Benign prostatic hyperplasia: an insight into current investigational medical therapies

In-vivo and in-silico studies revealed the molecular mechanisms of Colocasia esculenta phenolics as novel chemotherapy against benign prostatic hyperplasia via inhibition of 5α-reductase and α1-adrenoceptor

Benign Prostatic Hyperplasia (BPH) is a major cause of lower urinary tract infections and erectile dysfunction thus a major contributor to lowering the quality of life among older men. In this study, we investigated the molecular mechanism of Colocasia esculenta (CE) as a novel agent for BPH chemotherapy. In vivo, we assigned 45 male Wistar albino rats about 6 weeks old into 9 experimental groups (n = 5). BPH was induced in groups 2-9 with 3 mg/kg of Testosterone Propionate (TP) subcutaneously. Group 2 (BPH) was not treated. Group 3 was treated with 5 mg/kg Finasteride (standard drug). Group 4-9 were treated each with 200 mg/kg body weight (b.w) of CE crude tuber extracts/fractions (ethanol, hexane, dichloromethane, ethyl acetate, butanol, aqueous). At the end of treatment, we sampled the rats' serum to check the level of PSA. In silico, we conducted a molecular docking of the crude extract of CE phenolics (CyP) previously reported, targeting 5α-Reductase and α1-Adrenoceptor linked to the BPH progressions. We adopted the standard inhibitors/antagonists (5α-reductase: finasteride; α1-adrenoceptor: tamsulosin) of the target proteins as controls. Furthermore, the pharmacological properties of the lead molecules were studied in terms of ADMET using swissadme and pKCSM resources, respectively. Results showed that administration of TP in male Wistar albino rats significantly (p < 0.05) elevated serum PSA levels whereas CE crude extracts/fractions significantly (p < 0.05) lowered the serum PSA level. Also, fourteen of the CyPs bind to at least one or two of the target proteins with their binding affinity of between - 9.3 to - 5.6 kcal/mol and - 6.9 to - 4.2 kcal/mol, respectively. The CyPs possess better pharmacological properties compared to the standard drugs. Therefore, they have the potentials to be enlisted for clinical trials towards the management of BPH.

Graphical Abstract

Increased risk of subsequent benign prostatic hyperplasia in non-Helicobacter pylori-infected peptic ulcer patients: a population-based cohort study

The vagus nerve plays an essential role in homeostasis and inflammation. Clinically, peptic ulcer patients without helicobacter pylori (HP) infection may provide a population for studying the effect of vagal hyperactivity. There were interests in the association of gastrointestinal disease and urogenital disorders. Herein, we try to investigate subsequent risk of benign prostatic hyperplasia (BPH) in non-HP infected peptic ulcer patients. We identified 17,672 peptic ulcer admission male patients newly diagnosed in 1998-2007 from Taiwan Health Insurance Database, and 17,672 male comparison without peptic ulcer, frequency matched by age, and index-year. We assessed subsequent incidence of BPH in each cohort by the end of 2013, and then compared the risk of developing BPH between individuals with and without peptic ulcer. In addition, peptic ulcer patients underwent surgery were also examined. There were 2954 peptic ulcer patients and 2291 comparisons noted with the occurrence of BPH (25.35 and 16.70 per 1000 person-years, respectively). Compared to comparisons, peptic ulcer patients had a 1.45- and 1.26-fold BPH risk in multivariable Cox model and Fine and Gray model (95% CI 1.37-1.54 and 1.19-1.34). In age-stratified analysis, the highest risk of BPH was in 45-59 years (interaction p < 0.05). Regarding surgery types, peptic ulcer patients who underwent simple suture surgery (i.e.: with integrated vagus nerve) had a significant higher BPH risk than comparison (HR 1.50 and 95% CI 1.33-1.74; SHR 1.26 and 95% CI 1.07-1.48), while patients underwent truncal vagotomy/pyloroplasty showed a lower incidence of BPH. In this study, non-HP-infected male peptic ulcer patients were found to have an increased risk of subsequent BPH. Indicating that there might be a role of vagus nerve. Based on the limitations of retrospective nature, further studies are required.

