Intravesical resiniferatoxin for the treatment of hypersensitive disorder: a randomized placebo controlled study

Safety and efficacy of intravesical instillation of resiniferatoxin in healthy cats: A preliminary study

Objectives

To evaluate the safety of intravesical application of resiniferatoxin (RTX) in healthy cats and its effects on calcitonin gene-related peptide (CGRP) and substance P (SP) produced by C-fibers.

Methods

Seven adult female cats received either 25 mL of saline (control; n = 1), or intravesical RTX at 5, 25, or 50 μg in 25 mL of saline to a final concentration of 0.2 μg/mL (318 nM), 1 μg/mL (1,591 nM), and 2 μg/mL (3,181 nM) (n = 2 per group). The treatment was instilled into the urinary bladder for 20 min. Plasma concentrations of RTX were measured at 0, 0.5, 1, and 4 h. Physical exam, complete blood count, and serum biochemical analysis were performed on day 0, 7, and 14. After 14 days, the sacral dorsal root ganglia (DRG) and the urinary bladder were harvested for histological and immunofluorescence analysis.

Results

Intravesical RTX was well tolerated and plasma concentrations were below the quantifiable limits except for one cat receiving 1 μg/mL. Mild to moderate histopathological changes, including epithelial changes, edema, and blood vessel proliferation, were observed at lower doses (0.2 and 1 μg/mL), and were more severe at the higher dose (2 μg/mL). C-fiber ablation was observed in the urinary bladder tissue at all doses, as shown by an apparent reduction of both CGRP and SP immunoreactive axons.

Conclusion

A dose of 25 μg (1 μg/mL) of RTX instilled in the urinary bladder of healthy cats appeared to decrease the density of SP and CGRP nerve axons innervating bladder and induced moderate changes in the bladder tissue.

Acute Intravesical Capsaicin for the Study of TRPV1 in the Lower Urinary Tract: Clinical Relevance and Potential for Innovation

Capsaicin acts on sensory nerves via vanilloid receptors. TRPV1 has been extensively studied with respect to functional lower urinary tract (LUT) conditions in rodents and humans. We aimed to (1) provide background information on capsaicin and TRPV1 and its mechanisms of action and basis for clinical use, (2) review the use of acute intravesical capsaicin instillation (AICI) in rodents to mimic various LUT disorders in which capsaicin sensitive C-fibers are involved and (3) discuss future innovative treatments. A comprehensive search of the major literature databases until June 2022 was conducted. Both capsaicin-sensitive and resistant unmyelinated bladder afferent C-fibers are involved in non-neurogenic overactive bladder/detrusor overactivity (OAB/DO). AICI is a suitable model to study afferent hyperactivity mimicking human OAB. Capsaicin-sensitive C-fibers are also involved in neurogenic DO (NDO) and potential targets for NDO treatment. AICI has been successfully tested for NDO treatment in humans. Capsaicin-sensitive bladder afferents are targets for NDO treatment. TRPV1-immunoreactive nerve fibers are involved in the pathogenesis of interstitial cystitis/painful bladder syndrome (IC/PBS). The AICI experimental model appears relevant for the preclinical study of treatments targeting bladder afferents for refractory IC/BPS. The activity of capsaicin-sensitive bladder afferents is increased in experimental bladder outlet obstruction (BOO). The AICI model may also be relevant for bladder disorders resulting from C-fiber hyperexcitabilities related to BOO. In conclusion, there is a rationale for the selective blockade of TRPV1 channels for various bladder disorders. The AICI model is clinically relevant for the investigation of pathophysiological conditions in which bladder C-fiber afferents are overexcited and for assessing innovative treatments for bladder disorders based on their pathophysiology.

