Pharmacological profile of β3-adrenoceptor agonists in clinical development for the treatment of overactive bladder syndrome

The β3-Adrenergic Receptor: Structure, Physiopathology of Disease, and Emerging Therapeutic Potential

The discovery and characterization of the signal cascades of the β-adrenergic receptors have made it possible to effectively target the receptors for drug development. β-Adrenergic receptors are a class A rhodopsin type of G protein-coupled receptors (GPCRs) that are stimulated mainly by catecholamines and therefore mediate diverse effects of the parasympathetic nervous system in eliciting "fight or flight" type responses. They are detectable in several human tissues where they control a plethora of physiological processes and therefore contribute to the pathogenesis of several disease conditions. Given the relevance of the β-adrenergic receptor as a molecular target for many pathological conditions, this comprehensive review aims at providing an in-depth exploration of the recent advancements in β3-adrenergic receptor research. More importantly, we delve into the prospects of the β3-adrenergic receptor as a therapeutic target across a variety of clinical domains.

The impact of pharmacotherapy on sexual function in female patients being treated for idiopathic overactive bladder: a systematic review

BACKGROUND

Overactive bladder (OAB) is a condition defined by urgency with or without incontinence which disproportionately affects female patients and has a negative impact on sexual enjoyment and avoidance behaviour. Pharmacotherapy can be considered one of the main options for treating OAB. This research set out to determine the impact of pharmacotherapy on sexual function in females with OAB.

METHODS

This research used the robust methodology of a systematic review. The clinical question was formulated using the PICO (population, intervention, control, and outcomes) format to include females being treated with pharmacotherapy (anticholinergics or beta-3 adrenergic agonists) for idiopathic OAB with the use of a validated questionnaire assessing self-reported sexual function at baseline and post-treatment. The review incorporated the MEDLINE, PubMed and EMBASE databases. The AMSTAR 2 (A Measurement Tool to Assess Systematic Reviews) appraisal tool was used to guide the review process. Two reviewers worked independently in screening abstracts, deciding on the inclusion of full-texts, data extraction and risk of bias assessment.

RESULTS

In female patients with OAB, pharmacotherapy does seem to offer at least partial improvement in self-reported sexual function outcomes after 12 weeks of therapy. Still, the value of this finding is limited by an overall poor quality of evidence. Patients with a higher degree of bother at baseline stand to benefit the most from treatment when an improvement within this health-related quality of life domain is sought.

CONCLUSION

This research should form the basis for a well-conducted randomized controlled study to accurately assess sexual function improvements in females being treated with pharmacotherapy for OAB.

Efficacy and safety of pelvic floor magnetic stimulation combined with mirabegron in female patients with refractory overactive bladder: a prospective study

Objective

To observe the efficacy and safety of pelvic floor magnetic stimulation (PFMS) combined with mirabegron in female patients with refractory overactive bladder (OAB) symptoms.

Patients and methods

A total of 160 female patients with refractory OAB symptoms were prospectively randomized into two groups. Eighty cases in the combination group accepted PFMS and mirabegron therapy and 80 cases as control only accepted mirabegron therapy (The clinical trial registry number: ChiCTR2200070171). The lower urinary tract symptoms, OAB questionnaire (OAB-q) health-related quality of life (HRQol), symptom bother score and OABSS between two groups were compared at the 1st, 2nd and 4th week ends.

Results

All of 160 patients were randomly assigned to two groups, of which 80 patients were included in the combination group and 80 in the mirabegron group. The incidences of LUTS, including urgency, frequent urination, and incontinence episodes, in the 2nd week and the 4th week after combination treatment were significantly lower than those in the mirabegron group (p < 0.05). The incidence of drug-related adverse events between two groups was similar, and there was no statistically significant difference (p > 0.05). With respect to secondary variables, the OAB-q HRQol score in the combination group was statistically superior in comparison with that in the mirabegron group between the 2nd week and the 4th week (p < 0.05). This was consistent with the primary outcome. Meanwhile, from the second to fourth week, the OAB-q symptom bother score and OABSS in the combination group were both lower than in the mirabegron group (p < 0.05).

Conclusion

Combination therapy of PFMS and mirabegron demonstrated significant improvements over mirabegron monotherapy in reducing refractory OAB symptoms for female patients, and providing a higher quality of life without increasing bothersome adverse effects.

Clinical Trial Registration

https://www.chictr.org.cn/, ChiCTR-INR-22013524.

Inside the Biology of the β3-Adrenoceptor

Since the first discovery in 1989, the β3-adrenoceptor (β3-AR) has gained great attention because it showed the ability to regulate many physiologic and metabolic activities, such as thermogenesis and lipolysis in brown and white adipose tissue, respectively (BAT, WAT), negative inotropic effects in cardiomyocytes, and relaxation of the blood vessels and the urinary bladder. The β3-AR has been suggested as a potential target for cancer treatment, both in adult and pediatric tumors, since under hypoxia its upregulation in the tumor microenvironment (TME) regulates stromal cell differentiation, tumor growth and metastases, signifying that its agonism/antagonism could be useful for clinical benefits. Promising results in cancer research have proposed the β3-AR being targeted for the treatment of many conditions, with some drugs, at present, undergoing phase II and III clinical trials. In this review, we report the scientific journey followed by the research from the β3-Ars' discovery, with focus on the β3-Ars' role in cancer initiation and progression that elects it an intriguing target for novel antineoplastic approaches. The overview highlights the great potential of the β3-AR, both in physiologic and pathologic conditions, with the intention to display the possible benefits of β3-AR modulation in cancer reality.

Adrenoceptors: Receptors, Ligands and Their Clinical Uses, Molecular Pharmacology and Assays

The nine G protein-coupled adrenoceptor subtypes are where the endogenous catecholamines adrenaline and noradrenaline interact with cells. Since they are important therapeutic targets, over a century of effort has been put into developing drugs that modify their activity. This chapter provides an outline of how we have arrived at current knowledge of the receptors, their physiological roles and the methods used to develop ligands. Initial studies in vivo and in vitro with isolated organs and tissues progressed to cell-based techniques and the use of cloned adrenoceptor subtypes together with high-throughput assays that allow close examination of receptors and their signalling pathways. The crystal structures of many of the adrenoceptor subtypes have now been determined opening up new possibilities for drug development.

