Selectivity and Maximum Response of Vibegron and Mirabegron for β3-Adrenergic Receptors

Comparative Efficacy and Safety of Mirabegron and Vibegron in Female Patients With Overactive Bladder: A Systematic Review and Meta-analysis of Randomized Controlled Trials

This meta-analysis compared mirabegron and vibegron efficacy/safety in female overactive bladder (OAB) patients, adhering to PRISMA guidelines (PROSPERO CRD42024587945). Pooling data from 3 RCTs (n=371), vibegron showed superior urgency urinary incontinence relief versus mirabegron (p=0.02), while demonstrating comparable OAB symptom scores, urgency episodes, quality of life, and voided volumes. Safety profiles were similar for total adverse events, constipation, post-void residuals, and dizziness. Both medications exhibit comparable overall efficacy and safety, though vibegron may offer specific advantages in managing incontinence symptoms.

Up-and-coming pharmacotherapeutic options for treating patients with refractory overactive bladder

INTRODUCTION

Overactive bladder (OAB) is a prevalent disorder with a significant impact on quality of life. The pathophysiology of OAB is multifactorial and the majority of patients will require treatment with multiple therapies across the course of their disease. First-line treatments include bladder retraining, fluid advice and pelvic floor muscle training. Following this, patients may be offered treatment with anticholinergic and β3 agonist medications. Anticholinergics are known to have high rates of discontinuation due to side effects and there are concerns regarding anticholinergic load and its impact on cognitive function in older adults.

AREAS COVERED

This paper aims to discuss the current and emerging treatment options available for patients who suffer from OAB.

EXPERT OPINION

The management of OAB in the clinical setting remains challenging. The goal of newer pharmacotherapies in OAB would be treatment that provides long-term symptomatic relief with minimal side effects and an improved quality of life. The future of OAB research is promising and should consider the implications of the gut-bladder axis, regenerative medicine, biomarkers and the role of digital health.

Comparison of the 3-Year Continuation Rate and Discontinuation Factors Between Vibegron and Mirabegron in Patients With Overactive Bladder: A Retrospective Follow-Up Study in a Rehabilitation Hospital in Japan

OBJECTIVES

The objective of this study is to compare the 3-year continuation rate and discontinuation factors between vibegron and mirabegron in patients with overactive bladder in a rehabilitation hospital in Japan.

METHODS

The 3-year continuation rate of the target drugs and reasons for discontinuation as well as patients' backgrounds and adverse effects were evaluated retrospectively from the medical records between September 2018 and December 2020. After selecting patients according to our inclusion and exclusion criteria, 136 cases taking mirabegron and 82 taking vibegron were adjusted for intergroup variability by propensity score matching. We performed Cox proportional hazards regression for the 3-year continuation rate and Fine-Gray proportional hazards regression for the 3-year cumulative incidence of discontinuation events. Subgroup analysis was also performed.

RESULTS

Approximately 70% of the patients analyzed had neurogenic overactive bladder. The 3-year continuation rate was 65.2% in vibegron and 30.3% in mirabegron, and the hazard ratio was 0.41 (95% confidence interval: 0.25-0.68, p < 0.001) as for an incidence of discontinuation events of vibegron against mirabegron. The incidence of discontinuation due to inadequate efficacy was 22.7% in vibegron and 47.0% in mirabegron, and similarly the hazard ratio was 0.43 (95% confidence interval: 0.23-0.80, p < 0.01). In the subgroup analysis, vibegron continued significantly more than mirabegron for the 3-year continuation rate in non-neurogenic overactive bladder (p < 0.001), in spontaneous voiding (p < 0.001), in anticholinergic combination (p = 0.0017), in female (p < 0.001), and in 70 years or older (p = 0.0028). Additionally, a significant interaction was observed regarding the methods of emptying urine (p = 0.0066).

CONCLUSIONS

Vibegron was superior to mirabegron in the 3-year continuation rate of administration with a fewer discontinuation due to inadequate efficacy in a patient population with relatively high rates of neurogenic overactive bladder.

Safety and Effectiveness of Vibegron in Japanese Patients With Overactive Bladder: A Japanese Postmarketing Survey

OBJECTIVES

To evaluate the safety and effectiveness of vibegron, a highly selective β3-adrenoceptor agonist, in Japanese patients with overactive bladder (OAB) in a real-world clinical setting.

METHODS

This prospective survey was conducted from August 2019 to July 2023 using a central registration method. Patients newly treated with vibegron for OAB were followed for 12 weeks, and those who continued treatment were observed for up to 52 weeks. Adverse drug reactions (ADRs) and the overall improvement level were assessed, and overactive bladder symptom score (OABSS) and International Prostate Symptom Score-Quality of Life (IPSS QOL) score were collected.

