Perspectives on mirabegron in the treatment of overactive bladder syndrome: A new beta-3 adrenoceptor agonist

Contemporary use of prescription medications for neurogenic lower urinary tract dysfunction

OBJECTIVES

First-line treatment for patients with neurogenic detrusor overactivity (NDO) is anticholinergic or beta-3 agonist medication. The addition of a secondary medication in patients with NDO may avoid progression to third- and fourth-line therapies. We aim to identify patterns of medication use for patients with neurogenic lower urinary tract dysfunction (NLUTD) using a national database.

METHODS

The National Ambulatory Medical Care Survey (NAMCS) database was queried for a sample of ambulatory patient visits from 2003 to 2015. Outpatient visits were included for all patients aged 18 years or older diagnosed with NLUTD. Dual therapy was defined as prescription of two anticholinergics or one anticholinergic + beta-3 agonist on the same visit. Visits in which medications were prescribed were analyzed with descriptive statistics.

RESULTS

Out of a weighted sample of 5 391 680 patient visits with a primary diagnosis of NLUTD, 1 602 705 (30%) were prescribed medical therapy. Of included patients prescribed NDO medications, the majority were white (80%), located in the Northeast (71%), and of a mean age of 51 ± 3. Of these patients, at least 93% of patients were prescribed anticholinergics, and 37% were prescribed dual therapy. Patients 65 years and older were more likely to initiate a new NDO medication at their visit (43%) than patients under 65 (7%).

CONCLUSIONS

This is the first study to analyze the use of medical therapy for NLUTD in a large outpatient setting. Further prospective evaluation of patient satisfaction and efficacy of both single anticholinergic medication and dual therapy is needed.

β3-Adrenoceptor agonists inhibit purinergic receptor-mediated contractions of the murine detrusor

β₃-Adrenoceptor (β₃-AR) agonists are used to treat overactive bladder syndrome; however, their mechanism of action has not been determined. The aims of this study were to compare the effects of β₃-AR agonists on cholinergic versus purinergic receptor-mediated contractions of the detrusor and to examine the mechanisms underlying inhibition of the purinergic responses by β₃-AR agonists. Isometric tension recordings were made from strips of murine detrusor and whole cell current recordings were made from freshly isolated detrusor myocytes using the patch-clamp technique. Transcriptional expression of exchange protein directly activated by cAMP (EPAC) subtypes in detrusor strips was assessed using RT-PCR and real-time quantitative PCR. The β₃-AR agonists BRL37344 and CL316243 (100 nM) inhibited cholinergic nerve-mediated contractions of the detrusor by 19 and 23%, respectively, but did not reduce contractions induced by the cholinergic agonist carbachol (300 nM). In contrast, BRL37344 and CL316243 inhibited purinergic nerve-mediated responses by 55 and 56%, respectively, and decreased the amplitude of contractions induced by the P2X receptor agonist α,β-methylene ATP by 40 and 45%, respectively. The adenylate cyclase activator forskolin inhibited purinergic responses, and these effects were mimicked by a combination of the PKA activator N⁶-monobutyryl-cAMP and the EPAC activator 8-pCPT-2'-O-methyl-cAMP-AM (007-AM). Application of ATP (1 μM) evoked reproducible P2X currents in isolated detrusor myocytes voltage-clamped at -60 mV. These responses were reduced in amplitude in the presence of BRL37344 and also by 007-AM. This study demonstrates that β₃-AR agonists reduce postjunctional purinergic responses in the detrusor via a pathway involving activation of the cAMP effector EPAC.

Mirabegron 25 mg Monotherapy Is Safe but Less Effective in Male Patients With Overactive Bladder and Bladder Outlet Obstruction

OBJECTIVE

To compare the therapeutic efficacy and safety of mirabegron monotherapy in male patients with overactive bladder (OAB) with and without bladder outlet obstruction (BOO).

MATERIALS AND METHODS

Male patients with OAB aged ≥20 years, with or without BOO, receiving mirabegron 25 mg monotherapy once daily, were prospectively enrolled. The treatment results were assessed using global response assessment, international prostate symptom score and subscores, overactive bladder symptom score, patient perception on intensity of urgency scale, patient perception of bladder condition, and quality of life index at 1 and 3 months after treatment.