Mirabegron, a Selective β3-Adrenergic Receptor Agonist, as a Potential Anti-Obesity Drug

Obesity is becoming a global health epidemic. Brown and "beige" adipose tissue may produce heat, leading to energy expenditure enhancement and weight loss. Mirabegron, a selective β3-adrenergic receptor agonist, has been found to be effective as a brown adipose tissue activator, a "beige" cells stimulator and a metabolic homeostasis controller in animal and human studies. Although in animal studies, administration of mirabegron led to obesity improvement, significant weight loss in obese patients after mirabegron treatment has not been demonstrated so far, which may be associated with the too-short duration of the trials and the small number of participants in the studies. In humans, the most effective treatment for adipose tissue stimulation was high doses of mirabegron; however, cardiovascular side effects may limit the use of such doses, so the long-term safety must be evaluated. In cases of tachycardia or blood pressure elevation, the co-administration of a β1-adrenergic receptor blocker may be useful. It should be checked whether smaller doses of mirabegron, taken for a longer time, will be sufficient to stimulate brown and "beige" adipose tissue, leading to weight loss. The introduction of mirabegron into obesity treatment in the future will require long-term trials with larger numbers of subjects, to assess mirabegron efficacy, tolerability, and safety.

Efficacy and safety of combination of mirabegron and solifenacin in patients with double-J stent related overactive bladder: a prospective study

To observe the efficacy and safety of solifenacin and/or mirabegron as a medical expulsive therapy (MET) in patients with double-J stent-related overactive bladder (OAB) symptoms. A total of 219 patients with double-J stent-related OAB symptoms were prospectively randomized into two groups. One-hundred and nine cases in the combination group accepted mirabegron and solifenacin therapy and 110 cases as control only accepted solifenacin therapy. The lower urinary tract symptoms and overactive bladder questionnaire (OAB-q) health-related quality of life (HRQol) and symptom bother score between two groups were compared at the 1st, 2nd and 4th week ends. All of 219 patients were randomly assigned to two groups, of which 109 patients were included in the combination group and 110 in the solifenacin group. The incidences of LUTS, including urgency, frequent urination, and incontinence episodes, in the 2nd week (44.9% vs. 64.5%, P = 0.028; 48.6% vs. 62.7%, P = 0.036; and 40.4% vs. 56.4%, P = 0.018) and the 4th week (14.7% vs. 30.9%, P = 0.004; 16.5% vs. 33.6%, P = 0.003; and 11.9% vs. 26.4%, P = 0.007) after combination treatment were significantly lower than those in the solifenacin group. The incidence of drug-related adverse events in the solifenacin group was higher than that in the combination group, but there was no statistically significant difference (P > 0.05). In terms of secondary variables, the OAB-q HRQol score in the combination group was statistically superior in comparison with that in the solifenacin group between the second and fourth week (77.9 vs. 76.4, P = 0.020; and 87.9 vs. 85.6, P = 0.001). The OAB-q symptom bother score was higher in the solifenacin group than in the combination group (37.6 vs. 36.4, P = 0.016; and 26.2 vs. 24.8, P = 0.003). Combination therapy of solifenacin and mirabegron demonstrated significant improvements over solifenacin monotherapy in reducing OAB symptoms associated with double-J stents, and providing a higher quality of life without increasing bothersome adverse effects.

Inhibitory effects of vibegron, a β3-adrenoceptor agonist, on the myogenic contractile and mechanosensitive afferent activities in an obstructed rat bladder

To determine the role of β₃-adrenoceptor agonists on bladder sensory facilitation related to bladder myogenic contractile activities in bladder hyperactivity, we investigated the effects of vibegron, a β₃-adrenoceptor agonist, on the bladder and sensory function by evaluating cystometry and mechanosensitive single-unit afferent activities (SAAs), respectively, in a male rat model of bladder outlet obstruction (BOO). BOO was created by partial ligation of the urethra. Ten days after the surgical procedure, cystometric and SAA measurements were taken under two distinct conditions: a conscious-restrained condition, in which the bladder was constantly filled with saline, and a urethane-anesthetized condition involving an isovolumetric process with saline. For each measurement, vibegron (3 mg/kg) or its vehicle was administered intravenously after the data were reproducibly stable. In addition, the expression of β₃-adrenoceptor and substance P (SP), a sensory neuropeptide, in the bladder was further evaluated following immunohistochemical procedures. Number of non-voiding contractions (NVCs) in cystometry was decreased after vibegron-administration, which was a significant change from vehicle group. Number of microcontractions and SAAs of Aδ- and C-fibers were significantly decreased by vibegron-administration. Furthermore, β₃-adrenocepor and SP were co-expressed in the suburothelium layer of the bladder. These findings indicated that vibegron showed inhibitory effects on NVCs and microcontractions of the bladder, and SAAs of the Aδ- and C-fibers in BOO rats. The study suggested that vibegron can partly inhibit the mechanosensitive afferent transduction via Aδ- and C-fibers by suppressing bladder myogenic contractile activities in the rat bladder hyperactivity associated with BOO.

Mirabegron and solifenacin are effective for the management of the increased urinary frequency induced by psychological stress in female mice

Evidence to support the effectiveness of β3-adrenoceptor agonist mirabegron and anti-muscarinic solifenacin in the management of bladder dysfunction caused by psychological stress is lacking. This study investigates whether mirabegron or solifenacin reduces the bladder overactivity caused by water avoidance stress (WAS) in mice. Female mice were exposed to WAS for 1 h/day for 10 days and received either placebo, solifenacin or mirabegron in drinking water. Controls were age-matched without stress exposure. Voiding behaviour and functional isolated whole bladder responses during distension and in response to pharmacological agents and electrical field stimulation was investigated. Urinary frequency was significantly increased following stress. Mice treated with mirabegron or solifenacin displayed significantly fewer voiding events compared to the stressed mice, and voiding frequency in drug-treated animals was comparable to unstressed controls. The maximal contractile responses of bladders to carbachol were significantly enhanced by stress and reduced by mirabegron but not solifenacin. The frequency of phasic bladder contractions following stimulation with carbachol was significantly enhanced following stress and remained elevated in the mirabegron treated group. However, treatment with solifenacin significantly reduced the frequency of phasic contractions to unstressed control levels. Solifenacin and mirabegron are beneficial in reducing the overall voiding dysfunction caused by WAS in mice.

