Effect of intravesical capsaicin and vehicle on bladder integrity control and spinal cord injured rats

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.

Intravesical liposome and antisense treatment for detrusor overactivity and interstitial cystitis/painful bladder syndrome

Purpose. The following review focuses on the recent advancements in intravesical drug delivery, which brings added benefit to the therapy of detrusor overactivity and interstitial cystitis/painful bladder syndrome (IC/PBS). Results. Intravesical route is a preferred route of administration for restricting the action of extremely potent drugs like DMSO for patients of interstitial cystitis/painful bladder syndrome (IC/PBS) and botulinum toxin for detrusor overactivity. Patients who are either refractory to oral treatment or need to mitigate the adverse effects encountered with conventional routes of administration also chose this route. Its usefulness in some cases can be limited by vehicle (carrier) toxicity or short duration of action. Efforts have been underway to overcome these limitations by developing liposome platform for intravesical delivery of biotechnological products including antisense oligonucleotides. Conclusions. Adoption of forward-thinking approaches can achieve advancements in drug delivery systems targeted to future improvement in pharmacotherapy of bladder diseases. Latest developments in the field of nanotechnology can bring this mode of therapy from second line of treatment for refractory cases to the forefront of disease management.

Urodynamic and Immunohistochemical Evaluation of Intravesical Capsaicin Delivery Using Thermosensitive Hydrogel and Liposomes

PURPOSE

Aqueous insolubility of the vanilloids such as capsaicin is a major disincentive in their intravesical therapy of detrusor hyperreflexia. We sought to overcome the delivery of this hydrophobic neurotoxin by entrapping it in a lipid bilayer of positively charged multilamellar lipid vesicles (liposomes) or in a hydrophobic polymer matrix of thermosensitive hydrogel.

MATERIALS AND METHODS

Liposomes, hydrogel and 30% ethanol/normal saline were prepared with or without 1 mM capsaicin (0.5 ml) and administered intravesically for 30 minutes to 7 groups of age matched, normal female adult Sprague-Dawley rats under halothane anesthesia. At 48 hours after intravesical instillation cystometric studies were performed using urethane anesthesia (0.04 ml per minute). The animals were subsequently sacrificed and whole bladders were harvested for histology and immunohistochemistry.

RESULTS

In normal urethane anaesthetized rats capsaicin in 30% ethanol and liposomes completely blocked micturition reflexes. Capsaicin in hydrogel did not completely block the micturition reflex but it significantly decreased bladder contraction frequency compared with vehicle controls. The results of cystometry with capsaicin in liposomes and capsaicin in 30% ethanol correlated with a significant decrease in calcitonin gene-related peptide staining of afferent nerves in the bladder wall. Photographs taken after hematoxylin and eosin staining of the bladder treated with liposomes and hydrogel in the absence of capsaicin did not reveal any adverse histological changes. There were significant histological changes in bladders treated with 30% ethanol alone.

CONCLUSIONS

In comparison with 30% ethanol liposomes are a superior vehicle for the intravesical administration of capsaicin, producing comparable efficacy with less tissue damage. Hydrogel can also serve as safe alternative option for capsaicin delivery.

The effect of intravesical capsaicin on the suburothelial innervation in patients with detrusor hyper-reflexia

OBJECTIVE

To determine the effect of intravesical capsaicin on the suburothelial innervation in patients with detrusor hyper-reflexia, in whom a single dose of intravesical capsaicin (1-2 mmol/L) increases the bladder capacity for 3-6 months.

PATIENTS AND METHODS

Thirteen patients with detrusor hyper-reflexia underwent cystometry and had flexible cystoscopic biopsies taken before and 6 weeks after receiving instillations of intravesical capsaicin (1 mmol/L). Similar biopsies were also obtained from a control group of 12 neurologically normal patients with microscopic haematuria and normal bladders. Frozen sections were stained using antibodies to S100 and PGP 9.5. Using computerized analysis, the mean nerve density scores were expressed as nerves/mm2 for S100-positive structures and 'red%' and 'red in frame' for PGP 9.5.

RESULTS

The mean (SEM) functional bladder capacity increased from 193.2 (28.17) mL before to 396.3 (41.96) mL at 6 weeks after treatment with capsaicin, in nine of the 13 patients. The mean nerve density of S100-positive structures in the control group was 83 (3.18) nerves/mm2. In hyper-reflexic patients who responded to capsaicin by improved bladder capacity, the mean nerve density of S100-positive structures was reduced from 100 (12.2) before to 66 (9.4) nerves/mm2 6 weeks after treatment. In those who did not respond to capsaicin there was no significant difference in these scores. Similarly the 'red%' and 'red in frame' reduced from 3.41 (1.06) to 1.15 (0.32) and 824.7 (246.3) to 297.9 (83.5) units, respectively, before and 6 weeks after capsaicin treatment. The difference in those not responding was not significant.

CONCLUSIONS

Intravesical capsaicin causes a reduction in suburothelial nerve densities in the bladder of patients with detrusor hyper-reflexia. This may explain its prolonged beneficial effect in these patients.

The overactive bladder: neuropharmacological basis of clinical management

The overactive bladder continues to pose a major challenge to clinicians treating lower urinary tract disorders, not least because our understanding of the pathogenesis of detrusor overactivity is still relatively limited. However, progress in understanding the basis of the overactive bladder is moving steadily forward, accompanied by a growing number of different forms of treatment. New pharmacological treatments and variations in the mode of delivery of older agents offer hope of efficacy with fewer side-effects. Neuromodulation is also offering a viable alternative to surgery in patients unresponsive to medical treatment.

Intravesical capsaicin and resiniferatoxin therapy: spicing up the ways to treat the overactive bladder

PURPOSE

Pharmacological treatment of the overactive bladder relies on partially blocking the efferent parasympathetic innervation to the detrusor with anticholinergic drugs. However, often these drugs have troublesome side effects and doses are insufficient to restore continence in patients with detrusor instability. We present the background, basic and clinical research with intravesical instillation of capsaicin and resiniferatoxin as treatments for the overactive bladder.

MATERIALS AND METHODS

Capsaicin, the main pungent ingredient in hot peppers of the genus Capsicum, is a specific neurotoxin that desensitizes C fiber afferent neurons which may be responsible for signals that trigger detrusor overactivity.

RESULTS

In the last 6 years studies have demonstrated encouraging improvement in lower urinary tract symptoms with minimal long-term complications. Most of these studies have also demonstrated that the acute pain and irritation associated with capsaicin are major deterrents to widespread use. Therefore, resiniferatoxin, an ultra-potent analogue of capsaicin which appears to have similar efficacy but less acute side effects, may be more useful.

CONCLUSIONS

Intravesical capsaicin and resiniferatoxin are novel and promising treatments for the overactive bladder, with profound basic and clinical implications.

Overactive detrusor

Detrusor overactivity poses a major challenge to physicians from many specialities. Progress in our understanding of the pathogenesis of detrusor overactivity is slow but steady. Advances in treatment continue to be made, both with new agents and new methods of delivering older drugs. Neuromodulation is showing great promise as experience increases, and developments in bladder augmentation offer hope for lower morbidity treatments in future.