Naftopidil for the treatment of benign prostate hyperplasia: a systematic review

Early investigational agents for the treatment of benign prostatic hyperplasia'

INTRODUCTION

Benign prostatic hyperplasia (BPH), as a clinical entity that affects many people, has always been in the forefront of interest among researchers, pharmaceutical companies, and physicians. Patients with BPH exhibit a diverse range of symptoms, while current treatment options can occasionally cause adverse events. All the aforementioned have led to an increased demand for more effective treatment options.

AREAS COVERED

This review summarizes the outcomes of new medications used in a pre-clinical and clinical setting for the management of male lower urinary tract symptoms (LUTS)/BPH and provides information about ongoing trials and future directions in the management of this condition. More specifically, sheds light upon drug categories, such as reductase‑adrenoceptor antagonists, drugs interfering with the nitric oxide (NO)/cyclic guanosine monophosphate (GMP) signaling pathway, onabotulinumtoxinA, vitamin D3 (calcitriol) analogues, selective cannabinoid (CB) receptor agonists, talaporfin sodium, inhibitor of transforming growth factor beta 1 (TGF-β1), drugs targeting the hormonal control of the prostate, phytotherapy, and many more.

EXPERT OPINION

Clinical trials are being conducted on a number of new medications that may emerge as effective therapeutic alternatives in the coming years.

Repurposed Drugs in Gastric Cancer

Gastric cancer (GC) is one of the major causes of death worldwide, ranking as the fifth most incident cancer in 2020 and the fourth leading cause of cancer mortality. The majority of GC patients are in an advanced stage at the time of diagnosis, presenting a poor prognosis and outcome. Current GC treatment approaches involve endoscopic detection, gastrectomy and chemotherapy or chemoradiotherapy in an adjuvant or neoadjuvant setting. Drug development approaches demand extreme effort to identify molecular mechanisms of action of new drug candidates. Drug repurposing is based on the research of new therapeutic indications of drugs approved for other pathologies. In this review, we explore GC and the different drugs repurposed for this disease.

Long-term consequences of bilateral cavernous crush injury in normal and diabetic rats: a functional study

A recent statement from the European-Society-for-Sexual-Medicine has highlighted the limitations of using the rat model for nerve-sparing prostatectomy. The use of young rats with no comorbidities and the early evaluation of the erectile function (EF) are deemed a source of bias. Our aim was to evaluate the long-term consequences in EF of bilateral nerve cavernous crush- injury (BNCI) in type 1 diabetic (DM) rats 30-male/12-week-old rats were divided into four groups: Sham, BNCI, DM, and BNCI + DM. Sham group underwent an intraperitoneal injection (IP) of saline solution and after 1 month underwent a sham laparotomy. BNCI underwent an IP of saline solution and after 1 month to BNCI. DM underwent an IP of 60 mg/kg-1-streptozotocin (STZ) and after 1 month to a sham laparotomy. BNCI + DM underwent an IP of 60 mg/kg-1-STZ and after 1 month to BNCI. After 5 months from the induction of diabetes, all rats underwent measurement of intracorporeal pressure (ICP) and mean arterial pressure (MAP) during CN-electrostimulation. Multiple groups were compared using Kruskal-Wallis one-way analysis of variance followed by Mann-Whitney U test for post hoc comparisons. Blood glucose-level was higher (p < 0.05) in the groups with DM and BNCI + DM. After 5-months, DM and BNCI + DM also showed a lower weight compared to other groups (p < 0.05). No differences were noted in ICP/MAP between the sham and BNCI. BNCI + DM showed lower ICP/MAP compared to all the groups (p < 0.05). DM Showed lower ICP/MAP compared to Sham and BNCI (p < 0.05). BNCI in rats without comorbidities did not induce long-term erectile dysfunction (ED) suggesting a spontaneous EF recovery. BNCI in DM induced long-term ED. The results of previous short-term studies can only provide evidence on the time to recovery of spontaneous EF as to the actual EF recovery rate.