Transient receptor potential channels in sensory mechanisms of the lower urinary tract

Disruptions to sensory pathways in the lower urinary tract commonly occur and can give rise to lower urinary tract symptoms (LUTS). The unmet clinical need for treatment of LUTS has stimulated research into the molecular mechanisms that underlie neuronal control of the bladder and transient receptor potential (TRP) channels have emerged as key regulators of the sensory processes that regulate bladder function. TRP channels function as molecular sensors in urothelial cells and afferent nerve fibres and can be considered the origin of bladder sensations. TRP channels in the lower urinary tract contribute to the generation of normal and abnormal bladder sensations through a variety of mechanisms, and have demonstrated potential as targets for the treatment of LUTS in functional disorders of the lower urinary tract.

Interventions for treating people with symptoms of bladder pain syndrome: a network meta-analysis

BACKGROUND

Bladder pain syndrome (BPS), which includes the condition of interstitial cystitis, is a poorly understood clinical condition for which patients present with varying symptoms. Management of BPS is challenging for both patients and practitioners. At present, there is no universally accepted diagnosis and diverse causes have been proposed. This is reflected in wide-ranging treatment options, used alone or in combination, with limited evidence. A network meta-analysis (NMA) simultaneously comparing multiple treatments may help to determine the best treatment options for patients with BPS.

OBJECTIVES

To conduct a network meta-analysis to assess the effects of interventions for treating people with symptoms of bladder pain syndrome (BPS).

SEARCH METHODS

We searched the Cochrane Incontinence Specialised Register, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL, in the Cochrane Library), MEDLINE, MEDLINE In-Process, MEDLINE Epub Ahead of Print, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) and handsearched journals and conference proceedings (searched 11 May 2018) and the reference lists of relevant articles. We conducted a further search on 5 June 2019, which yielded four small studies that were screened for eligibility but were not incorporated into the review.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs of interventions for treating adults with BPS. All types of interventions (including conservative, pharmacological and surgical) were eligible.

DATA COLLECTION AND ANALYSIS

We assessed the risk of bias of included studies using Cochrane's 'Risk of bias' tool. Primary outcomes were the number of people cured or improved, pain, frequency and nocturia. For each outcome, random-effects NMA models were fitted using WinBUGS 1.4. We monitored median odds ratios (ORs) for binary outcomes and mean differences (MDs) for continuous outcomes with 95% credible intervals (Crls). We compared results of the NMA with direct evidence from pairwise meta-analysis of head-to-head trials. We used the CINeMA tool to assess the certainty of evidence for selected treatment categories.

MAIN RESULTS

We included 81 RCTs involving 4674 people with a median of 38 participants (range 10 to 369) per RCT. Most trials compared treatment against control; few trials compared two active treatments. There were 65 different active treatments, and some comparisons were informed by direct evidence from only one trial. To simplify, treatments were grouped into 31 treatment categories by mode of action. Most studies were judged to have unclear or high risk of bias for most domains, particularly for selection and detection bias. Overall, the NMA suggested that six (proportion cured/improved), one (pain), one (frequency) and zero (nocturia) treatment categories were effective compared with control, but there was great uncertainty around estimates of effect. Due to the large number of intervention comparisons in this review, we focus on three interventions: antidepressants, pentosan polysulfate (PPS) and neuromuscular blockade. We selected these interventions on the basis that they are given 'strong recommendations' in the EAU Guidelines for management of BPS (EAU Guidelines 2019). We found very low-certainty evidence suggesting that antidepressants were associated with greater likelihood of cure or improvement compared with control (OR 5.91, 95% CrI 1.12 to 37.56), but it was uncertain whether they reduced pain (MD -1.27, 95% CrI -3.25 to 0.71; low-certainty evidence), daytime frequency (MD -2.41, 95% CrI -6.85 to 2.05; very low-certainty evidence) or nocturia (MD 0.01, 95% CrI -2.53 to 2.50; very low-certainty evidence). There was no evidence that PPS had improved cure/improvement rates (OR 0.14, 95% CrI 0.40 to 3.35; very low-certainty evidence) or reduced pain (MD 0.42, 95% CrI -1.04 to 1.91; low-certainty evidence), frequency (MD -0.37, 95% CrI -5.00 to 3.44; very low-certainty evidence) or nocturia (MD -1.20, 95% CrI -3.62 to 1.28; very low-certainty evidence). There was evidence that neuromuscular blockade resulted in greater cure or improvement (OR 5.80, 95% CrI 2.08 to 18.30) but no evidence that it improved pain (MD -0.33, 95% CrI -1.71 to 1.03), frequency (MD -0.91, 95% CrI -3.24, 1.29) or nocturia (MD -0.04, 95% CrI -1.35 to 1.27). The certainty of this evidence was always very low.