RESULTS

Of the 1848 patients in the safety analysis set, 154 ADRs were reported in 141 patients (7.63%). Common ADRs were increased residual urine volume (1.30%), constipation (1.14%), dysuria and urinary retention (0.97% each), cystitis (0.65%), and dry mouth (0.32%). The incidence of urinary retention-related adverse events (AEs) was higher in male patients, patients ≥ 65 years old, and patients with benign prostatic hyperplasia. The effectiveness rate was 88.8% among the 1561 patients in the effectiveness analysis set. Significant improvement in both OABSS and IPSS QOL scores was observed at all observation periods. The rate of achieving the minimal clinically important change in OABSS total score at the final evaluation was 75.35%. OABSS scores were also significantly reduced in all subgroup analyses.

CONCLUSIONS

This survey found no major concerns regarding the safety and effectiveness of vibegron in Japanese OAB patients, except for urinary retention-related AEs. Vibegron is considered to represent a useful drug for treating OAB symptoms in a real-world clinical setting.

Physiological and metabolic functions of the β3-adrenergic receptor and an approach to therapeutic achievements

A specific type of beta-adrenergic receptor was discovered in the decade of 1980s and subsequently recognized as a new type of beta-adrenergic receptor, called beta3-adrenoceptor (β3-AR). β3-AR expresses in different tissues, including adipose tissue, gall bladder, stomach, small intestine, cardiac myocytes, urinary bladder, and brain. Structurally, β3-AR is very similar to β1- and β2-AR and belongs to a G-protein coupled receptor that uses cAMP as an intracellular second messenger. Alternatively, it also activates the NO-cGMP cascade. Stimulation of the β3-AR increases lipolysis, fatty acid oxidation, energy expenditure, and insulin action, leading to anti-obesity and anti-diabetic activity. Moreover, β3-AR differentially regulates the myocardial contraction and relaxes the urinary bladder to balance the cardiac activity and delay the micturition reflex, respectively. In recent years, this receptor has served as an attractive target for the treatment of obesity, type 2 diabetes, congestive heart failure, and overactive bladder syndrome. Several β3-AR agonists are in the emerging stage that can exert novel pharmacological benefits in different therapeutic areas. The present review focuses on the structure, signaling, physiological, and metabolic activities of β3-AR. Additionally, therapeutic approaches of β3-AR have also been considered.

Comparative Efficacy and Safety of the β3-Adrenoceptor Agonist Vibegron for Urgency and Mixed Urinary Incontinence: A Post Hoc Analysis of a Randomized, Double-Blind, Placebo-Controlled Phase 3 Study

Objective To compare the efficacy of vibegron for urgency urinary incontinence (UUI) and mixed urinary incontinence (MUI) in patients with overactive bladder (OAB). Methods We performed a post hoc analysis of a phase 3 study of vibegron in Japanese patients with OAB. Based on the patterns recorded in the three-day bladder diary, only female patients were categorized into UUI and MUI populations. The primary endpoint was the change in the mean micturition number per 24 hours from baseline to week 12. Other endpoints included the mean changes in urgency episodes per 24 hours, incontinence episodes per 24 hours, voided volume per micturition, and the number of nocturia episodes per night. The proportion of urinary incontinence (UI) normalization, quality of life (QOL) as measured by the King's Health Questionnaire (KHQ), and patient satisfaction level as assessed by the Patient Global Impression (PGI) were investigated. Result Data from a UUI population (vibegron 50 mg, n = 237; vibegron 100 mg, n = 231; placebo, n = 237) and an MUI population (vibegron 50 mg, n = 70; vibegron 100 mg, n = 77; placebo, n = 78) were analyzed. Vibegron 50 mg and 100 mg significantly improved the change in micturition number per 24 hours from baseline to week 12. Compared to those of patients receiving a placebo, all other endpoints of urinary parameters were significantly improved in patients receiving vibegron, except for nocturia in the vibegron 50 mg group in both populations. In the vibegron 50 mg, vibegron 100 mg, and placebo groups, the proportions of those who attained normalization of UI were stratified by the UUI (51.5%, 57.6%, and 44.7%, respectively) and MUI (40.0%, 41.6%, and 20.5%, respectively) populations. Furthermore, both vibegron doses improved KHQ scores in both populations, and PGI improvement was significantly higher than that in the placebo group in both populations. Conclusion This post hoc analysis demonstrated that vibegron has equivalent efficacy and safety in the MUI and UUI populations. The results of this study provide important information for the treatment of MUI.

