Distribution of the high-affinity binding site and intracellular target of botulinum toxin type A in the human bladder. Eur Urol. 2010;57:884-890. [PMID: 20044204 DOI: 10.1016/j.eururo.2009.12.022]

A Novel Catalytically Inactive Construct of Botulinum Neurotoxin A (BoNT/A) Directly Inhibits Visceral Sensory Signalling

Botulinum neurotoxin A (BoNT/A) is a potent neurotoxin that silences cholinergic neurotransmission through the cleavage of the synaptic protein SNAP-25. Previous studies have shown that, in addition to its paralytic effects, BoNT/A can inhibit sensory nerve activity. The aim of this study was to identify how BoNT/A inhibits afferent signalling from the bladder. To investigate the role of SNAP-25 cleavage in the previously reported BoNT/A-dependent inhibition of sensory signalling, we developed a recombinant form of BoNT/A with an inactive light chain, rBoNT/A (0), unable to paralyse muscle. We also developed recombinant light chain (LC)-domain-only proteins to better understand the entry mechanisms, as the heavy chain (HC) of the protein is responsible for the internalisation of the light chain. We found that, despite a lack of catalytic activity, rBoNT/A (0) potently inhibited the afferent responses to bladder distension to a greater degree than catalytically active rBoNT/A. This was also clear from the testing of the LC-only proteins, as the inactive rLC/A (0) protein inhibited afferent responses significantly more than the active rLC/A protein. Immunohistochemistry for cleaved SNAP-25 was negative, and purinergic and nitrergic antagonists partially and totally reversed the sensory inhibition, respectively. These data suggest that the BoNT/A inhibition of sensory nerve activity in this assay is not due to the classical well-characterised 'double-receptor' mechanism of BoNT/A, is independent of SNAP25 cleavage and involves nitrergic and purinergic signalling mechanisms.

Ultrasound-assisted intravesical botulinum toxin A delivery attenuates acetic acid-induced bladder hyperactivity in rats

Background: Intradetrusor injection of botulinum toxin A (BTX-A) is an effective treatment for overactive bladder (OAB). However, the occurrence of adverse events associated with BTX-A injection therapy hinders its acceptance among patients and its clinical promotion. Intravesical instillation of BTX-A offers a promising alternative to injection therapy for treating OAB. Nevertheless, due to the presence of the bladder permeability barrier (BPB) and the high molecular weight of BTX-A, direct instillation is unable to penetrate the bladder urothelium. Purpose: This study aims to investigate the safety and feasibility of ultrasound-assisted intravesical delivery of BTX-A and its potential benefits in a rat model of bladder hyperactivity induced by acetic acid instillation. Methods: Hengli BTX-A and microbubbles (MB) were mixed and prepared as a novel complex. The size distribution and zeta potentials of the complex were measured. On day 1, rats' bladders were instilled with 1 mL of saline, BTX-A (20 U in 1 mL), MB, or MB-BTX-A (20 U in 1 mL) complex with or without ultrasound (US) exposure (1 MHz, 1.5 W/cm2, 50% duty cycle, sonication for 10 s with a 10-s pause for a total of 10 min). The instillations were maintained for 30 min. After 7 days, cystometry was performed by filling the bladder with saline and 0.3% acetic acid (AA). Bladders were collected, weighed, and processed for immunoblotting, enzyme-linked immunosorbent assay (ELISA), histologic, and immunofluorescence analyses. Expression and distribution of SNAP-25 and SNAP-23 were assessed using Western blot and immunofluorescence. Calcitonin gene-related peptide (CGRP) in the bladder was detected using ELISA. Results: Intercontraction intervals (ICI) decreased by 72.99%, 76.16%, and 73.96% in rats pretreated with saline, BTX-A, and US + MB, respectively. However, rats treated with US + MB + BTX-A showed a significantly reduced response to AA instillation (57.31% decrease in ICI) without affecting amplitude, baseline pressure, or threshold pressure. Rats treated with US + MB + BTX-A exhibited increased cleavage of SNAP-25 and CGRP expression compared to the control group. Conclusion: Ultrasound-assisted intravesical delivery of BTX-A, with the assistance of MB cavitation, led to cleavage of SNAP-25, inhibition of calcitonin gene-related peptide release from afferent nerve terminals, and amelioration of acetic acid-induced bladder hyperactivity. These results support ultrasound-assisted intravesical delivery as an efficient non-injection method for administering BTX-A.

An evaluation of onobotulinumtoxinA as a therapeutic option for pediatric neurogenic detrusor overactivity

INTRODUCTION

Neurogenic detrusor overactivity (NDO) results in involuntary detrusor contractions during bladder filling or storage risking transmission of pressure to the upper urinary tracts and/or significant incontinence. The goals of bladder management in children with NDO prioritize the preservation of renal function, prevention of UTIs, and optimizing quality of life. First-line measures include intermittent catheterization and anticholinergic medication. However, when conservative measures fail, surgical intervention may be indicated. Historically, the next step was major reconstructive surgery to create a low-pressure urinary reservoir. The introduction of intravesical botulinum neurotoxin A (BoNT/A) for use in children in 2002 offered a less invasive option for management. However, its exact role is still evolving.

AREAS COVERED

This article summarizes the mechanism of action of BoNT/A for management of NDO and evaluates the current literature defining common practice and clinical efficacy in children with NDO. The findings of the recently completed phase III trial for intravesical onabotulinumtoxinA in children are discussed in detail.

EXPERT OPINION

As the first BoNT/A approved for use in children with NDO, onabotulinumtoxinA appears to be a safe and less invasive alternative to major reconstructive surgery. However, data defining appropriate patient selection and its role as a long-term treatment option continue to develop.

Real-Time Documentation of the Effect of Onabotulinumtoxin A Detrusor Injection in OAB Patients-Preliminary Results

Introduction: Detrusor injection with onabotulinumtoxin A (OnabotA-DI) is an established therapy for overactive bladder (OAB). Little is known about the exact onset and course of the effect in the days after the injection therapy. By using a new type of app-controlled automated diary pod, for the first time, the precise onset of the effect of OnabotA-DI can be documented in real time. Materials and methods: Patients due for OnabotA-DI were asked to document voiding 3 days before and up to 3 weeks after therapy using the Diary Pod app. The detrusor injection was performed with onabotulinumtoxin A (Botox®), 100 units, at 20 sites of the detrusor muscle in a standardized manner. Voiding on the injection day itself was not documented. Results: A total of 17 patients (15 women, 2 men; aged 33−83 (mean 64.6; median 70) years) were included in the study. The handling of the Diary Pod app was user-friendly, and elderly patients did not encounter technical problems. The results of patients with reliably documented micturitions showed a continuous reduction in micturition frequency every day from the first day and significantly from day 5. For 24 h voiding, from 12.83 ± 5.54 in the 3 days before injection, the following mean values were found with significant (p < 0.05) changes after the intervention: 9.17 ± 3.19 on day 5, 8.75 ± 3.69 on day 10, 7.17 ± 2.04 on day 15, and 5.75 ± 0.5 on day 20. These changes were in similar proportions during the daytime and nighttime. Conclusions: Contrary to previous knowledge, the effect of the OnabotA-DI set in from the first postoperative days and was reflected a similar extent in day and night micturition. This study is the first to document the onset of action of OnabotA-DI in real time.

