Insight into new potential targets for the treatment of overactive bladder and detrusor overactivity

Ultra-High Frequency Spinal Nerve Neuromodulation for Improving Bladder Continence: Implications for Overactive Bladder Management

OBJECTIVE

Ultrahigh frequencies (UHF) have been shown to selectively suppress the sensory pathway with a rapid onset and prolonged effect compared with low frequencies. Few studies have explored the feasibility of UHF electrical stimulation in treating overactive bladder. This study aimed to investigate whether bladder overactivity could be inhibited by UHF stimulation at the L6 nerve root.

MATERIALS AND METHODS

Female Sprague-Dawley rats (n = 12) were divided into two groups: sham and UHF groups. Bladder overactivity was induced by continuous intravesical infusion of 0.5% acetic acid (AA). UHF L6 nerve root stimulation (500 kHz, 20 mA for 5 minutes) was applied to the rats in the UHF group. To investigate the effects of the treatment, intravesical pressure was recorded by cystometrography during continuous transvesical infusion, with volume threshold (VT) and intercontraction interval (ICI) used to conduct the investigation.

RESULTS

Bladder overactivity was successfully developed in all rats with a significant decrease of median VT and ICI to 83.7% and 86.4%, respectively. UHF stimulation of the L6 nerve root was able to counteract the AA effect by significantly increasing median VT and ICI to 220% and 36.1%, respectively; these effects persisted for ≥two hours. There was a significant difference in the effects of UHF electrical stimulation between the sham and UHF groups (p < 0.05).

CONCLUSION

This preliminary study provides evidence for UHF stimulation of the L6 spinal nerve root, analogous to the sacral nerve root in humans, as a potential alternative neuromodulation technique to suppress bladder overactivity.

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.

Overactive bladder: A review and update

Overactive bladder syndrome is a chronic, disabling condition with physical, psychological and social consequences that significantly affects the quality of life of millions of patients worldwide. The economic impact of this disorder is crucial. Overactive bladder syndrome is a little-known condition, with different manifestations from patient to patient, which causes a great deal of frustration to the medical staff involved. The patient requires a clear explanation and the full support of the attending physician. It is extremely important to establish a correct diagnosis and an effective individualized treatment. The collaboration and understanding of these patients are extremely important aspects. Improving the quality of life in these patients is the main purpose in managing this condition. There are several treatment modalities that may be used progressively, with favorable albeit inconsistent results. This condition remains extremely challenging for specialists and, unfortunately, always one of maximum interest.

Identification and Characterization of a Novel Large-Conductance Calcium-Activated Potassium Channel Activator, CTIBD, and Its Relaxation Effect on Urinary Bladder Smooth Muscle

The large-conductance calcium-activated potassium channel (BK_Ca channel) is expressed on various tissues and is involved in smooth muscle relaxation. The channel is highly expressed on urinary bladder smooth muscle cells and regulates the repolarization phase of the spontaneous action potentials that control muscle contraction. To discover novel chemical activators of the BK_Ca channel, we screened a chemical library containing 8364 chemical compounds using a cell-based fluorescence assay. A chemical compound containing an isoxazolyl benzene skeleton (compound 1) was identified as a potent activator of the BK_Ca channel and was structurally optimized through a structure-activity relationship study to obtain 4-(4-(4-chlorophenyl)-3-(trifluoromethyl)isoxazol-5-yl)benzene-1,3-diol (CTIBD). When CTIBD was applied to the treated extracellular side of the channel, the conductance-voltage relationship of the channel shifted toward a negative value, and the maximum conductance increased in a concentration-dependent manner. CTIBD altered the gating kinetics of the channel by dramatically slowing channel closing without effecting channel opening. The effects of CTIBD on bladder muscle relaxation and micturition function were tested in rat tissue and in vivo. CTIBD concentration-dependently reduced acetylcholine-induced contraction of urinary bladder smooth muscle strips. In an acetic acid-induced overactive bladder (OAB) model, intraperitoneal injection of 20 mg/kg CTIBD effectively restored frequent voiding contraction and lowered voiding volume without affecting other bladder function parameters. Thus, our results indicate that CTIBD and its derivatives are novel chemical activators of the bladder BK_Ca channel and potential candidates for OAB therapeutics. SIGNIFICANCE STATEMENT: The novel BK_Ca channel activator CTIBD was identified and characterized in this study. CTIBD directly activates the BK_Ca channel and relaxes urinary bladder smooth muscle of rat, so CTIBD can be a potential candidate for overactive bladder therapeutics.

