Safety and efficacy of an α1 -blocker plus mirabegron compared with an α1 -blocker plus antimuscarinic in men with lower urinary tract symptoms secondary to benign prostatic hyperplasia and overactive bladder: A systematic review and network meta-analysis

AIM

Antimuscarinics and the β3-adrenoreceptor agonist, mirabegron, are commonly used for treating patients with overactive bladder (OAB) and α1 -adrenoreceptor antagonists (α1 -blockers) are the main pharmacological agents used for treating lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). As these conditions commonly occur together, the aim of this systematic review was to identify publications that compared the use of an α1 -blocker plus mirabegron with an α1 -blocker plus antimuscarinic in men with LUTS secondary to BPH and OAB. A meta-analysis was subsequently conducted to explore the safety and efficacy of these combinations.

METHODS

Included records had to be from a parallel-group, randomized clinical trial that was ≥8 weeks in duration. Participants were male with LUTS secondary to BPH and OAB. The indirect analyses that were identified compared an α1 -blocker plus OAB agent with an α1 -blocker plus placebo. The PubMed/Medical Literature Analysis and Retrieval System Online, the Excerpta Medica Database, the Cochrane Central Register of Controlled Trials, and the ClinicalTrials.gov registry were searched for relevant records up until March 5, 2020. Safety outcomes included incidences of overall treatment-emergent adverse events (TEAEs) and urinary retention, postvoid residual volume, and maximum urinary flow (Qmax ). Primary efficacy outcomes were micturitions/day, incontinence episodes/day, and urgency episodes/day, and secondary outcomes were Overactive Bladder Symptom Score and International Prostate Symptom Score. A Bayesian network meta-analysis approach was used for the meta-analysis.

RESULTS

Out of a total of 1039 records identified, 24 were eligible for inclusion in the meta-analysis. There were no statistically significant differences between the α1 -blocker plus mirabegron and α1 -blocker plus antimuscarinic groups in terms of the comparisons identified for all the safety and efficacy analyses conducted. Numerically superior results were frequently observed for the α1 -blocker plus mirabegron group compared with the α1 -blocker plus antimuscarinic group for the safety parameters, including TEAEs, urinary retention, and Qmax . For some of the efficacy parameters, most notably micturitions/day, numerically superior results were noted for the α1 -blocker plus antimuscarinic group. Inconsistency in reporting and study variability were noted in the included records, which hindered data interpretation.

CONCLUSION

This systematic review and meta-analysis showed that an α1 -blocker plus mirabegron and an α1 -blocker plus antimuscarinic have similar safety and efficacy profiles in male patients with LUTS secondary to BPH and OAB. Patients may, therefore, benefit from the use of either combination within the clinical setting.

Patient and Clinician Challenges with Anticholinergic Step Therapy in the Treatment of Overactive Bladder: A Narrative Review

Anticholinergics have been used in the treatment of overactive bladder (OAB), but their use is limited by poor tolerability and anticholinergic-related side effects. Increasingly, providers are discontinuing anticholinergic prescribing because of growing evidence of the association of anticholinergic use with increased risk of cognitive decline and other adverse effects. Newer medications for OAB, the β3-adrenergic receptor agonists mirabegron and vibegron, do not have anticholinergic properties and are typically well tolerated; however, many insurance plans have limited patient access to these newer OAB medications by requiring step therapy, meaning less expensive anticholinergic medications must be trialed and/or failed before a β3-agonist will be covered and dispensed. Thus, many patients are unable to easily access these medications. Step therapy and other drug utilization strategies (e.g., prior authorization) are often used to manage the growing costs of pharmaceuticals, but these policies do not always follow treatment guidelines and may harm patients as a result of treatment delays, discontinuations, or related increases in adverse events. Medical professionals have called for reform of drug utilization strategies through partnerships that include clinicians and policymakers. This narrative review discusses prescribing patterns for OAB treatment and the effect of switching between drugs, as well as the costs of step therapy and prior authorization on patients and prescribers.

Current optimal pharmacologic therapies for overactive bladder

INTRODUCTION

Overactive bladder (OAB) is a common syndrome in adults. Current pharmacologic treatment includes antimuscarinic agents and β-3 adrenoceptor agonists. For non-responders to oral medication, intravesical injection of botulinum toxin A (BoNT-A) is an effective option. However, these treatments have potential adverse events and should be cautiously selected for appropriate patients. This review presents the recently published results of clinical trials and studies for patients with OAB and the underlying pathophysiology of OAB. Appropriate medical therapy based on pathophysiology of OAB is also presented.