Effect of Bladder Injection of OnabotulinumtoxinA on the Central Expression of Genes Associated with the Control of the Lower Urinary Tract: A Study in Normal Rats

To investigate a possible central mechanism of action of Botulinum toxin A (BoNT/A) following injection in the bladder, complementary to the acknowledged peripheral bladder effect, we studied changes in the expression of neuropeptides and receptors involved in lower urinary tract function in the spinal cord (SC) and dorsal root ganglia (DRG) of normal rats following BoNT/A bladder injection. Thirty-six Sprague-Dawley rats, divided into three groups of n = 12, received bladder injections of 2U or 5U OnabotulinumtoxinA (BOTOX^®), or saline. Six animals from each group were sacrificed on days 7 and 14. Expression of Tachykinin 1 (Tac1), capsaicin receptor (TRPV1), neuropeptide Y (NPY), proenkephalin (PENK) and muscarinic receptors M1, M2, M3, was evaluated in the bladder, L6-S1 DRG, and SC segments using real-time PCR and Western blotting. Real-time PCR revealed increased expression of NPY in all tissues except for SC, and increased TRPV1 and PENK expression in DRG and SC, whereas expression of Tac1, M1 and M2 was decreased. Less significant changes were noted in protein levels. These findings suggest that bladder injections of OnabotulinumtoxinA may be followed by changes in the expression of sensory, sympathetic and cholinergic bladder function regulators at the DRG/SC level.

Effect of Intratrigonal Botulinum Toxin in Patients with Bladder Pain Syndrome/Interstitial Cystitis: A Long-Term, Single-Center Study in Real-Life Conditions

The high percentage of treatment failures seen in patients with bladder pain syndrome/interstitial cystitis (BPS/IC) managed conservatively frequently demands invasive treatment options. We aimed to evaluate the long-term efficacy and adverse events of intratrigonal botulinum toxin injection in such circumstances, as well as to determine possible predictors of response to toxin treatment. A retrospective cohort study included 47 female BPS/IC patients treated with onabotulinum toxin A (OnabotA) in a tertiary hospital between the years 2009 and 2022. All patients received 100 U of OnabotA in ten injections limited to the trigonal area. Patients were divided into three groups based on their treatment response as responders, non-responders and lost to follow-up due to non-medical reasons. The clinical and surgical records of the individuals were retrieved, including the 10-point visual analogue scale (VAS), the number of treatments, the time between injections, and the age at the first injection. A total of 25 patients (>50% of the cohort) were long-term responders, but none of the evaluated parameters was a predictor for this circumstance: age, pain intensity, or duration of improvement following the injection. The time between injections was stable (around 1 year). No severe adverse events were registered. The intratrigonal injection of botulinum toxin in patients with BPS/IC was an effective and safe long-term treatment for patients' refractory to conservative forms of treatment. Age, basal pain intensity, and time to injection request did not predict long-term response to OnaBotA.

Deterioration of bladder compliance after botulinum toxin A injection and discontinuation of medication for overactive bladder

Introduction

We report a case of deterioration of bladder compliance after botulinum toxin type A injection and discontinuation of medication for overactive bladder.

Case presentation

A female patient with overactive bladder in her sixties had been visiting our outpatient clinic regularly for 4 years. She had received posterolateral spondylus fusion twice, which resulted in a compression fracture. She had been receiving a combination therapy of anticholinergics and β3‐adrenoceptor agonist for the management of overactive bladder. She received botulinum toxin type A injection for refractory overactive bladder and discontinued medical treatment for overactive bladder. Three months after botulinum toxin type A injection, cystometry revealed the deterioration of bladder compliance. Renal dysfunction, hydronephrosis, and vesicoureteral reflux were shown. Renal function and hydronephrosis were improved after restarting anticholinergics and β3‐adrenoceptor agonist therapy and inserting a temporary transurethral catheter.

Conclusion

Deterioration of bladder compliance may occur after botulinum toxin type A injection and discontinuation of overactive bladder medication in some patients with underlying neurological disease.

Nano-BTA: A New Strategy for Intravesical Delivery of Botulinum Toxin A

Botulinum neurotoxin subtype A (BoNT-A) has been part of the urology treatment arsenal since it was first used in the treatment of detrusor-sphincter dyssynergia more than 30 years ago. BoNT-A has been recommended as an effective treatment for neurogenic detrusor overactivity and overactive bladder. However, direct intradetrusor injection of BoNT-A using cystoscopy after anesthesia may cause hematuria, pain, and infection; these adverse events have motivated urologists to find less invasive and more convenient ways to administer BoNT-A. The development of nanotechnology has led to the advancement of intravesical drug delivery. Using versatile nanocarriers to transport BoNT-A across the impermeable urothelium is a promising therapeutic option. In this review, we discuss the effectiveness and feasibility of liposomes, thermosensitive polymeric hydrogels, and hyaluronan-phosphatidylethanolamine as carriers of BoNT-A for intravesical instillation. To date, these carriers have not reached a similar efficacy as intradetrusor injections in long-term observations. Hopefully, researchers will make a breakthrough with new nanomaterials to develop clinical applications in the future.

BoNT/A in the Urinary Bladder-More to the Story than Silencing of Cholinergic Nerves

Botulinum neurotoxin (BoNT/A) is an FDA and NICE approved second-line treatment for overactive bladder (OAB) in patients either not responsive or intolerant to anti-cholinergic drugs. BoNT/A acts to weaken muscle contraction by blocking release of the neurotransmitter acetyl choline (ACh) at neuromuscular junctions. However, this biological activity does not easily explain all the observed effects in clinical and non-clinical studies. There are also conflicting reports of expression of the BoNT/A protein receptor, SV2, and intracellular target protein, SNAP-25, in the urothelium and bladder. This review presents the current evidence of BoNT/A’s effect on bladder sensation, potential mechanisms by which it might exert these effects and discusses recent advances in understanding the action of BoNT in bladder tissue.

The urethra in continence and sensation: Neural aspects of urethral function

AIMS

Traditionally, the urethra has been considered a mere conduit to guide urine from the bladder to the external side of the body. Building evidence indicates that the urethra may directly influence bladder function via mechanisms restricted to the lower urinary tract (LUT).

METHODS

Here, we discuss the tissue arrangement of the urethra and addressed the contribution of new paraneuronal cells to LUT function. We also briefly reviewed two frequent LUT pathologies associated with urethral dysfunction.

