Urodynamic and immunohistochemical evaluation of intravesical botulinum toxin A delivery using liposomes

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.

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.

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.

Treating Lower Urinary Tract Symptoms in Older Adults: Intravesical Options

This article provides an overview of the diagnosis and the treatment of lower urinary tract symptoms in older adults complicated by the neurodegenerative changes in the micturition reflex and further confounded by age-related decline in hepatic and renal clearance raising the propensity of adverse drug reactions. The first-line drug treatment for lower urinary tract symptoms, orally administered antimuscarinics, fails to reach the equilibrium dissociation constant of muscarinic receptors even at their maximum plasma concentration and tends to evoke a half-maximal response at a muscarinic receptor occupancy of just 0.206% in the bladder with a minimal difference from exocrine glands, which raises the adverse drug reaction risk. On the contrary, intravesical antimuscarinics are instilled at concentrations 1000-fold higher than the oral maximum plasma concentration and the equilibrium dissociation constant erects a downhill concentration gradient that drives passive diffusion and achieves a mucosal concentration around ten-fold lower than the instilled concentration for a long-lasting occupation of muscarinic receptors in mucosa and sensory nerves. A high local concentration of antimuscarinics in the bladder triggers alternative mechanisms of action and is supposed to engage retrograde transport to nerve cell bodies for neuroplastic changes that underlie a long-lasting therapeutic effect, while an intrinsically lower systemic uptake of the intravesical route lowers the muscarinic receptor occupancy of exocrine glands to lower the adverse drug reaction relative to the oral route. Thus, the traditional pharmacokinetics and pharmacodynamics of oral treatment are upended by intravesical antimuscarinics to generate a dramatic improvement (~ 76%) noted in a meta-analysis of studies enrolling children with neurogenic lower urinary tract symptoms on the primary endpoint of maximum cystometric bladder capacity as well as the secondary endpoints of filling compliance and uninhibited detrusor contractions. The therapeutic success of intravesical multidose oxybutynin solution or oxybutynin entrapped in the polymer for sustained release in the pediatric population bodes well for patients with lower urinary tract symptoms at the other extreme of the age spectrum. Though generally used to predict oral drug absorption, Lipinski's rule of five can also explain the ten-fold lower systemic uptake from the bladder of positively charged trospium over oxybutynin, a tertiary amine. Chemodenervation by an intradetrusor injection of onabotulinumtoxinA is merited for patients with idiopathic overactive bladder discontinuing oral treatment because of a lack of efficacy. However, age-related peripheral neurodegeneration potentiates the adverse drug reaction risk of urinary retention that motivates the quest of liquid instillation, delivering larger fraction of onabotulinumtoxinA to the mucosa as opposed to muscle by an intradetrusor injection can also probe the neurogenic and myogenic predominance of idiopathic overactive bladder. Overall, the treatment paradigm of lower urinary tract symptoms in older adults should be tailored to individual's overall health status and the risk tolerance for adverse drug reactions.

Botulinum Toxin Therapy for Bladder Pain Syndrome/Interstitial Cystitis

Purpose of Review

Bladder pain syndrome (BPS)/interstitial cystitis (IC) can also be classified as either non-ulcerative or ulcerative, corresponding to the characteristic cystoscopic findings under hydrodistention. Promising therapeutic effects, including decreased bladder pain, have been reported from recent clinical trials using botulinum toxin A (BoNTA) for the treatment of BPS/IC. This review summarizes the current state of the literature on the underlying mechanisms of BoNTA therapy in BPS/IC as well as new forms of its application.

Recent Findings

BoNTA has its effect in the central nervous system in the afferent nerves as well as in the bladder wall. Besides the well-known effects of BoNTA in the nervous system, pain control as well as reduction of urinary urgency in BPS patients could be achieved by mast cell stabilization effecting histamine release as well as modulation of TRPV and PGE2 pathways, among other systems. In addition, new forms of BoNTA administration have focused on intravesical instillation of the drug in order to circumvent bladder wall injections. Hyperthermia, intravesical hydrogel, and lysosomes have been studied as new ways of BoNTA application in BPS/IC patients. From the available studies, bladder instillation of BoNTA in combination with EMDA is the most promising and effective novel approach.

Summary

The most promising novel application methods for BoNTA in patient with BPS/IC are bladder instillations. Future research needs to point out if bladder instillations with BoNTA with some form of bladder absorption enhancement such as hyperthermia or EMDA would be able to replace BoNTA injections in patients with BPS/IC

Liposome-Encapsulated Botulinum Toxin A in Treatment of Functional Bladder Disorders

Botulinum toxin A (BoNT-A) intravesical injections have been used to treat patients with refractory functional bladder disorders such as overactive bladder (OAB) and interstitial cystitis/bladder pain syndrome (IC/BPS), but the risk of adverse events and the need for repeated injections continue to prevent widespread application of this treatment. Liposomes are vesicles that comprise concentric phospholipid layers and an aqueous core; their flexible compositions enable them to adsorb and fuse with cell membranes and to deliver drugs or proteins into cells. Therefore, liposomes have been considered as promising vehicles for the less invasive delivery of BoNT-A. In previous placebo-controlled trials including patients with OAB refractory to medical treatment, it was shown that liposomal BoNT-A could significantly decrease the frequency and urgency of urination. In patients with IC/BPS, it was shown that liposomal BoNT-A could also improve bladder pain, but the therapeutic efficacy was not superior to that of the placebo. As the therapeutic mechanisms of BoNT-A include the decreased expression of nerve growth factors, P2X3 receptors, and vanilloid receptors on C-fibers, liposomal BoNT-A might play a more promising role in the treatment of bladder oversensitivity. This article features the contemporary literature regarding BoNT-A, liposomes, and liposomal BoNT-A treatment for functional bladder disorders and potential clinical applications in the future.