A Novel Alternative in the Treatment of Detrusor Overactivity? In Vivo Activity of O-1602, the Newly Synthesized Agonist of GPR55 and GPR18 Cannabinoid Receptors

The aim of the research was to assess the impact of O-1602—novel GPR55 and GPR18 agonist—in the rat model of detrusor overactivity (DO). Additionally, its effect on the level of specific biomarkers was examined. To stimulate DO, 0.75% retinyl acetate (RA) was administered to female rats’ bladders. O-1602, at a single dose of 0.25 mg/kg, was injected intra-arterially during conscious cystometry. Furthermore, heart rate, blood pressure, and urine production were monitored for 24 h, and the impact of O-1602 on the levels of specific biomarkers was evaluated. An exposure of the urothelium to RA changed cystometric parameters and enhanced the biomarker levels. O-1602 did not affect any of the examined cystometric parameters or levels of biomarkers in control rats. However, the O-1602 injection into animals with RA-induced DO ameliorated the symptoms of DO and caused a reversal in the described changes in the concentration of CGRP, OCT₃, BDNF, and NGF to the levels observed in the control, while the values of ERK1/2 and VAChT were significantly lowered compared with the RA-induced DO group, but were still statistically higher than in the control. O-1602 can improve DO, and may serve as a promising novel substance for the pharmacotherapy of bladder diseases.

Are there different patterns of detrusor overactivity which are clinically relevant? ICI-RS 2018

INTRODUCTION

Different patterns of detrusor overactivity (DO) have been described and included in several standardization terminology documents. However, it is unclear if these different patterns have any clinical significance.

METHODS

This is a report of the proceedings of Proposal 3: "Are there different patterns of detrusor overactivity which are clinically relevant?" from the annual International Consultation on Incontinence-Research Society (ICIRS) meeting, which took place from 14 to 16 June 2018, in Bristol, UK.

RESULTS

We have collected and discussed, as a committee, the evidence about different urodynamic (UD) patterns of detrusor overactivity and their potential clinical significance. We reviewed the important previous basic research and clinical studies and compiled summaries. The discussion focused on clinical relevance of different UD patterns of DO and what further research is required.

CONCLUSIONS

There are several UD definitions of patterns of detrusor overactivity, however the clinical relevance of these definitions remains unclear. Future research should concentrate on defining the pattern of DO in relation to clinical diagnosis, gender, age, and treatment outcomes.

A short review of drug-food interactions of medicines treating overactive bladder syndrome

Background Overactive bladder syndrome is a condition where one or more of the symptoms such as pollakiuria, urgent need to urinate, nocturia and urinary incontinence is observed. Its prevalence ranges between 7 and 27 % in men and 9–43 % in women. The role of a pharmacist is to educate the patient on medications administration scheme, and drug interactions with particular food or food components. Aim of the review To assess a potential impact of food and fruit juice on the pharmacokinetic and therapeutic effects of medications used in treating overactive bladder syndrome. This information will enhance pharmaceutical care and is vital and helpful for pharmacists counseling their patients. Method In order to gather information on interactions of medications employed in bladder dysfunctions, the English language reports published in the PubMed, Embase, Cochrane and CINAHL database over the years 1996–2015 were studied. Additionally, other resources, namely drugs.com, Medscape, UpToDate, Micromedex, Medical Letter, as well as Stockley Drugs Interaction electronic publication were included in the study. The analysis also covered product data sheets for particular medicinal products. Results Meals and the consumption of grapefruit juice were found to exert a diversified effect on the pharmacokinetics of drugs employed in overactive bladder syndrome therapy. Neither tolterodine, nor mirabegron interact with food and citrus fruit juice, whereas darifenacin, fesoterodine, oxybutynin and solifenacin do interact with grapefruit and others citrus fruit juice. The effects of such interactions may potentially be negative to patients. Trospium absorption is significantly decreased by food. Conclusion For selected medicines used in treating bladder dysfunctions food and grapefruit juice consumption may significantly affect efficacy and safety of the therapy. All information on the topic is likely to enhance the quality of pharmaceutical care.

