Use of mirabegron in treating overactive bladder

Spectrofluorimetric methods for the determination of mirabegron by quenching tyrosine and L-tryptophan fluorophores: Recognition of quenching mechanism by stern volmer relationship, evaluation of binding constants and binding sites

Green spectrofluorimetric methods have been adopted for the determination of Mirabegron (MG) in pure drug and pharmaceutical dosage form. The developed methods based on fluorescence quenching of tyrosine and L-tryptophan amino acids fluorophores by the effect of Mirabegron as a quencher. Experimental conditions of the reaction were studied and optimized. The Fluorescence quenching (ΔF) values were proportional to the concentration range of MG 2-20 μg/ml for the tyrosine-MG system in buffered media pH 2 and 1-30 μg/ml for L-tryptophan-MG system pH 6. Good correlation coefficients with low detection limits of 0.163 and 0.234 μg/ml for the two systems respectively. Method validation was applied according to ICH guidelines. The cited methods were successively applied for MG determination in tablet formulation. No statistically significant difference between the results of the cited and the reference methods regarding t and F tests. The proposed spectrofluorimetric methods are simple, rapid, eco-friendly and can contribute to MG's methodologies in quality control labs. Stern-Volmer relationship, the effect of temperature, quenching constant (K_q), and UV spectra were studied to identify the mechanism by which the quenching might occur. The results demonstrated that fluorescence quenching of tyrosine was a dynamic quenching process and L-tryptophan was static. The double log plots were constructed to determine the binding constants and binding sites. The greenness profile of the developed methods has been assessed by Green Analytical procedure index (GAPI) and Analytical Greenness Metric Approach (AGREE).

Potato protease inhibitor II prevents obesity by inducing browning of white adipose tissue in mice via β3 adrenergic receptor signaling pathway

There are currently few effective and safe pharmacologic means for inducing beige adipogenesis in humans. This study highlights the role of potato protease inhibitor II (PPI II) in regulating the browning of adipose tissue. The in vitro results showed that PPI II increased the expression of the uncoupling protein 1 (UCP1) protein and gene and beige-specific genes, including Cd137, Cited1, Tbx1, and Tmem26 in vitro. PPI II treatment for three months in diet-induced obesity mice increased the levels of the UCP1 protein in white adipose tissue, causing elevated energy expenditure, thus preventing obesity and improving glucose tolerance. Mechanistic studies further revealed that PPI II regulated the abundance and activity of β₃ adrenergic receptor (β₃ -AR) in white adipocytes. Chemical-inhibition experiments revealed the crucial role of β₃ -AR-dependent protein kinase A (PKA)-p38 kinase (p38)/extracellular signal-related kinase1/2 (ERK1/2) signaling in PPI II-mediated browning program of white adipose tissues. In summary, our findings highlight the role of PPI II in beige adipocyte differentiation and thermogenesis and provide new insights into its use in preventing obesity.

Foxp1 controls brown/beige adipocyte differentiation and thermogenesis through regulating β3-AR desensitization

β-Adrenergic receptor (β-AR) signaling is a pathway controlling adaptive thermogenesis in brown or beige adipocytes. Here we investigate the biological roles of the transcription factor Foxp1 in brown/beige adipocyte differentiation and thermogenesis. Adipose-specific deletion of Foxp1 leads to an increase of brown adipose activity and browning program of white adipose tissues. The Foxp1-deficient mice show an augmented energy expenditure and are protected from diet-induced obesity and insulin resistance. Consistently, overexpression of Foxp1 in adipocytes impairs adaptive thermogenesis and promotes diet-induced obesity. A robust change in abundance of the β3-adrenergic receptor (β3-AR) is observed in brown/beige adipocytes from both lines of mice. Molecularly, Foxp1 directly represses β3-AR transcription and regulates its desensitization behavior. Taken together, our findings reveal Foxp1 as a master transcriptional repressor of brown/beige adipocyte differentiation and thermogenesis, and provide an important clue for its targeting and treatment of obesity.

Beta3-adrenergic receptor (b3-AR) signaling in response to cold activates adipose tissue thermogenesis. Here the authors identify the transcription factor FoxP1 as a direct negative regulator of b3-AR expression and show that loss of FoxP1 leads to enhanced development of thermogenic adipose tissue.