Pharmacophore-guided Virtual Screening to Identify New β3 -adrenergic Receptor Agonists

The β3 -adrenergic receptor (β3 -AR) is found in several tissues such as adipose tissue and urinary bladder. It is a therapeutic target because it plays a role in thermogenesis, lipolysis, and bladder relaxation. Two β3 -AR agonists are used clinically: mirabegron 1 and vibegron 2, which are indicated for overactive bladder syndrome. However, these drugs show adverse effects, including increased blood pressure in mirabegron patients. Hence, new β3 -AR agonists are needed as starting points for drug development. Previous pharmacophore modeling studies of the β3 -AR did not involve experimental in vitro validation. Therefore, this study aimed to conduct prospective virtual screening and confirm the biological activity of virtual hits. Ligand-based pharmacophore modeling was performed since no 3D structure of human β3 -AR is yet available. A dataset consisting of β3 -AR agonists was prepared to build and validate the pharmacophore models. The best model was employed for prospective virtual screening, followed by physicochemical property filtering and a docking evaluation. To confirm the activity of the virtual hits, an in vitro assay was conducted, measuring cAMP levels at the cloned β3 -AR. Out of 35 tested compounds, 4 compounds were active in CHO-K1 cells expressing the human β3 -AR, and 8 compounds were active in CHO-K1 cells expressing the mouse β3 -AR.

Mirabegron attenuates porcine ureteral contractility via α1-adrenoceptor antagonism

The β₃-agonist mirabegron is thought to induce relaxation of the detrusor muscle, contributing to the improvement of overactive bladder symptoms. There has been recent interest in purposing mirabegron as a medical expulsive therapy drug to improve the passage of smaller kidney stones by relaxing the ureteral smooth muscles. The aim of this study was to determine the effects of mirabegron on the activity of the ureter. Additionally, we investigated the receptor and mechanisms through which mirabegron exerts these effects. In vitro agonist-induced responses of isolated porcine distal ureteral tissues were measured in the absence and presence of mirabegron in organ bath experiments. The responses were expressed as frequency, area under the curve and maximum amplitude. Mirabegron at concentrations of 100 nM and lower failed to suppress phenylephrine- or 5-HT-induced contractions in the porcine ureteral strip. Mirabegron at 1 μM and 10 μM produced a rightward shift of phenylephrine concentration–response curves in these tissues. This effect of mirabegron (10 μM) was not present in 5-HT concentration–response curves. The mirabegron effect on phenylephrine-induced contractions was also not abolished by β-adrenoceptor antagonist SR 59230A (10 μM), β-adrenoceptor antagonist propranolol (10 μM), α₂-adrenoceptor antagonist yohimbine (30 nM), and nitric oxide synthase inhibitor l-NNA (10 μM). The present results show that mirabegron suppresses ureteral contractile responses in the porcine ureter via α₁-adrenoceptor antagonism, since their effects were not present when the tissues were contracted with 5-HT. Furthermore, the inhibitory effects by mirabegron were not affected by β₃-adrenoceptor antagonists.

Decoupling Oxygen Tension From Retinal Vascularization as a New Perspective for Management of Retinopathy of Prematurity. New Opportunities From β-adrenoceptors

Retinopathy of prematurity (ROP) is an evolutive and potentially blinding eye disease that affects preterm newborns. Unfortunately, until now no conservative therapy of active ROP with proven efficacy is available. Although ROP is a multifactorial disease, premature exposition to oxygen concentrations higher than those intrauterine, represents the initial pathogenetic trigger. The increase of oxygenation in a retina still incompletely vascularized promotes the downregulation of proangiogenic factors and finally the interruption of vascularization (ischemic phase). However, the increasing metabolic requirement of the ischemic retina induces, over the following weeks, a progressive hypoxia that specularly increases the levels of proangiogenic factors finally leading to proliferative retinopathy (proliferative phase). Considering non-modifiable the coupling between oxygen levels and vascularization, so far, neonatologists and ophthalmologists have "played defense", meticulously searching the minimum necessary concentration of oxygen for individual newborns, refining their diagnostic ability, adopting a careful monitoring policy, ready to decisively intervene only in a very advanced stage of disease progression. However, recent advances have demonstrated the possibility to pharmacologically modulate the relationship between oxygen and vascularization, opening thus the perspective for new therapeutic or preventive opportunities. The perspective of a shift from a defensive towards an attack strategy is now at hand.

How to choose appropriate medication for overactive bladder: Findings from the largest integrated clinical trial database analysis of mirabegron studies

Medical treatment of overactive bladder (OAB) includes antimuscarinic agents, beta-3 adrenoceptor agonist (mirabegron), or combination with both drugs. Recently, a meta-analysis reported the integrated clinical trial data from 10 phase 2–4, double-blind, 12-week mirabegron monotherapy studies. The results confirmed that mirabegron is as effective as the previously used antimuscarinic agent to treat OAB. The treatment-emergent adverse events were similar across subgroups. This article comments on this largest integrated clinical trial data analysis, and reviews the recently published literature and tries to reveal how to choose the appropriate medication for OAB. For OAB patients, starting from antimuscarinic agent is feasible. However, if the patients have risk of cognitive dysfunction, a history of constipation, dry mouth, and urinary retention, starting with mirabegron 50 mg might be more safe and appropriate. In the elderly patients with low detrusor contractility, with central nervous system lesion, and men with benign prostatic hyperplasia, starting from 25 mg mirabegron is recommended. If the treatment result is not satisfactory to the 25 mg mirabegron, increase dose to 50 mg mirabegron is appropriate. In patients who have failed from the first OAB medication either with antimuscarinics or mirabegron 50 mg, the exchange of the OAB medication to each other should be tried first. If the treatment result is still not satisfactory, a combination of antimuscarinics and mirabegron is recommended.

The Efficacy of Mirabegron in Medical Expulsive Therapy for Ureteral Stones: A Systematic Review and Meta-Analysis

BACKGROUND

This study aimed to assess the efficacy of mirabegron (50 mg daily) as a medical expulsive therapy for ureteral stones in adults.

MATERIALS AND METHODS

We searched PubMed, Embase, Cochrane Library, and Web of Science from inception to July 2021 to collect the clinical trials. Two reviewers independently screened literature, extracted data, and assessed the risk of bias of included studies by using the Cochrane risk of bias tool. Review Manager 5.3 software was used for the meta-analysis.

RESULTS

A total of four studies were included, involving 398 patients: 197 patients in mirabegron group and 201 patients in control group. The meta-analysis showed that the stone expulsion rate was higher in the mirabegron group than in the control group (OR: 2.12; 95% CI: 1.33 to 3.40; p=0.002). Subgroup analysis identified that the stone expulsion rate of patients with stone size <5/6 mm was significantly higher than that of patients with stone size ≥5/6 mm (OR: 0.31; 95% CI: 0.13 to 0.72; p=0.006). But no significant difference was identified between the mirabegron group and the control group for the stone expulsion interval (MD: -1.16, 95% CI: -3.56 to 1.24; p=0.35). In terms of pain episodes, the mirabegron group was significantly lower than that of the control group (MD: -0.34, 95% CI: -0.50 to 0.19; p < 0.0001).

