodosin versus placeboBased on four studies with a total of 1968 randomized participants, silodosin may reduce urologic symptom scores in an appreciable number of men (mean difference (MD) -2.65, 95% confidence interval (CI) -3.23 to -2.08; low-quality evidence). Silodosin likely does not result in a clinically important reduction in quality of life (MD -0.42, 95% CI -0.71 to -0.13; moderate-quality evidence). It may not increase rates of treatment withdrawal for any reason (relative risk (RR) 1.08, 95% CI 0.70 to 1.66; low-quality evidence). We are uncertain about the effect of silodosin on cardiovascular adverse events (RR 1.28, 95% CI 0.67 to 2.45; very low-quality evidence). Silodosin likely increases sexual adverse events (RR 26.07, 95% CI 12.36 to 54.97; moderate-quality evidence); this would result in 180 more sexual adverse events per 1000 men (95% CI 82 more to 388 more). Silodosin versus tamsulosinBased on 13 studies with a total of 2129 randomized participants, silodosin may result in little to no difference in urologic symptom scores (MD -0.04, 95% CI -1.31 to 1.24; low-quality evidence) and quality of life (MD -0.15, 95% CI -0.53 to 0.22; low-quality evidence). We are uncertain about treatment withdrawals for any reason (RR 1.02, 95% CI 0.62 to 1.69; very low-quality evidence). Silodosin may result in little to no difference in cardiovascular adverse events (RR 0.77, 95% CI 0.53 to 1.12; low-quality evidence). Silodosin likely increases sexual adverse events (RR 6.05, 95% CI 3.55 to 10.31; moderate-quality evidence); this would result in 141 more sexual adverse events per 1000 men (95% CI 71 more to 261 more). Silodosin versus naftopidilBased on five studies with a total of 763 randomized participants, silodosin may result in little to no differences in urologic symptom scores (MD -0.85, 95% CI -2.57 to 0.87; low-quality evidence), quality of life (MD -0.17, 95% CI -0.60 to 0.27; low-quality evidence), treatment withdrawal for any reason (RR 1.25, 95% CI 0.81 to 1.93; low-quality evidence), and cardiovascular adverse events (RR 1.02, 95% CI 0.41 to 2.56; low-quality evidence). Silodosin likely increases sexual adverse events (RR 5.93, 95% CI 2.16 to 16.29; moderate-quality evidence); this would result in 74 more sexual adverse events per 1000 men (95% CI 17 more to 231 more). Silodosin versus alfuzosinBased on two studies with a total of 155 randomized participants, silodosin may or may not result in a clinically important increase in urologic symptom scores (MD 3.83, 95% CI 0.12 to 7.54; low-quality evidence). Silodosin likely results in little to no difference in quality of life (MD 0.14, 95% CI -0.46 to 0.74; moderate-quality evidence). We found no event of treatment withdrawal for any reason. Silodosin may not reduce cardiovascular adverse events (RR 0.67, 95% CI 0.36 to 1.24; low-quality evidence) but likely increases sexual adverse events (RR 37.21, 95% CI 5.32 to 260.07; moderate-quality evidence); this would result in 217 more sexual adverse events per 1000 men (95% CI 26 more to 1000 more).

AUTHORS' CONCLUSIONS

Silodosin may reduce urologic symptom scores in an appreciable number of men compared to placebo. Quality of life and treatment withdrawals for any reason appears similar. Its efficacy appears similar to that of other alpha blockers (tamsulosin, naftopidil and alfuzosin) but the rate of sexual side effects is likely higher. Our certainty in the estimates of effect was lowered due to study limitations, inconsistency and imprecision.

Comparison of Silodosin Monotherapy vs Silodosin With Tadalafil Add-on Therapy in Patients With Benign Prostatic Hyperplasia

OBJECTIVE

To evaluate the efficacy and safety of add-on therapy with the phosphodiesterase type 5 inhibitor tadalafil for patients with lower urinary tract symptoms secondary to benign prostatic hyperplasia (LUTS/BPH) treated with the α₁-adrenoceptor blocker silodosin.

MATERIALS AND METHODS

We analyzed 103 patients with LUTS/BPH with an International Prostate Symptom Score (IPSS) of >8 after ≥4 weeks of silodosin treatment from April 2016 through December 2016 at Kori Hospital. The patients subsequently received silodosin 4.0 mg twice daily (monotherapy group) or silodosin 4.0 mg twice daily plus tadalafil 5.0 mg once daily (add-on therapy group) for 8 weeks. We assessed adverse events and evaluated the mean change from baseline to 8 weeks in the IPSS, Overactive Bladder Symptom Score (OABSS), maximum urine flow rate (Q_max), and post-void residual urine volume.

RESULTS

Of 103 patients, 101 (98.1%) could continue medical treatment. The IPSS, OABSS, and Q_max showed significantly greater improvement in the add-on therapy than in the monotherapy group (-3.92 vs -1.24, -1.18 vs 0.10, and 1.09 vs -1.04, respectively; all P <.05). Although 4 patients experienced adverse events (add-on therapy: n = 3, 5.7%; monotherapy: n = 1, 2.0%), no significant differences were observed (P = .62). Among patients with overactive bladder (n = 55), the IPSS storage symptom subscore, IPSS urgency subscore, and OABSS urgency subscore showed significantly greater improvement in the add-on therapy than in the monotherapy group (-2.23 vs 0.17, -0.88 vs 0.28, and -1.5 vs -0.48, respectively; all P <.05).