Novel pharmacotherapeutic avenues for bladder storage dysfunction in men

INTRODUCTION

Bladder storage dysfunction is associated with low quality of life in men and remains a challenging field in pharmacotherapy because of low persistence followed by patient-perceived lack of efficacy and adverse effects. The persistent desire for the development of novel pharmacotherapy is evident, leading to numerous research efforts based on its pathophysiology.

AREAS COVERED

This review describes the pathophysiology, current pharmacotherapeutic strategies, and emerging novel drugs for male bladder storage dysfunction. The section on emerging pharmacotherapy provides an overview of current research, focusing on high-potential target molecules, particularly those being evaluated in ongoing clinical trials.

EXPERT OPINION

As pharmacotherapies targeting alpha-adrenergic, beta-adrenergic, and muscarinic receptors - the current primary targets for treating male bladder storage dysfunction - have demonstrated insufficient efficacy and side effects, researchers are exploring various alternative molecular targets. Numerous targets have been identified as central to regulating bladder afferent nerve activity, and their pharmacological effects and potential have been evaluated in animal-based experiments. However, there is a limited number of clinical trials for these new pharmacotherapies, and they have not demonstrated clear superiority over current treatments. Further research is needed to develop new effective pharmacotherapies for bladder storage dysfunction in men.

Comparison of mirabegron and vibegron for clinical efficacy and safety in female patients with overactive bladder: a multicenter prospective randomized crossover trial

PURPOSE

To compare the efficacy and safety of mirabegron and vibegron in female OAB patients.

METHODS

We conducted a multicenter, prospective, randomized crossover study of female patients with OAB. The patients were assigned to Group MV (mirabegron for 8 weeks, followed by vibegron for 8 weeks) or group VM (vibegron for 8 weeks, followed by mirabegron for 8 weeks). The primary endpoint was the change in OABSS from baseline, and the secondary endpoint was the change in FVC parameters. After completion of the study, each patient was asked which drug was preferable.

RESULTS

A total of 83 patients were enrolled (40 and 43 in groups MV and VM, respectively). At 8th and 16th week, 33 and 29 in Group MV and 34 and 27 in Group VM continued to receive the treatment. The change in PVR was not significantly different between treatment with mirabegron and vibegron. The changes in OABSS, nighttime frequency, mean, and maximum voided volume were similar between mirabegron and vibegron. The mean change in the daytime frequency was greater in the vibegron than in the mirabegron. Of the 56 patients, 15 (27%) and 30 (53%) preferred mirabegron and vibegron, respectively. The remaining 11 patients (20%) showed no preference. The change in the urgency incontinence score during vibegron was better in patients who preferred vibegron to mirabegron.

CONCLUSION

The efficacies of mirabegron and vibegron in female patients was similar. The patients' preference for vibegron could depend on the efficacy of vibegron for urgency incontinence.

Risks of Dementia After Treatment with an Anticholinergic, Beta-3 Agonist, or Combination of Both for an Overactive Bladder: A Korean National Cohort Study

BACKGROUND AND OBJECTIVE

An overactive bladder (OAB) is primarily managed with behavioural therapy and using anticholinergics and beta-3 agonists. Reports have shown that the use of anticholinergics by OAB patients was associated with an increased risk of new-onset dementia compared with those using beta-3 agonists. This study compares the risks of dementia among patients with an OAB starting on a beta-3 agonist alone, an anticholinergic alone, or a combination treatment.

METHODS

Using data from the Korean National Health Insurance Service database, we studied a nationwide population cohort comprising patients newly diagnosed with an OAB who initiated their OAB medications between 2015 and 2020. The treatment types were categorised as anticholinergics (oxybutynin, solifenacin, tolterodine, trospium, fesoterodine, flavoxate, and propiverine) alone, a beta-3 agonist (mirabegron) alone, and combination therapy (an anticholinergic plus the beta-3 agonist). To evaluate the impact of cumulative drug exposure, we quantified the cumulative exposure to solifenacin and mirabegron as cumulative defined daily doses (cDDDs) using proportional hazards regression analyses, adjusted for factors known to be associated with dementia.

KEY FINDINGS AND LIMITATIONS

Among the study's 3 452 705 patients, 671 974 were new users of a beta-3 agonist alone (19.5%), 1 943 414 new users of anticholinergics alone (56.3%), and 837 317 receiving combination therapy (24.3%). The most common anticholinergic used both alone and as part of a combination treatment was solifenacin (42.9% and 56.3%, respectively). There was an increased risk of dementia between the users of an anticholinergic alone (adjusted hazard ratio [aHR] = 1.213; 95% confidence interval [CI], 1.195-1.232) and those taking a combination treatment (aHR = 1.345; 95% CI, 1.323-1.366) compared with the users of beta-3 agonists alone after the adjustment of covariates. However, the incidence of dementia was also significantly higher, with an increase in the cumulative dose of mirabegron (aHR = 1.062 [1.021-1.106] for 28-120 cDDDs and aHR = 1.044 [1.004-1.084)] for patients who received >121 cDDDs compared with those who received <27 cDDDs). A marked increased risk of dementia was associated with the use of solifenacin, tolterodine, fesoterodine, and propiverine, both separately and in combination with mirabegron.