Quercetin Loaded Cationic Solid Lipid Nanoparticles in a Mucoadhesive In Situ Gel-A Novel Intravesical Therapy Tackling Bladder Cancer

The study aim was to develop an intravesical delivery system of quercetin for bladder cancer management in order to improve drug efficacy, attain a controlled release profile and extend the residence time inside the bladder. Either uncoated or chitosan coated quercetin-loaded solid lipid nanoparticles (SLNs) were prepared and evaluated in terms of colloidal, morphological and thermal characteristics. Drug encapsulation efficiency and its release behaviour were assessed. Furthermore, cytotoxicity of SLNs on T-24 cells was evaluated. Ex vivo studies were carried out using bovine bladder mucosa. Spherical SLNs (≈250 nm) ensured good entrapment efficiencies (EE > 97%) and sustained drug release up to 142 h. Cytotoxicity profile revealed concentration-dependent toxicity recording an IC50 in the range of 1.6−8.9 μg/mL quercetin. SLNs were further dispersed in in situ hydrogels comprising poloxamer 407 (20%) with mucoadhesive polymers. In situ gels exhibited acceptable gelation temperatures (around 25 °C) and long erosion time (24−27 h). SLNs loaded gels displayed remarkably enhanced retention on bladder tissues relative to SLNs dispersions. Coated SLNs exhibited better penetration abilities compared to uncoated ones, while coated SLNs dispersed in gel (G10C-St-QCT-SLNs-2) showed the highest penetration up to 350 μm. Hence, G10C-St-QCT-SLNs-2 could be considered as a platform for intravesical quercetin delivery.

Nanotechnology as a tool to advance research and treatment of non-oncologic urogenital diseases

Nanotechnology represents an expanding area of research and innovation in almost every field of science, including Medicine, where nanomaterial-based products have been developed for diagnostic and therapeutic applications. Because of their small, nanoscale size, these materials exhibit unique physical and chemical properties that differ from those of each component when considered in bulk. In Nanomedicine, there is an increasing interest in harnessing these unique properties to engineer nanocarriers for the delivery of therapeutic agents. Nano-based drug delivery platforms have many advantages over conventional drug administration routes as this technology allows for local and transdermal applications of therapeutics that can bypass the first-pass metabolism, improves drug efficacy through encapsulation of hydrophobic drugs, and allows for a sustained and controlled release of encapsulated agents. In Urology, nano-based drug delivery platforms have been extensively investigated and implemented for cancer treatment. However, there is also great potential for use of nanotechnology to treat non-oncologic urogenital diseases. We provide an update on research that is paving the way for clinical translation of nanotechnology in the areas of erectile dysfunction (ED), overactive bladder (OAB), interstitial cystitis/bladder pain syndrome (IC/BPS), and catheter-associated urinary tract infections (CAUTIs). Overall, preclinical and clinical studies have proven the utility of nanomaterials both as vehicles for transdermal and intravesical delivery of therapeutic agents and for urinary catheter formulation with antimicrobial agents to treat non-oncologic urogenital diseases. Although clinical translation will be dependent on overcoming regulatory challenges, it is inevitable before there is universal adoption of this technology to treat non-oncologic urogenital diseases.

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.

Emerging molecular mechanisms and genetic targets for developing novel therapeutic strategies for treating bladder diseases

Bladder diseases affect millions of patients worldwide and compromise their quality of life with a substantial economic impact. The not fully understood aetiologies of bladder diseases limit the current diagnosis and therapeutic options to primarily symptomatic treatment. In addition, bladder targeted drug delivery is challenging due to its unique anatomical features and its natural physiological function of urine storage and frequent voiding. Therefore, current treatment options often fail to provide a highly effective, precisely targeted and long-lasting treatment. With the growing maturity of gene therapy, comprehensive studies are needed to provide a better understanding of the molecular mechanisms underpinning bladder diseases and help to identify novel gene therapeutic targets and biomarkers for treating bladder diseases. In this review, molecular mechanisms involved in pathology of bladder cancer, interstitial cystitis and overactive bladder syndrome are reviewed, with focus on establishing potential novel treatment options. Proposed novel therapies, including gene therapy combined with nanotechnology, localised drug delivery by nanoparticles, and probiotics, are discussed in regard to their safety profiles, efficacy, treatment lenght, precise targeting, and in comparison to conventional treatment methods.

The clinical application of intravesical botulinum toxin A injection in patients with overactive bladder and interstitial cystitis

Botulinum toxin A (BoNT-A) has been widely used in several urological functional disorders including neurogenic detrusor overactivity (NDO), overactive bladder (OAB), lower urinary tract dysfunction, and interstitial cystitis/bladder pain syndrome (IC/BPS). Chronic inflammation is found in a large proportion of patients with OAB and IC/BPS. The chronic inflammation activates sensory afferents which resulting in central sensitization and bladder storage symptoms. Because BoNT-A can inhibit the sensory peptides released from the vesicles in sensory nerve terminals, the inflammation can be reduced and symptom subsided. Previous studies have demonstrated that the quality of life improved after BoNT-A injections, both in neurogenic and non-NDO. Although the use of BoNT-A in treatment of IC/BPS has not been approved by FDA, intravesical BoNT-A injection has been included in the AUA guideline as the fourth line therapy. Generally, intravesical injections of BoNT-A are well tolerated, though transient hematuria and urinary tract infection can occur after the procedure. In order to prevent these adverse events, experimental trials have been conducted to test if BoNT-A can be delivered into the bladder wall without intravesical injection under anesthesia such as using liposomes encapsulated BoNT-A or application of low energy shock wave on the bladder to facilitate BoNT-A penetrating across the urothelium and treat OAB or IC/BPS. This article reviews current clinical and basic researches of BoNT-A on OAB and IC/BPS.

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.

Pharmacological Management of Urinary Incontinence: Current and Emerging Treatment

Pharmacological management of urinary incontinence (UI) is currently based on antimuscarinic and beta-3-agonist drugs. Botulinum toxin A detrusor injections represent an effective but more invasive alternative. This review covers the latest developments of the currently available drugs and the emerging compounds for the treatment of UI. Evidence shows that new antimuscarinics and beta-3-agonists with improved safety profiles may offer unique options to patients intolerant to currently available drugs. Combination therapy proved to be a non-invasive alternative for patients refractory to first-line monotherapy. Exciting advances are ongoing in the research to improve the efficacy/tolerability profile of botulinum toxin, through innovative routes of administration. Several new agents emerged from preclinical studies, some of which have now entered the clinical phase of development and could represent, in the coming years, a new way for the treatment of UI. Recent evidence on the existence of different overactive bladder phenotypes could be the key to tailored treatment. Rather than discovering new molecules, reaching the ability to identify the right drug for the right patient could be the real gamechanger of the future.