CONCLUSIONS

The medical expulsive therapy with mirabegron had a significant effect in improving the stone expulsion rate for patients with ureteral stones, especially in those whose stone size <5/6 mm. Mirabegron had no effect on the stone expulsion interval but did decrease the pain episodes.

Mirabegron in medical expulsive therapy for distal ureteral stones: a prospective, randomized, controlled study

OBJECTIVE

To observe the efficacy and safety of Mirabegron in patients with distal, ureteral stones ≤ 10 mm.

PATIENTS AND METHODS

A total of 90 patients with distal ureteral stones ≤ 10 mm were prospectively randomized into two groups. Forty-five cases in the study group and 45 cases as control. The stone-free rates (SFRs) and renal colic episodes between two groups were compared at the 1st, 2nd and 4th week end by imaging examinations.

RESULT

All of 90 patients were randomly assigned to two groups. In patients with ≤ 5 mm stones, the SFRs in the 1st week (63.6% vs. 33.3%, P = 0.040), the 2nd week (86.4% vs. 54.2%, P = 0.018), and the 4th week (90.9% vs. 66.7%, P = 0.046) after treatment were all significantly higher than that in the control group by the stratification analysis of stone size. Even though SFRs were all higher for patients with > 5 mm stones in study group, there was no statistically significant difference (All P > 0.05). In terms of renal colic episodes, the frequency of occurrence of the study group was significantly lower than that of the control group and need less antalgic.

CONCLUSIONS

The MET with Mirabegron has a significant role in improve SFR for the patients with distal ureteral stones ≤ 5 mm and no effect in > 5 mm stones. Furthermore, Mirabegron reduces the need for antalgic in ≤ 10 mm stones with low incidence of adverse effects.

β3-Adrenoreceptors as ROS Balancer in Hematopoietic Stem Cell Transplantation

In the last decades, the therapeutic potential of hematopoietic stem cell transplantation (HSCT) has acquired a primary role in the management of a broad spectrum of diseases including cancer, hematologic conditions, immune system dysregulations, and inborn errors of metabolism. The different types of HSCT, autologous and allogeneic, include risks of severe complications including acute and chronic graft-versus-host disease (GvHD) complications, hepatic veno-occlusive disease, lung injury, and infections. Despite being a dangerous procedure, it improved patient survival. Hence, its use was extended to treat autoimmune diseases, metabolic disorders, malignant infantile disorders, and hereditary skeletal dysplasia. HSCT is performed to restore or treat various congenital conditions in which immunologic functions are compromised, for instance, by chemo- and radiotherapy, and involves the administration of hematopoietic stem cells (HSCs) in patients with depleted or dysfunctional bone marrow (BM). Since HSCs biology is tightly regulated by oxidative stress (OS), the control of reactive oxygen species (ROS) levels is important to maintain their self-renewal capacity. In quiescent HSCs, low ROS levels are essential for stemness maintenance; however, physiological ROS levels promote HSC proliferation and differentiation. High ROS levels are mainly involved in short-term repopulation, whereas low ROS levels are associated with long-term repopulating ability. In this review, we aim summarize the current state of knowledge about the role of β3-adrenoreceptors (β3-ARs) in regulating HSCs redox homeostasis. β3-ARs play a major role in regulating stromal cell differentiation, and the antagonist SR59230A promotes differentiation of different progenitor cells in hematopoietic tumors, suggesting that β3-ARs agonism and antagonism could be exploited for clinical benefit.

Chemogenetic approaches to identify metabolically important GPCR signaling pathways: Therapeutic implications

DREADDs (Designer Receptors Exclusively Activated by a Designer Drug) are designer G protein-coupled receptors (GPCRs) that are widely used in the neuroscience field to modulate neuronal activity. In this review, we will focus on DREADD studies carried out with genetically engineered mice aimed at elucidating signaling pathways important for maintaining proper glucose and energy homeostasis. The availability of muscarinic receptor-based DREADDs endowed with selectivity for one of the four major classes of heterotrimeric G proteins (G_s , G_i , G_q , and G₁₂ ) has been instrumental in dissecting the physiological and pathophysiological roles of distinct G protein signaling pathways in metabolically important cell types. The novel insights gained from this work should inform the development of novel classes of drugs useful for the treatment of several metabolic disorders including type 2 diabetes and obesity.

Effects of different urodynamic characteristics on therapeutic outcomes of overactive bladder medication in a real-life clinical practice

Objective

This study retrospectively investigated the influence of urodynamic parameters and patient characteristics on success rates among patients with overactive bladder (OAB) and urodynamic detrusor overactivity (DO).

Materials and Methods

Consecutive patients with OAB and urodynamic DO initially received solifenacin, mirabegron, or combination of both for 1-3 months. If failed, patients were switched to another OAB medication subtype or provided additional OAB medication for a total of 6 months. A successful treatment was defined as an improvement in urgency severity and a global response assessment of ≥1. Success rates after initial or modulated OAB medication were analyzed based on patient and urodynamic characteristics.

Results

A total of 453 patients were enrolled, among whom 144, 255, and 54 received solifenacin, mirabegron, and combined medications, respectively. Among the patients, 259 (57.2%) had OAB dry and 194 (42.8%) had OAB wet. Patients receiving mirabegron alone had a significantly higher initial medication success rate compared to that of others. Patients with a phasic DO (50.7%), bladder outlet obstruction (BOO, 52.5%), and no central nervous system (CNS) lesions (47.5%) exhibited higher success rates than those with a terminal DO (42.0%), no BOO (42.7%), and CNS lesions (31.6%), respectively. After switching or modulating the initial OAB medication following treatment failure, 115 (62.2%) of 185 patients still showed improvement in OAB symptoms, with an overall success rate of 70.2% after 6 months of treatment.

Conclusion

Initial solifenacin or mirabegron treatment had a success rate of around 50%. In general, patients with a phasic DO, urodynamic BOO, and no CNS lesions have higher success rates than those with a terminal DO, no BOO, and CNS lesions, respectively. Success rates can further be improved by switching or modulating OAB medication.