RESULTS

Continence depends on an intact and functional urethral sphincter, composed of smooth, and striated muscle fibers and regulated by somatic and autonomic fibers. Recent studies suggest the existence of an urethro-vesical reflex that also contributes to normal LUT function. Indeed, the urethral lumen is lined by a specialized epithelium, the urothelium, in the proximal urethra. In this region, recent evidence demonstrates the presence of specific paraneuronal cells, expressing the neurotransmitters acetylcholine and serotonin. These cells are in close proximity of nerve fibers coursing in the lamina propria and are able to release neurotransmitters and rapidly induce detrusor contractions, supporting the existence of an urethro-vesical crosstalk.

CONCLUSION

The mechanism underlying the fast communication between the urethra and thebladder are beginning to be understood and should involve the interaction between specificepithelial cells and fibres innervating the urethral wall. It is likely that this reflex should bealtered in pathological conditions, becoming an attractive therapeutic target.

The influence of Potentilla chinensis aqueous extract on urinary bladder function in retinyl acetate-induced detrusor overactivity in rats

INTRODUCTION & OBJECTIVES

In overactive bladder (OAB) therapy several herbal medicines presented promising effects, however the results are sparse to provide their efficacy. Herbals may become a popular alternative for OAB therapy. Therefore, we investigated whether Potentilla chinensis extract (PCE) would reverse retinyl acetate (RA)-induced detrusor overactivity (DO).

MATERIAL & METHODS

60 rats were divided into 4 groups, as follows: I - control, II - rats with RA-induced DO, III - rats received PCE in dose of 500 mg/kg, and IV - rats with RA-induced DO which received PCE. PCE or vehicle were administered orally for 14 days. The cystometry and bladder blood flow assessment were performed 3 days after the last dose of the PCE. Then the rats were put into the metabolic cages for 24 h. Next, urothelium thickness measurement and biochemical analyses were performed. < /p><p> Results. Intravesical infusion of RA solution induced DO. PCE had no influence on the urinary bladder function and&nbsp; micturition cycles in normal rats. PCE diminished the severity of RA-induced DO. In the urothelium the RA induced the elevation of ATP, CGRP, substance P, VEGF-A, OTC3, and ERK1/2. The concentration of NOS2, CDH1, and ZO1 decreased. Moreover, RA affected the concentration of SNARE proteins (increased concentration of SNAP23, SNAP25, and SV2A). Also in detrusor the elevated level of ROCK1 and VAChT were observed. In turn, PCE in RA-induced DO caused a reversal of the described biochemical changes within urothelium, detrusor muscle and urine. < /p><p> Conclusions. PCE attenuates detrusor overactivity. The potential mechanisms of action of PCE in the urinary bladder seem to be multifactorial and complex. PCE seems to become a reasonable novel OAB therapy.

Therapeutic Effect of Botulinum Toxin A on Sensory Bladder Disorders-From Bench to Bedside

Bladder oversensitivity arises from several different conditions involving the bladder, bladder outlet, systemic or central nervous system diseases. Increase of the bladder sensation results from activation of the sensory receptors in the urothelial cells or suburothelial tissues. Medical treatment targeting the overactive bladder (OAB) or interstitial cystitis (IC) might relieve oversensitive bladder symptoms (frequency, urgency and pain) in a portion of patients, but a certain percentage of patients still need active management. Botulinum toxin A (BoNT-A) has been demonstrated to have anti-inflammatory and antinociceptive effects in bladder sensory disorders and has been shown effective in the reduction of bladder oversensitivity and the increase of functional bladder capacity. For patients with OAB, urgency and urinary incontinence improved, while in patients with IC, bladder pain could be relieved in association with reduction of bladder oversensitivity after BoNT-A intravesical injection. Histological evidence has confirmed the therapeutic mechanism and clinical efficacy of intravesical BoNT-A injection on patients with OAB or IC. Bladder oversensitivity can also be relieved with the instillation of liposome encapsulated BoNT-A or low energy show waves (LESWs), which enable the BoNT-A molecule to penetrate into the urothelium and suburothelial space without affecting the detrusor contractility. Liposome encapsulated BoNT-A or combined LESWs and BoNT-A instillation might be future treatment alternatives for bladder oversensitivity in sensory bladder disorders.

Mechanism of Action of Botulinum Toxin A in Treatment of Functional Urological Disorders

Intravesical botulinum toxin (BoNT) injection is effective in reducing urgency and urinary incontinence. It temporarily inhibits the detrusor muscle contraction by blocking the release of acetylcholine (Ach) from the preganglionic and postganglionic nerves in the efferent nerves. BoNT-A also blocks ATP release from purinergic efferent nerves in the detrusor muscle. In afferent nerves, BoNT-A injection markedly reduces the urothelial ATP release and increases nitric oxide (NO) release from the urothelium. BoNT-A injection in the urethra or bladder has been developed in the past few decades as the treatment method for detrusor sphincter dyssyndergia, incontinence due to neurogenic or idiopathic detrusor overactivity, sensory disorders, including bladder hypersensitivity, overactive bladder, and interstitial cystitis/chronic pelvic pain syndrome. Although the FDA only approved BoNT-A injection treatment for neurogenic detrusor overactivity and for refractory overactive bladder, emerging clinical trials have demonstrated the benefits of BoNT-A treatment in functional urological disorders. Cautious selection of patients and urodynamic evaluation for confirmation of diagnosis are crucial to maximize the successful outcomes of BoNT-A treatment.

Neuronal selectivity of botulinum neurotoxins

Botulinum neurotoxins (BoNTs) are highly potent toxins responsible for a severe disease, called botulism. They are also efficient therapeutic tools with an increasing number of indications ranging from neuromuscular dysfunction to hypersecretion syndrome, pain release, depression as well as cosmetic application. BoNTs are known to mainly target the motor-neurons terminals and to induce flaccid paralysis. BoNTs recognize a specific double receptor on neuronal cells consisting of gangliosides and synaptic vesicle protein, SV2 or synaptotagmin. Using cultured neuronal cells, BoNTs have been established blocking the release of a wide variety of neurotransmitters. However, BoNTs are more potent in motor-neurons than in the other neuronal cell types. In in vivo models, BoNT/A impairs the cholinergic neuronal transmission at the motor-neurons but also at neurons controlling secretions and smooth muscle neurons, and blocks several neuronal pathways including excitatory, inhibitory, and sensitive neurons. However, only a few reports investigated the neuronal selectivity of BoNTs in vivo. In the intestinal wall, BoNT/A and BoNT/B target mainly the cholinergic neurons and to a lower extent the other non-cholinergic neurons including serotonergic, glutamatergic, GABAergic, and VIP-neurons. The in vivo effects induced by BoNTs on the non-cholinergic neurons remain to be precisely investigated. We report here a literature review of the neuronal selectivity of BoNTs.

OnabotulinumtoxinA (botulinum toxin type A) for the treatment of Japanese patients with overactive bladder and urinary incontinence: Results of single-dose treatment from a phase III, randomized, double-blind, placebo-controlled trial (interim analysis)

OBJECTIVE

To evaluate the efficacy and safety of onabotulinumtoxinA (botulinum toxin type A) 100 U in patients with overactive bladder and urinary incontinence.