AUTHORS' CONCLUSIONS

We are uncertain whether some treatments may be effective in treating patients with BPS because the certainty of evidence was generally low or very low. Data were available for a relatively large number of trials, but most had small sample sizes and effects of treatments often could not be estimated with precision. An NMA was successfully conducted, but limited numbers of small trials for each treatment category hampered our ability to fully exploit the advantages of this analysis. Larger, more focused trials are needed to improve the current evidence base.

Optogenetic silencing of nociceptive primary afferents reduces evoked and ongoing bladder pain

Patients with interstitial cystitis/bladder pain syndrome (IC/BPS) suffer from chronic pain that severely affects quality of life. Although the underlying pathophysiology is not well understood, inhibition of bladder sensory afferents temporarily relieves pain. Here, we explored the possibility that optogenetic inhibition of nociceptive sensory afferents could be used to modulate bladder pain. The light-activated inhibitory proton pump Archaerhodopsin (Arch) was expressed under control of the sensory neuron-specific sodium channel (sns) gene to selectively silence these neurons. Optically silencing nociceptive sensory afferents significantly blunted the evoked visceromotor response to bladder distension and led to small but significant changes in bladder function. To study of the role of nociceptive sensory afferents in freely behaving mice, we developed a fully implantable, flexible, wirelessly powered optoelectronic system for the long-term manipulation of bladder afferent expressed opsins. We found that optogenetic inhibition of nociceptive sensory afferents reduced both ongoing pain and evoked cutaneous hypersensitivity in the context of cystitis, but had no effect in uninjured, naïve mice. These results suggest that selective optogenetic silencing of nociceptive bladder afferents may represent a potential future therapeutic strategy for the treatment of bladder pain.

Intravesical treatment for interstitial cystitis/painful bladder syndrome: a network meta-analysis

INTRODUCTION AND HYPOTHESIS

Interstitial cystitis/painful bladder syndrome (IC/PBS) is a chronic inflammatory condition of the submucosal and muscular layers of the bladder. So far, there is no effective and targeted treatment strategy for IC/PBS. This study aimed to assess the efficacy and safety of intravesical instillation treatment in IC/PBS patients.

METHODS

We searched various databases up to October 2015. A network meta-analysis was performed to compare global response assessment (GRA) for different treatment strategies, including botulinum toxin A (BoNTA), bacillus Calmette-Guerin (BCG), resiniferatoxin (RTX), lidocaine, chondroitin sulfate (CS), oxybutynin, and pentosan polysulfate (PPS). A traditional meta-analysis was also performed.

RESULTS

Sixteen trials evaluating 905 patients were included. Network meta-analysis indicated that BoNTA had the highest probability of being the best treatment course according to GRA assessment results (probability 81.7 %). BCG or BoNTA therapy yielded significant improvement in GRA incidence according to traditional meta-analysis. Patients who received PPS showed higher urinary frequency results compared with the placebo groups. BCG- and PPS-treated patients had elevated urinary urgency treatment effects compared with placebo groups. Bladder capacity restoration results also showed significant improvements in patients who received BoNTA compared with placebo-treated individuals.

CONCLUSIONS

These findings indicate that BoNTA therapy has the highest probability of being the best therapy according to GRA, and significantly improves bladder capacity in IC/PBS patients. BCG treatment also significantly increases the incidence of GRA and improves the symptoms of urinary urgency. PPS can significantly improve urinary frequency and urgency symptoms in IC/PBS patients.