α1-adrenoceptor activity of β-adrenoceptor ligands - An expected drug property with limited clinical relevance

Many β-adrenoceptor agonists and antagonists including several clinically used drugs have been reported to also exhibit binding to α₁-adrenoceptors. Such promiscuity within the adrenoceptor family appears to occur more often than off-target effects of drugs in general. It should not be considered surprising based on the amino acid homology among the nine adrenoceptor subtypes including the counter-ions for binding the endogenous catecholamines. When β-adrenoceptor ligands also bind to α₁-adrenoceptors, they almost always act as antagonists, regardless of being agonists or antagonists at the β-adrenoceptor. The α₁-adrenoceptor affinity of β-adrenoceptor ligands in most cases is at least one, and often more log units lower than at their cognate receptor. Consistent evidence from multiple investigators indicates that β-adrenoceptor ligands relatively have the highest affinity for α_1A- and lowest for α_1B-adrenoceptors. While promiscuity among adrenoceptor subtypes causes misleading interpretation of experimental in vitro data, it is proposed based on the law of mass action that α₁-adrenoceptor binding of β-adrenoceptor ligands rarely contributes to the clinical profile of such drugs, particularly if they are agonists at the β-adrenoceptor.

Use of DREADD Technology to Identify Novel Targets for Antidiabetic Drugs

G protein-coupled receptors (GPCRs) form a superfamily of plasma membrane receptors that couple to four major families of heterotrimeric G proteins, G_s, G_i, G_q, and G₁₂. GPCRs represent excellent targets for drug therapy. Since the individual GPCRs are expressed by many different cell types, the in vivo metabolic roles of a specific GPCR expressed by a distinct cell type are not well understood. The development of designer GPCRs known as DREADDs (designer receptors exclusively activated by a designer drug) that selectively couple to distinct classes of heterotrimeric G proteins has greatly facilitated studies in this area. This review focuses on the use of DREADD technology to explore the physiological and pathophysiological roles of distinct GPCR/G protein cascades in several metabolically important cell types. The novel insights gained from these studies should stimulate the development of GPCR-based treatments for major metabolic diseases such as type 2 diabetes and obesity.

Additive effects of intravenous and intravesical application of vibegron, a β3-adrenoceptor agonist, on bladder function in rats with bladder overactivity

To examine the effects of intravenous and intravesical application of vibegron, a new β₃-adrenoceptor (β₃-AR) agonist, on bladder function in rats with oxotremorine methiodide (oxo-M: a nonselective muscarinic receptor agonist)-induced bladder overactivity. Cystometry was performed in conscious female rats with intravesical instillation of oxo-M (200 μM). In oxo-M-treated rats, vehicle or vibegron (1 and 10 mg/kg) was cumulatively applied intravenously at 30-min intervals. In other groups of rats, oxo-M + vehicle or oxo-M + vibegron (10, 100 μM, and 1 mM) was cumulatively instilled intravesically at 60-min intervals followed by intravenous application of vibegron (10 mg/kg). Expression of β₃-ARs in the bladder was also evaluated using immunohistochemical staining. Intravenous application of vibegron (10 mg/kg) significantly increased bladder capacity (1.3 times) and decreased baseline, threshold, and maximal voiding pressure compared with vehicle. Next, intravesical application of vibegron (1 mM) significantly increased threshold pressure and bladder capacity (1.2 times) compared with vehicle. Combined treatments of intravesical (1 mM) and intravenous (10 mg/kg) application of vibegron induced a significantly larger degree of increases in bladder capacity (1.4 times) compared with vehicle. In addition, β₃-ARs were expressed throughout the rat bladder, mainly in the urothelium. These results suggest that vibegron excreted in urine as an unchanged compound can induce the additive inhibitory effects on bladder overactivity possibly through urothelial β₃-AR activation, which inhibits the afferent limb of micturition reflex rather than the efferent function as evidenced by the increases in threshold pressure and bladder capacity without affecting bladder contractile function after intravesical vibegron application.

The Regulator of G Protein Signaling Homologous Domain of G Protein-Coupled Receptor Kinase 2 Mediates Short-Term Desensitization of β3-Adrenergic Receptor

G protein coupled receptor (GPCR) kinases (GRKs) are key regulators of GPCR signaling. Canonical mechanism of GPCR desensitization involves receptor phosphorylation by GRKs followed by arrestin recruitment and uncoupling from heterotrimeric G protein. Although β3-adrenergic receptor (β3AR) lacks phosphorylation sites by GRKs, agonist treatment proved to induce β3AR desensitization in many cell types. Here we show that GRK2 mediates short-term desensitization of β3AR by a phosphorylation independent mechanism but mediated by its domain homologous to the regulator of G protein signaling (RGS). HEK293T cells overexpressing human β3AR presented a short-term desensitization of cAMP response stimulated by the β3AR agonist, BRL37344, and not by forskolin. We found that β3AR desensitization was higher in cells co-transfected with GRK2. Similarly, overexpression of the RGS homology domain but not kinase domain of GRK2 increased β3AR desensitization. Consistently, stimulation of β3AR increased interaction between GRK2 and Gαs subunit. Furthermore, in rat cardiomyocytes endogenously expressing β3AR, transfection with dominant negative mutant of RH domain of GRK2 (GRK2/D110A) increased cAMP response to BRL37344 and inhibited receptor desensitization. We expect our study to be a starting point for more sophisticated characterization of the consequences of GRK2 mediated desensitization of the β3AR in heart function and disease.

β3 -Adrenoceptors in the normal and diseased urinary bladder-What are the open questions?

β₃ -Adrenoceptor agonists are used in the treatment of overactive bladder syndrome. Although the relaxant response to adrenergic stimulation in human detrusor smooth muscle cells is mediated mainly via β₃ -adrenoceptors, the plasma concentrations of the therapeutic dose of mirabegron, the only clinically approved β₃ -adrenoceptor agonist, are considerably lower than the EC₅₀ for causing direct relaxation of human detrusor, suggesting a mechanism of action other than direct relaxation of detrusor smooth muscle. However, the site and mechanism of action of β₃ -adrenoceptor agonists in the bladder have not been firmly established. Postulated mechanisms include prejunctional suppression of ACh release from the parasympathetic nerves during the storage phase and inhibition of micro-contractions through β₃ -adrenoceptors on detrusor smooth muscle cells or suburothelial interstitial cells. Implications of possible desensitization of β₃ -adrenoceptors in the bladder upon prolonged agonist exposure and possible causes of rarely observed cardiovascular effects of mirabegron are also discussed. LINKED ARTICLES: This article is part of a themed section on Adrenoceptors-New Roles for Old Players. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.14/issuetoc.