METHODS

This was a phase III, randomized, double-blind, placebo-controlled trial in Japanese patients who were inadequately managed with overactive bladder medications (anticholinergics and/or β₃ -adrenergic receptor agonists). Eligible patients were randomized 1:1 to receive a single dose of either onabotulinumtoxinA or placebo into the detrusor muscle (n = 124 each). The primary end-point was the change in the number of daily urinary incontinence episodes at week 12 from baseline. Secondary end-points included volume voided per micturition, other symptomatic measures (urinary urgency incontinence, micturition, urgency and nocturia) and patient-reported outcomes.

RESULTS

In the onabotulinumtoxinA group, there was a significantly greater decrease from baseline in the mean number of daily urinary incontinence episodes compared with the placebo group (2.16; P < 0.001), and significantly greater improvement for all secondary end-points (P < 0.05). Urinary tract infection, dysuria, urinary retention and post-void residual urine volume increased represented adverse events occurring at a higher rate in the onabotulinumtoxinA group. The majority of these were mild or moderate in severity.

CONCLUSIONS

Statistically significant and clinically relevant improvements in symptoms and patient-reported outcomes, and tolerability were seen in patients with overactive bladder and urinary incontinence who had been inadequately managed with overactive bladder medications after using onabotulinumtoxinA.

Cho W, Soleimanpour S. Bacteriotherapy in Breast Cancer

Breast cancer is the second most common cause of cancer-related mortality among women around the world. Conventional treatments in the fight against breast cancer, such as chemotherapy, are being challenged regarding their effectiveness. Thus, strategies for the treatment of breast cancer need to be continuously refined to achieve a better patient outcome. We know that a number of bacteria are pathogenic and some are even associated with tumor development, however, recent studies have demonstrated interesting results suggesting some bacteria may have potential for cancer therapy. Therefore, the therapeutic role of bacteria has aroused attention in medical and pharmaceutical studies. Furthermore, genetic engineering has been used in bacterial therapy and may led to greater efficacy with few side effects. Some genetically modified non-pathogenic bacterial species are more successful due to their selectivity for cancer cells but with low toxicity for normal cells. Some live, attenuated, or genetically modified bacterias are capable to multiply in tumors and inhibit their growth. This article aims to review the role of bacteria and their products including bacterial peptides, bacteriocins, and toxins for the treatment of breast cancer.

The Botulinum Treatment of Neurogenic Detrusor Overactivity: The Double-Face of the Neurotoxin

Botulinum neurotoxin (BoNT) can counteract the highly frequent involuntary muscle contractions and the uncontrolled micturition events that characterize the neurogenic detrusor overactivity (NDO) due to supra-sacral spinal cord lesions. The ability of the toxin to block the neurotransmitter vesicular release causes the reduction of contractions and improves the compliance of the muscle and the bladder filling. BoNT is the second-choice treatment for NDO once the anti-muscarinic drugs have lost their effects. However, the toxin shows a time-dependent efficacy reduction up to a complete loss of activity. The cellular mechanisms responsible for BoNT effects exhaustion are not yet completely defined. Similarly, also the sites of its action are still under identification. A growing amount of data suggest that BoNT, beyond the effects on the efferent terminals, would act on the sensory system recently described in the bladder mucosa. The specimens from NDO patients no longer responding to BoNT treatment displayed a significant increase of the afferent terminals, likely excitatory, and signs of a chronic neurogenic inflammation in the mucosa. In summary, beyond the undoubted benefits in ameliorating the NDO symptomatology, BoNT treatment might bring to alterations in the bladder sensory system able to shorten its own effectiveness.

AbobotulinumtoxinA for the treatment of overactive bladder

INTRODUCTION

Overactive bladder is a common condition that can have a negative impact on quality of life. Botulinum Toxin A is a third line treatment for overactive bladder following conservative measures and anticholinergic medication. At present, OnabotulinumtoxinA is the only preparation licensed for this indication. More recently, trials have been undertaken to compare the efficacy of this to AbobotulinumtoxinA. Areas covered: This article aims to provide an overview of AbobotulinumtoxinA, which is currently not yet licensed for overactive bladder or neurogenic detrusor overactivity. It will detail the pharmacokinetics and dynamics, assess the available clinical trial data and make comparisons with current clinical practice. A systematic literature search was completed, using ovid Medline and Embase, with the aim to review all data concerning the administration of AbobotulinumtoxinA for the treatment of overactive bladder. Expert opinion: Currently, there are a lack of data on the use of AbobotulinumtoxinA for overactive bladder or neurogenic detrusor overactivity. Current evidence concentrates on its use in neurogenic detrusor overactivity, and there are data to show it may be as efficacious as OnabotulinumtoxinA. However, there is a lack of homogenous data to compare the two products and therefore we are unable to recommend this currently.

The Expanding Therapeutic Utility of Botulinum Neurotoxins

Botulinum neurotoxin (BoNT) is a major therapeutic agent that is licensed in neurological indications, such as dystonia and spasticity. The BoNT family, which is produced in nature by clostridial bacteria, comprises several pharmacologically distinct proteins with distinct properties. In this review, we present an overview of the current therapeutic landscape and explore the diversity of BoNT proteins as future therapeutics. In recent years, novel indications have emerged in the fields of pain, migraine, overactive bladder, osteoarthritis, and wound healing. The study of biological effects distal to the injection site could provide future opportunities for disease-tailored BoNT therapies. However, there are some challenges in the pharmaceutical development of BoNTs, such as liquid and slow-release BoNT formulations; and, transdermal, transurothelial, and transepithelial delivery. Innovative approaches in the areas of formulation and delivery, together with highly sensitive analytical tools, will be key for the success of next generation BoNT clinical products.

The binding of botulinum neurotoxins to different peripheral neurons

Botulinum neurotoxins are the most potent toxins known. The double receptor binding modality represents one of the most significant properties of botulinum neurotoxins and largely accounts for their incredible potency and lethality. Despite the high affinity and the very specific binding, botulinum neurotoxins are versatile and multi-tasking toxins. Indeed they are able to act both at the somatic and at the autonomic nervous system. In spite of the preference for cholinergic nerve terminals botulinum neurotoxins have been shown to inhibit to some extent also the noradrenergic postganglionic sympathetic nerve terminals and the afferent nerve terminals of the sensory neurons inhibiting the release of neuropeptides and glutamate, which are responsible of nociception. Therefore, there is increasing evidence that the therapeutic effect in both motor and autonomic disorders is based on a complex mode of botulinum neurotoxin action modulating the activity of efferent as well as afferent nerve fibres.

Intratrigonal OnabotulinumtoxinA Improves Bladder Symptoms and Quality of Life in Patients with Bladder Pain Syndrome/Interstitial Cystitis: A Pilot, Single Center, Randomized, Double-Blind, Placebo Controlled Trial

PURPOSE

We compared the efficacy and safety of trigonal injections of onabotulinumtoxinA and saline in patients with bladder pain syndrome/interstitial cystitis.