Pathophysiology, Clinical Importance, and Management of Neurogenic Lower Urinary Tract Dysfunction Caused by Suprasacral Spinal Cord Injury

Management of persistent lower urinary tract dysfunction resulting from severe thoracolumbar spinal cord injury can be challenging. Severe suprasacral spinal cord injury releases the spinal cord segmental micturition reflex from supraspinal modulation and increases nerve growth factor concentration in the bladder wall, lumbosacral spinal cord, and dorsal root ganglion, which subsequently activates hypermechanosensitive C-fiber bladder wall afferents. Hyperexcitability of bladder afferents and detrusor overactivity can cause urine leaking during the storage phase. During urine voiding, the loss of supraspinal control that normally coordinates detrusor contraction with sphincter relaxation can lead to spinal cord segmental reflex-mediated simultaneous detrusor and sphincter contractions or detrusor-sphincter dyssynergia, resulting in inefficient urine voiding and high residual volume. These disease-associated changes can impact on the quality of life and life expectancy of spinal-injured animals. Here, we discuss the pathophysiology and management considerations of lower urinary tract dysfunction as the result of severe, acute, suprasacral spinal cord injury. In addition, drawing from experimental, preclinical, and clinical medicine, we introduce some treatment options for neurogenic lower urinary tract dysfunction that are designed to: (1) prevent urine leakage arising because of detrusor overactivity during bladder filling, (2) preserve upper urinary tract integrity and function by reducing intravesical pressure and subsequent vesicoureteral reflux, and (3) prevent urinary tract and systemic complications by treating and preventing urinary tract infections.

Overactive bladder syndrome pharmacotherapy: future treatment options

Overactive bladder syndrome (OAB) is a lifestyle disease and its incidence increases with age. Although it is not a life-threatening disease, it is known to have a significant impact on the quality of life. The first-choice pharmacological treatment of OAB is antimuscarinics. However, their limited clinical effectiveness and unsatisfactory tolerance profile, combined with the advancement of knowledge on the aetiopathogenesis of the disease, have inspired research on new pharmacotherapy options for OAB. Basic research has provided foundations for the development of new OAB treatments, which seem very promising and can be applied in clinical practice. The mechanisms of the studied compounds are based on their effect on certain receptors and neurotransmitters that contribute to regulating the micturition reflex. These compounds are not only more receptor-specific as compared to currently used drugs, but also some of them are organ-specific. Some of such compounds have already passed the proof-of-concept stage of development and have the therapeutic potential to determine the future of OAB pharmacotherapy. This review focuses on the mechanisms of substances that are now undergoing pre-clinical and clinical tests and their effects on the micturition cycle, while also identifying opportunities for using them with specific groups of patients. Due to the fact that OAB is a disease of symptoms and its aetiopathogenesis is complex, it seems that modern treatment methods should be tailor-made and based on the pathophysiological mechanisms that induce disease symptoms, rather than only treating the symptoms by inhibiting the contractility of the urinary bladder.

Research Findings on Overactive Bladder

Several physiopathologic conditions lead to the manifestation of overactive bladder (OAB). These conditions include ageing, diabetes mellitus, bladder outlet obstruction, spinal cord injury, stroke and brain injury, Parkinson's disease, multiple sclerosis, interstitial cystitis, stress and depression. This review has discussed research findings in human and animal studies conducted on the above conditions. Several structural and functional changes under these conditions have not only been observed in the lower urinary tract, but also in the brain and spinal cord. Significant changes were observed in the following areas: neurotransmitters, prostaglandins, nerve growth factor, Rho-kinase, interstitial cells of Cajal, and ion and transient receptor potential channels. Interestingly, alterations in these areas showed great variation in each of the conditions of the OAB, suggesting that the pathophysiology of the OAB might be different in each condition of the disease. It is anticipated that this review will be helpful for further research on new and specific drug development against OAB.

Chapter 2: Pathophysiology of neurogenic detrusor overactivity and the symptom complex of "overactive bladder"

It is now clearly recognized that the function of the lower urinary tract represents a complex interaction between the bladder and its outlet, acting under the control of the central nervous system. While in the past attention has principally focused on the motor (efferent) control of the bladder, sensory (afferent) innervation is now known to be an important therapeutic target. This change in emphasis is strongly supported by both basic science and clinical evidence demonstrating the efficacy of therapy directed at the afferent system. This chapter summarizes the neurophysiological control mechanism that underpins normal lower urinary tract function, emphasizing the importance of the afferent system as a potential therapeutic target.

Does hypercholesterolemia affect the relaxation of the detrusor smooth muscle in rats? In vitro and in vivo studies