CONCLUSIONS AND CLINICAL IMPLICATIONS

In this large Korean cohort, the use of anticholinergics with or without a beta-3 agonist increased the risk of new-onset dementia compared with the use of a beta-3 agonist alone. Given that the risk of dementia was most significantly elevated with combination treatments, care should be taken when considering combination treatment for OAB patients with risk factors for dementia. Furthermore, there could be a possible association between beta-3 agonists and dementia, although future studies are needed.

PATIENT SUMMARY

This study investigated the risk of dementia induced by overactive bladder (OAB) treatment in a large Korean cohort. Two representative OAB treatment drugs, anticholinergics and beta-3 agonists, both increased the risk of new-onset dementia. Clinicians should be cautious in using OAB treatment drugs since no drugs could be concluded as safe.

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.

KLİNİKTE ÖNEMLİ OLAN KATEKOLAMİN VE TÜREVLERİNİN YAPILARININ İNCELENMESİ

Amaç: Katekolaminler olarak adlandırılan monoamin yapısındaki 3,4-dihidroksifeniletilamin türevi dopamin, epinefrin ve norepinefrin, çok önemli biyolojik rolleri olan endojen bileşiklerdir. Katekol yapısı taşıyan bu biyomoleküllerin, kendine özgü reseptörleri uyararak, organizmadaki pek çok sistemi kontrol ettiği bilinmektedir. Özellikle bu endojen bileşiklerin, adrenerjik ve dopaminerjik sistem üzerinden uyarıcı etkilerinin olduğu görülmektedir. Pek çok biyolojik süreçte hormon veya nörotransmitter olarak yer alan bu bileşikler, terapötik önemleri nedeniyle sentetik olarak da elde edilerek klinikte kullanılmaktadır. Ayrıca, endojen katekolaminlerin farmakolojik ve farmasötik özelliklerini iyileştirmek amacıyla, kimyasal modifikasyonlar ile yeni pek çok türevi geliştirilmiştir. Klinikteki kullanımlarının geniş ve önemli olması, bu bileşikleri araştırmacılar için değerli kılmaktadır. Katekolamin ve türevi bileşiklerin aktivitelerinin incelenmesi kadar kimyasal yapılarının anlaşılması ve sentez yöntemlerinin araştırılması da yeni türevlerin geliştirilmesi açısından çok önemlidir. Sonuç ve Tartışma: Bu nedenle bu çalışmada klinik önemleri olan katekolamin türevlerinin yapıları ve özellikleri araştırılmıştır. Çalışma sonucunda katekolaminlerin kimyasal özellikleri, biyosentezleri ve sentetik olarak elde edilme yöntemleri ile biyolojik aktiviteleri ve klinikteki kullanımları ortaya konulmuştur.

Therapeutic Potential for Beta-3 Adrenoreceptor Agonists in Peripheral Arterial Disease and Diabetic Foot Ulcers

Annually, peripheral arterial disease is estimated to cost over USD 21 billion and diabetic foot disease an estimated at USD 9-13 billion. Mirabegron is a TGA-approved beta-3 adrenoreceptor agonist, shown to be safe and effective in the treatment of overactive bladder syndrome by stimulating bladder smooth muscle relaxation. In this review, we discuss the potential use of beta-3 adrenoreceptor agonists as therapeutic agents repurposed for peripheral arterial disease and diabetic foot ulcers. The development of both conditions is underpinned by the upregulation of oxidative stress pathways and consequential inflammation and hypoxia. In oxidative stress, there is an imbalance of reactive oxygen species and nitric oxide. Endothelial nitric oxide synthase becomes uncoupled in disease states, producing superoxide and worsening oxidative stress. Agonist stimulation of the beta-3 adrenoreceptor recouples and activates endothelial nitric oxide synthase, increasing the production of nitric oxide. This reduces circulating reactive oxygen species, thus decreasing redox modification and dysregulation of cellular proteins, causing downstream smooth muscle relaxation, improved endothelial function and increased angiogenesis. These mechanisms lead to endothelial repair in peripheral arterial disease and an enhanced perfusion in hypoxic tissue, which will likely improve the healing of chronic ulcers.

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.