The efficacy of resiniferatoxin in prevention of catheter related bladder discomfort in patients after TURP - a pilot, randomized, open study

Background

Resiniferatoxin (RTX) has been shown to have variable efficacy in the treatment of intractable lower urinary tract symptoms and symptoms associated with neurogenic detrusor overactivity. It has also been used successfully in treating overactive bladder (OAB). In order to evaluate the potential and efficiency of RTX in treatment of catheter related bladder discomfort (CRBD) over post-operative period of transurethral resection of the prostate (TURP), we conducted the current pilot, randomized open study.

Methods

The study was comprised of 48 patients undergoing TURP in a single institute from September 2007 to September 2008. Patients were randomly divided into Group-RTX and Group-control. CRBD was classified into 4 degrees: degree 0, 1, 2, and 3. Patients with the most severed CRBD (degree-3) were treated with tolterodine.

Results

There were no statistical difference of patients' age, prostate volume, IPSS score, storage score and void score in IPSS, and QOL score between the two study groups(P=0.213, 0.356, 0.471, 0.554, 0.055 and 0.380, respectively). RTX pre-treatment reduced incidence of CRBD. 25% of the patients in RTX group had CRBD, at 6 hours/1 day and 3 days after TURP, significantly lower than the control group in which 75% of the patients during the same period (P=0.001). During the three days post-operative period, RTX also reduced severity of CRBD, compared with the control group. No patient in Group RTX sufferred CRBD of degree 3, a clear contrast to the control group in which 7 patients had degree 3 CRBD, during three days post-operative. Finally, less patients in RTX group required tolterodine, compared with control, P=0.009. Interestingly, the difference of CRBD incidence between Group RTX (50%) and control (75%) diminished 5 days after TURP, P=0.135.

Conclusions

Pretreatment with intravesical resiniferatoxin significantly reduces the incidence and severity of catheter related bladder discomfort in patients after TURP.

Bladder afferent hyperexcitability in bladder pain syndrome/interstitial cystitis

Bladder pain syndrome/interstitial cystitis is a disease with lower urinary tract symptoms, such as bladder pain and urinary frequency, which results in seriously impaired quality of life of patients. The extreme pain and urinary frequency are often difficult to treat. Although the etiology of bladder pain syndrome/interstitial cystitis is still not known, there is increasing evidence showing that afferent hyperexcitability as a result of neurogenic bladder inflammation and urothelial dysfunction is important to the pathophysiological basis of symptom development. Further investigation of the pathophysiology will lead to the effective treatment of patients with bladder pain syndrome/interstitial cystitis.

Variations in the reporting of outcomes used in systematic reviews of treatment effectiveness research in bladder pain syndrome

This paper investigates the quality of outcomes reported in systematic reviews and randomised controlled trials (RCTs) of bladder pain syndrome and its relationship with study quality and journal impact factor. We searched until August 2013 the Cochrane Library, EMBASE, Medline, CINAHL, LILACS and SIGLE, without language restrictions. Quality of outcome reporting in systematic reviews and constituent RCTs was assessed using a 6-point scale. Overall study quality was assessed using the AMSTAR and Jadad scoring systems, and impact factor in the year of publication was noted. Spearman's rank correlation was calculated. There were 8 systematic reviews, with a total of 28 RCTs (1732 patients), reporting 5 outcomes using 19 different measurement scales. The outcomes reported in individual RCTs were urinary symptoms (100%), pain (64%), quality of life (39%), general wellbeing (36%) and bladder capacity (36%). The mean quality of outcomes reported was 1.63 (95% CI 0.29-2.96) for systematic reviews and 3.25 (95% CI 2.80-3.70) for RCTs. The quality of outcomes reported showed correlation with overall study quality (0.90, 95% CI 0.79-0.95, p<0.0001) but not with journal impact factor (0.07, 95% CI -0.31-0.43, p=0.35). Multivariable linear regression showed a relationship between quality of outcome reporting and study quality (β=0.05, p<0.0001), adjusting for effects of study type, impact factor and journal type. There is a need to generate consensus over a set of core outcomes in bladder pain syndrome using standardised reporting tools and to disseminate these through good publication practice.