To evaluate the effects of hypercholesterolemia on the relaxation function of the urinary bladder, we examined the physiological mechanisms involved in the isoproterenol-induced relaxation in isolated detrusor strips in vitro and voiding behavior in vivo in rats. Adult male Sprague-Dawley rats were fed standard (control, N = 16) or 4 % cholesterol diet (hypercholesterolemia, N = 17) for 4 weeks. Concentration-response curves for isoproterenol-induced relaxations in carbachol-precontracted detrusor muscle strips were recorded. The contributions of β2- and β3-adrenoceptors and ATP-dependent and Ca(2+)-dependent potassium channels to the relaxation response were investigated by using selective adrenergic agonists salbutamol and BRL 37344 and specific potassium channel inhibitors glibenclamide and charybdotoxin, respectively. Cystometrography was performed to assess bladder function. Hypercholesterolemic rats had higher serum cholesterol and low- and high-density lipoprotein levels than the controls with no sign of atherosclerosis. Isoproterenol-induced relaxation was significantly enhanced in the hypercholesterolemia group. Preincubation with the M2 receptor antagonist attenuated the relaxation response in both groups. The relaxation responses to isoproterenol and salbutamol were similar in both groups, while BRL 37344 appeared to produce a greater relaxant effect in the hypercholesterolemic rats. Also, the inhibitory effects of potassium channel inhibitors on relaxation responses were comparable among the groups. The cystometric findings revealed that threshold and basal pressure values were higher in the hypercholesterolemia group compared with controls. We showed that hypercholesterolemia leads to greater relaxation responses to isoproterenol, appears to impair the braking function of M2 cholinergic receptors on adrenoceptor-induced relaxations in the isolated detrusor muscle, and affects the voiding function in rats.

Expert consensus on scientific evidence available on the use of botulinum toxin in overactive bladder

OBJECTIVES

Overactive bladder (OAB) is a pathology impairing patients' quality of life and with a high percentage of patients who are refractory to medication. In this paper, technical opinion of an «expert panel» is assessed in order to gain the most reliable professional consensus on scientific evidence available on the criteria of use of Onabotulinumtoxin A (OnabotA) in OAB.

MATERIAL AND METHODS

according to DELPHI method, 42 panelists answered a survey of 93 items divided into four strategic areas including clinical criteria and recommendations in order to improve, at different levels, the current approach to patients with OAB. The recent advances in the field, areas of controversy and their real application possibilities in the different areas of our health care system were taken into consideration.

RESULTS

Two rounds of the questionnaire were completed by all experts. In the first round, a criteria consensus was reached for 64 of 93 (68.8%) questions analyzed; in the second round the consensus reached was for 83 items evaluated (89.25%). An agreement among panelist was reached for: 1) definition, classification, detection and differential diagnosis; 2) medical treatment; 3) surgical treatment; 4) role of OnabotA in the treatment of OAB.

CONCLUSIONS

the consensus is broadly in line with the latest scientific evidence on OAB. The panelists believe that it is necessary to propose a change in the current definition of OAB and that it seems necessary to improve the screening tools too. Medical treatment of OAB must be tailored to each patient, staged and progressive. The use of OnabotA (Botox(®)) could imply therapeutic advantages with respect to other treatments, and positions itself as a safe and effective alternative to treat drug refractory OAB.

Impact of mirabegron extended-release on the treatment of overactive bladder with urge urinary incontinence, urgency, and frequency

Overactive bladder is a highly prevalent disorder with a significant impact on quality of life. Antimuscarinic agents are commonly used, but persistence is limited due to unsatisfactory efficacy and/or tolerability. Mirabegron is the first beta-3 adrenoceptor agonist approved for the treatment of overactive bladder syndrome. This paper reviews the pharmacology, mechanism of action, efficacy, and safety of mirabegron. A PubMed search of all English articles pertaining to mirabegron was performed. An alternative to antimuscarinics, mirabegron has a unique mechanism, improves overactive bladder symptoms and quality of life, and has limited adverse effects and few contraindications.

Overactive bladder syndrome and the potential role of prostaglandins and phosphodiesterases: an introduction

In this paper, a general introduction is given, presenting the overactive bladder syndrome (OAB) and its impact on the quality of life and economical burden in patients affected. Moreover, the anatomy, physiology and histology of the lower urinary tract are discussed, followed by a brief overview on the possible role of prostaglandin (PG) and phosphodiesterase type 5 (PDE5) in the urinary bladder. The current literature on the role and distribution of PGE2 and its receptors in the urinary bladder is discussed. In both animal models and in human studies, high levels of signaling molecules such as PG and cGMP have been implicated, in decreased functional bladder capacity and micturition volume, as well as in increased voiding contraction amplitude. As a consequence, inhibition of prostanoid production, the use of prostanoid receptor antagonists, or PDE inhibitors might be a rational way to treat patients with detrusor overactivity. Similarly, prostanoid receptor agonists, or agents that stimulate their production, might have a function in treating bladder underactivity.

Botulinum toxin-A injections for idiopathic overactive bladder: a systematic review and meta-analysis

OBJECTIVE

To review the current evidence on the efficacy and safety of botulinum toxin-A in the management of idiopathic overactive bladder (OAB).