Repurposing the β3-Adrenergic Receptor Agonist Mirabegron in Patients With Structural Cardiac Disease: The Beta3-LVH Phase 2b Randomized Clinical Trial

Importance

Left ventricular (LV) hypertrophy contributes to the onset and progression of heart failure (HF), particularly for patients with pre-HF (stage B) for whom no treatment has yet proven effective to prevent transition to overt HF (stage C). The β3-adrenergic receptors (β3ARs) may represent a new target, as their activation attenuates LV remodeling.

Objective

To determine whether activation of β3ARs by repurposing a β3AR agonist, mirabegron, is safe and effective in preventing progression of LV hypertrophy and diastolic dysfunction among patients with pre- or mild HF.

Design, Setting, and Participants

The Beta3-LVH prospective, triple-blind, placebo-controlled phase 2b randomized clinical trial enrolled patients between September 12, 2016, and February 26, 2021, with a follow-up of 12 months. The trial was conducted at 10 academic hospitals in 8 countries across Europe (Germany, Poland, France, Belgium, Italy, Portugal, Greece, and the UK). Patients aged 18 years or older with or without HF symptoms (maximum New York Heart Association class II) were screened for the presence of LV hypertrophy (increased LV mass index [LVMI] of ≥95 g/m2 for women or ≥115 g/m2 for men) or maximum wall thickness of 13 mm or greater using echocardiography. Data analysis was performed in August 2022.

Intervention

Participants were randomly assigned (1:1) to mirabegron (50 mg/d) or placebo, stratified by the presence of atrial fibrillation and/or type 2 diabetes, for 12 months.

Main Outcomes and Measures

The primary end points were LVMI determined using cardiac magnetic resonance imaging and LV diastolic function (early diastolic tissue Doppler velocity [E/e'] ratio assessed using Doppler echocardiography) at 12 months. Patients with at least 1 valid measurement of either primary end point were included in the primary analysis. Safety was assessed for all patients who received at least 1 dose of study medication.

Results

Of the 380 patients screened, 296 were enrolled in the trial. There were 147 patients randomized to mirabegron (116 men [79%]; mean [SD] age, 64.0 [10.2] years) and 149 to placebo (112 men [75%]; mean [SD] age, 62.2 [10.9] years). All patients were included in the primary intention-to-treat analysis. At 12 months, the baseline and covariate-adjusted differences between groups included a 1.3-g/m2 increase in LVMI (95% CI, -0.15 to 2.74; P = .08) and a -0.15 decrease in E/e' (95% CI, -0.69 to 0.4; P = .60). A total of 213 adverse events (AEs) occurred in 82 mirabegron-treated patients (including 31 serious AEs in 19 patients) and 215 AEs occurred in 88 placebo-treated patients (including 30 serious AEs in 22 patients). No deaths occurred during the trial.

Conclusions

In this study, mirabegron therapy had a neutral effect on LV mass or diastolic function over 12 months among patients who had structural heart disease with no or mild HF symptoms.

Trial Registration

ClinicalTrials.gov Identifier: NCT02599480.

Vibegron shows high selectivity and potent agonist activity for β3-adrenoceptors, irrespective of receptor density

β3-Adrenoceptor (AR) agonists are used to treat patients with an overactive bladder (OAB). Clinical proof-of-concept data have been obtained for the β3-AR agonists vibegron, mirabegron, solabegron, and ritobegron; however, the selectivities of these agents have not been compared directly under the same experimental conditions. Moreover, the bladders of some patients express lower β3-AR densities than those of healthy individuals, and the β3-AR density might be expected to affect agonist activity. This study assessed the β3-AR selectivities of four β3-AR agonists and examined the effects of β-AR density on their pharmacological profiles. Functional cellular assays were performed using Chinese hamster ovary-K1 cells expressing three human β-AR subtypes transfected with different amounts of plasmid DNA (0.1, 0.05, 0.025 μg/well). The half-maximal effective concentration values, intrinsic activities (IAs), and β3-AR selectivities of vibegron, mirabegron, solabegron, and ritobegron were calculated to assess their pharmacological profiles. The β3-AR selectivities of vibegron, mirabegron, solabegron, and ritobegron were >7937-, 517-, 21.3-, and >124-fold higher than for β1-ARs, and >7937-, 496-, >362- and 28.1-fold higher than for β2-ARs, respectively, under the same experimental conditions. The IAs of mirabegron, solabegron, and ritobegron decreased in line with decreasing receptor density, while the IA of vibegron was maintained at the same level as that of the full agonist isoproterenol at various β3-AR densities. Vibegron has high β3-AR selectivity and exhibits full agonist activity, regardless of the β3-AR density. These results suggest that vibegron is a highly effective and safe drug for treating OAB.