Bladder cancer and urothelial impairment: the role of TRPV1 as potential drug target

Urothelium, in addition to its primary function of barrier, is now understood to act as a complex system of cell communication that exhibits specialized sensory properties in the regulation of physiological or pathological stimuli. Furthermore, it has been hypothesized that bladder inflammation and neoplastic cell growth, the two most representative pathological conditions of the lower urinary tract, may arise from a primary defective urothelial lining. Transient receptor potential vanilloid channel 1 (TRPV1), a receptor widely distributed in lower urinary tract structures and involved in the physiological micturition reflex, was described to have a pathophysiological role in inflammatory conditions and in the genesis and development of urothelial cancer. In our opinion new compounds, such as curcumin, the major component of turmeric Curcuma longa, reported to potentiate the effects of the chemotherapeutic agents used in the management of recurrent urothelial cancer in vitro and also identified as one of several compounds to own the vanillyl structure required to work like a TRPV1 agonist, could be thought as complementary in the clinical management of both the recurrences and the inflammatory effects caused by the endoscopic resection or intravesical chemotherapy administration or could be combined with adjuvant agents to potentiate their antitumoral effect.

TRP channels in lower urinary tract dysfunction

Lower urinary tract dysfunction (LUTd) represents a major healthcare problem. Although it is mostly not lethal, associated social disturbance, medical costs, loss of productivity and especially diminished quality of life should not be underestimated. Although more than 15% of people suffer from a form of LUTd to some extent, pathophysiology often remains obscure. In the past 20 years, transient receptor potential (TRP) channels have become increasingly important in this field of research. These intriguing ion channels are believed to be the main molecular sensors that generate bladder sensation. Therefore, they are intensely pursued as new drug targets for both curative and symptomatic treatment of different forms of LUTd. TRPV1 was the first of its class to be investigated. Actually, even before this channel was cloned, it had already been targeted in the bladder, with clinical trials of intravesical capsaicin instillations. Several other polymodally gated TRP channels, particularly TRPM8, TRPA1 and TRPV4, also appear to play a prominent role in bladder (patho)physiology. With this review, we provide a brief overview of current knowledge on the role of these TRP channels in LUTd and their potential as molecular targets for treatment.

The TRPA1 channel in migraine mechanism and treatment

Migraine remains an elusive and poorly understood disease. The uncertainty is reflected by the currently unsatisfactory acute and prophylactic treatments for this disease. Genetic and pharmacological information points to the involvement of some transient receptor potential (TRP) channels in pain mechanisms. In particular, the TRP vanilloid 1 (TRPV1) and TRP ankyrin 1 (TRPA1) channels seem to play a major role in different models of pain diseases. Recent findings have underscored the possibility that TRP channels expressed in the nerve terminals of peptidergic nociceptors contribute to the migraine mechanism. Among this channel subset, TRPA1, a sensor of oxidative, nitrative and electrophilic stress, is activated by an unprecedented series of irritant and pain-provoking exogenous and endogenous agents, which release the pro-migraine peptide, calcitonin gene-related peptide, through this neuronal pathway. Some of the recently identified TRPA1 activators have long been known as migraine triggers. Furthermore, specific analgesic and antimigraine medicines have been shown to inhibit or desensitize TRPA1 channels. Thus, TRPA1 is emerging as a major contributing pathway in migraine and as a novel target for the development of drugs for pain and migraine treatment.