Novel Applications of Non-Invasive Intravesical Botulinum Toxin a Delivery in the Treatment of Functional Bladder Disorders

Although intravesical botulinum toxin type A (BoNT-A) injection for functional bladder disorders is effective, the injection-related problems-such as bladder pain and urinary tract infection-make the procedure invasive and inconvenient. Several vehicles have recently been developed to deliver BoNT-A without injection, thereby making the treatment less or non-invasive. Laboratory evidence revealed that liposome can carry BoNT-A across the uroepithelium and act on sub-urothelial nerve endings. A randomized placebo controlled study revealed that intravesical administration of liposome-encapsulated BoNT-A and TC-3 hydrogel embedded BoNT-A can improve urinary frequency, urgency, and reduce incontinence in patients with overactive bladders. A single-arm prospective study also revealed that intravesical administration of TC-3 hydrogel embedded BoNT-A can relieve bladder pain in patients with interstitial cystitis/bladder pain syndrome (IC/BPS). We recently administered suprapubic energy shock wave (ESW) after BoNT-A intravesical administration in six patients with IC/BPS. Although pain reduction and symptom improvement were not significant, immunochemical staining showed cleaved synaptosome-associated protein 25 in the bladder after the procedure. This suggests that ESW can promote passage of BoNT-A across the uroepithelium. In conclusion, using vehicles to intra-vesically deliver BoNT-A for functional bladder disorders is promising. Further studies are necessary to confirm the efficacy and explore novel applications.

Natural and Designed Toxins for Precise Therapy: Modern Approaches in Experimental Oncology

Cancer cells frequently overexpress specific surface receptors providing tumor growth and survival which can be used for precise therapy. Targeting cancer cell receptors with protein toxins is an attractive approach widely used in contemporary experimental oncology and preclinical studies. Methods of targeted delivery of toxins to cancer cells, different drug carriers based on nanosized materials (liposomes, nanoparticles, polymers), the most promising designed light-activated toxins, as well as mechanisms of the cytotoxic action of the main natural toxins used in modern experimental oncology, are discussed in this review. The prospects of the combined therapy of tumors based on multimodal nanostructures are also discussed.

Drug Delivery Approaches for Managing Overactive Bladder (OAB): A Systematic Review

Overactive bladder syndrome (OAB) is characterised by urgency symptoms, with or without urgency incontinence, usually with frequency and nocturia and severely affects the quality of life. This systematic review evaluates the various drug delivery strategies used in practice to manage OAB. Advanced drug delivery strategies alongside traditional strategies were comprehensively analysed and comparatively evaluated. The present review was conducted according to the preferred reporting items for systematic reviews and meta-analyses guidelines. A total of 24 studies reporting the development of novel formulations for the treatment of OAB were considered eligible and were further categorised according to the route of drug administration. The review found that various drug delivery routes (transdermal, intravesicular, oral, vaginal and intramuscular) are used for the administration of drugs for managing OAB, however, the outcomes illustrated the marked potential of transdermal drug delivery route. The findings of the current review are expected to be helpful for pharmaceutical scientists to better comprehend the existing literature and challenges and is anticipated to provide a basis for designing and fabricating novel drug delivery systems to manage OAB.

Local drug delivery systems for inflammatory diseases: Status quo, challenges, and opportunities

Inflammation that is not resolved in due course becomes a chronic disease. The treatment of chronic inflammatory diseases involves a long-term use of anti-inflammatory drugs such as corticosteroids and nonsteroidal anti-inflammatory drugs, often accompanied by dose-dependent side effects. Local drug delivery systems have been widely explored to reduce their off-target side effects and the medication frequency, with several products making to the market or in development over the years. However, numerous challenges remain, and drug delivery technology is underutilized in some applications. This review showcases local drug delivery systems in different inflammatory diseases, including the targets well-known to drug delivery scientists (e.g., joints, eyes, and teeth) and other applications with untapped opportunities (e.g., sinus, bladder, and colon). In each section, we start with a brief description of the disease and commonly used therapy, introduce local drug delivery systems currently on the market or in the development stage, focusing on polymeric systems, and discuss the remaining challenges and opportunities in future product development.

Biomaterial-assisted drug delivery for interstitial cystitis/bladder pain syndrome treatment

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic and painful bladder condition afflicting patients with increased urinary urgency and frequency as well as incontinence. Owing to the elusive pathogenesis of IC/BPS, obtaining effective therapeutic outcomes remains challenging. Current administrational routes such as intravesical-bladder injection improve the treatment efficacy and reduce systemic side effects. However, the bladder permeability barrier hinders drug penetration into the bladder wall to meet the desired therapeutic expectation. These issues can be addressed by encapsulating drugs into biomaterials. When appropriately exploited, they would increase the drug dwelling time in the bladder, enhance the penetration of mucosa and improve the therapeutic response of IC/BPS. In this review, we first elucidate the pathogenesis and animal models of IC/BPS. Then, we highlight recent representative biomaterial-assisted drug delivery systems for IC/BPS treatment. Finally, we discuss the challenges and outlook for further developing biomaterial-based delivery systems for IC/BPS management.

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.

Therapeutic Efficacy of onabotulinumtoxinA Delivered Using Various Approaches in Sensory Bladder Disorder

Cystoscopic onabotulinumtoxinA (onaBoNTA) intradetrusor injection is an efficient and durable modality for treating sensory bladder disorders. However, the inconvenience of using the cystoscopic technique and anesthesia, and the adverse effects of direct needle injection (e.g., haematuria, pain, and infections) have motivated researchers and clinicians to develop diverse injection-free procedures to improve accessibility and prevent adverse effects. However, determining suitable approaches to transfer onaBoNTA, a large molecular and hydrophilic protein, through the impermeable urothelium to reach therapeutic efficacy remains an unmet medical need. Researchers have provided potential solutions in three categories: To disrupt the barrier of the urothelium (e.g., protamine sulfate), to increase the permeability of the urothelium (e.g., electromotive drug delivery and low-energy shock wave), and to create a carrier for transportation (e.g., liposomes, thermosensitive hydrogel, and hyaluronan-phosphatidylethanolamine). Thus far, most of these novel administration techniques have not been well established in their long-term efficacy; therefore, additional clinical trials are warranted to validate the therapeutic efficacy and durability of these techniques. Finally, researchers may make progress with new combinations or biomaterials to change clinical practices in the future.