AREAS COVERED

Literature search from Pubmed from 2001 to 2023 including clinical background, pharmacology, and clinical studies for OAB medications.

EXPERT OPINION

Treatment of OAB syndrome with any antimuscarinic or β-3 adrenoceptor agonist is feasible as a first-line approach. For patients with suboptimal therapeutic effect to full-dose antimuscarinics or mirabegron, combination with both drugs can improve efficacy. Intravesical BoNT-A 100-U injection provides therapeutic effects for refractory OAB. Patients who are refractory to initial pharmacotherapies should be investigated for the underlying pathophysiology; then an appropriate medication can be added, such as an α1-blocker or anti-inflammatory agents. Patient education about behavioral modification and therapies should always be provided with oral medication or BoNT-A injection for OAB patients.

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.

Effect of Pharmacotherapy for Overactive Bladder on the Incidence of and Factors Related to Urinary Tract Infection: A Systematic Review and Meta-analysis

PURPOSE

The aim of this meta-analysis was to investigate the effect of pharmacotherapy for overactive bladder on the pathogenesis of urinary tract infection.

MATERIALS AND METHODS

A comprehensive search was performed in MEDLINE and the Cochrane Library using terms for overactive bladder, antimuscarinic agents, and beta 3-adrenoceptor agonists. The primary end point was the emergence of urinary tract infection after pharmacotherapy for overactive bladder. The secondary end point was the emergence of urinary retention, dysuria, and/or increased residual urine volume after overactive bladder treatment. Meta-analyses were conducted using random-effects models.

RESULTS

A total of 35,939 patients in 33 trials (29 trials of antimuscarinic agents vs placebo, and 9 trials of beta 3-adrenoceptor agonists vs placebo) that included patients with overactive bladder were identified. At 1-3 months after treatment, the incidence of urinary tract infections was statistically significantly higher in the patients treated with antimuscarinic agents (RR: 1.23, 95% CI: 1.04, 1.45; P = .013) than in the placebo control group. The incidence of urinary tract infections was not increased in the patients treated with beta 3-adrenoceptor agonists (RR: 1.04, 95% CI: 0.76, 1.42; P = .796). Antimuscarinic agents also statistically significantly increased the risks of urinary retention, dysuria, and/or increased residual urine volume (RR: 2.88, 95% CI: 1.79, 4.63; P < .001), whereas beta 3-adrenoceptor agonists did not (RR: 1.26, 95% CI: 0.38, 4.14; P = .708).

CONCLUSIONS

This meta-analysis showed that antimuscarinic agents statistically significantly increased the incidences of urinary tract infection and lower urinary tract symptoms and dysfunction, but beta 3-adrenoceptor agonists did not. To prevent urinary tract infection emergence, beta 3-adrenoceptor agonists might be safer than antimuscarinic agents.

Cost-effectiveness of vibegron for the treatment of overactive bladder in the United States

AIMS

To evaluate the cost-effectiveness of vibegron compared with other oral pharmacologic therapies as treatment for overactive bladder (OAB).

METHODS

A semi-Markov model with monthly cycles was developed to support a lifetime horizon of vibegron 75 mg from a US commercial payor or Medicare perspective. The model incorporated efficacy (reductions in daily micturitions and urinary incontinence episodes), adverse events, OAB-related comorbidities, drug-drug interactions, anticholinergic burden, and treatment persistence. Direct costs and quality-adjusted life years (QALY) were accumulated over time. The primary outcome was the cost per QALY incremental cost-effectiveness ratio (ICER). One-way (OWSA) and probabilistic sensitivity analyses (PSA) were performed.

RESULTS

For commercial payors, vibegron was cost-effective at a willingness-to-pay (WTP) threshold of $50,000/QALY versus mirabegron 50 mg (ICER, $9,311) and at a WTP threshold of $150,000/QALY versus mirabegron 25 mg (ICER, $141,957) and versus an anticholinergic basket based on market share (ICER, $118,121). For Medicare, vibegron was cost-effective at a WTP threshold of $50,000/QALY versus mirabegron 50 mg (ICER, $12,154) and at a WTP threshold of $100,000/QALY versus mirabegron 25 mg (ICER, $99,150) and versus an anticholinergic market basket (ICER, $60,756). For commercial payors and Medicare, OWSAs for vibegron versus mirabegron indicated cost-effectiveness was most sensitive to vibegron persistence at 1 and 12 months. PSAs indicated that vibegron was cost-effective versus mirabegron 50 mg 98.6% and 100% of the time at $50,000/QALY for commercial payors and Medicare payors, respectively.