Neural mechanisms underlying lower urinary tract dysfunction

This article summarizes anatomical, neurophysiological, and pharmacological studies in humans and animals to provide insights into the neural circuitry and neurotransmitter mechanisms controlling the lower urinary tract and alterations in these mechanisms in lower urinary tract dysfunction. The functions of the lower urinary tract, to store and periodically release urine, are dependent on the activity of smooth and striated muscles in the bladder, urethra, and external urethral sphincter. During urine storage, the outlet is closed and the bladder smooth muscle is quiescent. When bladder volume reaches the micturition threshold, activation of a micturition center in the dorsolateral pons (the pontine micturition center) induces a bladder contraction and a reciprocal relaxation of the urethra, leading to bladder emptying. During voiding, sacral parasympathetic (pelvic) nerves provide an excitatory input (cholinergic and purinergic) to the bladder and inhibitory input (nitrergic) to the urethra. These peripheral systems are integrated by excitatory and inhibitory regulation at the levels of the spinal cord and the brain. Therefore, injury or diseases of the nervous system, as well as disorders of the peripheral organs, can produce lower urinary tract dysfunction, leading to lower urinary tract symptoms, including both storage and voiding symptoms, and pelvic pain. Neuroplasticity underlying pathological changes in lower urinary tract function is discussed.

Intravesical resiniferatoxin for the treatment of storage lower urinary tract symptoms in patients with either interstitial cystitis or detrusor overactivity: a meta-analysis

Background

While Resin­iferatoxin (RTX) has been widely used for patients with storage lower urinary tract symptoms (LUTS), its clinical efficiency hasn't yet been well evaluated. A meta-analysis was performed to evaluate the exact roles of intravesical RTX for the treatment of storage LUTS in patients with either interstitial cystitis (IC) or detrusor overactivity (DO).

Methods

A meta-analysis of RTX treatment was performed through a comprehensive search of the literature. In total, 2,332 records were initially recruited, 1,907 from Elsevier, 207 from Medline and 218 from the Web of Science. No records were retrieved from the Embase or Cochrane Library. Seven trials with 355 patients were included and one trial was excluded because of the lack of extractable data. The analyses were all performed using RevMan 5.1 and MIX 2.0.

Results

Bladder pain was significantly reduced after RTX therapy in patients with either IC or DO. The average decrease of the visual an alogue pain scale was 0.42 after RTX treatment (p = 0.02). The maximum cystometric capacity (MCC) was significantly increased in patients with DO (MCC increase, 53.36 ml, p = 0.006) but not in those with IC (MCC increase, −19.1 ml, p = 0.35). No significant improvement in urinary frequency, nocturia, incontinence or the first involuntary detrusor contraction (FDC) was noted after RTX therapy (p = 0.06, p = 0.52, p = 0.19 and p = 0.41, respectively).

Conclusions

RTX could significantly reduce bladder pain in patients with either IC or DO, and increase MCC in patients with DO; however, no significant improvement was observed in frequency, nocturia, incontinence or FDC. Given the limitations in the small patient size and risk of bias in the included trials, great caution should be taken when intravesical RTX is used before a large, multicenter, well-designed random control trial with a long-term follow-up is carried out to further assess the clinical efficacy of RTX in in patients with storage LUTS.

Resiniferatoxin for Pain Treatment: An Interventional Approach to Personalized Pain Medicine

This review examines existing preclinical and clinical studies related to resiniferatoxin (RTX) and its potential uses in pain treatment. Like capsaicin, RTX is a vanilloid receptor (TRPV1) agonist, only more potent. This increased potency confers both quantitative and qualitative advantages in terms of drug action on the TRPV1 containing nerve terminal, which result in an increased efficacy and a long duration of action. RTX can be delivered by a central route of administration through injection into the subarachnoid space around the lumbosacral spinal cord. It can also be administered peripherally into a region of skin or deep tissue where primary afferents nerves terminate, or directly into a nerve trunk or a dorsal root ganglion. The central route is currently being evaluated as a treatment for intractable pain in patients with advanced cancer. Peripheral administration offers the possibility to treat a wide diversity of pain problems because of the ability to bring the treatment to the site of the pain (the peripheral generator). While not all pain disorders are appropriate for RTX, tailoring treatment to an individual patient's needs via a selective and local intervention that chemically targets a specific population of nerve terminals provides a new capability for pain therapy and a simplified and effective approach to personalized pain medicine.