Clinical application of intravesical botulinum toxin type A for overactive bladder and interstitial cystitis

After decades of clinical and basic science research, the clinical application of botulinum toxin A (Botox) in urology has been extended to neurogenic detrusor overactivity (NDO), idiopathic detrusor overactivity, refractory overactive bladder (OAB), interstitial cystitis/bladder pain syndrome (IC/BPS), lower urinary tract symptoms, benign prostatic hyperplasia, and neurogenic or non-neurogenic lower urinary tract dysfunction in children. Botox selectively disrupts and modulates neurotransmission, suppresses detrusor overactivity, and modulates sensory function, inflammation, and glandular function. In addition to motor effects, Botox has been found to have sensory inhibitory effects and anti-inflammatory effects; therefore, it has been used to treat IC/BPS and OAB. Currently, Botox has been approved for the treatment of NDO and OAB. Recent clinical trials on Botox for the treatment of IC/BPS have reported promising therapeutic effects, including reduced bladder pain. Additionally, the therapeutic duration was found to be longer with repeated Botox injections than with a single injection. However, the use of Botox for IC/BPS has not been approved. This paper reviews the recent advances in intravesical Botox treatment for OAB and IC/BPS.

Botulinum toxin A for refractory OAB and idiopathic urinary retention: Can phenotyping improve outcome for patients: ICI-RS 2019?

AIMS

Botulinum toxin A (BTX-A) is a well-established treatment for refractory idiopathic overactive bladder (OAB). It has also been used with short-term success in treating idiopathic urinary retention. However, efficacy and complication rates are variable and predicting those likely to benefit most from treatment would enable personalization of therapy and optimization of outcomes. At the International Consultation on Incontinence-Research Society (ICI-RS) meeting in 2019 a Think Tank addressed the question of how we can improve the way we phenotype patients undergoing BTX-A treatment.

METHODS

The Think Tank conducted a literature review and expert consensus meeting focussing on how advances in basic science research of the mechanism of action of BTX-A, as well as assessment of psychological comorbidity, can be translated into clinical practice to improve patient selection for therapy.

RESULTS

Idiopathic OAB and idiopathic urinary retention are heterogenous conditions encompassing several phenotypes with multiple potential pathophysiological mechanisms. Animal models have demonstrated a central nervous system mechanism of action of intravesically injected BTX-A and this has been confirmed in human functional MRI studies, but whether this tool can be used to predict outcome from treatment remains to be determined. Phenotyping based on psychological comorbidity using validated screening tools should be studied as a way to potentially optimize patient selection for therapy.

CONCLUSIONS

Advances in basic science research into the mechanism of action of BTX-A have improved our understanding of the pathophysiology of OAB and may lead to novel ways to phenotype patients. Psychological assessment is another way in which phenotyping may be improved. Areas for further research are proposed.

Managing urinary incontinence in women - a review of new and emerging pharmacotherapy

INTRODUCTION

The pharmacological treatment of urinary incontinence and overactive bladder (OAB) has been, for a longer time, based on antimuscarinic agents. In recent years, two other pharmacological principles have been introduced for the treatment of OAB and urgency urinary incontinence: the β3-adrenergic agent mirabegron and botulinum neurotoxin. Meanwhile, there is lack of effective drugs for the treatment of stress incontinence.

AREAS COVERED

This literature review presents synthetic compounds aimed to treat female urinary incontinence that are in phase II-III clinical development.

EXPERT OPINION

Antimuscarinic agents will continue to represent the current gold standard for the first-line pharmacological management of OAB and urgency urinary incontinence. The class of β3-agonists will certainly expand with the discovery and clinical development of novel agents. Combination therapy of antimuscarinic agents and β3-agonists could offer an alternative treatment in these patients, including those with symptoms refractory to first-line monotherapy. A huge number of preclinical studies are underway in this field exploring the therapeutic potential of many novel compounds while some have advanced to clinical phases of development.

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.

Role of neurogenic inflammation in local communication in the visceral mucosa

Intense research has focused on the involvement of the nervous system in regard to cellular mechanisms underlying neurogenic inflammation in the pelvic viscera. Evidence supports the neural release of inflammatory factors, trophic factors, and neuropeptides in the initiation of inflammation. However, more recently, non-neuronal cells including epithelia, endothelial, mast cells, and paraneurons are likely important participants in nervous system functions. For example, the urinary bladder urothelial cells are emerging as key elements in the detection and transmission of both physiological and nociceptive stimuli in the lower urinary tract. There is mounting evidence that these cells are involved in sensory mechanisms and can release mediators. Further, localization of afferent nerves next to the urothelium suggests these cells may be targets for transmitters released from bladder nerves and that chemicals released by urothelial cells may alter afferent excitability. Modifications of this type of communication in a number of pathological conditions can result in altered release of epithelial-derived mediators, which can activate local sensory nerves. Taken together, these and other findings highlighted in this review suggest that neurogenic inflammation involves complex anatomical and physiological interactions among a number of cell types in the bladder wall. The specific factors and pathways that mediate inflammatory responses in both acute and chronic conditions are not well understood and need to be further examined. Elucidation of mechanisms impacting on these pathways may provide insights into the pathology of various types of disorders involving the pelvic viscera.