MATERIALS AND METHODS

This phase II study enrolled women who had had bladder pain syndrome/interstitial cystitis for more than 6 months and pain for 4 months or longer on a visual analogue scale of 0 to 10, which were refractory to common treatment. OnabotulinumtoxinA 100 U in 10 or saline as placebo in 9 was administered as 10 trigonal injections of 1 ml. The primary study end point was the change from baseline pain intensity reported at week 12. Additional end points included O'Leary-Sant scores, micturition frequency, quality of life at week 4, 8 and 12, and the treatment benefit scale at week 12. Safety assessments included urinary tract infection, post-void residual urine and the initiation of clean intermittent catheterization.

RESULTS

At week 12 onabotulinumtoxinA had significantly reduced pain compared with saline (mean ± SD -3.8 ± 2.5 vs -1.6 ± 2.1, p <0.05). The proportion of patients who achieved a 50% or greater reduction in the pain visual analog scale was 60% for onabotulinumtoxinA vs 22% for placebo. OnabotulinumtoxinA significantly improved O'Leary-Sant scores and quality of life over placebo at weeks 4, 8 and 12. Important numerical reductions in voiding frequency were also observed with the toxin. OnabotulinumtoxinA was well tolerated. Urinary tract infections developed in 3 patients who received onabotulinumtoxinA vs 2 who received saline. Mean post-void residual urine at week 12 was 5 ± 13 ml for onabotulinumtoxinA vs 0 ml with saline. This study had the limitations inherent to a single center trial with a small number of patients enrolled.

CONCLUSIONS

OnabotulinumtoxinA 100 U caused significant and clinically relevant improvements in bladder pain and quality of life in patients with bladder pain syndrome/interstitial cystitis refractory to common therapy. It was also well tolerated.

Beta-3 adrenergic receptor is expressed in acetylcholine-containing nerve fibers of the human urinary bladder: An immunohistochemical study

AIMS

To identify in the human bladder the structures which express the Beta-3 adrenoceptor (β3AR).

METHODS

Human bladders from cadaveric organ donors (equally balanced in sex and age) were collected. Bladders were immediately fixed in paraformaldehyde and further processed for cryostat sectioning. Single and double immunohistochemistry was performed using antibodies against β3AR C-terminal, β3AR N-terminal, a pan-neuronal marker (β3-Tubulin) and markers of cholinergic (Vesicular Acetylcholine Transporter), adrenergic (Tyrosine Hidroxylase), and peptidergic (Calcitonin Gene-Related Peptide) nerve fibers.

RESULTS

Nerve fibers expressing immunoreactivity for β3AR were abundantly found in the mucosa and muscular layers of the human bladder. No β3AR-IR was detected on urothelial or smooth muscle cells. The presence of β3AR-IR in nerve fibers was confirmed by co-expression with β3-Tubulin. Nerve fibers expressing β3AR-IR were cholinergic, VAChT⁺ , and abundantly observed in the suburothelium. The cholinergic fibers were in close proximity and intermingled with adrenergic TH⁺ and peptidergic CGRP⁺ fibers.

CONCLUSIONS

We demonstrated that β3AR is abundantly located in acetylcholine-containing nerve fibers. These findings have important consequences to understand the mechanism of action of β3AR agonists currently used for the treatment of OAB.

Botulinum Neurotoxins Serotypes A and B induce paralysis of mouse striated and smooth muscles with different potencies

To address the scarcity of direct comparison of botulinum neurotoxin serotypes activity on smooth versus striatal muscle, we have studied the action of BoNT/A1 and BoNT/B1 on ex vivo preparations of both muscle types. We have set up and characterized a model of neurogenic contractions in the isolated mouse bladder, and used this model to explore the effects of the two serotypes on contractions evoked by electrical field stimulation. Both toxins were also tested in the mouse phrenic nerve hemidiaphragm assay, to compare their potency in smooth versus striated muscle. The characterization of the model of neurogenic contractions in the isolated mouse bladder indicates that about half of the activity is driven by purinergic signaling, and about half by cholinergic signaling. Furthermore, we find that BoNT/B1 is more potent than BoNT/A1 in inhibiting activity in the mouse detrusor smooth muscle preparation, but that both toxins have comparable potency on the striated muscle activity of the phrenic nerve hemidiaphragm model. We also show that these findings are mouse strain independent. In conclusion, the established mouse bladder detrusor smooth muscle model is able to discriminate between different botulinum neurotoxin serotypes and could be a useful preclinical tool to explore the pathophysiology of bladder overactivity, as well as the effects of new therapeutic candidates. It is interesting to note that the high proportion of purinergic transmission driving detrusor contractions in this model is similar to that seen in neurodetrusor overactivity disease, making this model relevant with regard to pathophysiological interest.

Mucosal modulation of contractility in bladder strips from normal and overactive rat models and the effect of botulinum toxin A on overactive bladder strips

AIMS

To investigate the local, regulatory role of the mucosa on bladder strip contractility from normal and overactive bladders and to examine the effect of botulinum toxin A (BoNT-A).

METHODS

Bladder strips from spontaneously hyperactive rat (SHR) or normal rats (Sprague Dawley, SD) were dissected for myography as intact or mucosa-free preparations. Spontaneous, neurogenic and agonist-evoked contractions were investigated. SHR strips were incubated in BoNT-A (3 h) to assess effects on contractility.

RESULTS

Spontaneous contraction amplitude, force-integral or frequency were not significantly different in SHR mucosa-free strips compared with intacts. In contrast, spontaneous contraction amplitude and force-integral were smaller in SD mucosa-free strips than in intacts; frequency was not affected by the mucosa. Frequency of spontaneous contractions in SHR strips was significantly greater than in SD strips. Neurogenic contractions in mucosa-free SHR and SD strips at higher frequencies were smaller than in intact strips. The mucosa did not affect carbachol-evoked contractions in intact versus mucosa-free strips from SHR or SD bladders. BoNT-A reduced spontaneous contractions in SHR intact strips; this trend was also observed in mucosa-free strips but was not significant. Neurogenic and carbachol-evoked contractions were reduced by BoNT-A in mucosa-free but not intact strips. Depolarisation-induced contractions were smaller in BoNT-A-treated mucosa-free strips.

CONCLUSIONS

The mucosal layer positively modulates spontaneous contractions in strips from normal SD but not overactive SHR bladder strips. The novel finding of BoNT-A reduction of contractions in SHR mucosa-free strips indicates actions on the detrusor, independent of its classical action on neuronal SNARE complexes.