Effects of combination treatment of intravesical resiniferatoxin instillation and hydrodistention in patients with refractory painful bladder syndrome/interstitial cystitis: a pilot study

PURPOSE

Painful bladder syndrome/interstitial cystitis (PBS/IC) is a disabling disease of the urinary bladder, and its etiology and treatment are not yet established. Current medications used in the treatment of PBS/IC have shown limited efficacy. This prospective study investigated the efficacy of intravesical resiniferatoxin (RTX) in PBS/IC refractory to medical treatment.

METHODS

Patients with proven PBS/IC refractory to traditional medical treatment were enrolled. By randomized trial, a total of 18 consecutive patients were divided into two groups: treatment with hydrodistention and intravesical RTX (group 1) or treatment with hydrodistension only (group 2). We assessed bladder pain by use of a visual analogue pain scale, the maximal urine flow rate, post-void residual urine volume, and a voiding diary before and 3 months after treatment.

RESULTS

The median age of the 18 patients was 55.8±6.9 years, and the median duration of symptoms before diagnosis was 3.6±1.6 years. Frequency, functional bladder capacity, and score on a 5-point pain scale were significantly improved at 3-month after treatment in both groups. Intravesical RTX instillation plus hydrodistention, compared with hydrodistention only, did not have a significant effect on the voiding symptoms or uroflowmetry of the patients but significantly improved scores on the pain scale.

CONCLUSIONS

Intravesical RTX instillation plus hydrodistention was effective in relieving pain but was not effective in improving lower urinary tract symptoms. Further larger studies are needed to clarify the efficacy of combination treatment of intravesical RTX instillation and hydrodistention.

Pelvic pain in urogynaecology. Part I: evaluation, definitions and diagnoses

Aim of this review is to summarise the available literature on the definitions and assessment of pelvic pain in the urogynaecological patient. A MEDLINE search and a hand search of conference proceedings of the International Continence Society and International Urogynecological Association were performed. Sixty-nine articles were reviewed. The site of pain was specified in 45% of the articles, 20% used the digital examination of pelvic myofascial trigger points for the diagnosis; 20%, the Pelvic Pain and Urgency/Frequency Symptom Scale; 26%, the Interstitial Cystitis Symptom and Problem Index and 39%, a simple visual analogue scale. The diagnosis was interstitial cystitis in 67% and chronic pelvic pain in 19% of the articles. Consensus on the diagnostic procedures and definition of pelvic pain in the urogynaecological patient should be achieved in order to provide exact diagnostic information which will lead to more satisfying treatment options.

TRPV1: a target for next generation analgesics

Transient Receptor Potential Vanilloid 1 (TRPV1) is a Ca²⁺ permeant non-selective cation channel expressed in a subpopulation of primary afferent neurons. TRPV1 is activated by physical and chemical stimuli. It is critical for the detection of nociceptive and thermal inflammatory pain as revealed by the deletion of the TRPV1 gene. TRPV1 is distributed in the peripheral and central terminals of the sensory neurons and plays a role in initiating action potentials at the nerve terminals and modulating neurotransmitter release at the first sensory synapse, respectively. Distribution of TRPV1 in the nerve terminals innervating blood vessels and in parts of the CNS that are not subjected to temperature range that is required to activate TRPV1 suggests a role beyond a noxious thermal sensor. Presently, TRPV1 is being considered as a target for analgesics through evaluation of different antagonists. Here, we will discuss the distribution and the functions of TRPV1, potential use of its agonists and antagonists as analgesics and highlight the functions that are not related to nociceptive transmission that might lead to adverse effects.