Clinicopathological and immunohistochemical evaluation of lonidamine-entrapped lipid-polymer hybrid nanoparticles in treatment of benign prostatic hyperplasia: An experimental rat model

Benign prostatic hyperplasia (BPH) is a progressive proliferative disease, the incidence of which is constantly increasing due to aging of population. In this research, a hexokinase-II enzyme inhibiting agent, lonidamine - the use of which is limited in BPH treatment due to high hepatic toxicity observed after three months of treatment - was selected as an active agent, based on its mechanism of action in treating BPH. The aim of this study was to evaluate in vivo therapeutic efficacy and hepatic toxicity of lipid-polymer hybrid nanoparticles of lonidamine in a rat BPH model created in rat prostates. After local injections of hybrid nanoparticles of lonidamine were administered to the rat prostates, hyperplasic structures of prostates were evaluated in terms of prostatic index values, immunohistochemical evaluations, and histopathological findings. Liver blood enzyme values were also determined to specify hepatic toxicity. Apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) reaction and histopathological methods to determine intravital degenerative destruction in liver. Through this study, lonidamine-loaded hybrid nanoparticles were found to reduce the hepatic toxicity and increase therapeutic efficiency of lonidamine. Therefore, lonidamine-entrapped hybrid nanoparticles may provide a promising, and very safe, drug delivery strategy in the treatment of BPH.

Pharmacokinetics, bioavailability and metabolism of cligosiban, an antagonist of oxytocin receptor, in rat by liquid chromatography hyphenated with electrospray ionization tandem mass spectrometry

Cligosiban is a highly-affinity nonpeptide oxytocin receptor antagonist. In this study, a simple an sensitive LC-MS/MS method was developed and validated for the determination of cligosiban in rat plasma. The plasma samples were pretreated with acetonitrile as precipitant and then separated on an ACQUITY BEH C₁₈ column (2.1 × 50 mm, 1.7 μm) with 0.1% formic acid in water and acetonitrile as mobile phase. The analytes were monitored using selected reaction monitoring (SRM) mode with transitions at m/z 420.1→248.1 for cligosiban and m/z 304.1→161.1 for IS. The developed method showed good linearity over the concentration range of 1-1000 ng/mL with coefficient of correlation > 0.996. The lower limit of quantification (LLOQ) is 1 ng/mL. The method was validated for selectivity, precision, accuracy, recovery, and stability in accordance with FDA's guidance. The validated assay has been successfully applied to the pharmacokinetic study of cligosiban in rat plasma after intravenous and oral administration. According to the current results, the oral bioavailability of cligosiban was 63.82%. Furthermore, the metabolites present in rat liver microsomes (RLM), human liver microsomes (HLM) and rat plasma were analyzed by UHPLC-LTQ-Orbitrap-MS method, and four metabolites structurally identified based on their accurate masses, and fragment ions. The proposed metabolic pathways of cligosiban were demethylation and glucuronidation. This study is the first report on the pharmacokinetic and metabolic information of cligosiban, which would provide insights into the effectiveness and toxicity of cligosiban.

Testosterone-induced benign prostatic hyperplasia rat and dog as facile models to assess drugs targeting lower urinary tract symptoms

Benign prostatic hyperplasia (BPH) is an age-related disease, affecting a majority of elderly men worldwide. Medical management of BPH is an alternative to surgical treatment of this disease. Currently, α1-adrenergic receptor (α1-AR) antagonists are among the first line drugs to treat BPH by reducing the tension of urinary track and thus the obstructive symptoms in voiding. In drug development, old male dogs with spontaneous BPH are considered the golden standard of the animal models. However, old dogs (>6 years) are expensive and not all old dogs develop BPH. So it is necessary to develop more accessible animal models for drug efficacy evaluation. Here we describe the development of testosterone-induced BPH models in both rats and young adult dogs and their applications in the in vivo evaluation of α1-AR antagonist. The BPH rats and dogs induced by chronic testosterone treatment have significantly increased micturition frequency and reduced mean voided volume, very similar to the clinical symptoms of BPH patients. Silodosin, an α1-AR antagonist, significantly reduces the urinary frequency and increases the voided volume in BPH model animals in a dose-dependent manner. The results demonstrate that testosterone-induced BPH rat and dog models might provide a more efficient way to evaluate micturition behavior in anti-BPH drug studies.