A prospective, double-blind, randomized, two-period crossover, multicenter study to evaluate tolerability and patient preference between mirabegron and tolterodine in patients with overactive bladder (PREFER study)

INTRODUCTION AND HYPOTHESIS

The objective of this study was to assess the tolerability and treatment preference in patients with overactive bladder (OAB) treated with mirabegron or tolterodine.

METHODS

This was a two-period, 8-week crossover, double-blind, phase IV study (PREFER; NCT02138747) in treatment-naive adults with OAB for 3 months or longer randomized to one of four treatment sequences in a 5:5:1:1 ratio (mirabegron/tolterodine, tolterodine/mirabegron, mirabegron/mirabegron, or tolterodine/tolterodine), separated by a washout period of 2 weeks. The primary endpoint was drug tolerability using the Medication Tolerability scale of the OAB Treatment Satisfaction (OAB-S) questionnaire at end of treatment (EoT). Period-by-treatment interactions were analyzed to determine any effect of drug order. Patient preference, change from baseline in OAB symptoms, and treatment-emergent adverse events (TEAEs) were assessed.

RESULTS

A total of 358 randomized patients completed the OAB-S Medication Tolerability scale questionnaire at one or more visits after the baseline evaluation. The mean (95% CI) OAB-S Medication Tolerability scores were significantly higher (better tolerability) for mirabegron (86.29 [83.50, 89.08]) than for tolterodine (83.40 [80.59, 86.20]; p = 0.004). The period-by-treatment interaction was not significant (p = 0.955). Improvements in OAB-S Medication Tolerability scores at EoT were more evident in women, patients aged ≥65 years, and in patients without baseline incontinence, and were greater with mirabegron than with tolterodine extended release. There were no significant differences in patient preference or improvements in OAB symptoms. Significant differences in favor of mirabegron were observed for anticholinergic TEAEs (20.4% vs. 27.4%; p = 0.042) and specifically for gastrointestinal disorders (14.7% vs. 22.5%; p = 0.015).

CONCLUSIONS

Tolerability of mirabegron was significantly higher than that of tolterodine, and patient preference and improvements in OAB symptoms were comparable. Both treatments were well tolerated; however, anticholinergic side effects were higher with tolterodine.

Characterization of stress degradation products of mirabegron using UPLC-QTOF-MS/MS and in silico toxicity predictions of its degradation products

Mirabegron is a novel beta-3 adrenergic receptor agonist in the treatment of overactive bladder disorder.

What do we know and not know about mirabegron, a novel β3 agonist, in the treatment of overactive bladder?

INTRODUCTION AND HYPOTHESIS

Mirabegron is a novel β3-adrenoceptor agonist recently approved by Japanese, American, and European authorities for overactive bladder (OAB) therapy. Here we review existing knowledge on this new class of medication, analyze existing literature on the topic, and make recommendations regarding its administration and necessary future studies.

METHODS

We reviewed the current literature and analyzed mirabegron efficacy, safety, and suitability for treating OAB symptoms. We performed a systematic search of Medline/PubMed, and Embase. Studies exploring mechanisms involved in the effects of mirabegron were included. Searches were limited to the English language.

RESULTS

Two phase II and two large-scale phase III multinational randomized controlled trials have supported mirabegron efficacy and tolerability with up to 12 weeks of therapy in OAB patients. The reported frequency and severity of treatment-emergent and serious adverse events were similar to antimuscarinics but with more than threefold lower incidence of dry mouth than with tolterodine. However, effects on the cardiovascular system, cognitive functions, pharmacokinetic interactions with other drugs, and long-term adverse events have not yet been fully investigated.

CONCLUSION

Anticholinergic drugs should remain the first-line pharmacologic treatment for OAB until head-to-head comparative study eventually shows that mirabegron has equivalent or superior efficacy. However, it seems logical to use mirabegron as second-line treatment of OAB in patients who are poor responders or intolerant to anticholinergics.