RESULTS

Of the 289 enrolled patients (mean age, 71.2 years), 207 did not have BOO (71.6%) and 82 had BOO (28.4%). The baseline OAB symptoms were similar between patients with and without BOO. After mirabegron treatment, the satisfactory rate (global response assessment score ≧1) were similar between those without BOO (61.3%) and with BOO (57.1%). The improvement of quality of life index and patient perception of bladder condition was also found in both groups. However, only patients without BOO had significantly improved international prostate symptom score and subscores, overactive bladder symptom score, and patient perception on intensity of urgency scale. Although most adverse events (AEs) were mild, patients with BOO had significantly higher AEs rate (18.6%) than those without BOO (8.2%, P = .026).

CONCLUSION

Mirabegron monotherapy in male patients with OAB and BOO was safe. However, the storage symptoms improvement was less in patients with BOO and AEs rate was higher.

Evaluating the efficacy and tolerability of mirabegron, a β3-adrenoceptor agonist, for the treatment of overactive bladder: Systematic review and network meta-analysis

Purpose:

Overactive bladder (OAB) is a common condition affecting approximately 11% of individuals worldwide. One of the newest treatment options for OAB symptoms is mirabegron. The objective of this network meta-analysis is to evaluate the extent of the efficacy and tolerability of mirabegron compared both to placebo and first-line anticholinergic pharmacotherapies.

Methods:

Articles were identified through the MEDLINE, EMBASE, and Cochrane databases using the search term ‘mirabegron’. All original, prospective, randomised, controlled, double-blind clinical trials studying mirabegron in adults receiving initial treatment for OAB were included. Efficacy was assessed based on outcome variables and responder data. Tolerability was evaluated for reported adverse events.

Results:

Thirteen studies including a total of 13,333 individuals were included. Mirabegron demonstrated better efficacy compared to placebo and tolterodine extended release 4 mg. Compared to placebo, the incidence of tachycardia and nasopharyngitis was greater with mirabegron 50 mg, and the incidence of cardiac arrhythmia was greater in 100 mg treatment groups. Mirabegron 100 mg also demonstrated a lower incidence of cardiac arrhythmia compared to tolterodine.

Conclusions:

The current study presents new information that may affect patient-centred strategies for the management of OAB, with a particular concern for cardiovascular safety.

High satisfaction with direct switching from antimuscarinics to mirabegron in patients receiving stable antimuscarinic treatment

Mirabegron, which was the first β3-adrenoceptor agonist introduced for use in clinical practice, has been extensively evaluated in overactive bladder (OAB) patients in several phase II and III studies. However, most of the enrolled patients were treatment naive or had experienced a wash-out period before the introduction of mirabegron. No study has reported the treatment results of a direct switch from antimuscarinics to mirabegron, which may more commonly occur in clinical practice. This is an observational study to assess the therapeutic efficacy and safety of directly switching from antimuscarinics to mirabegron in patients with OAB receiving stable antimuscarinic treatment. Moreover, we sought to identify the patients who benefited more from the change.Patients aged ≥20 years with OAB receiving stable antimuscarinics for >3 months were enrolled. Antimuscarinics were discontinued in all patients and mirabegron 25 mg, once daily was initiated. Primary end-point was global response assessment (GRA) at 1 month after medication switching. Baseline parameters and parameters changed 1 month after medication switching were compared between patients with GRA ≥ 1 and GRA < 1.Of the 282 enrolled patients (209 men, 73 women; mean age, 74.4 years), 55.3% had better (GRA ≥ 1), 31.2% had similar (GRA = 0), and 10.3% had worse (GRA < 0) outcomes. The overall adverse events (AE) rate decreased from 24.1% to 12.8%. In overall patients, there was no significant improvement of OAB symptoms, but postvoid residual (PVR) urine decreased and voiding symptoms and quality of life index improved significantly. Patients with GRA ≥ 1 had significantly improved both storage and voiding symptoms. A total of 195 patients (69.1%) can maintain mirabegron without adding or resuming antimuscarinics for more than 3 months. Logistic regression analysis indicated that higher baseline OAB symptoms scores were predictor of satisfactory outcome.More than 50% patients exhibited better outcomes after switching from antimuscarinics to mirabegron. Significantly lower AE rates and decreased PVR were noted. Higher baseline OAB symptom scores may predict a better outcome.

Mirabegron: A new option in treating overactive bladder

Antimuscarinic medications have long been the mainstay of drug treatment for overactive bladder. This article describes mirabegron, one of a new class of agents that relaxes the detrusor muscle directly via a beta3 adrenoceptor agonist. Mirabegron's efficacy on frequency, urgency, and urge incontinence was tested in several trials before its wide clinical introduction. However, caution is still needed as data are lacking on the drug's efficacy and safety in frail older adults and for long-term therapy.