Design, synthesis and biological evaluation of novel androst-3,5-diene-3-carboxylic acid derivatives as inhibitors of 5α-reductase type 1 and 2

5α-Reductase is a key enzyme responsible for dihydrotestosterone biosynthesis and has been recognized as an important target for discovering new drugs against benign prostatic hyperplasia (BPH). In this study, a series of novel steroidal androst-3,5-diene-3-carboxylic acids have been designed and synthesized. Biological evaluations were performed on their 5α-reductase inhibitory activities by both in vitro enzyme inhibition assay and in vivo by prostate weighing method. Results showed that most of them displayed excellent 5α-reductase inhibitory potency. Detailed evaluation indicated that most of the compounds displayed slightly higher inhibition potency towards type 2 isozyme. Among all the compounds, 16a was found to be the most potential inhibitor with the IC₅₀ of 0.25μM and 0.13μM against type 1 and 2 isozymes respectively. In vivo 5a-reductase inhibitory evaluation of 16a also showed a more significant reduction effect (p<0.001) in rat prostate weight than epristeride. Furthermore, the results of in silico ADME study indicated that compound 16a exhibited good pharmacokinetic properties. Thus, 16a could serve as promising lead candidates for further study.

Therapeutic Rationales, Progresses, Failures, and Future Directions for Advanced Prostate Cancer

Patients with localized prostate cancer (PCa) have several therapeutic options with good prognosis. However, survival of patients with high-risk, advanced PCa is significantly less than patients with early-stage, organ-confined disease. Testosterone and other androgens have been directly linked to PCa progression since 1941. In this review, we chronicle the discoveries that led to modern therapeutic strategies for PCa. Specifically highlighted is the biology of androgen receptor (AR), the nuclear receptor transcription factor largely responsible for androgen-stimulated and castrate-recurrent (CR) PCa. Current PCa treatment paradigms can be classified into three distinct but interrelated categories: targeting AR at pre-receptor, receptor, or post-receptor signaling. The continuing challenge of disease relapse as CR and/or metastatic tumors, destined to occur within three years of the initial treatment, is also discussed. We conclude that the success of PCa therapies in the future depends on targeting molecular mechanisms underlying tumor recurrence that still may affect AR at pre-receptor, receptor, and post-receptor levels.

Anti-proliferation effects of Cistanches salsa on the progression of benign prostatic hyperplasia

Cistanche salsa has been used in traditional medicine for the treatment of kidney deficiency, neurasthenia, sexual dysfunction diseases, and benign prostatic hyperplasia (BPH). The aim of this study was to investigate the mechanism by which C. salsa extract (CSE) elicits an anti-proliferative effect on the prostate tissue of BPH-induced rats. The effects of CSE on BPH were evaluated in terms of prostate weight, production of serum dihydrotestosterone (DHT), and the mRNA expression of 5α-reductase type 1 and type 2 in the prostate tissue of BPH-induced rats. In addition, hematoxylin and eosin (H&E) staining was performed for histological examination of prostate gland morphology, and protein expression levels in prostate tissue were investigated by western blot analysis. CSE treatment decreased prostate weight, serum DHT concentration, and the mRNA expression of 5α-reductase type 1 and type 2 in prostate tissue of BPH-induced rats. In addition, CSE treatment suppressed cell proliferation by regulating the expression levels of inflammatory-related proteins (inducible nitric oxide synthase and cyclooxygenase 2) and apoptosis-associated proteins (caspase-3 and Bcl-2 family proteins). CSE may be a potential therapeutic candidate for BPH owing to its ability to regulate the expression of inflammatory and apoptosis-related proteins.