Impairment of sensory afferents by intrathecal administration of botulinum toxin A improves neurogenic detrusor overactivity in chronic spinal cord injured rats

Spinal cord injury (SCI) often leads to neurogenic detrusor overactivity (NDO) due to sprouting of sensory afferents on the lumbosacral spinal cord. NDO is characterized by high frequency of voiding contractions and increased intravesical pressure that may lead to urinary incontinence. The latter has been described as one of the consequences of SCI that mostly decreases quality of life. Bladder wall injections of botulinum toxin A (Onabot/A) are an effective option to manage NDO. The toxin strongly impairs parasympathetic and sensory fibres coursing the bladder wall. However the robust parasympathetic inhibition may inhibit voiding contractions and cause urinary retention in patients that retain voluntary voiding. Here, we hypothesised that by restricting the toxin activity to sensory fibres we can improve NDO without impairing voiding contractions. In the present work, we assessed the effect of Onabot/A on sensory neurons in chronic (4weeks) SCI rats by injecting the toxin intrathecally (IT), at lumbosacral spinal cord level. This route of administration was shown before to have an effect on bladder pain and contractility in an animal model of bladder inflammation. We found that IT Onabot/A led to a significant reduction in the frequency of expulsive contractions and a normalization of bladder basal pressure while maintaining voiding contractions of normal amplitude. Cleavage of SNAP-25 protein occurred mainly at the dorsal horn regions where most of the bladder afferents end. Cleaved SNAP-25 was not detected in motor or preganglionic parasympathetic neurons. A significant decrease in CGRP expression, a peptide exclusively present in sensory fibres in the spinal cord, occurred at the L5/L6 segments and associated dorsal root ganglia (DRG) after Onabot/A injection in SCI animals. Onabot/A strongly increased the expression of ATF3, a marker of neuronal stress, in L5/L6 DRG neurons. Taken together, our results suggest that IT Onabot/A has a predominant effect on bladder sensory fibres, and that such effect is enough to control NDO following chronic SCI. The mechanism of action of Onabot/A includes not only the cleavage of SNAP-25 in sensory terminals but also impairment of basic cellular machinery in the cell body of sensory neurons.

Use of Botulinum Toxin A in the Treatment of Lower Urinary Tract Disorders: A Review of the Literature

Botulinum neurotoxin (BoNT) is used to treat a variety of ailments, and its therapeutic application in lower urinary tract disorders (LUTDs) is well studied. Robust evidence supporting the efficacy and tolerability of BoNT in the treatment of neurogenic detrusor overactivity (NDO) and non-neurogenic overactive bladder (OAB) has led to regulatory approval for these conditions. Use of BoNT in the treatment of interstitial cystitis/bladder pain syndrome, chronic pelvic pain, and detrusor sphincter dyssynergia has demonstrated some promise, but is still evolving and off-label for these indications. Trials to date do not support the use of BoNT for benign prostatic hyperplasia. This comprehensive review outlines the mechanisms of BoNT in the treatment of LUTDs in adults and presents background and updated data examining the efficacy and adverse events associated with the use of BoNT in common urologic applications.

How botulinum toxin in neurogenic detrusor overactivity can reduce upper urinary tract damage?

Intradetrusor injections of botulinum toxin are the cornerstone of medical treatment of neurogenic detrusor overactivity. The primary aim of this treatment is to ensure a low pressure regimen in the urinary bladder, but the mechanisms leading to long-term protection of the urinary tract remain poorly understood. In this paper, we highlight the potential benefits of intradetrusor injections of botulinum toxin regarding local effects on the bladder structures, urinary tract infections, stone disease, vesico ureteral reflux, hydronephrosis, renal function based on a comprehensive literature review.

Treatment of painful bladder syndrome/interstitial cystitis with botulinum toxin A: why isn't it effective in all patients?

Botulinum toxin A (BTA) is currently used to treat a variety of painful disorders, including painful bladder syndrome/interstitial cystitis (PBS/IC). However, BTA is not consistently effective in all patients. This may be due to the disparity of causes of pain, but this may also relate to the processes by which BTA exerts anti-nociceptive effects. This review discusses mechanisms by which BTA may inhibit pain and studies of the use of BTA in PSB/IC patients. It is doubtful that any single treatment will effectively control pain in PBS/IC patients, and it is highly probable that multiple strategies will be required, both within individual patients and across the population of PBS/IC patients. The purpose of this review is to discuss those mechanisms by which BTA acts, with the intent that alternative strategies exploiting these mechanism, or work through alternative pathways, can be identified to more effectively treat pain in PBS/IC patients in the future.

Practical Aspects of Botulinum Toxin-A Treatment in Patients With Overactive Bladder Syndrome

Intravesical onabotulinumtoxinA (BoNT-A) injection is an effective treatment for overactive bladder syndrome (OAB) that is refractory to antimuscarinics. An injectable dose of 100 U has been suggested to achieve the optimal balance of benefit and safety in patients with OAB. BoNT-A (total volume of 10 mL) was administered as evenly distributed intradetrusor injections (5 U) across 20 sites approximately 1 cm apart (0.5 mL per site) using a flexible or rigid cystoscope. Treatment with BoNT-A was generally well tolerated by most patients, and most treatment-related adverse events were localized to the urinary tract. The prevalence of OAB increases with age, and elderly patients are more vulnerable to complications. The short-term efficacy of intravesical BoNT-A injection for refractory OAB with no treatment-related complications in the elderly population has been documented. Frail elderly patients can experience the same treatment results, such as significantly improved urgent urinary incontinence and quality of life, as young and nonfrail elderly patients with 100-U BoNT-A injections. However, increased risk of larger postvoid residual (PVR) urine and lower long-term success rates were noted in frail elderly patients; around 11% had acute urinary retention, while 60% had PVR urine volume >150 mL after treatment. In addition, intravesical injection of BoNT-A effectively decreased urgency symptoms in elderly patients with OAB and central nervous system lesions. The adverse effects were acceptable, while the long-term effects were comparable to those in patients with OAB without central nervous system lesions. Nonetheless, the possibility of longstanding urinary retention and chronic catheterization in this vulnerable population requires careful evaluation before treatment with intravesical BoNT-A. In conclusion, the current findings indicate that intravesical BoNT-A is an effective and safe treatment for OAB in elderly patients.

Current and potential urological applications of botulinum toxin A

Botulinum toxin subtype A (BoNT-A) is a potent neurotoxin that can selectively modulate neurotransmitter release from nerve endings, resulting in muscular paralysis. BoNT-A might also act on sensory nerves, and have an anti-inflammatory effect. In the first urological use of BoNT-A, injection into the urethral sphincters of patients with detrusor-sphincter dyssynergia resulted in a reduction of urethral resistance and improved voiding efficiency. Subsequently, intravesical BoNT-A injections have received regulatory approval for treatment of neurogenic detrusor overactivity owing to spinal cord lesions or multiple sclerosis, and idiopathic overactive bladder in adults. BoNT-A has also been widely used to treat patients with the off-label indications of neurogenic or non-neurogenic voiding dysfunction and male lower urinary tract symptoms owing to BPH and bladder-neck dysfunction. Other indications for which urologists have applied BoNT-A injections include interstitial cystitis/bladder pain syndrome, bladder oversensitivity and chronic pelvic pain syndrome. BoNT-A is currently delivered as an intravesical injection; however, use of liposome encapsulated formulations is also beginning to show some therapeutic potential.