Functional BK channels facilitate the β3-adrenoceptor agonist-mediated relaxation of nerve-evoked contractions in rat urinary bladder smooth muscle isolated strips

The large-conductance voltage- and Ca(2+)-activated K(+) (BK) channel is a major regulator of detrusor smooth muscle (DSM) contractility thus facilitating urinary bladder function. Recent findings suggest that activation of β3-adrenoceptors causes DSM relaxation. However, it is unknown whether the β3-adrenoceptor-mediated DSM relaxation is BK channel-dependent during nerve-evoked contractions. To test this hypothesis, we induced nerve-evoked contractions in rat DSM isolated strips by using a tissue bath system equipped with platinum electrodes for electrical field stimulation (EFS). (±)-(R(*),R(*))-[4-[2-[[2-(3-chlorophenyl)-2-hydroxyethyl]amino]propyl]phenoxy] acetic acid sodium hydrate (BRL37344), a β3-adrenoceptor agonist, significantly decreased the amplitude and muscle force of the 20 Hz EFS-induced DSM contractions in a concentration-dependent manner. The BRL37344 inhibitory effect was significantly antagonized by 1-(2-ethylphenoxy)-3-[[(1S)-1,2,3,4-tetrahydro-1-naphthalenyl]amino]-(2S)-2-propanol hydrochloride (SR59230A), a β3-adrenoceptor antagonist. We further isolated the cholinergic from the purinergic component of the 0.5-50 Hz EFS-induced DSM contractions by using selective inhibitors, atropine as well as suramin and α,β-methylene-ATP. We found that BRL37344 inhibited both the purinergic and cholinergic components of the nerve-evoked contractions in rat DSM isolated strips. The pharmacological blockade of the BK channels with iberiotoxin, a selective BK channel inhibitor, increased the amplitude and muscle force of the 20 Hz EFS-induced contractions in rat DSM isolated strips. In the presence of iberiotoxin, there was a significant reduction in the BRL37344-induced inhibition of the 20 Hz EFS-induced contractions in rat DSM isolated strips. These latter findings suggest that BK channels play a critical role in the β3-adrenoceptor-mediated inhibition of rat DSM nerve-evoked contractions.

Drug updates and approvals: 2012 in review

Each year, the FDA approves many pharmaceuticals and products designed to treat or improve a patient's condition. The following is a sampling of some of the most important drugs approved in 2012 that specifically apply to nurse practitioner practice.

Assessment of drug-induced increases in blood pressure during drug development: report from the Cardiac Safety Research Consortium

This White Paper, prepared by members of the Cardiac Safety Research Consortium, discusses several important issues regarding the evaluation of blood pressure (BP) responses to drugs being developed for indications not of a direct cardiovascular (CV) nature. A wide range of drugs are associated with off-target BP increases, and both scientific attention and regulatory attention to this topic are increasing. The article provides a detailed summary of scientific discussions at a Cardiac Safety Research Consortium-sponsored Think Tank held on July 18, 2012, with the intention of moving toward consensus on how to most informatively collect and analyze BP data throughout clinical drug development to prospectively identify unacceptable CV risk and evaluate the benefit-risk relationship. The overall focus in on non-CV drugs, although many of the points also pertain to CV drugs. Brief consideration of how clinical assessment can be informed by nonclinical investigation is also outlined. These discussions present current thinking and suggestions for furthering our knowledge and understanding of off-target drug-induced BP increases and do not represent regulatory guidance.

Does conservative management really benefit patients with OAB?

The benefit that patients with overactive bladder (OAB) experience with conservative management is an important aspect in the evaluation of this therapy. The first-line options include behavioral interventions, and several techniques are available. Clinical research indicates amelioration of individual symptoms with these techniques, but few studies have shown a positive effect on health-related quality-of-life parameters. After failure of behavioral therapy or in combination with a training program, pharmacological therapy with anticholinergics is the next step. Extensive clinical research into different pharmacological compounds has shown significant effects on the symptomatic elements of OAB. The clinical relevance and the effects on quality-of-life parameters with pharmacological therapy have also been evaluated and show a significant effect on specific aspects. Recently, clinical research in conservative management of patients with OAB has focused more on evaluating patients' perceptions of their condition and the effects of treatment with patient-reported outcome instruments. Future studies should include these tools in the evaluation of any therapy in OAB.