miRNA Regulation Network Analysis in Qianliening Capsule Treatment of Benign Prostatic Hyperplasia

Objective. The objective of this study was to evaluate the molecular mechanism by which Qianliening capsule (QC) treats benign prostatic hyperplasia (BPH). Methods. Benign prostatic hyperplasia epithelial cell line BPH-1 was treated with 0, 1.25, 2.5, and 5 mg/mL QC for 48 h, respectively. Evaluation of cell viability and observation of morphologic changes of BPH-1 cell gene expression and miRNA expression profiles were analyzed. Real-time quantitative PCR was used to confirm changes in miRNA and gene expression. GO and KEGG pathway-based approaches were used to investigate biological functions and signaling pathways affected by differentially expressed mRNAs. Results. QC inhibited BPH-1 cell proliferation. Differential expression of 19 upregulated and 2 downregulated miRNAs was observed in QC-treated BPH-1 cells compared to untreated control cells. 107 upregulated and 71 downregulated genes were identified between the two groups. Significantly enriched signaling pathways based on deregulated mRNAs were mainly involved in regulation of cell proliferation, apoptosis, and so on. Additionally, miRNA-mRNA network analysis integrated these miRNAs and genes by outlining interactions of miRNA and related genes. Conclusion. The study was the first report of differentially expressed miRNA and mRNA in QC-treated BPH-1 cells.

Preventive effects of Monascus on androgen-related diseases: androgenetic alopecia, benign prostatic hyperplasia, and prostate cancer

Androgen-related diseases impair the well-being of many aging men. Unfortunately, the medications used to treat these diseases have many side effects. Therefore, there is a significant need for the development of novel drugs to treat androgen-related diseases. In this study, we investigated the effects of Monascus cursory extraction (M-CE) on androgen-related diseases, including androgenetic alopecia (AGA), benign prostatic hyperplasia (BPH) and prostate cancer. We found that M-CE suppressed baldness in male B6CBAF1/j mice. Furthermore, M-CE decreased PSA levels, indicating a protective effect of M-CE on testosterone-induced hyperplasia. M-CE also significantly decreased tumor volume and tumor incidence in an N-methyl-N-nitrosourea (MNU)/testosterone-induced rat prostate cancer model and markedly decreased dihydrotestosterone (DHT) but not testosterone. Additionally, PCNA expression was decreased in the prostate of rats treated with M-CE. These results suggest that M-CE could be a new potential therapeutic candidate for the treatment of androgen-related diseases.

Prostatic relaxation induced by loperamide is reduced in spontaneously hypertensive rats

This paper shows a new finding about the decrease of relaxative response to loperamide in prostate of spontaneously hypertensive rats (SHR) as compare to normal rats (WKY). Authors demonstrated the reduction of ATP-sensitive potassium channels is resposible for this change using immunoblotting analysis and the decrease of action induced by diazoxide. This view is not mentioned before and is the first one reporting this result.

Targeting 5α-reductase for prostate cancer prevention and treatment

Testosterone is the most abundant circulating androgen, and can be converted to dihydrotestosterone (DHT), a more potent androgen, by the 5α-reductase enzymes in target tissues. Current treatments for prostate cancer consist of reducing androgen levels by chemical or surgical castration or pure antiandrogen therapy that directly targets the androgen receptor (AR). Although these therapies reduce tumor burden and AR activity, the cancer inevitably recurs within 18-30 months. An approach targeting the androgen-AR axis at different levels could, therefore, improve the efficacy of prostate cancer therapy. Inhibition of 5α-reductase is one such approach; however, the two largest trials to investigate the use of the 5α-reductase inhibitors (5ARIs) finasteride and dutasteride in patients with prostate cancer have shown that, although the incidence of cancer was reduced by 5ARI treatment, those cancers that were detected were more aggressive than in patients treated with placebo. Thus, the best practice for using these drugs to prevent and treat prostate cancer remains unclear.