LIMITATIONS

Due to lack of real-world data available on persistence, vibegron was assumed to have the same persistence as mirabegron 50 mg. Long-term efficacy was assumed to be sustained beyond 52 weeks in the absence of clinical trials longer than 52 weeks.

CONCLUSIONS

Vibegron is cost-effective from a commercial payor (WTP threshold $150,000/QALY) and Medicare (WTP threshold $100,000/QALY) perspective when compared with other oral pharmacologic treatments for OAB.

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.

Monotherapy with mirabegron had a better tolerance than the anticholinergic agents on overactive bladder: A systematic review and meta-analysis

BACKGROUND

We conducted this meta-analysis to explore the tolerance of monotherapy with mirabegron (50 mg) on an overactive bladder, compared with a common dosage of anticholinergic agents.

MATERIALS AND METHODS

A comprehensive search for all randomized controlled trials that evaluated the safety of mirabegron and anticholinergic agents on overactive bladder was performed, and we searched the Cochrane Central Register of Controlled trials databases, Pubmed, Embase, and relevant trials from 2013.02 to 2019.10.

RESULTS

Eight studies included 5500 patients with treatment of monotherapy on overactive bladder were identified. The total number of treatment-emergent adverse events had no significantly difference between two monotherapies (RR = 0.88 95%CI: 0.76-1.01; P = .08); however, patients would have a better tolerance with mirabegron (50 mg) in adverse events of dry mouth (RR = 0.42; 95%CI: 0.33-0.53; P < .01) and tachycardia (RR = 0.52; 95%CI: 0.29-0.94; P = .03); and there were no significant differences between two groups in hypertension (RR = 1.02; 95%CI: 0.80-1.30; P = .90), constipation (RR = 0.91; 95%CI: 0.65-1.26; P = 0.57), blurred vision (RR = 1.03; 95%CI: 0.60-1.77; P = 0.92), and urinary tract infection (RR = 0.90; 95%CI: 0.70-1.16; P = .41).

CONCLUSIONS

Treatment-emergent adverse events in patients with overactive bladder who underwent monotherapy of mirabegron (50 mg) or the anticholinergic agents had no significant differences, but mirabegron has a better tolerance in the aspect of dry mouth and tachycardia.

Systematic review and meta-analysis of the efficacy and safety of vibegron vs antimuscarinic monotherapy for overactive bladder

BACKGROUND

Vibegron is a new β3-adrenergic receptor agonist which has been demonstrated for the treatment of overactive bladder (OAB). We carried out meta-analysis to evaluate the efficiency of vibegron vs antimuscarinic monotherapy for treating OAB.

METHODS

Randomized controlled trials (RCTs) of Vibegron vs antimuscarinic monotherapy for OAB were searched systematically by using EMBASE, MEDLINE, and the Cochrane Controlled Trials Register. The RevMan version 5.3.0. was used to analysis the data.

RESULTS

Three RCTs involving a total of 1751 patients were studied in the Systematic review and Meta-analysis. Efficacy end points: the mean number of micturitions episodes/d (P = .16); the mean number of urgency episodes/d (P = .05); mean number of urgency incontinence episodes/d (P = .11) and mean number of incontinence episodes/d (P = .14) indicated that vibegron and antimuscarinic had no significant differences in terms of OAB treatment. Mean volume voided/micturition showed a distinct difference in the two groups (P = .009). With regard to dry mouth and drug related treatment-emergent adverse event (TEAE), vibegron showed better tolerance than antimuscarinic. Serious adverse event (SAE) and discontinuations due to adverse event (AE) did not show a significant difference between the two groups.

CONCLUSIONS

The therapeutic effect of vibegron is similar to that of antimuscarinic, but vibegron does not increase the risk of AE.