METHODS

A systematic search of PubMed, Embase and the Cochrane Central Search Library was performed. All randomized controlled trials comparing botulinum toxin-A with placebo, different doses and injection techniques, in patients with idiopathic OAB was included. The analyzed outcomes were quantification of symptoms, urodynamic outcomes, quality of life and adverse events.

RESULT

A total of 1,020 participants from 12 randomized controlled trials were included. Botulinum toxin-A was associated with less urinary frequency, less incontinence episodes, improvement in quality of life, higher post-void residual-related catheterization and higher urinary tract infection. Doses of 100-300 U were not consistently differentiated from each other in voiding diary, quality of life and urge urinary incontinence. No statistically significant difference was seen between bladder body and bladder base, bladder body and bladder body plus trigone in urinary retention and urinary tract infection.

CONCLUSION

Botulinum toxin-A is associated with significant improvement in OAB symptoms in patients with idiopathic OAB. However, there is a higher incidence of postoperative urinary retention and urinary infection compared to placebo. Low-dose botulinum toxin-A seems to be the optimum dose that appropriately balances the benefits with adverse events. Trigone inclusion seems as safe and effective as trigone-sparing injection.

Prevalence, risk factors and quality of life in Turkish women with urinary incontinence: a synthesis of the literature

BACKGROUND

Urinary incontinence (UI) is not a life threatening condition but it adversely affects physical and mental health, sexual function and quality of life in women.

AIM

To review the related literature to identify prevalence, risk factors and quality of life among only Turkish women.

METHODS

Computerized searches on PubMed, Turkish Medline, EBSCO Host; articles from indexed journals related to the topics in this review and published between 1996 and 30 April 2012 were evaluated. After completion of database searches, a final total of 20 studies were identified that fitted the inclusion criteria.

RESULTS

This review revealed that the prevalence of UI among Turkish women was reported by 16 studies ranged from 16.4% to 49.7%. The most common risk factors were age, number of births, body mass index > 25 kg/m(2), recurrent urinary infection, diabetes mellitus and vaginal delivery. The effect of UI on the quality of life was mild to moderate.

CONCLUSIONS

We found that the prevalence of UI of Turkish women showed a wide range. It is important for health professionals to be aware of the high prevalence of UI in women and to ask about its possible presence. Improving the quality of life in women with UI is an important issue and nurses should direct women to seek psychosocial support. The findings of this review could serve as a source of information for health systems that deal with UI, and it may help to inform health professionals and women with UI on early diagnosis, treatment and management.

New developments in the management of overactive bladder: focus on mirabegron and onabotulinumtoxinA

In the last few years, much new information has been generated on the pathophysiology, possible therapeutic targets, and pharmacologic treatment of overactive bladder (OAB). Antimuscarinic drugs are still first-line pharmacologic treatment for OAB and often have good initial response rates, but adverse effects and decreasing efficacy cause long-term compliance problems, prompting a search for new therapeutic alternatives. Mirabegron and onabotulinumtoxinA, two drugs with different mechanisms of action, and with adverse effect profiles different from those of antimuscarinics, were recently approved for treatment of OAB. However, their place in the treatment of this disorder has not yet been established. In this short review, the mechanisms of action, clinical efficacy, and safety profiles of these drugs are discussed and compared with those of the current gold standard, antimuscarinic agents.

Morphological Changes of Bladder Mucosa in Patients Who Underwent Instillation with Combined Sodium Hyaluronic Acid-Chondroitin Sulphate (Ialuril®)

<b><i>Objective:</i></b> To investigate what changes are endoscopically evident after glycosaminoglycans (GAGs) therapy by hyaluronic acid (HA) and chondroitin sulphate (CS) (Ialuril®) in female patients affected by bladder pain syndrome(BPS)/ interstitial cystitis (IC) or recurrent urinary tract infections (rUTIs). <b><i>Patients and Methods:</i></b> 21 female patients over 18 years affected by rUTIs or BPS/IC received intravesical instillation of HA and CS (4 weekly instillations followed by 2 instillations every 2 weeks and 2 instillation monthly). Post-treatment evaluation included cystoscopy and patient assessment of improvement in symptoms and satisfaction on a visual analogue scale (VAS) from 0 to 10. <b><i>Results:</i></b> The post-treatment endoscopy showed a positive effect on bladder mucosa morphology. In 2 cases, treatment did not change endoscopic findings and clinical symptoms. In the other patients, when macroscopic features of the bladder mucosa normalized, the clinical picture improved. <b><i>Conclusions:</i></b> GAGs therapy by HA and CS (Ialuril) improves the morphology of bladder mucosa in patients with rUTI or BPS/IC.