Effects of a nanocomposite containing Orbignya speciosa lipophilic extract on Benign Prostatic Hyperplasia

ETHNOPHARMACOLOGICAL RELEVANCE

Lower urinary tract symptoms (LUTS) are a common complaint among aging men and are usually caused by Benign Prostatic Hyperplasia (BPH). A number of medical treatments for LUTS/BPH exist, such as α-blockers, 5α-reductase inhibitors, phytotherapeutical drugs and combination therapies. Babassu is the common name of a Brazilian native palm tree called Orbignya speciosa, whose kernels are commonly used (eaten entirely or as a grounded powder), in parts of Brazil for the treatment of urinary disorders. This study investigates the effects of Orbignya speciosa nanoparticle extract, a newly developed phytotherapic formulation derived from the kernels of babassu, in the treatment of BPH.

MATERIALS AND METHODS

Orbignya speciosa extract was obtained from the kernels, a nanoparticulate system was developed and acute toxicity test was performed. BPH primary stromal cell and tissue cultures were established and treated with 300μg/mL Orbignya speciosa nanoparticle (NanoOse) extract in order to evaluate its effects on apoptosis induction, cytotoxicity, cell morphology and proliferation.

RESULTS

Our results indicated that NanoOSE shows no toxicity in animals and acts incisively by promoting morphological cell changes, reducing cell proliferation as well as inducing necrosis/apoptosis on BPH cells and tissues.

CONCLUSIONS

This study provided the first report of the successful use of NanoOSE on BPH treatment which corroborates with the popular use of the kernels of this plant. The results also suggest the potential of NanoOSE as a candidate new phytotherapeutic agent on the management of BPH.

Prostatic relaxation induced by loperamide is mediated through activation of opioid μ-2 receptors in vitro

The merit of opioid μ-receptor activation in the improvement of benign prostatic hyperplasia (BPH) remains obscure. In the present study, we used loperamide to identify the subtype of opioid μ-receptors involved in prostatic relaxation and investigate the possible mechanism of this relaxation. Prostate strips were isolated from 12-week-old male Wistar rats for identification of isometric tension. The prostate strips were precontracted with either 1 μmol/l phenylephrine or 50 mmol/l KCl. The decrease in muscle tone (relaxation) was then characterized after cumulative administration of loperamide (0.1 to 10 μmol/l) into the organ bath for the concentration-dependent study. Pretreatment with specific blockers or antagonists was carried out to compare the changes in loperamide-induced relaxation. Loperamide produced a marked relaxation in the isolated prostates precontracted with phenylephrine or KCl in a dose-dependent manner. This relaxation was abolished by cyprodime, a selective opioid μ-receptor antagonist, but was not modified by naloxonazine at a dose sufficient to block the opioid μ-1 receptors. Treatment with an agonist for opioid μ-1 receptors also failed to modify the muscle tone. Moreover, the relaxation by loperamide was attenuated by glibenclamide at a dose sufficient to block ATP-sensitive K(+) channels. In addition, this action of loperamide was abolished by protein kinase A (PKA) inhibitor and enhanced by the inhibitor of phosphodiesterase for cyclic AMP (cAMP). Our results suggest that loperamide induces prostatic relaxation through activation of opioid μ-2 receptors via the cAMP-PKA pathway to open ATP-sensitive K(+) channels.

Ligand-based pharmacophore model of N-Aryl and N-Heteroaryl piperazine alpha 1A-adrenoceptors antagonists using GALAHAD

Computer aided drug discovery for selective antagonism effects on alpha(1A) subtypes of G-protein coupled receptors are important in the treatment of benign prostatic hyperplasia (BPH). Ligand-based pharmacophore models of N-Aryl and N-Heteroaryl piperazine alpha(1A)-antagonists were developed using two separate training sets. Pharmacophore models were generated using the flexible align method within the GALAHAD module, implemented in SYBYL8.1 software. The most significant pharmacophore hypothesis, characterized by the conflicting demands of maximizing pharmacophore consensus, maximizing steric consensus, and minimizing energy, consisted of one positive nitrogen center, one donor atom center, two acceptor atom centers, and two hydrophobic groups. The most active compound in each class training set showed a good fit with all features of the pharmacophore proposed. The resulting models also had something in common with the hypothesis using the Catalyst software reported in other publications. These alpha(1A) pharmacophore models could predict compounds well, both in the training set and the test set. The pharmacophore models were also validated by an external dataset using a portion of the ZINC database. A 3D-QSAR model using the pharmacophore model to align the compounds was established in this study. The CoMFA model with the cross-validated q(2) value of 0.735 revealed that the model was valid. Our research provides a valuable tool for designing new therapeutic compounds with desired biological activity.