Potential Orphan Drug Therapy of Intravesical Liposomal Onabotulinumtoxin-A for Ketamine-Induced Cystitis by Mucosal Protection and Anti-inflammation in a Rat Model

Ketamine abusers may develop ulcerative cystitis and severe lower urinary tract symptoms, which is a medical dilemma. Recently, researchers have found the endemic of ketamine-induced cystitis worldwide. The intravesical administration of liposome-encapsulated onabotulinumtoxinA (Lipotoxin) might facilitate the healing of the damaged urothelium from liposomes, and reduce the urinary symptoms by onabotulinumtoxinA-induced chemo-denervation. Using female Sprague-Dawley rats, we investigated the effects of Lipotoxin on ketamine-induced cystitis. Functional magnetic resonance imaging, metabolic cage study, and cystometry were conducted. Paraffin-embedded sections were stained. The bladder mucosa and muscle proteins were assessed through Western blotting. We observed that repeated intravesical Lipotoxin instillation could improve suburothelial hemorrhage, recover the urothelial tight junction and adhesion proteins (zonula occludens-1 and E-cadherin), ensure less substance P in the urothelium, inhibit the overexpression of inflammatory mediators (IL-6, TNF-α, nuclear NF-κB, and COX-2) in the detrusor, suppress the upregulation of the mucosal TRPV1 and detrusor M₂-mAChR, and ameliorate bladder overactivity in the ketamine-treated rats. These data reveal the mechanisms underlying the action of Lipotoxin in ketamine-induced cystitis of rats, which provide a basis of Lipotoxin for further treating ketamine-induced cystitis in humans.

Early experimental results of using a novel delivery carrier, hyaluronan-phosphatidylethanolamine (HA-PE), which may allow simple bladder instillation of botulinum toxin A as effectively as direct detrusor muscle injection

INTRODUCTION

Botulinum toxin A (BTX-A) is a neurotoxin that inhibits acetylcholine release by cleaving cytosolic synaptosome-associated protein 25 (SNAP-25) and results in bladder relaxation. A BTX-A intravesical injection has been established as an effective option for treating detrusor overactivity.

STUDY DESIGN

Sixty female Sprague Dawley rats were equally divided into control and experimental groups. Control Groups 1 to 3 received: BTX-A 10 units + saline instillation; hyaluronan-phosphatidylethanolamine (HA-PE) 0.5 g + saline instillation; and BTX-A 5 Uintra-detrusor injections, respectively. Treatment Groups 4 to 6 received: Alexa^®594-labeled BTX-A 10 U + HA-PE 0.5 g + saline instillation; BTX-A 5 U + HA-PE 0.2-0.5 g instilled for 60 min; and BTX-A 10 U + HA-PE 0.2-0.5 g instilled for 30 min, respectively. All procedures were performed under isoflurane general anesthesia. The primary outcome of this study was the degree of SNAP-25 staining in control and experimental groups compared to Group 3 (detrusor muscle injection). Urodynamic studies were performed at baseline and at day 14 after 1% acetic acid (AA) instillation, to evaluate the maximum pressure during filling (MP) and inter-contraction intervals (ICI). Group 4 rats were examined for Alexa^®594 fluorescence to demonstrate physical translocation of BTX-A-HA-PE complex. Standard histology was performed to assess the effect of HA-PE on bladder mucosa and detrusor muscle.

RESULTS

Group 3 showed the least SNAP-25 staining (7.3 ± 5.0%) compared with all groups except Group 5A (12.4 ± 12.27%, P = 1.0). Group 6A, which had high HA-PE dose but a shorter instillation time, showed fairly extensive SNAP-25 staining (22.9 ± 10%). Confocal microscopy of Group 4 confirmed the presence of Alexa^®594 fluorescence across the urothelium. Urodynamic parameters were not significantly different at baseline (P = 1.0). After acetic acid instillation, Group 5A showed minimal change in ICI, which was comparable to ICI in Group 3 rats.

DISCUSSION

SNAP-25 staining in Group 5A was comparable to Group 3, suggesting that adequate HA-PE and instillation time allows the efficacy of this carrier mechanism to be comparable to standard intra-detrusor injections. All other groups showed significantly higher SNAP-25 staining compared to Group 3. A dose response effect was demonstrated; higher dose of HA-PE (Group 5A vs Group 5B) and longer instillation time (Group 5 vs Group 6) led to lower SNAP-25 staining.

CONCLUSION

This novel method of BTX-A delivery to the bladder using a carrier (HA-PE) is promising and requires further investigation. Using a larger animal model, identifying an optimal dose of HA-PE and instillation time, and reproducing the current results are further required to validate this carrier.

The efficacy of botulinum toxin A and sacral neuromodulation in the management of interstitial cystitis (IC)/bladder pain syndrome (BPS), what do we know? ICI-RS 2017 think thank, Bristol

AIMS

This manuscript aims to address the evidence availale in the literature on the efficacy of Botulinum Toxin A (BoNT-A) and sacral neuromodulation (SNM) in patients suffering from Interstitial Cystitis (IC)/BPS and propose further research to identify mechanisms of action and establish the clinical efficacy of either therapy.

METHODS

At the International Consultation on Incontinence-Research Society (ICI-RS) in 2017, a panel of Functional Urologists and Urogynaecologists participated in a Think Tank (TT) discussing the management of IC/BPS by BoNT-A and SNM, using available data from both PubMed and Medicine literature searches.

RESULTS

The role of BoNT-A and SNM in the treatment of IC/BPS are discussed and mechanisms of actions are proposed. Despite the available randomized trial data on the effect of intravesical BoNT-A treatment on symptoms of IC/BPS, a consistent conclusion of a positive effect cannot be drawn at the moment, as the published studies are small and heterogeneous in design. There is substantive evidence for the positive effects of SNM on symptoms of IC/BPS patients however, during patient selection, it is important to distinguish the degree and the location of pain in order to tailor the best therapy to the right patients.

CONCLUSIONS

Both intravesical BoNT-A treatment and SNM have been shown to have positive effects in patients with IC/BPS. However, firm conclusions cannot yet be drawn. Patient-reported outcomes and quality of life should be assessed in addition to urinary and pain symptoms. Since current treatments mainly focus on symptomatic relief, future research should also focus on clarifying the pathogenic mechanisms involved in IC/BPS.