Naftopidil enantiomers suppress androgen accumulation and induce cell apoptosis via the UDP-glucuronosyltransferase 2B15 in benign prostate hyperplasia

Accumulation of androgens mediate alterations in prostate growth and has emerged as an essential factor in benign prostate hyperplasia (BPH). Dihydrotestosterone (DHT), the most potent natural androgen, binds to androgen receptors (AR) and regulates the prostate growth. Many inhibitors of DHT synthesis have been developed to reduce DHT levels and used in the treatment of prostate diseases. However, therapies targeting the elimination of the DHT remain limited. The DHT in prostate is metabolized by UDP-glucuronosyltransferase 2B (UGT2B) and transforms into inactive products. In this study, we analyzed and demonstrated that two enantiomers of naftopidil (NAF), an α1D/1A-adrenoceptor blocker, induced expression and activity of UGT2B in BPH rat prostate models as well as UGT2B15 in human prostate cells, BPH-1. The NAF enantiomers reduced intraprostatic and intracellular DHT levels, thus promoting cell apoptosis. Besides, assays with siRNA UGT2B15 transfection showed that UGT2B15 played an essential role in mediating the effects of the NAF enantiomers. The UGT2B15 mediated the inhibition of AR and PSA expression by NAF enantiomers. The data showed that the mechanism of upregulating UGT2B15 by the NAF enantiomers might differ from that of AR antagonists and 5α-reductase inhibitors. Together, our results demonstrated that NAF enantiomers could be potential and novel UGT2B15 regulators, which accelerated the DHT elimination and promoted apoptosis of BPH-1 cells. This study could help expand the clinical application of NAF and support the development of new therapeutic strategies targeting the elimination of androgens for the treatment of BPH and other androgen-sensitive diseases.

Drug Repositioning of the α1-Adrenergic Receptor Antagonist Naftopidil: A Potential New Anti-Cancer Drug?

Failure of conventional treatments is often observed in cancer management and this requires the development of alternative therapeutic strategies. However, new drug development is known to be a high-failure process because of the possibility of a lower efficacy than expected for the drug or appearance of non-manageable side effects. Another way to find alternative therapeutic drugs consists in identifying new applications for drugs already approved for a particular disease: a concept named "drug repurposing". In this context, several studies demonstrated the potential anti-tumour activity exerted by α1-adrenergic receptor antagonists and notably renewed interest for naftopidil as an anti-cancer drug. Naftopidil is used for benign prostatic hyperplasia management in Japan and a retrospective study brought out a reduced incidence of prostate cancer in patients that had been prescribed this drug. Further studies showed that naftopidil exerted anti-proliferative and cytotoxic effects on prostate cancer as well as several other cancer types in vitro, as well as ex vivo and in vivo. Moreover, naftopidil was demonstrated to modulate the expression of Bcl-2 family pro-apoptotic members which could be used to sensitise cancer cells to targeting therapies and to overcome resistance of cancer cells to apoptosis. For most of these anti-cancer effects, the molecular pathway is either not fully deciphered or shown to involve α1-adrenergic receptor-independent pathway, suggesting off target transduction signals. In order to improve its efficacy, naftopidil analogues were designed and shown to be effective in several studies. Thereby, naftopidil appears to display anti-cancer properties on different cancer types and could be considered as a candidate for drug repurposing although its anti-cancerous activities need to be studied more deeply in prospective randomized clinical trials.

Synthesis and pharmacological evaluation of naftopidil-based arylpiperazine derivatives containing the bromophenol moiety

BACKGROUND

Prostate cancer (PCa) is the most common malignancy in men and in the absence of any effective treatments available.

METHODS

For the development of potential anticancer agents, 24 kinds of naftopidil-based arylpiperazine derivatives containing the bromophenol moiety were synthesized and characterized by using spectroscopic methods. Their pharmacological activities were evaluated against human PCa cell lines (PC-3 and LNCaP) and a₁-adrenergic receptors (a₁-ARs; α_1a, α_1b, and α_1d-ARs). The structure-activity relationship of these designed arylpiperazine derivatives was rationally explored and discussed.

RESULTS

Among these derivatives, 3c, 3d, 3h, 3k, 3o, and 3s exhibited the most potent activity against the tested cancer cells, and some derivatives with potent anticancer activities exhibited better a₁-AR subtype selectivity than others did (selectivity ratio > 10).

CONCLUSION

This work provided a potential lead compound for the further development of anticancer agents for PCa therapy.