Identification of a urea bioisostere of a triazole oxytocin antagonist

A series of azetidine ureas were investigated as potential bioisosteres of previously reported azetidinyltriazole oxytocin antagonists. Although potency was somewhat reduced in several close-in analogues, one compound, 9, was both a potent oxytocin antagonist and demonstrated significant selectivity over the closely related vasopressin V(1A) receptor.

Clinical and experimental aspects of Adreno-muscarinic synergy in the bladder base and prostate

Recent clinical trials have shown that combination therapy using an alpha-receptor antagonist and an antimuscarinic is more effective than either agent alone in improving quality of life and objective urodynamic variables in men with bladder outflow obstruction. There appear to be no negative effects on bladder function. The mode of action of this combination is unknown but presumed to be an antimuscarinic reduction in detrusor overactivity and the alpha-receptor antagonist reduced outflow tract resistance. We have shown with in vitro experiments that in smooth muscles influencing outflow tract resistance (prostate, trigone) there is a profound contractile synergy between adrenergic and muscarinic pathways. We propose the hypothesis that both arms of the combination therapy reduce contractile tone of the outflow tract and that their simultaneous attenuation has a disproportionately large effect on outflow tract resistance. Our data from trigone muscle suggest that adrenergic and muscarinic receptor activation increase the intracellular [Ca(2+)] but the adrenergic pathway also operates through Ca(2+)-sensitisation of the contractile apparatus, primarily through a PKC-dependent pathway.

Identification of amide bioisosteres of triazole oxytocin antagonists

A series of amides were investigated as potential bioisosteres of previously reported triazole oxytocin antagonists. A range of potent analogues were identified, although SAR for potency and selectivity over the related V(1A) and V(2) receptors was found to be somewhat divergent from that observed for the corresponding triazole series. The high synthetic accessibility of this new amide series also facilitated the identification of a range of alternative left hand side (biaryl replacement) substituents which gave good levels of oxytocin antagonism.

A role for epithelial-mesenchymal transition in the etiology of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is usually described as a pathological proliferation of prostatic fibroblasts/myofibroblasts and epithelial cells. In the present study of BPH samples, we have made a morphological and immunohistochemical study of BPH prostatic sections using markers of proliferation, apoptosis, hormone receptors, and TGF-beta signaling. We found no evidence of proliferation in the stroma but in the epithelium of some ducts; 0.7% of the basal and 0.4% of luminal cells were positive for Ki67 and PCNA. Androgen receptor and estrogen receptor beta (ERbeta)1 and ERbetacx were abundant in both stromal and epithelial compartments but cells expressing ERalpha were very rare. What was very common in all BPH samples was the following: (i) regions of the ductal epithelium where the epithelial cells did not express E-cadherin, had lost their polarization, and become spindle shaped (the nuclei of these cells were strongly positive for pSmad 3 and Snail); and (ii) regions where the walls of the blood vessels were extremely thick and there was loss of endothelial layer. Loss of E-cadherin, increased pSmad 3, and high expression of Snail are all characteristic of epithelial-mesenchymal transition (EMT). We conclude that BPH is not a disease of prostatic stromal proliferation but rather of accumulation of mesenchymal-like cells derived from the prostatic epithelium and the endothelium. TGF-beta is thought to play a key role in EMT. Our data suggests that TGF-beta/Smad should be considered as targets for treatment of BPH.