Use of botulinum toxin for voiding dysfunction

The use of botulinum toxin A (BoNT-A) has expanded across a range of lower urinary tract conditions. This review provides an overview of the current indications for BoNT-A in the lower urinary tract and critically evaluates the published evidence within each area. The classic application of BoNT-A has been in the management of refractory neurogenic detrusor overactivity (NDO) and overactive bladder (OAB). There is a large volume of high-quality evidence, including numerous randomized placebo-controlled trials, which demonstrate the efficacy of BoNT-A over a long follow-up period. The culmination of this robust evidence-base has led to onabotulinumtoxin A (onaBoNT-A) receiving regulatory approval as a second-line treatment for NDO at a dose of 200 U and OAB at dose of 100 U. Other applications for BoNT-A are used on an off-license basis and include interstitial cystitis/bladder pain syndrome (IC/BPS), benign prostatic hyperplasia (BPH), and detrusor sphincter dyssynergia (DSD). These applications are associated with a less mature evidence-base although the literature is rapidly evolving. At present, the results for painful bladder syndrome (PBS) are promising and BoNT-A injections are recommended as a fourth line option in recent international guidelines, although larger randomized study with longer follow-up are required to confirm the initial findings. As a treatment for DSD, BoNT-A injections have shown potential but only in a small number of trials of limited quality. No definite recommendation can be made based on the current evidence. Finally, the results for the treatment of BPH have been variable and recent high quality randomized controlled trials (RCTs) have suggested no benefit over placebo so at present it cannot be recommended for routine clinical practice. Future advances of BoNT-A include liposome encapsulated formulations which are being developed as an alternative to intravesical injections.

Nanotechnology in Urology

Introduction:

Nanotechnology has revolutionized our approach to medical diagnostics as well as therapeutics and has spanned an entirely new branch of research. This review addresses the potential applications of Nanotechnology in Urology. This article is based on the Dr. Sitharaman Best Essay award of the Urological Society of India for 2016.

Methods:

A PubMed search was performed for all relevant articles using the terms, “nanotechnology, nanoparticles, nanoshells, nanoscaffolds, and nanofibers.”

Results:

The developments in diagnostics include novel techniques of imaging of genitourinary malignancies, prostate-specific antigen measurement, early detection of mutations that are diagnostic for polycystic kidney disease. The potential applications of nanotechnology are in the targeted therapy of genitourinary malignancies, erectile dysfunction, overactive bladder, bladder reconstruction, construction of artificial kidneys and biodegradable stents as well as in robotic surgery.

Conclusions:

Nanotechnology is a rapidly emerging branch of research in urology with diverse and clinically significant applications in diagnostics as well as therapeutics.

A Prospective, Multicenter, Double-Blind, Randomized Trial of Bladder Instillation of Liposome Formulation OnabotulinumtoxinA for Interstitial Cystitis/Bladder Pain Syndrome

PURPOSE

Intravesical instillation of liposomal formulated botulinum toxin A (lipotoxin) has shown therapeutic effects as treatment of refractory overactive bladder without needle injections. We assessed lipotoxin to treat refractory interstitial cystitis/bladder pain syndrome.

MATERIALS AND METHODS

This 2-center, double-blind, randomized, placebo controlled, physician initiated study enrolled patients with refractory interstitial cystitis/bladder pain syndrome. A total of 31 patients were assigned to intravesical instillation of lipotoxin (onabotulinumtoxinA 200 U with 80 mg sphingomyelin), 28 were assigned to onabotulinumtoxinA 200 U in normal saline and 31 were assigned to normal saline alone. The primary end point was the average change in O'Leary-Sant symptom scores, including ICSI (Interstitial Cystitis Symptom Index) and ICPI (Interstitial Cystitis Problem Index) between baseline and 4 weeks after treatment. Other end points included the average changes in a 3-day voiding diary, a visual analog scale for pain and a global response assessment of patient satisfaction.

RESULTS

Improvements in the pain scale and O'Leary-Sant symptom scores occurred in all 3 groups by 4 weeks after treatment. Lipotoxin instillation was associated with a statistically significant decrease in O'Leary-Sant symptom scores (mean ± SD 7.38 ± 8.75), ICSI (4.00 ± 4.28), ICPI (3.35 ± 5.11) and the visual analog scale pain scale (1.64 ± 2.52), and an increase in the global response assessment (1.35 ± 1.28). However, there was no difference in improvement among the 3 groups. No significant adverse events were found in any group.

CONCLUSIONS

Lipotoxin failed to demonstrate a positive proof of concept compared to onabotulinumtoxinA or placebo. However, a single intravesical instillation of lipotoxin was associated with decreased interstitial cystitis/bladder pain syndrome symptoms compared to baseline in patients with moderate to severe interstitial cystitis/bladder pain syndrome. The effect was likely due to a significant placebo effect.

Past, Present and Future of Chemodenervation with Botulinum Toxin in the Treatment of Overactive Bladder

PURPOSE

We systematically reviewed preclinical and clinical studies on bladder chemodenervation with onabotulinumtoxin A to highlight current limitations and future drug delivery approaches.

MATERIALS AND METHODS

We identified peer reviewed basic and clinical research studies of onabotulinumtoxin A in the treatment of neurogenic bladder and refractory idiopathic overactive bladder published between March 2000 and March 2016. Paired investigators independently screened 125 English language articles to identify controlled studies on onabotulinumtoxin A administration in the MEDLINE® database and abstracts presented at annual American Urological Association meetings. The review yielded an evidence base of more than 50 articles relevant to the approach of injection-free onabotulinumtoxin A chemodenervation.

RESULTS

The efficacy and safety of intradetrusor injection of onabotulinumtoxin A for the treatment of overactive bladder are sensitive to injection volume and depth, and this issue has motivated researchers to study injection-free modes of drug delivery into the bladder. Urothelial denudation with protamine sulfate or dimethyl sulfoxide, liposome encapsulated onabotulinumtoxin A and other physical approaches are being studied to increase toxin permeability and avoid intradetrusor injections. Liposome encapsulated onabotulinumtoxin A enhances toxin activity while reducing its toxin degradation. The safety and efficacy of liposome encapsulated onabotulinumtoxin A were tested in a multicenter, placebo controlled study. Although this treatment successfully reduced urinary frequency and urgency, it did not significantly reduce urgency urinary incontinence episodes.

CONCLUSIONS

Intradetrusor injection of onabotulinumtoxin A is a safe and effective treatment as reported in several large multicenter, randomized controlled trials. Injection of the toxin into the bladder wall impairs afferent and efferent nerves, but injection-free drug delivery approaches only impair the bladder afferent nerves. Further studies are needed to develop better drug delivery platforms that overcome the drawbacks of intradetrusor injection, increase patient acceptance and reduce treatment costs.

