Early investigational β3 adreno-receptor agonists for the management of the overactive bladder syndrome

Emerging therapies for overactive bladder: preclinical, phase I and phase II studies

INTRODUCTION

Overactive bladder syndrome is a common chronic condition with a significant impact on quality of life and economic burden. Persistence with pharmacologic therapy has been limited by efficacy and side effects. A greater understanding of the pathophysiology of overactive bladder has led to the initial evaluation of several drugs affecting ion channels, the autonomic nervous system, and enzymes which may provide useful alternatives for the management of overactive bladder.

AREAS COVERED

A comprehensive review was performed using PubMed and Cochrane databases as well as reviewing clinical trials in the United States. The current standard of care for overactive bladder will be discussed, but this paper focuses on investigational drugs currently in preclinical studies and phase I and II clinical trials.

EXPERT OPINION

Current therapies for overactive bladder have limitations in efficacy and side effects. A greater understanding of the pathophysiology of overactive bladder has identified the role(s) of other pathways in the overactive bladder syndrome. Targeting alternative pathways including ion channels and enzymes may provide alternative therapies of overactive bladder and a more tailored approach to the management of overactive bladder.

Clinical practice guideline for acupuncture and moxibustion: Female urinary incontinence

Urinary incontinence (UI) is a common problem worldwide. It has a major impact on physical and social activities and interpersonal relationships. UI is common in women, but is under-reported and under-treated. It affects the quality of life of female patients severely. Acupuncture and moxibustion have been proposed as potentially effective interventions for female UI. Hence, for the benefit of acupuncture practitioners around the world, the World Federation of Acupuncture-moxibustion Societies initiated a project to develop a clinical practice guideline (CPG) for the use of acupuncture and moxibustion to treat female UI. This CPG was developed according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology, referring to the principles of the World Health Organization Handbook for Guideline Development. During the development of the CPG, the guideline development group (GDG) played an important role. The clinical questions, recommendations and therapeutic protocols were all formulated by GDG using the modified Delphi method. This CPG contains ten recommendations about the use of acupuncture and moxibustion interventions for ten clinical questions, which include nine conditional recommendations for the intervention and one conditional recommendation for either the intervention or the comparison. This CPG also provides one protocol for conventional filiform needle therapy, two therapy protocols for deep needling stimulation on lumbosacral acupoints, and four moxibustion therapy protocols, based on the protocols presented in randomized controlled trials reviewed by the GDG. Please cite this article as: Yang C, Wang SZ, Chen S, Du S, Wang GQ, Guo W, Xie XL, Peng BH, Du SH, Zhao JP. Clinical practice guideline for acupuncture and moxibustion: Female urinary incontinence. J Integr Med. 2024; 22(3): 258-269.

Advances in pharmacotherapy for the treatment of overactive bladder

Purpose of review

To present the current literature on the pharmacologic management of overactive bladder, including combination therapies, agents still in clinical development, and special considerations related to individuals with cognitive decline, frailty and cardiovascular risk.

Recent Findings

Combination therapy is shown to be more effective than monotherapy, without additional side effects. Preliminary studies on novel treatment methods, including new medications, as well was novel use of established medications, demonstrates improved efficacy with a favorable side effect profile. Investigation into new target pathways may be an area for future pharmacologic development. Special consideration should be given when prescribing anti-muscarinic medication in the frail adult population. Overactive bladder has been associated with frailty and anti-muscarinic medications have been associated with the worsening cognitive decline.

Summary

Combination therapy is a safe and effective alternative to patients with refractory overactive bladder. Caution should be taken in prescribing medications for the frail older adult, and alternative first- and third-line treatments should be considered. Future studies should involve long term data on safety and outcomes stratified by age with objective measurements of cognition and frailty.

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

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

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

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

Sequential Addition Reaction of Sulfanylmethyllithiums and Grignard Reagents to Thioformamides Leading to the Formation of 2-Phenyl-2-sulfanylethyl Tertiary Amines

The reaction of sulfanylmethyllithiums generated from benzylsulfanes and n-BuLi with N,N-dimethylthioformamide followed by the addition of Grignard reagents gave 2-phenyl-2-sulfanyl tertiary amines in moderate to good yields. A range of Grignard reagents involving primary alkyl, aryl, vinyl, and alkynyl Grignard reagents were used. Two carbon-carbon bond-forming reactions were achieved through a one-pot reaction. The reaction showed good to high diastereoselectivity, particularly with alkynyl Grignard reagents.

Translational approaches to the treatment of benign urologic conditions in elderly women

PURPOSE OF REVIEW

Stress urinary incontinence, overactive bladder, interstitial cystitis/painful bladder syndrome, and underactive bladder are highly prevalent among elderly women, and have significant impact on quality of life; however, existing treatments are limited and are not always successful for all patients. Researchers are investigating a multitude of new therapies to treat these conditions. This review will summarize the recent literature on investigative therapies for these conditions.

RECENT FINDINGS

Multiple new treatments are being developed for lower urinary tract dysfunction. Some of these treatments, including balloon therapy and muscle-derived stem cells for stress urinary incontinence, could provide alternatives to existing therapies. Others require further research before being used in patients, such as pudendal nerve stimulation for overactive bladder and intravesical liposomes for drug delivery in interstitial cystitis/painful bladder syndrome.

SUMMARY

Multiple new therapies are being investigated that could provide clinicians with additional tools to treat lower urinary tract disorders in millions of elderly women.