β-Adrenoceptors as drug targets in melanoma: novel preclinical evidence for a role of β3 -adrenoceptors

Stress plays a role in tumourigenesis through catecholamines acting at β-adrenoceptors including β₁ -, β₂ - and β₃ -adrenoceptors, and the use of β-adrenoceptor antagonists seems to counteract tumour growth and progression. Preclinical evidence and meta-analysis data demonstrate that melanoma shows a positive response to β-adrenoceptor blockers and in particular to propranolol acting mainly at β₁ - and β₂ -adrenoceptors. Although evidence suggesting that β₃ -adrenoceptors may play a role as a therapeutic target in infantile haemangiomas has been recently reviewed, a comprehensive analysis of the data available from preclinical studies supporting a possible role of β₃ -adrenoceptors in melanoma was not available. Here, we review data from the literature demonstrating that propranolol may be effective at counteracting melanoma growth, and we provide preclinical evidence that β₃ -adrenoceptors may also play a role in the pathophysiology of melanoma, thus opening the door for further clinical assays trying to explore β₃ -adrenoceptor blockers as novel alternatives for its treatment. LINKED ARTICLES: This article is part of a themed section on Adrenoceptors-New Roles for Old Players. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.14/issuetoc.

Managing urinary incontinence in women - a review of new and emerging pharmacotherapy

INTRODUCTION

The pharmacological treatment of urinary incontinence and overactive bladder (OAB) has been, for a longer time, based on antimuscarinic agents. In recent years, two other pharmacological principles have been introduced for the treatment of OAB and urgency urinary incontinence: the β3-adrenergic agent mirabegron and botulinum neurotoxin. Meanwhile, there is lack of effective drugs for the treatment of stress incontinence.

AREAS COVERED

This literature review presents synthetic compounds aimed to treat female urinary incontinence that are in phase II-III clinical development.

EXPERT OPINION

Antimuscarinic agents will continue to represent the current gold standard for the first-line pharmacological management of OAB and urgency urinary incontinence. The class of β3-agonists will certainly expand with the discovery and clinical development of novel agents. Combination therapy of antimuscarinic agents and β3-agonists could offer an alternative treatment in these patients, including those with symptoms refractory to first-line monotherapy. A huge number of preclinical studies are underway in this field exploring the therapeutic potential of many novel compounds while some have advanced to clinical phases of development.

Efficacy of mirabegron in medical expulsive therapy

To show the efficacy of mirabegron for medical expulsive treatment, in patients had intramural located distal ureteral stone. A 80 patients had intramural ureteral stone were assessed retrospectively between April 2017 and January 2018. Mirabegron 50 mg/day + diclofenac 100 mg/day (group 1, n = 40), and only diclofenac 100 mg/day (group 2, n = 40) were administered to patients, consecutively. Age, gender, stone size, laterality, and severity of hydronephrosis were recorded. Spontaneous stone expulsion rates (SER), stone expulsion time, and the number of daily colic episodes were evaluated. In the group 1, one (2.5%) patient was excluded due to nasopharyngitis, and one (2.5%) patient was excluded due to 5 mmHg systolic blood pressure increase. In addition, four (10%) patients in group 1, and six (15%) patients in group 2, who did not attend follow-up examinations, were excluded from the study. There was not any statistically significant difference between the two groups in terms of age, gender, stone location, severity of hydronephrosis, stone size (p = 0.736, p = 0.310, p = 0.467, p = 0.801, p = 0.761, consecutively). Spontaneous expulsion ratios were calculated as 73.52% in group 1, and 47.05% in group 2 (p = 0.026). However, there was not any statistically significant difference in terms of stone expulsion time (p = 0.979). SER for patients had ≤ 6 mm stones was higher in group 1 (87.5 vs 52.49%, p = 0.031). In addition, group 2 patients had more pain episodes (1.02 ± 0.52 vs. 1.29 ± 0.57, p = 0.049). In the current study, mirabegron has been shown to be an efficient, safe and a new treatment modality, with lower side effect profile for the intramural located distal ureteral stones.

Urological dysfunction in synucleinopathies: epidemiology, pathophysiology and management

OBJECTIVE

Parkinson's disease (PD) and multiple system atrophy (MSA) are major neurogenerative diseases characterized pathologically by abnormal alpha-synuclein aggregation. PD and MSA are clinically characterized by motor disorder and bladder dysfunction (mainly urinary urgency and frequency, also called overactive bladder). However, few literatures are available concerning bladder dysfunction in PD or MSA.

METHOD

A systematic review.

RESULTS

The bladder dysfunction in MSA is more severe than that in PD for large post-void residual or urinary retention. These bladder dysfunctions presumably reflect the different nervous system pathologies. Overactive bladder in PD reflects lesions in the brain, e.g., in the prefrontal-nigrostriatal D1 dopaminergic bladder-inhibitory pathway. Overactive bladder in MSA reflects lesions similar to PD and the cerebellum (bladder-inhibitory), and the urinary retention in MSA presumably reflects lesions in the pontine micturition center and the sacral intermediolateral nucleus of the spinal cord (bladder-facilitatory). Bladder dysfunction not only impairs an individual's quality of life, it can also cause emergency hospitalizations due to acute retention and early institutionalization. Anticholinergics are the first-line treatment for bladder dysfunction in PD and MSA patients, but care should be taken for the management of bladder dysfunction-particularly in MSA patients due to the high prevalence of difficult emptying, which needs clean, intermittent catheterization.

CONCLUSIONS

This review summarizes the epidemiology, pathophysiology, and management of bladder dysfunction in individuals with PD or MSA.