CONCLUSION

Add-on therapy with tadalafil may be effective for patients with LUTS/BPH resistant to silodosin monotherapy.

Potential functional and pathological side effects related to off-target pharmacological activity

Most pharmaceutical companies test their discovery-stage proprietary molecules in a battery of in vitro pharmacology assays to try to determine off-target interactions. During all phases of drug discovery and development, various questions arise regarding potential side effects associated with such off-target pharmacological activity. Here we present a scientific literature curation effort undertaken to determine and summarize the most likely functional and pathological outcomes associated with interactions at 70 receptors, enzymes, ion channels and transporters with established links to adverse effects. To that end, the scientific literature was reviewed using an on-line database, and the most commonly reported effects were summarized in tabular format. The resultant table should serve as a practical guide for research scientists and clinical investigators for the prediction and interpretation of adverse side effects associated with molecules interacting with components of this screening battery.

The Effect of Seoritae Extract in Men with Mild to Moderate Lower Urinary Tract Symptoms Suggestive of Benign Prostatic Hyperplasia

We evaluated the effects of Seoritae extract (SE) on mild to moderate lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH). Seventy-six subjects with mild to moderate LUTS suggestive of BPH were prospectively recruited from the urology outpatient clinic and assigned to either SE (4200 mg or 6 tablets 3 times a day) or matching placebo. The primary outcome variable, the International Prostatic Symptom Score (IPSS), was evaluated at baseline and at 4 and 12 weeks. Postvoid residual volume (PVR), maximum urine flow rate (Q max), and prostate-specific antigen (PSA) levels were evaluated. IPSSs decreased significantly from baseline to 12 weeks within the SE group. Significant improvements in IPSS voiding scores at 4 and 12 weeks were also observed in the SE group compared to the placebo group. IPSS storage and quality of life scores were also significantly decreased at 12 weeks in the SE group. There was no change in Q max or PVR in both groups after 12 weeks. Administration of SE for 12 weeks led to significant improvements in LUTS, and it can be concerned as a reasonable and safe alternative for men with mild to moderate LUTS.

Placebo Medication and Sham Surgery Responses in Benign Prostatic Hyperplasia Treatments: Implications for Clinical Trials

Placebo medications and sham surgeries have long been thought to be inert treatments. These groups served as a threshold to which an active treatment should be compared in a randomized trial to determine the true efficacy of the active treatment. However, surprising changes in subjective symptom scores and objective measures of voiding have been demonstrated in numerous placebo medication or sham surgery arms of trials. The exact mechanisms by which these inactive treatments augment patient outcomes are not clearly defined and multiple theories have been proposed to explain the often pronounced response. It appears that urologic outcomes are particularly prone to these effects and the astute physician should keep these responses in mind when interpreting any trial on a new therapy.

Cell membrane chromatography coupled with UHPLC-ESI-MS/MS method to screen target components from Peucedanum praeruptorum Dunn acting on α1A adrenergic receptor

Peucedanum praeruptorum Dunn (BaiHuaQianHu in Chinese) is a traditional Chinese medicine that has a long history of use in China. In this study, HEK 293 α1A adrenergic cell membrane chromatography was coupled with UHPLC-ESI-MS/MS and successfully used to identify active components from Peucedanum praeruptorum Dunn. Paeruptorin A, paeruptorin B, and paeruptorin C were identified with α1A adrenergic receptor activity. Pharmacological assays showed that tamsulosin hydrochloride, paeruptorin A, paeruptorin B, and paeruptorin C in concentrations of 1×10(-8) to 1×10(-4)mol/mL could relax prostate strips pre-contracted with adrenalin in a concentration dependent manner. Therefore, the HEK293 α1A cell membrane chromatography coupled UHPLC-ESI-MS/MS system may be a potentially useful drug discovery method for screening for medicinal herbal components with α1A adrenergic receptor inhibitory activity.

Use of Silodosin to Visualize the Posterior Urethra in Pelvic Floor Urethral Distraction Defect Patients

Background:

Retrograde urethrogram and voiding cystourethrogram are used to define length and location of urethral stricture prior to surgery. We used a single dose of silodosin prior to VCUG to relax the bladder neck and achieve visualization of posterior urethra.

Objectives:

To evaluate the efficacy of silodosin in visualization of posterior urethra during VCUG, and to compare the findings with a control group.

Patients and Methods:

Patients were divided into two groups A and B containing 20 and 15 patients, respectively. Patients in group A were given a single dose of silodosin prior to radiological studies.

Results:

In group A 19 out of 20 patients were able to achieve satisfactory bladder neck opening while in group B 10 out of 15 patients were able to achieve bladder neck opening.

Conclusions:

Silodosin use prior to VCUG confers a statistically significant increase in bladder neck opening and visualization of posterior urethra.

Impact of alpha blockers, 5-alpha reductase inhibitors and combination therapy on sexual function

Medical treatments for lower urinary tract symptoms due to benign prostatic hyperplasia are frequently associated with changes in sexual function. While these medications are generally well-tolerated and have both reduced and delayed more invasive surgical options, the ramifications of long-term chronic use are largely unknown. Sexual side effects of these medications are frequently either reported as part of a short-term initial drug study or have inflexible endpoints that are not able to gauge more subtle changes in sexual performance. This review will delineate the currently known effects of these medications on sexual function and will consider mechanisms of dysfunction.