Clinical pharmacology of β-3 adrenergic receptor agonists for cardiovascular diseases

INTRODUCTION

Few agonists of the third isotype of beta-adrenergic receptors, the β3-adrenoreceptor, are currently used clinically, and new agonists are under development for the treatment of overactive bladder disease. As the receptor is expressed in human cardiac and vascular tissues, it is important to understand their beneficial (or adverse) effect(s) on these targets.

AREAS COVERED

We discuss the most recent results of clinical trials testing the benefit and safety of β3-adrenoreceptor activation on cardiovascular outcomes in light of current knowledge on the receptor biology, genetic polymorphisms, and agonist pharmacology.

EXPERT OPINION

While evidence from small clinical trials is limited so far, the β3-agonist, mirabegron seems to be safe in patients at high cardiovascular risk but produces benefits on selected cardiovascular outcomes only at higher than standard doses. Activation of cardiovascular β3-adrenoreceptors deserves to be tested with more potent agonists, such as vibegron.

Treating and Managing Urinary Incontinence: Evolving and Potential Multicomponent Medical and Lifestyle Interventions

Incontinence is defined by either ICS 2002 or IUGA/ICS 2010 as the involuntary loss of urine and includes urgency urinary incontinence (UUI), stress urinary incontinence (SUI) or mixed urinary incontinence (MUI). It has a high worldwide prevalence with an associated impact on quality of life. Despite existing management options for the management of urinary incontinence, patients continue to be troubled by symptoms or side effects of existing treatment. There is therefore a requirement for ongoing research into treatment options for the management of UUI and SUI, that are more effective and tolerable to patients. Advances in treatment of UUI include a more selective beta 3 agonist, Vibegron, which has less impact on cardiac function than Mirabegron. Hormonal treatment, including Ospemifene and Prasterone, may improve GSM and in turn symptoms of UUI. There are advances in the types of neuromodulators available, including those that are rechargeable at home and are MRI safe. Laser has shown promising initial results. There is developing interest in the microbiome, and how this may impact future treatment modalities. Advances in treatment of SUI include the use of mobile health applications to support delivery of pelvic floor muscle training. Litoxetine, a selective serotonin reuptake inhibitor, has shown promising results at phase III trials. Functional magnetic stimulation is being developed to improve contractility of pelvic floor muscles. We also discuss interventions that improve tissue elasticity and regeneration, such as platelet rich plasma, autologous stem cell transplantation, laser therapy and radiofrequency treatment, which show short term benefits.

Mirabegron is better tolerated than solifenacin in Sjogren's syndrome patients with overactive bladder symptoms-A randomized controlled trial

OBJECTIVES

This study investigates the efficacy and adverse events of beta-3 agonists and antimuscarinic agents for managing overactive bladder syndrome in Sjogren syndrome.

METHODS

Sjogren's syndrome patients with an Overactive Bladder Symptom Score (OABSS) >5 were enrolled and were randomly assigned to mirabegron 50 mg/day or solifenacin 5 mg/day. Patients were evaluated on the recruitment day and reassessed at Week 1, 2, 4, and 12. The study's primary endpoint was to have a significant change in OABSS at Week 12. The secondary endpoint was the adverse event and crossover rate.

RESULTS

A total of 41 patients were included in the final analysis, with 24 in the mirabegron group and 17 in the solifenacin group. The study's primary outcome was a change of the OABSS at Week 12. We found that both mirabegron and solifenacin significantly reduce patients' OABSS after 12 weeks of treatment. The evolution of the OABSS was -3.08 for mirabegron and -3.71 for solifenacin (p = .56). Six out of 17 patients from the solifenacin group crossed over to the mirabegron arm due to severe dry mouth or constipation, while none from the mirabegron arm crossed over to the solifenacin group. Sjogren's syndrome-related pain was also improved in the mirabegron group (4.96-1.67, p = .008) compared to the solifenacin group (4.39-3.4, p = .49).

CONCLUSIONS

Our study showed that mirabegron is equally effective as solifenacin in treating Sjogren's syndrome patients with overactive bladder. Mirabegron is superior to solifenacin in terms of treatment-related adverse events.

Comment on: Pharmacist-driven interventions to de-escalate urinary antimuscarinics in the Programs of All-Inclusive Care for the Elderly

See the Reply by David Bankes and Jacques Turgeon.