Investigational drugs for bladder pain syndrome (BPS) / interstitial cystitis (IC)

INTRODUCTION

Bladder pain syndrome (BPS)/interstitial cystitis (IC) is associated with sensory lower urinary tract symptoms. Unfortunately, many of the existing oral treatments are ineffective in most patients of BPS/IC, which is the motivation for developing new drugs and therapeutic approaches. This review covers the latest drugs that have been investigated in BPS/IC patients. Intravesical treatments offer the opportunity to directly target the painful bladder with less systemic side effects.

AREAS COVERED

In this review, the authors analyze the existing literature supporting the treatment of BPS/IC with conventional drugs including heparin, hyaluronic acid, chondroitin sulfate, and dimethylsulfoxide (DMSO). Furthermore, investigational drugs such as tanezumab and adalimumab, capable of sequestering nerve growth factor (NGF), and Tumor necrosis factor-α (TNF- α) are discussed. Investigational treatments such as liposomes, botulinum toxin (BTX), liposomal BTX, PD-0299685 (a Ca(2+) channel ɑ2δ ligand), continuous intravesical lidocaine, and AQX-1125 (a novel SHIP1 activating compound) are also covered.

EXPERT OPINION

New investigational drugs offer promising improvements in clinical outcomes for BPS/IC patients; however, BPS/IC is a chronic pain disorder that is very vulnerable to a strong placebo effect. In addition, BPS/IC is a heterogeneous disorder that can be classified into several phenotypes. Since different phenotypes of BPS/IC respond differently to systemic and intravesical treatments, the authors believe that new drugs developed for BPS/IC are more likely to meet their predetermined clinical endpoints if the inclusion/exclusion criterion is tailored to specific phenotype of BPS/IC patients.

Potential Effect of Liposomes and Liposome-Encapsulated Botulinum Toxin and Tacrolimus in the Treatment of Bladder Dysfunction

Bladder drug delivery via catheter instillation is a widely used treatment for recurrence of superficial bladder cancer. Intravesical instillation of liposomal botulinum toxin has recently shown promise in the treatment of overactive bladder and interstitial cystitis/bladder pain syndrome, and studies of liposomal tacrolimus instillations show promise in the treatment of hemorrhagic cystitis. Liposomes are lipid vesicles composed of phospholipid bilayers surrounding an aqueous core that can encapsulate hydrophilic and hydrophobic drug molecules to be delivered to cells via endocytosis. This review will present new developments on instillations of liposomes and liposome-encapsulated drugs into the urinary bladder for treating lower urinary tract dysfunction.

The role of botulinum toxin A in treating neurogenic bladder

Neurogenic detrusor overactivity (NDO) can result in lower and upper urinary tract complications and eventually even in end-stage kidney failure. Since the driving force of this clinical cascade is high bladder pressure, controlling intravesical pressure in NDO patients improves both quality of life and life-expectancy in these patients. Botulinum toxin A (BTX-A) has proven its efficacy in reducing intravesical pressure and in reducing incontinence episodes. BTX-A also improves quality of life in patients with NDO. Both onabotulinumtoxinA (Botox^®, Allergan, Irvine, USA) and abobotulinumtoxinA (Dysport^®, Ipsen, Paris, France) have a level A recommendation for NDO-treatment. The recommended dose for intradetrusor injections in NDO patients is 200 U of onabotulinumtoxinA or 500 U of abobotulinumtoxinA. The drug is generally administered extratrigonal in the detrusor muscle, via cystoscopic guided injection at 20 sites in 1 mL injections. Intradetrusor BTX-A injections are safe, with mostly local complications such as urinary tract infection and high post-void residual or retention. The effect of the toxin lasts for approximately 9 months. Repeat injections can be performed without loss of efficacy. Different injection techniques, novel ways of BTX-A administration, eliminating the need for injection or new BTX-A types with better/longer response rates could change the field in the future.

Intravesical liposome drug delivery and IC/BPS

Intravesical therapy has previously shown to be effective in delaying or preventing recurrence of superficial bladder cancer. This local route of drug administration is now demonstrating promise in the treatment of interstitial cystitis/bladder pain syndrome (IC/BPS) with the benefit of minimal systemic side effects. Liposomes (LPs) are lipid vesicles composed of phospholipid bilayers surrounding an aqueous core. They can incorporate drug molecules, both hydrophobic and hydrophilic, and vastly improve cellular uptake of these drug molecules via endocytosis. Intravesical LPs have therapeutic effects on IC/BPS patients, mainly due to their ability to form a protective lipid film on the urothelial surface and repair the damaged urothelium. This review considers the current status of intravesical LPs and LP mediated drug delivery for the treatment of IC/BPS.

Does Reduction of Number of Intradetrusor Injection Sites of aboBoNTA (Dysport®) Impact Efficacy and Safety in a Rat Model of Neurogenic Detrusor Overactivity?

Intradetrusor injections of Botulinum toxin A—currently onabotulinumtoxinA—is registered as a second-line treatment to treat neurogenic detrusor overactivity (NDO). The common clinical practice is 30 × 1 mL injections in the detrusor; however, protocols remain variable and standardization is warranted. The effect of reducing the number of injection sites of Dysport^® abobotulinumtoxinA (aboBoNTA) was assessed in the spinal cord-injured rat (SCI). Nineteen days post-spinalization, female rats received intradetrusor injections of saline or aboBoNTA 22.5 U distributed among four or eight sites. Two days after injection, continuous cystometry was performed in conscious rats. Efficacy of aboBoNTA 22.5 U was assessed versus aggregated saline groups on clinically-relevant parameters: maximal pressure, bladder capacity, compliance, voiding efficiency, as well as amplitude, frequency, and volume threshold for nonvoiding contractions (NVC). AboBoNTA 22.5 U significantly decreased maximal pressure, without affecting voiding efficiency. Injected in four sites, aboBoNTA significantly increased bladder capacity and compliance while only the latter when in eight sites. AboBoNTA significantly reduced NVC frequency and amplitude. This preclinical investigation showed similar inhibiting effects of aboBoNTA despite the number of sites reduction. Further studies are warranted to optimize dosing schemes to improve the risk-benefit ratio of BoNTA-based treatment modalities for NDO and further idiopathic overactive bladder.

