Intravesical Therapy for Overactive Bladder

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.

Spray-dried mucoadhesives for intravesical drug delivery using N-acetylcysteine- and glutathione-glycol chitosan conjugates

This work describes N-acetylcysteine (NAC)- and glutathione (GSH)-glycol chitosan (GC) polymer conjugates engineered as potential platform useful to formulate micro-(MP) and nano-(NP) particles via spray-drying techniques. These conjugates are mucoadhesive over the range of urine pH, 5.0-7.0, which makes them advantageous for intravesical drug delivery and treatment of local bladder diseases. NAC- and GSH-GC conjugates were generated with a synthetic approach optimizing reaction times and purification in order to minimize the oxidation of thiol groups. In this way, the resulting amount of free thiol groups immobilized per gram of NAC- and GSH-GC conjugates was 6.3 and 3.6mmol, respectively. These polymers were completely characterized by molecular weight, surface sulfur content, solubility at different pH values, substitution and swelling degree. Mucoadhesion properties were evaluated in artificial urine by turbidimetric and zeta (ζ)-potential measurements demonstrating good mucoadhesion properties, in particular for NAC-GC at pH 5.0. Starting from the thiolated polymers, MP and NP were prepared using both the Büchi B-191 and Nano Büchi B-90 spray dryers, respectively. The resulting two formulations were evaluated for yield, size, oxidation of thiol groups and ex-vivo mucoadhesion. The new spray drying technique provided NP of suitable size (<1μm) for catheter administration, low degree of oxidation, and sufficient mucoadhesion property with 9% and 18% of GSH- and NAC-GC based NP retained on pig mucosa bladder after 3h of exposure, respectively.

STATEMENT OF SIGNIFICANCE

The aim of the present study was first to optimize the synthesis of NAC-GC and GSH-GC, and preserve the oxidation state of the thiol moieties by introducing several optimizations of the already reported synthetic procedures that increase the mucoadhesive properties and avoid pH-dependent aggregation. Second, starting from these optimized thiomers, we studied the feasibility of manufacturing MP and NP by spray-drying techniques. The aim of this second step was to produce mucoadhesive drug delivery systems of adequate size for vesical administration by catheter, and comparable mucoadhesive properties with respect to the processed polymers, avoiding thiolic oxidation during the formulation. MP with acceptable size produced by spray-dryer Büchi B-191 were compared with NP made with the apparatus Nano Büchi B-90.

Management and rehabilitation of neurologic patients with lower urinary tract dysfunction

Diverse lower urinary tract problems arise in neurologic disease, caused by dysfunctions of the bladder and outlet, both during urine storage and voiding. Most neurologic diseases cause some lower urinary tract dysfunction (LUTD), and the type of dysfunction is related to the location of the nervous system lesion. Clinical evaluation requires identification of risk factors for major morbidity, particularly renal dysfunction, and mechanisms underlying symptoms. A holistic approach is needed to cover influential aspects (e.g., cognitive function, mobility, and urinary tract infections) and related issues (e.g., sexual function, bowel function, and autonomic dysreflexia), requiring a multidisciplinary team. Comprehensive history and examination are supported by a bladder diary, urinalysis, and renal assessment, supplemented by urodynamic tests. The simplest classification of neurogenic LUTD describes both bladder and sphincter function, cataloging each structure as normal, overactive, or underactive. Treatment aims to protect life expectancy and improve quality of life, noting the possibility of neurologic disease progression and comorbid disorders. Conservative measures include fluid advice and assessment of suitable containment products. Urine storage can be improved with antimuscarinic medications, bladder injections with botulinum neurotoxin A, and less established methods such as nerve stimulation, intravesical instillations, and beta-3 agonist. For severe storage dysfunction, sacral neuromodulation or surgery to improve reservoir function, increase outlet resistance, or divert the urinary tract may be needed. Voiding is usually replaced by intermittent or indwelling catheterization, which has largely superseded triggered reflex voiding, bladder expression, or sphincterotomy. Treatment selection is hampered by a limited, low-quality evidence base.

Thiolated particles as effective intravesical drug delivery systems for treatment of bladder-related diseases

AIM

To prove in vivo mucoadhesiveness of thiolated and well-established polymeric microparticles and nanoparticles (NPs) as a promising nanomedical tool for the treatment of bladder-related diseases.

MATERIALS & METHODS

Spray drying and ionic gelation were used in order to generate microparticles and NPs. For particle detection, the fluorescent marker, fluorescein diacetate, was incorporated in microparticles and NPs, respectively. Mucoadhesive properties of the particles were pre-evaluated via rheological measurements and ex vivo in the porcine urinary bladder model to identify the most appropriate particles for in vivo application in female Sprague Dawley rats.

RESULTS

Pretrials indicated that particles based on chitosan were most suitable as an intravesical drug delivery system for in vivo application. The retention time of thiolated chitosan NPs on the rat urinary bladder mucosa was approximately 170-fold higher in comparison with the pure fluorescent marker, fluorescein diacetate, having being applied as aqueous suspension without polymeric excipients.

CONCLUSION

This advanced nanomedical tool based on thiolated chitosan seems to be a promising approach for the treatment of bladder-related diseases.