Identification of HUHS190, a human naftopidil metabolite, as a novel anti-bladder cancer drug

We carried out structure-activity relationship study on anti-cancer effects of naftopidil (1) and its metabolites, resulted in identification of 1-(4-hydroxy-2-methoxyphenyl)piperazin-1-yl)-3-(naphthalen-1-yloxy) propan-2-ol (2, HUHS190), a major human metabolite of 1, which exhibited the most selective toxicities between against normal and cancer cells (Table 1). 2 was more hydrophilic compared to 1, was enough to be prepared in high concentration solution of more than 100 μM in saline for an intravesical instillation drug. Moreover, serum concentration of 2 was comparable to that of 1, an oral preparation drug, after oral administration at 32 mg/kg (Fig. 3). Both of 1 and 2 showed broad-spectrum anti-cancer activities in vitro, for example, 1 and 2 showed inhibitory activity IC₅₀ = 21.1 μM and 17.2 μM for DU145, human prostate cancer cells, respectively, and IC₅₀ = 18.5 μM and 10.5 μM for T24 cells, human bladder cancer cells. In this study, we estimated anticancer effects of 2 in a bladder cancer model after intravesical administration similar to clinical cases. A single intravesical administration of 2 exhibited the most potent inhibitory activities among the clinical drugs for bladder cancers, BCG and Pirarubicin, without obvious side effects and toxicity (Fig. 4). Thus, HUHS190 (2) can be effective for patients after post-TURBT therapy of bladder cancer without side effects, unlike the currently available clinical drugs.

Emerging drugs to target lower urinary tract symptomatology (LUTS)/benign prostatic hyperplasia (BPH): focus on the prostate

OBJECTIVES

The benign prostatic syndrome, comprising lower urinary tract symptomatology secondary to benign prostatic hyperplasia/enlargement, represents a major health care issue in westernized countries. The pharmacological management involves alpha-adrenoceptor antagonists, intervention into the hormonal control of prostate growth using inhibitors of the enzyme 5-alpha-reductase, and stimulation of the nitric oxide/cyclic GMP pathway by tadalafil, an inhibitor of the phosphodiesterase type 5.

METHODS

This review summarizes the achievements which have been made in the development of drug candidates assumed to offer opportunities as beneficial treatment options in the management of the benign prostatic syndrome.

RESULTS

A review of the literature has revealed that the line of development is focusing on drugs interfering with peripheral neuromuscular/neuronal mechanisms (nitric oxide donor drugs, agonists/antagonists of endogenous peptides, botulinum toxin, NX-1207), the steroidal axis (cetrorelix) or the metabolic turn-over (lonidamine), as well as the combination of drugs already established in the treatment of lower urinary tract symptomatology/benign prostatic hyperplasia (phosphodiesterase 5 inhibitor plus alpha-adrenoceptor antagonist).

CONCLUSION

Many research efforts have provided the basis for the development of new therapeutic modalities for the management of lower urinary tract dysfunctions, some of which might be offered to the patients in the near future.

Naftopidil for the treatment of lower urinary tract symptoms compatible with benign prostatic hyperplasia

BACKGROUND

Benign prostatic hyperplasia (BPH) is a common condition in ageing men that may cause lower urinary tract symptoms (LUTS). Treatment aims are to relieve symptoms and prevent disease-related complications. Naftopidil is an alpha-blocker (AB) that has a high affinity for the A1d receptor that may have advantages in treating LUTS in this setting. This is an update of a Cochrane Review first published in 2009. Since that time, several large randomised controlled trials (RCTs) have been reported, making this update relevant.

OBJECTIVES

To evaluate the effects of naftopidil for the treatment of LUTS associated with BPH.

SEARCH METHODS

We performed a comprehensive search using multiple databases (the Cochrane Library, MEDLINE, Embase, Scopus, LILAC, 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 to 31 May 2018 SELECTION CRITERIA: We included all parallel RCTs. We also included cross-over design trials.

DATA COLLECTION AND ANALYSIS

Two review authors independently classified 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. Primary outcomes were urological symptom scores, quality of life (QoL) and treatment withdrawals for any reason; secondary outcomes were treatment withdrawals due to adverse events, acute urinary retention, surgical intervention for BPH, and cardiovascular and sexual adverse events. We considered outcomes measured up to 12 months after randomisation as short term, and later than 12 months as long term. We rated the certainty of the evidence according to the GRADE approach.