Treating Lower Urinary Tract Symptoms in Older Adults: Intravesical Options

This article provides an overview of the diagnosis and the treatment of lower urinary tract symptoms in older adults complicated by the neurodegenerative changes in the micturition reflex and further confounded by age-related decline in hepatic and renal clearance raising the propensity of adverse drug reactions. The first-line drug treatment for lower urinary tract symptoms, orally administered antimuscarinics, fails to reach the equilibrium dissociation constant of muscarinic receptors even at their maximum plasma concentration and tends to evoke a half-maximal response at a muscarinic receptor occupancy of just 0.206% in the bladder with a minimal difference from exocrine glands, which raises the adverse drug reaction risk. On the contrary, intravesical antimuscarinics are instilled at concentrations 1000-fold higher than the oral maximum plasma concentration and the equilibrium dissociation constant erects a downhill concentration gradient that drives passive diffusion and achieves a mucosal concentration around ten-fold lower than the instilled concentration for a long-lasting occupation of muscarinic receptors in mucosa and sensory nerves. A high local concentration of antimuscarinics in the bladder triggers alternative mechanisms of action and is supposed to engage retrograde transport to nerve cell bodies for neuroplastic changes that underlie a long-lasting therapeutic effect, while an intrinsically lower systemic uptake of the intravesical route lowers the muscarinic receptor occupancy of exocrine glands to lower the adverse drug reaction relative to the oral route. Thus, the traditional pharmacokinetics and pharmacodynamics of oral treatment are upended by intravesical antimuscarinics to generate a dramatic improvement (~ 76%) noted in a meta-analysis of studies enrolling children with neurogenic lower urinary tract symptoms on the primary endpoint of maximum cystometric bladder capacity as well as the secondary endpoints of filling compliance and uninhibited detrusor contractions. The therapeutic success of intravesical multidose oxybutynin solution or oxybutynin entrapped in the polymer for sustained release in the pediatric population bodes well for patients with lower urinary tract symptoms at the other extreme of the age spectrum. Though generally used to predict oral drug absorption, Lipinski's rule of five can also explain the ten-fold lower systemic uptake from the bladder of positively charged trospium over oxybutynin, a tertiary amine. Chemodenervation by an intradetrusor injection of onabotulinumtoxinA is merited for patients with idiopathic overactive bladder discontinuing oral treatment because of a lack of efficacy. However, age-related peripheral neurodegeneration potentiates the adverse drug reaction risk of urinary retention that motivates the quest of liquid instillation, delivering larger fraction of onabotulinumtoxinA to the mucosa as opposed to muscle by an intradetrusor injection can also probe the neurogenic and myogenic predominance of idiopathic overactive bladder. Overall, the treatment paradigm of lower urinary tract symptoms in older adults should be tailored to individual's overall health status and the risk tolerance for adverse drug reactions.

The β3 adrenoceptor in proliferative retinopathies: "Cinderella" steps out of its family shadow

In the retina, hypoxic condition leads to overgrowing leaky vessels resulting in altered metabolic supply that may cause impaired visual function. Hypoxia-inducible factor-1 (HIF-1) is a central regulator of the retinal response to hypoxia by activating the transcription of numerous target genes, including vascular endothelium growth factor, which acts as a major player in retinal angiogenesis. In the present review, oxygen urge by the retina and its oxygen sensing systems including HIF-1 are discussed in respect to the role of the beta-adrenergic receptors (β-ARs) and their pharmacologic manipulation in the vascular response to hypoxia. In the β-AR family, β1- and β2-AR have long been attracting attention because their pharmacology is intensely used for human health, while β3-AR, the third and last cloned receptor is no longer increasingly emerging as an attractive target for drug discovery. Here, β3-AR, a main character in several organs including the heart, the adipose tissue and the urinary bladder, but so far a supporting actor in the retina, has been thoroughly examined in respect to its function in retinal response to hypoxia. In particular, its oxygen dependence has been taken as a key indicator of β3-AR involvement in HIF-1-mediated responses to oxygen. Hence, the possibility of β3-AR transcription by HIF-1 has been discussed from early circumstantial evidence to the recent demonstration that β3-AR acts as a novel HIF-1 target gene by playing like a putative intermediary between oxygen levels and retinal vessel proliferation. Thus, targeting β3-AR may implement the therapeutic armamentarium against neovascular pathologies of the eye.

Comparison of Mirabegron and Vibegron in Women With Treatment-Naive Overactive Bladder: A Randomized Controlled Study

OBJECTIVE

To compare the efficacy and safety of mirabegron versus vibegron in postmenopausal women with treatment-naïve overactive bladder (OAB).

METHODS

We conducted a prospective randomized controlled study of women with treatment-naïve OAB. The patients received mirabegron or vibegron at 50 mg daily for 12 weeks by a stratified randomized method. The OAB symptom score (OABSS) and quality of life (QOL) index were evaluated before and 4 and 12 weeks after the treatment. The patients' 3-day voiding diary and postvoided residual urine volumes were evaluated before and 12 weeks after the treatment.