Presence of Cleaved Synaptosomal-Associated Protein-25 and Decrease of Purinergic Receptors P2X3 in the Bladder Urothelium Influence Efficacy of Botulinum Toxin Treatment for Overactive Bladder Syndrome

OBJECTIVES

To evaluate whether botulinum toxin A (BoNT-A) injection and Lipotoxin (liposomes with 200 U of BoNT-A) instillation target different proteins, including P2X3, synaptic vesicle glycoprotein 2A, and SNAP-25, in the bladder mucosa, leading to different treatment outcomes.

MATERIALS AND METHODS

This was a retrospective study performed in a tertiary teaching hospital. We evaluated the clinical results of 27 OAB patients treated with intravesical BoNT-A injection (n = 16) or Lipotoxin instillation (n = 11). Seven controls were treated with saline. Patients were injected with 100 U of BoNT-A or Lipotoxinin a single intravesical instillation. The patients enrolled in this study all had bladder biopsies performed at baseline and one month after BoNT-A therapy. Treatment outcome was measured by the decreases in urgency and frequency episodes at 1 month. The functional protein expressions in the urothelium were measured at baseline and after 1 month. The Wilcoxon signed-rank test and ordinal logistic regression were used to compare the treatment outcomes.

RESULTS

Both BoNT-A injection and Lipotoxin instillation treatments effectively decreased the frequency of urgency episodes in OAB patients. Lipotoxin instillation did not increase post-void residual volume. BoNT-A injection effectively cleaved SNAP-25 (p < 0.01). Liposome encapsulated BoNT-A decreased urothelial P2X3 expression in the five responders (p = 0.04), while SNAP-25 was not significantly cleaved.

CONCLUSIONS

The results of this study provide a possible mechanism for the therapeutic effects of BoNT-A for the treatment of OAB via different treatment forms. BoNT-A and Lipotoxin treatments effectively decreased the frequency of urgency episodes in patients with OAB.

Regulation of ACh release from guinea pig bladder urothelial cells: potential role in bladder filling sensations

BACKGROUND AND PURPOSE

The aim of this study was to quantify and characterize the mechanism of non-neuronal ACh release from bladder urothelial cells and to determine if urothelial cells could be a site of action of anti-muscarinic drugs.

EXPERIMENTAL APPROACH

A novel technique was developed whereby ACh could be measured from freshly isolated guinea pig urothelial cells in suspension following mechanical stimulation. Various agents were used to manipulate possible ACh release pathways in turn and to study the effects of muscarinic receptor activation and inhibition on urothelial ATP release.

KEY RESULTS

Minimal mechanical stimulus achieved full ACh release, indicating a small dynamic range and possible all-or-none signal. ACh release involved a mechanism dependent on the anion channel CFTR and intracellular calcium concentration, but was independent of extracellular calcium, vesicular trafficking, connexins or pannexins, organic cation transporters and was not affected by botulinum-A toxin. Stimulating ACh receptors increased ATP production and antagonizing them reduced ATP release, suggesting a link between ACh and ATP release.

CONCLUSIONS AND IMPLICATIONS

These results suggest that release of non-neuronal ACh from the urothelium is large enough and well located to act as a modulator of ATP release. It is hypothesized that this pathway may contribute to the actions of anti-muscarinic drugs in reducing the symptoms of lower urinary tract syndromes. Additionally the involvement of CFTR in ACh release suggests an exciting new direction for the treatment of these conditions.

Ulcerative and nonulcerative forms of bladder pain syndrome/interstitial cystitis do not differ in symptom intensity or response to onabotulinum toxin A

OBJECTIVE

To determine whether intratrigonal Onabotulinum toxin A (OnabotA) injection produces a different symptomatic outcome and duration of effect on ulcerative (Ulc) and nonulcerative (NUlc) bladder pain syndrome/interstitial cystitis (BPS/IC) patients and to compare the urinary levels of neurotrophines (NGF, BDNF, and GDNF) in response to OnabotA.

METHODS

Ten Ulc and 14 NUlc bladder pain syndrome/interstitial cystitis patients were included in this study. OnabotA (100 U) was injected in 10 trigonal sites, each receiving 10 U in 1 mL of saline. Outcome measures included pain visual analog scale (0-10), a 3-day voiding chart, O'Leary-Sant Score (OSS), and quality of life (QoL) from International Prostate Symptoms Score assessed before treatment, 1 month after injection, and every 3 months afterwards. Urinary NGF, BDNF, and GDNF were accessed using ELISA, at same time points. Treatment duration was determined at the time patients requested another injection.

RESULTS

Patients had a mean age of 40 ± 12 years in the Ulc and 47 ± 13 years in the NUlc group (ns). Mean values at baseline of pain intensity, frequency, nocturia, OSS, QoL, and urinary NGF, BDNF, GDNF were identical in the 2 groups. Patients with the Ulc phenotype had a longer duration of symptoms (28.8 ± 11 vs 19.2 ± 8 months, P = .018). Both groups responded equally to OnabotA, with significant improvements in pain intensity, frequency, nocturia, OSS, QoL, and urinary NGF, BDNF, GDNF. The effect lasted for 9 ± 2.8 (Ulc) and 10.5 ± 2 (NUlc) months.

CONCLUSION

In this cohort, Ulc and NUlc patients had similar symptoms at baseline and comparable clinical response to intratrigonal OnabotA. These findings suggest that pain may not be directly related with ulcers themselves.

Understanding clinic options for overactive bladder

Overactive bladder (OAB) is a symptom complex of urinary frequency, nocturia and urgency with or without urgency incontinence that adversely impacts patient's quality of life. Conservative management begins in the outpatient clinic, often with significant improvement and patient satisfaction. In this review we will discuss the evaluation of OAB and review treatment options focusing on behavioral modification, medical therapy, and neuromodulation. These treatment options are offered in a stepwise fashion, remembering that more than one may be needed and can be used concomitantly.

Purinergic signalling in the urinary tract in health and disease

Purinergic signalling is involved in a number of physiological and pathophysiological activities in the lower urinary tract. In the bladder of laboratory animals there is parasympathetic excitatory cotransmission with the purinergic and cholinergic components being approximately equal, acting via P2X1 and muscarinic receptors, respectively. Purinergic mechanosensory transduction occurs where ATP, released from urothelial cells during distension of bladder and ureter, acts on P2X3 and P2X2/3 receptors on suburothelial sensory nerves to initiate the voiding reflex, via low threshold fibres, and nociception, via high threshold fibres. In human bladder the purinergic component of parasympathetic cotransmission is less than 3 %, but in pathological conditions, such as interstitial cystitis, obstructed and neuropathic bladder, the purinergic component is increased to 40 %. Other pathological conditions of the bladder have been shown to involve purinoceptor-mediated activities, including multiple sclerosis, ischaemia, diabetes, cancer and bacterial infections. In the ureter, P2X7 receptors have been implicated in inflammation and fibrosis. Purinergic therapeutic strategies are being explored that hopefully will be developed and bring benefit and relief to many patients with urinary tract disorders.