MAIN RESULTS

We included 22 RCTs with 2223 randomised participants across four comparisons for short-term follow-up. This abstract focuses on only two of four comparisons for which we found data since two comparators (i.e. propiverine and Eviprostat (phytotherapy)) are rarely used. One study comparing naftopidil to placebo did not report any relevant outcomes and was therefore excluded. There were no trials that compared to combination therapy with naftopidil or any 5-alpha reductase inhibitors (5-ARIs) to combination therapy with other ABs and any 5-ARIs.All included studies were conducted in Asian countries. Study duration ranged from four to 12 weeks. Mean age was 67.8 years, prostate volume was 35.4 mL, and International Prostate Symptom Score was 18.3. We were unable to perform any of the preplanned subgroup analyses based on age and baseline symptom score.Naftopidil versus tamsulosinBased on 12 studies with 965 randomised participants, naftopidil may have resulted in little or no difference in urological symptom score (mean difference (MD) 0.47, 95% confidence interval (CI) -0.09 to 1.04 measured on a scale from 0 to 35 with higher score representing increased symptoms), QoL (MD 0.11, 95% CI -0.09 to 0.30; measured on a scale from 0 to 6 with higher scores representing worse QoL), and treatment withdrawals for any reason (risk ratio (RR) 0.92, 95% CI 0.64 to 1.34; corresponding to 7 fewer per 1000 participants, 95% CI 32 fewer to 31 more). Naftopidil may have resulted in little to no difference in sexual adverse events (RR 0.54, 95% CI 0.24 to 1.22); this would result in 26 fewer sexual adverse events per 1000 participants (95% CI 43 fewer to 13 more). We rated the certainty of evidence as moderate for urological symptom score and low for the other outcomes.Naftopidil versus silodosinBased on five studies with 652 randomised participants, naftopidil may have resulted in little or no difference in the urological symptom scores (MD 1.04, 95% CI -0.78 to 2.85), QoL (MD 0.21, 95% CI -0.23 to 0.66), and treatment withdrawals for any reason (RR 0.80, 95% CI 0.52 to 1.23; corresponding to 26 fewer per 1000 participants, 95% CI 62 fewer to 32 more). We rated the certainty of evidence as low for all these outcomes. Naftopidil likely reduced sexual adverse events (RR 0.15, 95% CI 0.06 to 0.42; corresponding to 126 fewer sexual adverse events per 1000 participants, 95% CI 139 fewer to 86 fewer). We rated the certainty of evidence as moderate for sexual adverse events.

AUTHORS' CONCLUSIONS

Naftopidil appears to have similar effects in the urological symptom scores and QoL compared to tamsulosin and silodosin. Naftopidil has similar sexual adverse events compared to tamsulosin but has fewer compared to silodosin.

Synthesis and Pharmacological Evaluation of Novel Silodosin-Based Arylsulfonamide Derivatives as α1A/α1D-Adrenergic Receptor Antagonist with Potential Uroselective Profile

Benign prostatic hyperplasia (BPH) is the most common male clinical problem impacting the quality of life of older men. Clinical studies have indicated that the inhibition of α_1A-/α_1D adrenoceptors might offer effective therapy in lower urinary tract symptoms. Herein, a limited series of arylsulfonamide derivatives of (aryloxy)ethyl alicyclic amines was designed, synthesized, and biologically evaluated as potent α₁-adrenoceptor antagonists with uroselective profile. Among them, compound 9 (3-chloro-2-fluoro-N-([1-(2-(2-(2,2,2-trifluoroethoxy)phenoxy]ethyl)piperidin-4-yl)methyl)benzenesulfonamide) behaved as an α_1A-/α_1D-adrenoceptor antagonist (K_i(α₁) = 50 nM, EC₅₀(α_1A) = 0.8 nM, EC₅₀(α_1D) = 1.1 nM), displayed selectivity over α₂-adrenoceptors (K_i(α₂) = 858 nM), and a 5-fold functional preference over the α_1B subtype. Compound 9 showed adequate metabolic stability in rat-liver microsome assay similar to the reference drug tamsulosin (Cl_int = 67 and 41 µL/min/mg, respectively). Compound 9 did not decrease systolic and diastolic blood pressure in normotensive anesthetized rats in the dose of 2 mg/kg, i.v. These data support development of uroselective agents in the group of arylsulfonamides of alicyclic amines with potential efficacy in the treatment of lower urinary tract symptoms associated to benign prostatic hyperplasia.

New alpha blockers to treat male lower urinary tract symptoms

PURPOSE OF REVIEW

To date it is unclear whether the selectivity of new alpha-blockers to alpha-adrenergic receptor subtypes translates into more clinical benefits and less adverse effects in clinical practice. We performed a systematic review of the two new Abs silodosin and naftopidil. With the availability of numerous alpha-blockers to treat lower urinary tract symptoms secondary to benign prostatic hyperplasia, the findings of this review will be highly relevant to the field of urology.