RESULTS

Of 213 patients initially enrolled in this study, 199 patients were randomized to the mirabegron group (n = 97) or vibegron group (n = 102). Twelve weeks after the treatment, OABSS, QOL index, the numbers of micturition, urgency episodes, incontinence episodes, and voided volume per 24 hours were significantly improved compared with the baseline in both groups, and there was no significant difference in the rate of change in both groups. The postvoid residual urine volume was not significantly different in the 2 groups at 12 weeks. Discontinuation because of adverse effects was observed in 6.2% of patients in the mirabegron group and 6.8% in the vibegron group, with no significant difference between 2 groups.

CONCLUSION

Both mirabegron at 50 mg and vibegron at 50 mg improved OAB symptoms and the parameters of voiding diary equally in postmenopausal women with treatment naïve OAB.

β3 adrenoceptor agonist mirabegron protects against right ventricular remodeling and drives Drp1 inhibition

Background

The right ventricular (RV) function determines the prognosis of patients with pulmonary hypertension (PH). Metabolic disorders have been observed in the RV myocardium in PH. Activation of the β3 adrenoceptor improves cardiac function and restores cardiac metabolic efficiency in rodents with heart failure; however, its role in the RV remains uncertain.

Methods

Experimental PH was induced by monocrotaline (MCT) in rats. Mirabegron, a selective β3 adrenoceptor agonist, was given to MCT rats daily from the day after MCT injection at the dose of 10 mg/kg. In vivo echocardiography and RV catheterization were performed to assess RV hemodynamics, structure, and function. RV fibrosis and hypertrophy were assessed by Sirius Red (SR) and wheat germ agglutinin (WGA) staining respectively. Western blotting was performed to examine the markers of RV fibrosis and hypertrophy, as well as the levels of the key molecules and their phosphorylated forms. The molecular changes were confirmed in the cardiac hypertrophy model of angiotensin II (Ang II) treated H9c2 cardiomyocytes using western blotting.

Results

The overloaded RV had increased β3 adrenoceptor expression, which was further increased by mirabegron. Mirabegron reduced RV pressure and reduced RV structural and functional deterioration in MCT rats. Mirabegron decreased cardiac fibrosis and hypertrophy in the overloaded RV. Mirabegron suppressed dynaminrelated protein 1 (Drp1) and promoted AMP-activated protein kinase (AMPK) signaling in the overloaded RV and Ang II treated cardiomyocytes.

Conclusions

The β3 adrenoceptor agonist mirabegron reduced RV hypertrophy and fibrosis in PH rats. The treatment effect involved Drp1 inhibition and AMPK activation.

Long-term efficacy and safety of vibegron versus mirabegron and anticholinergics for overactive bladder: a systematic review and network meta-analysis

Background

Few randomized controlled trials evaluate the long-term efficacy and safety of pharmacotherapy for overactive bladder (OAB). This network meta- analysis compares the long-term (52-week) efficacy and safety of vibegron, mirabegron and anticholinergics for the treatment of OAB.

Methods

A systematic literature review and network meta-analysis were conducted following PRISMA guidelines using MEDLINE, Embase and Cochrane Central Register of Controlled Trials and terms related to OAB. Efficacy outcomes included change from baseline to week 48-52 in mean daily total urinary incontinence (UI) episodes, mean daily number of micturitions and volume voided/micturition. Efficacy outcomes were analysed using Bayesian models. Commonly reported adverse events (AEs) are described.

Results

Of 2098 hits retrieved, 5 publications and 1 study report describing 5 unique randomized controlled trials were included in the analyses. Mean (95% credible interval) change from baseline in total UI episodes for vibegron 75 mg (-2.2; -2.9 to -1.5) showed a significantly greater reduction than mirabegron 50 mg (-1.3; -1.9 to -0.8) and tolterodine 4 mg extended release (-1.6; -2.1 to -1.1). No significant differences were observed between vibegron and comparators for daily micturitions or volume voided/micturition. Within the manuscripts, the 4 most common AEs (range) for anticholinergics included dry mouth (5.2-90.0%), constipation (7.7-65.0%), blurred vision (3.8-35.0%) and hypertension (8.6-9.6%); the 4 most commonly reported AEs for β3-adrenergic agonists included hypertension (8.8-9.2%), urinary tract infection (5.9-6.6%), headache (5.5%) and nasopharyngitis (4.8-5.2%).

Conclusion

Vibegron was associated with significantly greater improvement in daily total UI episodes at 52 weeks than mirabegron and tolterodine. When reported, the most common AE for anticholinergics was dry mouth and for β3-adrenergic agonists was hypertension. Hypertension incidence was similar between drug classes.