Inhibition of cholinergic neurotransmission by β3-adrenoceptors depends on adenosine release and A1-receptor activation in human and rat urinary bladders

The direct detrusor relaxant effect of β₃-adrenoceptor agonists as a primary mechanism to improve overactive bladder symptoms has been questioned. Among other targets, activation of β₃-adrenoceptors downmodulate nerve-evoked acetylcholine (ACh) release, but there is insufficient evidence for the presence of these receptors on bladder cholinergic nerve terminals. Our hypothesis is that adenosine formed from the catabolism of cyclic AMP in the detrusor may act as a retrograde messenger via prejunctional A₁ receptors to explain inhibition of cholinergic activity by β₃-adrenoceptors. Isoprenaline (1 µM) decreased [³H]ACh release from stimulated (10 Hz, 200 pulses) human (-47 ± 5%) and rat (-38 ± 1%) detrusor strips. Mirabegron (0.1 µM, -53 ± 8%) and CL316,243 (1 µM, -37 ± 7%) mimicked isoprenaline (1 µM) inhibition, and their effects were prevented by blocking β₃-adrenoceptors with L748,337 (30 nM) and SR59230A (100 nM), respectively, in human and rat detrusor. Mirabegron and isoprenaline increased extracellular adenosine in the detrusor. Blockage of A₁ receptors with 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 100 nM) or the equilibrative nucleoside transporters (ENT) with dipyridamole (0.5 µM) prevented mirabegron and isoprenaline inhibitory effects. Dipyridamole prevented isoprenaline-induced adenosine outflow from the rat detrusor, and this effect was mimicked by the ENT1 inhibitor, S-(4-nitrobenzyl)-6-thioinosine (NBTI, 30 µM). Cystometry recordings in anesthetized rats demonstrated that SR59230A, DPCPX, dipyridamole, and NBTI reversed the decrease in the voiding frequency caused by isoprenaline (0.1-1,000 nM). Data suggest that inhibition of cholinergic neurotransmission by β₃-adrenoceptors results from adenosine release via equilibrative nucleoside transporters and prejunctional A₁-receptor stimulation in human and rat urinary bladder.

On the Site and Mechanism of Action of β3-Adrenoceptor Agonists in the Bladder

The clinical success of mirabegron as the first β₃-adrenoceptor (AR) agonist for treatment of the overactive bladder (OAB) syndrome, has resulted in substantial interest in its site and mechanism of action. Even if the adrenergic innervation of the bladder and urethra has been well studied, the location(s) of β₃-ARs in different structures within the bladder wall and urethra, and the mode(s) of action of β₃-AR stimulation have still not been established. The recent demonstration of β₃-ARs on cholinergic nerve terminals with no immunoreactivity in urothelium or detrusor smooth muscle, is not in agreement with previous morphological studies, and functional data strongly suggest that β₃-ARs can be found these structures. However, recent studies suggest that the β₃-ARs on detrusor smooth muscle may not be the functionally most relevant. The assumption that β₃-AR activation during bladder filling inhibits acetylcholine release from parasympathetic neurons by a prejunctional mechanism and that this decreases bladder micromotions that generate afferent activity, is an attractive hypothesis. It does not exclude that other mechanisms may be contributing, and supports combined approaches to reduce afferent activity for treatment of the OAB syndrome.

Safety and tolerability of β3-adrenoceptor agonists in the treatment of overactive bladder syndrome - insight from transcriptosome and experimental studies

INTRODUCTION

We have reviewed the safety and tolerability of β3-adrenoceptor agonists, specifically mirabegron and solabegron, a newly emerging drug class for the treatment of the overactive bladder syndrome. We discuss them mechanistically in the context of expression and other preclinical data.

AREAS COVERED

Based on a systematic PubMed search, incidence of overall adverse events, hypertension, dry mouth, and constipation are comparable between mirabegron or solabegron and placebo. Hypertension is the most frequently observed adverse event, but has a similar incidence with mirabegron and placebo. Nevertheless, severe uncontrolled hypertension has become a contraindication for use of mirabegron based on observation of severe hypertension in association with mirabegron exposure. The overall incidence of adverse events is also similar between mirabegron and the muscarinic receptor antagonist tolterodine, but the incidence of dry mouth is much lower with mirabegron.

EXPERT OPINION

The high β3-adrenoceptor mRNA expression in the human ovaries is not associated with reproductive side effects. Generally, β3-adrenoceptors exhibit a rather restricted expression in human tissues, which may explain the overall good tolerability of agonists acting on this receptor. We propose that expression profiles and functional preclinical studies can be important tools in the prediction of adverse event profiles in first-in-class drugs.

Overactive bladder - 18 years - Part II

Traditionally, the treatment of overactive bladder syndrome has been based on the use of oral medications with the purpose of reestablishing the detrusor stability. The recent better understanding of the urothelial physiology fostered conceptual changes, and the oral anticholinergics - pillars of the overactive bladder pharmacotherapy - started to be not only recognized for their properties of inhibiting the detrusor contractile activity, but also their action on the bladder afference, and therefore, on the reduction of the symptoms that constitute the syndrome. Beta-adrenergic agonists, which were recently added to the list of drugs for the treatment of overactive bladder, still wait for a definitive positioning - as either a second-line therapy or an adjuvant to oral anticholinergics. Conservative treatment failure, whether due to unsatisfactory results or the presence of adverse side effects, define it as refractory overactive bladder. In this context, the intravesical injection of botulinum toxin type A emerged as an effective option for the existing gap between the primary measures and more complex procedures such as bladder augmentation. Sacral neuromodulation, described three decades ago, had its indication reinforced in this overactive bladder era. Likewise, the electric stimulation of the tibial nerve is now a minimally invasive alternative to treat those with refractory overactive bladder. The results of the systematic literature review on the oral pharmacological treatment and the treatment of refractory overactive bladder gave rise to this second part of the review article Overactive Bladder - 18 years, prepared during the 1st Latin-American Consultation on Overactive Bladder.

β3-Adrenoceptor agonists for overactive bladder syndrome: Role of translational pharmacology in a repositioning clinical drug development project

β3-Adrenoceptor agonists were originally considered as a promising drug class for the treatment of obesity and/or type 2 diabetes. When these development efforts failed, they were repositioned for the treatment of the overactive bladder syndrome. Based on the example of the β3-adrenoceptor agonist mirabegron, but also taking into consideration evidence obtained with ritobegron and solabegron, we discuss challenges facing a translational pharmacology program accompanying clinical drug development for a first-in-class molecule. Challenges included generic ones such as ligand selectivity, species differences and drug target gene polymorphisms. Challenges that are more specific included changing concepts of the underlying pathophysiology of the target condition while clinical development was under way; moreover, a paucity of public domain tools for the study of the drug target and aspects of receptor agonists as drugs had to be addressed. Nonetheless, a successful first-in-class launch was accomplished. Looking back at this translational pharmacology program, we conclude that a specifically tailored and highly flexible approach is required. However, several of the lessons learned may also be applicable to translational pharmacology programs in other indications.

Delivery methods for drugs used in the treatment of overactive bladder

INTRODUCTION

Overactive bladder affects a significant portion of the population and results in prescribing of numerous medications for its treatment. Traditional drug delivery systems used in therapy are associated with multiple commonly reported side effects. Adherence rates with use of these medications are low. It is likely that low adherence rates with the use of these drugs are due in some part to drug side effects. It is therefore important that alternate methods for drug delivery be explored to reduce side effect profiles and improve patient compliance.