Efficacy of newer medications for lower urinary tract symptoms attributed to benign prostatic hyperplasia: a systematic review

We conducted a systematic review to evaluate the efficacy and adverse effects of newer drugs used to treat lower urinary tract symptoms (LUTS). The drugs were either Food and Drug Administration (FDA) approved for benign prostatic hyperplasia (BPH) or not FDA approved for BPH but have been evaluated for treatment of BPH since 2008. We searched bibliographic databases through September 2017. We included randomized controlled trials (RCTs) lasting one month or longer published in English. Outcomes of interest were LUTS assessed by validated measures. Efficacy was interpreted using established thresholds indicating clinical significance that identified the minimal detectable difference. Twenty-three unique, generally short-term, RCTs evaluating over 9000 participants were identified. Alpha-blocker silodosin and phosphodiesterase type 5 inhibitor tadalafil were more effective than placebo in improving LUTS (moderate strength evidence) but these drugs had more adverse effects, including abnormal ejaculation (silodosin). Anticholinergics were only effective versus placebo when combined with an alpha-blocker. Evidence was generally low strength or insufficient for other drugs. Evidence was insufficient to assess long-term efficacy, prevention of symptom progression, need for surgical intervention, or long-term adverse effects. Longer trials are needed to assess the effect of these therapies on response rates using established minimal detectable difference thresholds, disease progression, and harms.

Cardiovascular safety in refractory incontinent patients with overactive bladder receiving add-on mirabegron therapy to solifenacin (BESIDE)

AIMS/OBJECTIVES

In the BESIDE study, combination therapy (antimuscarinic [solifenacin] and β₃ -adrenoceptor agonist [mirabegron]) improved efficacy over solifenacin monotherapy without exacerbating anticholinergic side effects in overactive bladder (OAB) patients; however, a potential synergistic effect on the cardiovascular (CV) system requires investigation.

METHODS

OAB patients remaining incontinent despite daily solifenacin 5 mg during 4-week single-blind run-in, were randomised 1:1:1 to double-blind daily combination (solifenacin 5 mg/mirabegron 25 mg, increasing to 50 mg after week 4), solifenacin 5 or 10 mg for 12 weeks. CV safety assessments included frequency of CV-related treatment-emergent adverse events (TEAEs), change from baseline in vital signs (systolic blood pressure [SBP], diastolic blood pressure [DBP], pulse rate) and electrocardiogram (ECG) parameters.

RESULTS

The frequency of hypertension, tachycardia and ECG QT prolongation, respectively, was low and comparable across combination (1.1%, 0.3%, 0.1%), solifenacin 5 mg (0.7%, 0.1%, 0.1%), and solifenacin 10 mg groups (0.8%, 0%, 0.1%). Adjusted mean (SE) change from baseline to end of treatment (EoT) in SBP, DBP, and pulse rate with combination (0.07 mm Hg [0.38], -0.35 mm Hg [0.26], 0.47 bpm [0.28]), solifenacin 5 mg (-0.93 mm Hg [0.38], -0.45 mm Hg [0.26], 0.43 bpm [0.28]) and solifenacin 10 mg (-1.28 mm Hg [0.38], -0.48 mm Hg [0.26], 0.27 bpm [0.28]) was generally comparable, with the exception of a mean treatment difference of ~1 mm Hg in SBP between combination and solifenacin monotherapy; SBP was unchanged with combination and decreased with solifenacin monotherapy. Mean changes from baseline to EoT in ECG parameters were generally similar across treatment groups, except for QT interval corrected using Fridericia's formula, which was higher with solifenacin 10 mg (3.30 mseconds) vs. combination (0.49 mseconds) and solifenacin 5 mg (0.77 mseconds).

CONCLUSION

The comparable frequency of CV-related TEAEs, changes in vital signs and ECG parameters indicates no synergistic effect on CV safety outcomes when mirabegron and solifenacin are combined.

Pharmacokinetic drug interaction study between overactive bladder drugs mirabegron and tolterodine in Japanese healthy postmenopausal females

Mirabegron, the first selective β₃-adrenoceptor agonist for the treatment of overactive bladder (OAB), inhibits cytochrome P450 isozyme CYP2D6. This study was performed in Japanese healthy postmenopausal female volunteers to assess any pharmacokinetic drug interaction between mirabegron and tolterodine, another OAB drug and a sensitive substrate of CYP2D6. Tolterodine 4 mg was orally administered from Days 1-7 and co-administered with mirabegron 50 mg from Days 8-14. Mirabegron 50 mg increased maximum concentration (C_max) and area under the concentration-time curve from zero to 24 h after dosing (AUC_24h) of tolterodine by 2.06-fold (90% confidence interval [CI] 1.81, 2.34) and 1.86-fold (90% CI 1.60, 2.16), respectively, and increased C_max and AUC_24h of the metabolite 5-hydroxymethyl tolterodine by 1.36-fold (90% CI 1.26, 1.47) and 1.25-fold (90% CI 1.15, 1.37), respectively. This suggested a weak pharmacokinetic drug interaction between mirabegron and tolterodine. Mean change from baseline of Fridericia's QT correction formula (ΔQTcF) was slightly higher on Day 14 than on Day 7. No subject had QTcF >480 msec or ΔQTcF >60 msec. All the treatment-emergent adverse events were mild. Mirabegron 50 mg was considered to be safe and well tolerated when coadministered with tolterodine 4 mg in healthy postmenopausal female volunteers.