RECENT FINDINGS

Silodosin was found to be more effective than placebo in improving International Prostate Symptom Score (IPSS) and quality of life scores and as effective as other alpha-blockers. Although the incidence of cardiovascular adverse events of silodosin was similar compared with placebo and other alpha-blockers (tamsulosin, naftopidil, alfuzosin), the sexual adverse events were more common with silodosin. No placebo-controlled randomized trial exists investigating the effects of naftopidil in men with lower urinary tract symptoms secondary to benign prostatic hyperplasia. Naftopidil had similar efficacy with regards to IPSS and quality of life compared with tamsulosin. The rate of adverse events was similar compared with tamsulosin.

SUMMARY

The two new selective alpha-blockers, silodosin, and naftopidil showed similar efficacy in IPSS and quality of life compared with other alpha-blockers. However, silodosin has more sexual adverse events.

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.

Crystal structures, absolute configurations and molecular docking studies of naftopidil enantiomers as α1D-adrenoceptor antagonists

Chiral drug naftopidil (NAF), a specific α_1D-adrenoceptor (AR) antagonist for the treatment of benign prostatic hyperplasia, was used in racemic form for several decades. Our recent work declared that NAF enantiomers showed the same antagonistic effects on the α_1D-AR, but the binding mechanism of these two stereochemical NAF isomers to the α_1D receptor remained unclear. Herein, we reported the crystallographic structures of optically pure NAF stereoisomers for the first time and unambiguously determined their absolute configurations. The crystal data of R and S enantiomers matched satisfactorily the pharmacophore model for α_1D-selective antagonists. Based on the constructed α_1D homology model, molecular docking studies shed light on the molecular mechanism of NAF enantiomers binding to α_1D-AR. The results indicated that NAF enantiomers exhibited the very similar binding poses and occupied the same binding pocket.

Design, synthesis, crystal structure, biological evaluation and molecular docking studies of carbazole-arylpiperazine derivatives

Subtype-selective α₁-adrenoceptor (AR) antagonists display optimum therapeutic efficacies for the treatment of benign prostatic hyperplasia (BPH). In this study, we designed and synthesized novel carbazole-arylpiperazines derivatives (1 and 2) on the basis of the proposed pharmacophore model for α₁-AR antagonists. Structural properties were investigated using single-crystal X-ray diffraction analysis. Comparison of crystal structures with ligand-based pharmacophore models revealed that the two agents may possess antagonistic effects on α_1D subtype. Tissue functional assay in vitro showed that compound 2 exerted strong antagonistic activity on α_1B-AR (pA₂ 7.13) with a poor selectivity for α_1A and α_1D subtypes. Compound 1 exhibited enhanced antagonistic effect on α_1D subtype (pA₂ 7.06) and excellent selectivity for α_1D over α_1B (α_1D/α_1B ratio=79.4). To illustrate the relationship between antagonistic activity and chemical structure, molecular docking studies were performed using the homology models of α₁ receptors. Binding mechanism indicated that small hydrophobic substituents attached to the arylpiperazine moiety were essential for rational design of α_1D-selective antagonists.

Arylsulfonamide derivatives of (aryloxy)ethyl pyrrolidines and piperidines as α1-adrenergic receptor antagonist with uro-selective activity

A series of arylsulfonamide derivatives of (aryloxy)ethyl pyrrolidines and piperidines was synthesized to develop new α₁-adrenoceptor antagonists with uroselective profile. Biological evaluation for α₁- and α₂-adrenorecepor showed that tested compounds 13-37 displayed high-to-moderate affinity for the α₁-adrenoceptor (K_i=34-348nM) and moderate selectivity over α₂-receptor subtype. Compounds with highest affinity and selectivity for α₁-adrenoceptor were evaluated in vitro for their intrinsic activity toward α_1A- and α_1B-adrenoceptor subtypes. All compounds behaved as antagonists at both α₁-adrenoceptor subtypes, displaying 2- to 6-fold functional preference to α_1A-subtype. Among them, N-{1-[2-(2-methoxyphenoxy)ethyl]piperidin-4-yl}isoquinoline-4-sulfonamide (25) and 3-chloro-2-fluoro-N-{[1-(2-(2-isopropoxyphenoxy)ethyl)piperidin-4-yl]methyl}benzene sulfonamide (34) displayed the highest preference to α_1A-adrenoceptor. Finally, compounds 25 and 34 (2-5mg/kg, iv), in contrast to tamsulosin (1-2mg/kg, iv), did not significantly decrease systolic and diastolic blood pressure in normotensive anesthetized rats to determine their influence on blood pressure.