AREAS COVERED

This article addresses the various forms of drug delivery for overactive bladder medications, focusing on those currently in use. Newer systems of drug delivery are also discussed. Through thorough review of research data, randomized trials and meta analyses, drug delivery systems were evaluated.

EXPERT OPINION

EXPERT OPINION favors the use of the transdermal patch and recognizes the necessity for further research and development of other delivery methods. The patch delivery method offers the most effective means of treating symptoms and minimizing drug related adverse side effects leading to treatment discontinuation. Development of OAB medications aimed at alternate receptor targets has the potential to facilitate the creation of new treatment methods to compete with the current standard of care used in OAB treatment.

Discovery of benzamides as potent human β3 adrenergic receptor agonists

The paper will describe the synthesis and SAR studies that led to the discovery of benzamide (reverse amide) as potent and selective human β3-adrenergic receptor agonist. Based on conformationally restricted pyrrolidine scaffold we discovered earlier, pyrrolidine benzoic acid intermediate 22 was synthesized. From library synthesis and further optimization efforts, several structurally diverse reverse amides such as 24c and 24i were found to have excellent human β3-adrenergic potency and good selectivity over the β1 and β2 receptors. In addition to human β1, β2, β3 and hERG data, PK of selected compounds will be described.

Drug therapy of overactive bladder--what is coming next?

After the approval and introduction of mirabegron, tadalafil, and botulinum toxin A for treatment of lower urinary tract symptoms/overactive bladder, focus of interest has been on their place in therapy versus the previous gold standard, antimuscarinics. However, since these agents also have limitations there has been increasing interest in what is coming next - what is in the pipeline? Despite progress in our knowledge of different factors involved in both peripheral and central modulation of lower urinary tract dysfunction, there are few innovations in the pipe-line. Most developments concern modifications of existing principles (antimuscarinics, β₃-receptor agonists, botulinum toxin A). However, there are several new and old targets/drugs of potential interest for further development, such as the purinergic and cannabinoid systems and the different members of the transient receptor potential channel family. However, even if there seems to be good rationale for further development of these principles, further exploration of their involvement in lower urinary tract function/dysfunction is necessary.

Video-urodynamic effects of mirabegron, a β3 -adrenoceptor agonist, in patients with low-compliance bladder

OBJECTIVES

To investigate video-urodynamic effects of mirabegron, a β3 -adrenoceptor agonist, on low-compliance bladder.

METHODS

We retrospectively reviewed nine patients (three men, six women, age 17-68 years) who had been diagnosed with lower urinary tract dysfunction with low-compliance bladder, and who underwent video-urodynamic study before and during administration of mirabegron 50 mg once daily. Urodynamic parameters were compared before and after treatment.

RESULTS

Mirabegron treatment significantly increased first desire to void and cystometric capacity with an average increment of 80 mL (P = 0.027) and 123 mL (P = 0.005), respectively. Bladder compliance also significantly increased (mean value 8.1 mL/cmH2 O before, 18.2 mL/cmH2 O after, P = 0.024). In the six patients who had been taking anticholinergic agents at baseline video-urodynamic study and then switched to mirabegron, mean cystometric capacity and bladder compliance were also increased significantly from 208.3 to 346.8 mL (P = 0.015) and from 7.2 to 17.5 mL/cmH2 O (P = 0.047), respectively. Vesicoureteral reflux grade was improved in three of the four patients who had shown vesicoureteral reflux on cystography before treatment.

CONCLUSIONS

Mirabegron improves cystometric capacity and bladder compliance, and it lowers vesicoureteral reflux grade in patients with low-compliance bladder. Thus, mirabegron might represent a good alternative drug for low-compliance bladder refractory to anticholinergic treatment.

β3-Adrenoceptor-mediated relaxation of rat and human urinary bladder: roles of BKCa channels and Rho kinase

Previous studies suggest that the large-conductance Ca(2+)-activated K(+) (BKCa) channel and Rho-kinase play major roles in the control of urinary bladder tone. Here, we investigated their involvement in β-adrenoceptor (AR)-mediated relaxation of rat and human bladder. Concentration-response curves of isoprenaline and mirabegron-induced bladder relaxation were generated against passive tension and KCl- and carbachol-induced tone, in the absence or presence of the BKCa channel inhibitor iberiotoxin (100 nM) or the Rho-kinase inhibitor Y27,632 (1 μM). Myosin light chain (MLC) phosphorylation was studied by Western blot. In rat, iberiotoxin only slightly altered isoprenaline- and mirabegron-induced relaxation against KCl-induced tone but attenuated relaxation by both agonists against carbachol-induced tone. Y27,632 enhanced isoprenaline- or mirabegron-induced relaxation only against carbachol-induced tone. In humans, iberiotoxin slightly enhanced relaxation by both agonists against carbachol-induced pre-contraction. Y27,632 did not change isoprenaline-induced relaxation but enhanced that by mirabegron. Under passive tension, MLC phosphorylation was markedly reduced by both β-AR agonists, an effect insensitive to Y27,632. In the presence of carbachol, both β-AR agonists increased MLC phosphorylation, an effect reduced by Y27,632 only in the presence of 1 μM carbachol. These results indicate that the extent of BKCa channel and Rho-kinase involvement in relaxation induced by β-AR agonists depends on pre contractile stimulus and species.

A current perspective on geriatric lower urinary tract dysfunction

Lower urinary tract dysfunction-such as urinary incontinence (UI), detrusor overactivity, and benign prostatic hyperplasia-is prevalent in elderly persons. These conditions can interfere with daily life and normal functioning and lead to negative effects on health-related quality of life. UI is one of the most common urologic conditions but is poorly understood elderly persons. The overall prevalence of UI increases with age in both men and women. Elderly persons often neglect UI or dismiss it as part of the normal aging process. However, UI can have significant negative effects on self-esteem and has been associated with increased rates of depression. UI also affects quality of life and activities of daily living. Although UI is more common in elderly than in younger persons, it should not be considered a normal part of aging. UI is abnormal at any age. The goal of this review is to provide an overview of the cause, classification, evaluation, and management of geriatric lower urinary tract dysfunction.

Mirabegron

Mirabegron is used for the treatment of symptoms associated with overactive bladder syndrome. It selectively stimulates the β3 -adrenoreceptor, which relaxes the detrusor muscle. This improves urine storage by distension of the bladder body.