OnabotulinumtoxinA Treatment for Overactive Bladder in the Elderly: Practical Points and Future Prospects

Overactive bladder (OAB) increases with age. OAB in the elderly may be associated with increased risks of falls, fractures and mortality. Degeneration of the central nervous system in the elderly is proposed as one of the pathogenic factors for OAB. Recently, onabotulinumtoxinA (BoNT-A) 100 U has been demonstrated to be well tolerated, and it significantly improves all OAB symptoms and health-related quality of life in patients who are inadequately managed with anticholinergics. However, an increased risk of a large post-void residual volume and a lower long-term success rate were noted in frail elderly patients. Careful patient selection for BoNT-A injection treatment is important in elderly OAB patients. Patients who are frail, are elderly, have comorbidity or have a post-void residual volume >100 mL should be monitored carefully after BoNT-A injection treatment to prevent urinary retention and subsequent urinary tract infection. Use of liposomes to carry BoNT-A across the urothelial barrier decreases urgency-frequency episodes without compromising detrusor contractility and might avoid urinary tract infection. This treatment might prevent undesired detrusor underactivity after BoNT-A injection treatment, especially in elderly patients who have low detrusor contractility. For treatment of OAB in the elderly, clinicians should be aware of the balance between therapeutic efficacy and safety.

Advances in intravesical therapy for urinary tract disorders

INTRODUCTION

Intravesical therapy is a valuable option in the clinical management of urinary tract disorders such as interstitial cystitis/ painful bladder syndrome (IC/PBS) and refractory overactive bladder. This review will cover the latest advances in this field using polymer and liposomes as delivery platform for drugs, protein and nucleic acids.

AREAS COVERED

This review summarizes the significance of intravesical therapy for lower urinary tract disorders. The recent advancement of liposomes as a drug delivery platform for botulinum toxin, tacrolimus and small interfering RNA is discussed. The importance of polymers forming indwelling devices and hydrogels are also discussed, where all preparations improved efficacy parameters in rodent models. Clinical experience of treating IC/PBS with indwelling devices and liposomes are summarized and preclinical evidence about the downregulation of target gene expression in rodent bladder with liposomes complexed with siRNA is also reviewed.

EXPERT OPINION

There have been several advances in the field of intravesical therapy for improving clinical outcomes. One of the most promising research avenues is the repurposing of drugs, given previously by other routes of administration, such as tacrolimus. Intravesical therapy also opens up novel therapeutic targets with improved efficacy and safety for underactive bladder.

The safety and efficiency of onabotulinumtoxinA for the treatment of overactive bladder: a systematic review and meta-analysis

PURPOSE

To assess the impact on safety and efficiency of onabotulinumtoxinA (BOTOX1, Allergan, Inc.) treatment in patients with an overactive bladder.

MATERIALS AND METHODS

We searched the PubMed(®), Embase(®), and Cochrane Library Databases to identify all randomized controlled trials comparing the outcomes of onabotulinumtoxinA and placebo for overactive bladder. The outcomes included reductions in overactive bladder symptoms or improvements in the function of bladder and the side effects of two treatments. The Cochrane Collaboration Review Manager software (RevMan 5.1.4) was used for statistical analysis.

RESULTS

The study inclusion criteria were met by eight randomized controlled trials involving 1875 patients. The synthesized data from these randomized controlled trials indicated that onabotulinumtoxinA was better than placebo in decreasing most overactive bladder symptoms (p < 0.00001, p < 0.00001, p < 0.00001, p < 0.00001, p = 0.0003) in the micturition, urgency, urinary incontinence, urgency urinary incontinence (UUI), and nocturia per day change, respectively; however, the maximum cystometric capacity change from the baseline appeared not to be significantly different between two methods (p = 0.05). In addition, the side effects in the onabotulinumtoxinA group were more serious than the placebo group (p < 0.00001, p = 0.009, p = 0.07, p < 0.0001, p = 0.03 in the UTI, bacteriuria, dysuria, urinary retention, residual urine volume, respectively).

CONCLUSIONS

Compared with the placebo, onabotulinumtoxinA had significantly and clinically relevant reductions in overactive bladder symptoms, but it also leaded to more side effects.

Drug therapy of overactive bladder--what is coming next?

After the approval and introduction of mirabegron, tadalafil, and botulinum toxin A for treatment of lower urinary tract symptoms/overactive bladder, focus of interest has been on their place in therapy versus the previous gold standard, antimuscarinics. However, since these agents also have limitations there has been increasing interest in what is coming next - what is in the pipeline? Despite progress in our knowledge of different factors involved in both peripheral and central modulation of lower urinary tract dysfunction, there are few innovations in the pipe-line. Most developments concern modifications of existing principles (antimuscarinics, β₃-receptor agonists, botulinum toxin A). However, there are several new and old targets/drugs of potential interest for further development, such as the purinergic and cannabinoid systems and the different members of the transient receptor potential channel family. However, even if there seems to be good rationale for further development of these principles, further exploration of their involvement in lower urinary tract function/dysfunction is necessary.

Emerging drugs for overactive bladder

INTRODUCTION

Overactive bladder (OAB) is a common problem which can have disastrous effects on the quality of life of the sufferer. There are established treatments for the problem but they have significant adverse effects. Better drugs and new treatment modalities are necessary to deal with OAB.

AREA COVERED

Antimuscarinics, mirabegron and intravesical injection of botulinum toxin A are established treatments for OAB. Sacral neuromodulation is more invasive but has been successful in treating OAB. Phase II and III trials are in progress for newer β3-agonists and various combinations of antimuscarinics, β3-agonists and antidiuretics. Targeted secretion inhibitors (TSI) can increase efficacy and reduce adverse effects. Liposome integrated botulinum toxin A has an advantage of effective administration by intravesical instillation. Both medicines are in Phase II trials. Many other drugs which have promising results are discussed.

EXPERT OPINION

Newer antimuscarinics have better tolerability. Long-term data for mirabegron has shown that it is more effective in severe OAB. Combination drugs may prove to be more effective with less adverse effects. Emerging treatments with TSI, lipotoxin and gene therapy appear promising.

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.