Three-year outcome analysis of alpha 1-blocker naftopidil for patients with benign prostatic hyperplasia in a prospective multicenter study in Japan

PURPOSE

Our aim was to prospectively analyze the 3-year outcomes of naftopidil treatment for patients with benign prostatic hyperplasia (BPH), including those who dropped out during follow-up and had retreatment for BPH after termination of the drug within 3 years.

PATIENTS AND METHODS

Naftopidil, 50 mg/d or 75 mg/d, was given to 117 patients having BPH aged 50 years and older who had international prostate symptom scores (IPSS) ≥8. They were prospectively followed for 3 years with periodic evaluation. If naftopidil was terminated, the reason was determined. For patients with termination, an outcome survey was done to evaluate the status of retreatment for BPH at 3 years.

RESULTS

Twenty-five patients (21.4%) continued the same medication for 3 years. The total IPSS, quality of life index, BPH problem index, and maximum flow rate were significantly improved during 3 years. Treatment failure defined as symptomatic progression (an increase in the IPSS of ≥4 points compared to the baseline value), development of acute urinary retention, conversion to other α1-blockers, add-on of a 5α-reductase inhibitor, or conversion to surgery was observed in 41 patients (35.0%). In the univariate analysis, age, prostate volume, and serum prostate-specific antigen were predictors of treatment failure. Of the 50 patients who discontinued naftopidil during the follow-up, only 13 (26%) patients reported that they needed retreatment with α1-blockers and/or surgery within 3 years.

CONCLUSION

Long-term efficacy of naftopidil was observed, although older age, increased prostate volume, and elevated prostate-specific antigen at baseline were highly likely to result in treatment failure. Even after termination for various reasons, only a small portion of the patients needed retreatment for BPH within 3 years.

X-ray Crystallography, DFT Calculations and Molecular Docking of Indole-Arylpiperazine Derivatives as α1A-Adrenoceptor Antagonists

Indole-arylpiperazine derivatives have exhibited good selectivity for the α_1A-adrenoceptor, but the structure-activity-binding mechanism relationship remains unclear. In the current study, three compounds (1, 2 and 3) were investigated through single-crystal X-ray diffraction analysis, density functional theory (DFT) calculations and molecular docking using a homology model of the α_1A receptor. Compounds 1 and 3 form H-bonds networks to stabilize their three-dimensional structures, while C–H···π interactions play a significant role in the packing of 2. Based on DFT-optimized conformations, the HOMO-LUMO energy gaps and molecular electrostatic potential (MEP) were theoretically calculated at the B3LYP/6-311G (d, p) level of theory. Chemical reactivity increases in the order of 3 < 2 < 1, and the maximum positive region of the MEP maps is mainly localized over the NH group. The binding mechanisms of ligand-α_1A-adrenoceptor complexes were illustrated by molecular docking. Binding to Gln177 of the second extracellular loop region via hydrogen bonds is likely to be essential for α_1A-selective antagonists. The present work sheds light on the studies of structure-activity-binding mechanism and aids in the design of α_1A antagonists with high selectivity.

A synopsis of drugs currently in preclinical and early clinical development for the treatment of benign prostatic hyperplasia

INTRODUCTION

Benign prostatic hyperplasia (BPH) is a common disease among men and significantly impacts quality of life by causing lower urinary tract symptoms (LUTS). Current medical therapies are not always adequate in controlling LUTS or slowing disease progression, and there is unmet need for new effective therapeutic options.

AREAS COVERED

The authors review the standard current medical therapies for BPH which include the use of α-1 blockers, 5-α reductase inhibitors, combination therapy and PDE inhibitors. Following this, the authors then discuss new therapies that are currently undergoing preclinical and clinical investigation.

EXPERT OPINION

Existing preclinical and clinical trials have highlighted many promising therapies to treat BPH. Further investigation with larger clinical trials is needed to establish these drugs as standard therapies. As the number of drugs in the arsenal against BPH continues to grow, providers and patients will have to engage in a discussion that weighs the risks and benefits of each therapy.