Treating acute cystitis with biodegradable micelle-encapsulated quercetin

Intravesical application of an anti-inflammatory drug is an efficient strategy for acute cystitis therapy. Quercetin (QU) is a potent anti-inflammatory agent; however, its poor water solubility restricts its clinical application. In an attempt to improve water solubility of QU, biodegradable monomethoxy poly(ethylene glycol)-poly(ɛ-caprolactone) (MPEG-PCL) micelles were used to encapsulate QU by self-assembly methods, creating QU/MPEG-PCL micelles. These QU/MPEG-PCL micelles with DL of 7% had a mean particle size of <34 nm, and could release QU for an extended period in vitro. The in vivo study indicated that intravesical application of MPEG-PCL micelles did not induce any toxicity to the bladder, and could efficiently deliver cargo to the bladder. Moreover, the therapeutic efficiency of intravesical administration of QU/MPEG-PCL micelles on acute cystitis was evaluated in vivo. Results indicated that QU/MPEG-PCL micelle treatment efficiently reduced the edema and inflammatory cell infiltration of the bladder in an Escherichia coli-induced acute cystitis model. These data suggested that MPEG-PCL micelle was a candidate intravesical drug carrier, and QU/MPEG-PCL micelles may have potential application in acute cystitis therapy.

An intravesical device for the sustained delivery of lidocaine to the bladder

Intravesical instillation is a single compartment therapy providing high drug concentration at the bladder and reduced systemic exposure. Therapies based on this method, however, often require repeated instillations with intermittent transurethral catheterizations due to the short drug residence time in the bladder. Here we describe an intravesical device to achieve extended and localized delivery of lidocaine to the bladder. The device is a non-resorbable system that can be non-surgically deployed into the bladder. An in vivo rabbit study showed that lidocaine concentration in the bladder tissue was higher than 0.1μg/g during the 3 day period of device release while a single instillation yielded immeasurable amounts within 24h. The device can be used for the delivery of other therapeutic agents, currently delivered to the bladder by intravesical instillations.

Gosha-jinki-gan reduces transmitter proteins and sensory receptors associated with C fiber activation induced by acetic acid in rat urinary bladder

AIM

We determined if Gosha-jinki-gan, a traditional Chinese herbal mixture, reduced the presence of the tachykinins neurokinin A, neurokinin B, and substance P, as well as the transient receptor potential vanilloid 1 (TRPV1) and P2X3 purine receptors that are functionally associated with C fibers in the urinary bladder.

METHODS

Thirty-six female rats were fed with either a standard diet or one supplemented with 1.08% Gosha-jinki-gan. After 4 weeks, the urinary bladders were instilled with either saline or 0.1% acetic acid. After 30 min, the bladders were removed and expression of the tachykinins and the TRPV1 and P2X3 receptors was determined by immunohistochemistry and mRNA expression.

RESULTS

In rats fed with the standard diet, the tachykinins and the TRPV1 and P2X3 receptors expressed nearby or within urothelium of the acetic acid-treated rats increased compared with the saline-instilled rats. In rats pretreated with Gosha-jinki-gan, the tachykinins and the TRPV1 and P2X3 receptors in the acetic acid-treated rats also increased compared with the saline-instilled rats. However, with the instillation of acetic acid, the tachykinins and the TRPV1 and P2X3 receptors of Gosha-jinki-gan pretreated rats decreased compared with standard diet fed rats. The mRNA expression levels of neurokinin A, substance P, and the TRPV1 receptor in acetic acid-treated Gosha-jinki-gan pretreated rats were lower than that in acetic acid-treated standard diet fed rats. Gosha-jinki-gan did not destroy nerve fibers within the bladders.

CONCLUSIONS

Gosha-jinki-gan partially reduced the tachykinins and TRPV1 and P2X3 purine receptors without destroying the nerve fibers.

Intravesikale Therapie des Overactive-bladder-Syndroms

Overactive bladder and urgency incontinence are common conditions generally treated with oral anticholinergic medication. Despite the development of new antimuscarinic substances, many patients are refractory to or cannot tolerate the oral therapy due to severe side effects. Intravesical instillation therapy can provide an alternative method to manage detrusor overactivity. Intravesical instillation of anticholinergics such as oxybutynin and trospium chloride can achieve cholinergic blockade without producing systemic side effects. Botulinum toxin type A injections into the detrusor have been shown to increase bladder capacity and to decrease detrusor overactivity for 6 or more months. Intravesical local anesthetics such as lidocaine and bupivacaine block the conduction of unmyelinated C fibers which results in an increase of functional bladder capacity. Intravesical capsaicin and resiniferatoxin also affect the afferent C fiber innervation of the bladder, leading to a decrease in detrusor overactivity and also an increased bladder capacity. The use of intravesical anticholinergics and of local anesthetic medications, both known for their short-term efficacy, is limited due to the necessity of daily intermittent catheterization. In conclusion, intravesical therapies can provide an alternative treatment for the management of overactive bladder.

The Physiological Function of the Urothelium – More than a Simple Barrier

The urothelium, the epithelium lining the surface of the urinary bladder, is a unique cell type with high plasticity and a variety of cellular functions. The urothelium represents the first line of bladder defense and an interface between pathogens and defense mechanisms. Functions of the urothelium include control of permeability, immune responses and cell-cell communication, which seems to play a pivotal role in responding to injuries and infections. The urothelium responds to stretch, during the filling phase of micturition reflex, by increasing the size of apical umbrella cells and by releasing mediators which activate the sensory fibers. For this reason the concept of 'neuron-like properties' was suggested. Finally, despite the fact that the urothelium is a frequent site of cancer formation, few experimental model systems are currently available or well characterized for studying urothelial cancer in the era of genomics and proteomics. The purpose of this review is to give emphasis to urothelial physiology and pathophysiology in different bladder disorders and to offer an up-to-date contribution to the field of urothelial research.