Advances in the development of hormonal modulators for the treatment of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a leading disorder of the ageing male population and is characterized by a progressive enlargement of the prostate, resulting in the obstruction of the proximal urethra and hence the disturbance in normal urinary flow and further quality of life of the patients. Therefore, there is an imperative need to develop a therapeutic modality to combat the overgrowth of the prostate with improvements in both the urinary flow rate and the quality of life of the patients. At present, alpha-blockers, which act on the dynamic component of the disease to regulate the increased adrenergic tone of the lower urinary tract smooth muscles, and 5-alpha-reductase inhibitors, which control the overgrowth of the prostate and hence static component by regulating the levels of androgens, are the mainstay of therapies for the treatment of BPH and associated lower urinary tract symptoms. However, each target class has its own limitations in terms of compromised efficacy or tolerability. Therefore, it is pertinent to have an effective and safe therapeutic modality for the further improvement of life of the geriatric male population. Hormone modulators, which regulate the overgrowth of the prostate, represent one of the important categories that have been explored and that is still undergoing certain investigations towards the development of a therapeutic entity for the treatment of BPH. The key lies in achieving the differentiation in terms of improved tolerability with comparable or better efficacy over the existing class of drugs. Gonadotropin receptor modulators and vitamin D receptor agonists may represent promising druggable targets in this therapeutic area, due to the availability of proof of principles and concepts in preclinical animal models and human subjects.

Current and emerging investigational medical therapies for the treatment of overactive bladder

Overactive bladder (OAB) is a chronic distressing condition characterised by urinary urgency with or without urge incontinence, usually with frequency (voiding at least eight times daily) and nocturia. It affects millions of people worldwide independent of age, sex and race. The prevalence increases with age and is relatively higher in women compared with men. The treatment of OAB is aimed at reducing the debilitating symptoms so as to improve the overall quality of life for patients. Anticholinergic agents targeting the muscarinic receptors in the bladder represent the mainstay of pharmacotherapy for the treatment of OAB. Besides their status as the current standard of care, use of antimuscarinic drugs is limited by certain side effects, particularly dry mouth and constipation; therefore, various attempts have been made to improve the organ selectivity of these drugs to overcome the side effects. These include the development of new antimuscarinic agents with structural modifications and the use of innovative drug delivery methods. The advancement in the drug delivery systems extends to the long-term therapeutic efficacy with improved tolerability and patient compliance; however, future prospective therapies are aimed at novel targets with novel mechanisms of action, including beta3-adrenoceptor agonists, K+ channel openers, 5-HT modulators and botulinum toxin, which are currently under different stages of clinical development. Among other investigational therapies, neurokinin receptor antagonists, alpha-adrenoceptor antagonists, nerve growth factor inhibitors, gene therapy and stem cell-based therapies are of considerable interest. The future for the development of new modalities for the treatment of OAB looks promising.

A Shifted Paradigm for the Further Understanding, Evaluation, and Treatment of Lower Urinary Tract Symptoms in Men: Focus on the Bladder

Lower urinary tract symptoms (LUTS) are highly prevalent among older men and have a negative impact on health-related quality of life. Frequent comorbidity with potential prostatic disease adds complexity to the management of male LUTS. In this review, we discuss the pathophysiological conditions that underlie male LUTS, and examine the relationship between symptoms and urodynamic findings. The contribution of bladder dysfunction to male LUTS, with a particular emphasis on overactive bladder (OAB) symptoms, is explored. We also consider pharmacotherapeutic options for male LUTS. Pharmacotherapies that target the prostate (alpha1-receptor antagonists and 5alpha-reductase inhibitors) often fail to alleviate OAB symptoms, and may not be the most appropriate therapy for men with storage LUTS. Multiple studies have suggested that antimuscarinic therapy alone or in combination with alpha1-receptor antagonists improve OAB symptoms in men with and without bladder outlet obstruction. Although these agents may represent appropriate first-line therapies for men with OAB symptoms, the therapeutic potential of antimuscarinics alone or in combination with alpha1-receptor antagonists in this population should be evaluated in large-scale, well-designed clinical trials.