mirabegron (BETMIGA⁰). Poorly effective in urge urinary incontinence

Mirabegron interacts with many other drugs via cytochrome P450 isoenzymes. It also has additive adverse effects, in particular cardiac disorders, when combined with antimuscarinic drugs. In view of animal data and the lack of clinical data, mirabegron should not be used by women who are or may be pregnant. In practice, drugs have little value in treating urinary urgency attributed to "overactive bladder". The risk of adverse drug reactions is rarely justified, even when the disorder is severe. Antimuscarinic disorders, such as dry mouth, are less frequent with mirabegron than with antimuscarinic drugs. Like antimuscarinic drugs, mirabegron can cause cardiac arrhythmias, especially tachycardia. Mirabegron may also cause a dose-dependent increase in blood pressure. Other adverse effects include rare cases of kidney stones and rare but sometimes serious skin reactions. When a treatable cause of urinary urgency with incontinence has been ruled out and non-drug measures have failed, recourse to an antimuscarinic drug is slightly effective but exposes patients to numerous, potentially severe adverse effects. Mirabegron (Betmiga⁰, Astellas Pharma), a beta-3 adrenergic receptor agonist, is authorised for use in this setting in the European Union. Clinical evaluation of mirabegron is mainly based on five randomised, double-blind trials versus antimuscarinic drugs, lasting 3 to 12 months and including about 8000 patients with urinary urgency. Mirabegron and the antimuscarinic comparators were similarly effective, even after antimuscarinic drug failure. A meta-analysis of four placebo-controlled trials including about 3500 patients suggested that mirabegron was poorly effective: on average, treatment prevented one episode of urinary incontinence every 2 days.

Cost-Effectiveness of Mirabegron Compared with Antimuscarinic Agents for the Treatment of Adults with Overactive Bladder in the United Kingdom

BACKGROUND

Mirabegron, a first-in-class selective oral β3-adrenoceptor agonist, has similar efficacy to most antimuscarinic agents and a lower incidence of dry mouth in patients with overactive bladder (OAB).

OBJECTIVES

To evaluate the cost-effectiveness of mirabegron 50 mg compared with oral antimuscarinic agents in adults with OAB from a UK National Health Service perspective.

METHODS

A Markov model including health states for symptom severity, treatment status, and adverse events was developed. Cycle length was 1 month, and the time horizon was 5 years. Antimuscarinic comparators were tolterodine extended release, solifenacin, fesoterodine, oxybutynin extended release and immediate release (IR), darifenacin, and trospium chloride modified release. Transition probabilities for symptom severity levels and adverse events were estimated from a mirabegron trial and a mixed treatment comparison. Estimates for other inputs were obtained from published literature or expert opinion. Quality-adjusted life-years (QALYs) and total health care costs, including costs of drug acquisition, physician visits, incontinence pad use, and botox injections, were modeled. Deterministic and probabilistic sensitivity analyses were performed.

RESULTS

Base-case incremental cost-effectiveness ratios ranged from £367 (vs. solifenacin 10 mg) to £15,593 (vs. oxybutynin IR 10 mg) per QALY gained. Probabilistic sensitivity analyses showed that at a willingness-to-pay threshold of £20,000/QALY gained, the probability of mirabegron 50 mg being cost-effective ranged from 70.2% versus oxybutynin IR 10 mg to 97.8% versus darifenacin 15 mg. A limitation of our analysis is the uncertainty due to the lack of direct comparisons of mirabegron with other agents; a mixed treatment comparison using rigorous methodology provided the data for the analysis, but the studies involved showed heterogeneity.

CONCLUSIONS

Mirabegron 50 mg appears to be cost-effective compared with standard oral antimuscarinic agents for the treatment of adults with OAB from a UK National Health Service perspective.

The efficacy and tolerability of the β3-adrenoceptor agonist mirabegron for the treatment of symptoms of overactive bladder in older patients

INTRODUCTION

mirabegron is a β3-adrenoceptor agonist developed for the treatment of symptoms of overactive bladder (OAB). As the prevalence of OAB increases with age, a prospective subanalysis of individual and pooled efficacy and tolerability data from three 12-week, randomised, Phase III trials, and of tolerability data from a 1-year safety trial were conducted in order to evaluate the efficacy and tolerability of mirabegron in subgroups of patients aged ≥65 and ≥75 years.