Effect of botulinum toxin A on urothelial-release of ATP and expression of SNARE targets within the urothelium

AIMS

Botulinum neurotoxin serotype A (BoNT/A) has emerged as an effective treatment of urinary bladder overactivity. Intravesical lipotoxin (BoNT/A delivery using liposomes), which may target the urothelium, is effective in blocking acetic acid induced hyperactivity in animals. The objective of this study was to assess the possible site of toxin action within the urothelium.

METHODS

We examined expression of the toxin receptor (SV2) and its cleavage targets (SNAP-25 and SNAP-23) within urothelium as well as effects of the toxin on mechanically evoked release of ATP from cultured rat urothelial cells. ATP release was measured using the luciferin-luciferase assay; we examined expression of SNAP-23 and -25 in urothelial cells and mucosa of rat and human bladders.

RESULTS

BoNT/A (1.5 U; 1-3 hr) blocked hypotonic evoked release of urothelial ATP, without affecting morphology. The expression of protein targets for BoNT/A binding (SV2) was detected in human and rat bladder mucosa and catalytic action (SNAP-23, -25) in urothelial cells and mucosa (differed in intensity) from rat and human bladder. Incubation of cultured (rat) urothelial cells with BoNT/A decreased expression levels of both SNAP-23 (44%) and SNAP-25 (80%).

CONCLUSIONS

Our findings reveal that the bladder urothelium expresses the intracellular targets and the binding protein for cellular uptake of BoNT/A; and that the toxin is able to suppress the levels of these targets as well as hypotonic-evoked ATP release. These data raise the possibility that intravesical treatment with BoNT/A suppresses bladder reflex and sensory mechanisms by affecting a number of urothelial functions including release of transmitters.

Use of botulinum toxin in individuals with neurogenic detrusor overactivity: state of the art review

BACKGROUND

Botulinum neurotoxin (BoNT) injection into the bladder wall has been shown to be an effective alternative to anticholinergic (antimuscarinic) medications and more invasive surgery in those with multiple sclerosis and spinal cord injury with neurogenic detrusor overactivity (NDO) and urinary incontinence who are not tolerating anticholinergic medications. In August 2011, Botox(®) (onabotulinumtoxinA) received Food and Drug Administration (FDA) approval for this use. Clinically, intradetrusor injection of BoNT has been found to decrease urinary incontinence and improve quality of life. Its impact on urodynamic parameters is an increase in the maximum cystometric (bladder) capacity and decrease in the maximum detrusor pressures. The most common side effects are urinary tract infections and urinary retention. There have been rare reports and a black box warning of distant spread of BoNT. BoNT has gained popularity because of its effectiveness and long duration of action, relative ease of administration, easy learning curve, reproducibility of results on repeated administration, and low incidence of complications.

OBJECTIVE

To discuss the structure and function, mechanisms of action, clinical and urodynamic studies, injection technique, potential beneficial and adverse effects, and potential areas of research of BoNT.

METHODS

Literature search focused on botulinum toxin in MEDLINE/PubMed. Search terms included botulinum toxin, neurogenic bladder, NDO, botox bladder, botox spinal cord injury, botox, FDA, botox side effects. All papers identified were English language, full-text papers. In addition, English abstracts of non-English papers were noted. The reference list of identified articles was also searched for further papers.

CONCLUSION

Botulinum toxin is an alternative treatment for individuals with NDO who fail to tolerate anticholinergic medications. Its popularity has increased because of the literature, which has supported its effectiveness, safety, easy use and learning curve, reproducibility of results on repeated use, and recent FDA approval of Botox(®) (onabotulinumtoxinA).

Bladder management in multiple sclerosis

This article reviews the basic principles and therapeutic options in the management of the neurogenic bladder due to multiple sclerosis (MS), written primarily for the non-urology provider. An algorithm for the initial management of the MS patient with lower urinary tract symptoms is provided.

OnabotulinumtoxinA significantly attenuates bladder afferent nerve firing and inhibits ATP release from the urothelium

OBJECTIVE

To investigate the direct effect of onabotulinumtoxinA (OnaBotA) on bladder afferent nerve activity and release of ATP and acetylcholine (ACh) from the urothelium.

MATERIALS AND METHODS

Bladder afferent nerve activity was recorded using an in vitro mouse preparation enabling simultaneous recordings of afferent nerve firing and intravesical pressure during bladder distension. Intraluminal and extraluminal ATP, ACh, and nitric oxide (NO) release were measured using the luciferin-luciferase and Amplex(®) Red assays (Molecular Probes, Carlsbad, CA, USA), and fluorometric assay kit, respectively. OnaBotA (2U), was applied intraluminally, during bladder distension, and its effect was monitored for 2 h after application. Whole-nerve activity was analysed to classify the single afferent units responding to physiological (low-threshold [LT] afferent <15 mmHg) and supra-physiological (high-threshold [HT] afferent >15 mmHg) distension pressures.

RESULTS

Bladder distension evoked reproducible pressure-dependent increases in afferent nerve firing. After exposure to OnaBotA, both LT and HT afferent units were significantly attenuated. OnaBotA also significantly inhibited ATP release from the urothelium and increased NO release.

CONCLUSION

These data indicate that OnaBotA attenuates the bladder afferent nerves involved in micturition and bladder sensation, suggesting that OnaBotA may exert its clinical effects on urinary urgency and the other symptoms of overactive bladder syndrome through its marked effect on afferent nerves.

Botulinum toxin A detrusor injections reduce postsynaptic muscular M2, M3, P2X2, and P2X3 receptors in children and adolescents who have neurogenic detrusor overactivity: a single-blind study

OBJECTIVE

To analyze the effect of OnabotulinumtoxinA detrusor injections on postsynaptic muscular receptors in children and adolescents with neurogenic detrusor overactivity.

MATERIALS AND METHODS

A bladder augmentation became necessary in 10 children and adolescents (7 males, 3 females; median age, 12 years) who had neurogenic detrusor overactivity. Seven had previously received 1 to 8 (average 3.86) OnabotulinumtoxinA detrusor injections, but their detrusor pressure could not be maintained at tolerable levels because of low-compliance bladder. The last injection session had been completed an average of 3 months (range, 1.5-3.5 months) previously. Three patients had never received that therapy and were considered controls. On the bladder dome resections, a specific receptor analysis (muscarinic M2 and M3 and purinergic P2X1, P2X2, and P2X3) was performed with confocal immunofluorescence, and nerve fiber density was analyzed with light-microscopic 3,3'-diaminobenzidine-immunohistochemical staining.

RESULTS

Receptor analysis showed a downregulation of all examined receptors after OnabotulinumtoxinA injections; the reductions in M2, M3, P2X2, and P2X3 receptors reached a significance level of P <.05 (Mann-Whitney test). The ratios of means (OnabotulinumtoxinA-to-control) were 0.26 for M2, 0.33 for M3, 0.35 for P2X1, 0.19 for P2X2, and 0.37 for P2X3.

CONCLUSION

OnabotulinumtoxinA detrusor injections led to significant reductions in muscular M2, M3, P2X2, and P2X3 receptors. The reductions probably affect the generated force in the urinary bladder and could contribute to the clinically observed increase in residual urine.