METHODS

primary efficacy outcomes were change from baseline to final visit in the mean number of incontinence episodes/24 h and the mean number of micturitions/24 h. Tolerability was assessed by the incidence of treatment-emergent adverse events (TEAEs).

RESULTS

over 12 weeks mirabegron 25 mg and 50 mg once-daily reduced the mean numbers of incontinence episodes and micturitions/24 h from baseline to final visit in patients aged ≥65 and ≥75 years. Mirabegron was well tolerated: in both age groups, hypertension and urinary tract infection were among the most common TEAEs over 12 weeks and 1 year. The incidence of dry mouth, a typical anticholinergic TEAE, was up to sixfold higher among the older patients randomised to tolterodine than any dose of mirabegron.

CONCLUSIONS

these analyses have demonstrated the efficacy of mirabegron over 12 weeks and the tolerability of mirabegron over 12 weeks and 1 year in OAB patients aged ≥65 and ≥75 years, supporting mirabegron as a therapeutic option in older patients with OAB.

β3-Adrenoceptor agonist mirabegron is effective for overactive bladder that is unresponsive to antimuscarinic treatment or is related to benign prostatic hyperplasia in men

PURPOSE

To investigate the safety and efficacy of mirabegron for patients with overactive bladder (OAB) that is unresponsive to antimuscarinic agents or is related to benign prostatic hyperplasia (BPH).

METHODS

Fifty-two newly diagnosed OAB patients (M group) and 45 patients with OAB that was unresponsive to antimuscarinics (S group) received mirabegron 50 mg once daily and were evaluated by OAB symptom score (OABSS), IPSS-QOL index, and IPSS at the time of baseline, 4 and 8 weeks. Newly diagnosed OAB patients treated with antimuscarinic agents were compared as controls.

RESULTS

Mirabegron was effective for 85.2 % in M group. Significant improvements were seen in each domain of OABSS, and there was no significant difference with antimuscarinic therapy. Mirabegron was efficacious for 61.6 % of S group, and significant decreases of OABSS and IPSS-QOL index were observed. Significant improvements were also seen in voiding symptoms in men. Post-void residual urine volumes before and after treatment were 32.1 and 34.8 ml, and 26.2 and 31.3 ml in M and S group, respectively, and there was no significant difference. The incidence of adverse events was 8.4 %, although none were serious, and the patients recovered spontaneously after mirabegron was discontinued.

CONCLUSION

The present study suggests mirabegron is as effective as antimuscarinics for OAB. It improves OAB symptoms in patients with OAB for which antimuscarinic agents are insufficient. This study revealed that mirabegron improves not only OAB symptoms related to BPH, but also voiding symptoms in men. Low and mild incidences of side effects support the safe utility of mirabegron.

Mirabegron, a β₃-adrenoceptor agonist for the potential treatment of urinary frequency, urinary incontinence or urgency associated with overactive bladder

Mirabegron (YM-178), currently in development by Astellas Pharma Inc, is an orally active β₃-adrenoceptor (AR) agonist for the potential symptomatic treatment of overactive bladder (OAB). Mirabegron demonstrates nanomolar EC50 values against the human β₃-AR in biochemical assays with potent selectivity over the β₁- and β₂-ARs. Originally developed as a treatment for diabetes, the development of mirabegron was later refocused to OAB. Cystometric experiments in rats reported a reduction in resting intravesical pressure and contraction frequency in anesthetized rats, without any effect on the amplitude of micturition contraction. Mirabegron also reduced non-micturition bladder contractions in an awake rat model of bladder outlet obstruction. Top-line results from clinical trials to date indicate that mirabegron has been well tolerated with significant efficacy in reducing the number of incontinence episodes and mean micturition frequency in patients. Evidence of cytochrome P450 (CYP)2D6 inhibition in clinical trials highlighted a concern for pharmacokinetic interaction with other drugs that are CYP2D6 substrates, as confirmed by a rise in the pharmacokinetic parameters of desipramine with concomitant administration of mirabegron. Mirabegron exhibits a novel mode of action in targeting the β₃-AR for bladder relaxation, and the studies and trials conducted to date suggest mirabegron as a promising new treatment in the management of OAB symptoms, such as increased urinary urgency and frequency, and urgency incontinence.