TRP family proteins in the lower urinary tract: translating basic science into new clinical prospective

The lower urinary tract (LUT) is densely innervated by capsaicin-sensitive primary afferent neurons, a sub set of sensory nerves, in a number of species including humans. These fibers exhibit both a sensory (afferent) function, including the regulation of the micturition reflex and the perception of pain, and an 'efferent' function, involved in the detrusor smooth muscle contractility and plasma protein extravasation. The discovery of specific binding sites for capsaicin, the pungent ingredient of red chilli, initiated a rush that ended up with the cloning of the 'vanilloid receptor', which belongs to the TRP (transient receptor potential) family. Here we reviewed the knowledge about the presumable functions of TRP family proteins in the LUT as regulators of bladder reflex activity, pain perception and cell differentiation. This review will focus on experimental evidence and promising clinical applications of targeting these proteins for the treatment of detrusor overactivity and bladder pain syndrome. As TRP receptor ligands may promote cellular death, and inhibit the growth of normal and neoplastic cells, the translation of basic science evidence into new clinical prospective for bladder and prostate cancer will be shown.

Herpes simplex virus vector-mediated gene delivery for the treatment of lower urinary tract pain

Interstitial cystitis (IC)/painful bladder syndrome (PBS) is a painful debilitating chronic visceral pain disorder of unknown etiology that affects an estimated 1 million people in the United States alone. It is characterized by inflammation of the bladder that results in chronic pelvic pain associated with bladder symptoms of urinary frequency and urgency. Regardless of the etiology, IC/PBS involves either increased and/or abnormal activity in afferent nociceptive sensory neurons. Pain-related symptoms in patients with IC/PBS are often very difficult to treat. Both medical and surgical therapies have had limited clinical utility in this debilitating disease and numerous drug treatments, such as heparin, dimethylsulfoxide and amitriptyline, have proven to be palliative at best, and in some IC/PBS patients provide no relief whatsoever. Although opiate narcotics have been employed to help alleviate IC/PBS pain, this strategy is fraught with problems as systemic narcotic administration causes multiple unwanted side effects including mental status change and constipation. Moreover, chronic systemic narcotic use leads to dependency and need for dose escalation due to tolerance; therefore, new therapies are desperately needed to treat refractory IC/PBS. This has led our group to develop a gene therapy strategy that could potentially alleviate chronic pelvic pain using the herpes simplex virus-directed delivery of analgesic proteins to the bladder.

Persistent detrusor overactivity after transurethral resection of the prostate

Detrusor overactivity is associated with aging and benign prostatic obstruction and often causes the troublesome symptoms of urgency and urgency incontinence (overactive bladder), persistent detrusor overactivity after transurethral resection of the prostate being the cause of more than a third of poor symptomatic outcomes following surgery. Most of the evidence currently suggests that neurons of the urothelium at the bladder neck play a significant role in the genesis of detrusor overactivity. Treatment options including botulinum toxin injections and intravesical vanilloids have been studied in the treatment of persistent detrusor overactivity, but further studies are needed specifically in patients with persistent detrusor overactivity after transurethral resection of the prostate. As urodynamic studies are able to predict a proportion of postoperative failures, more widespread use is advocated by many in the routine assessment of lower urinary tract symptoms thought to be due to benign prostatic obstruction.

Pharmacologic management of painful bladder syndrome/interstitial cystitis: a systematic review

BACKGROUND

More than 180 different types of therapy have been used in the treatment and management of painful bladder syndrome/interstitial cystitis (PBS/IC), yet evidence from clinical trials remains inconclusive. This study aimed to evaluate the efficacy of pharmacologic approaches to PBS/IC, to quantify the effect size from randomized controlled trials, and to begin to inform a clinical consensus of treatment efficacy for PBS/IC.

METHODS

We identified randomized controlled trials for the pharmacologic treatment of patients with PBS/IC diagnosed on the basis of National Institute of Diabetes and Digestive and Kidney Diseases or operational criteria. Study limitations include considerable patient heterogeneity as well as variability in the definition of symptoms and in outcome assessment.

RESULTS

We included a total of 1470 adult patients from 21 randomized controlled trials. Only trials for pentosan polysulfate sodium had sufficient numbers to allow a pooled analysis of effect. According to a random-effects model, the pooled estimate of the effect of pentosan polysulfate therapy suggested benefit, with a relative risk of 1.78 for patient-reported improvement in symptoms (95% confidence interval, 1.34-2.35). This result was not heterogeneous (P = .47) and was without evidence of publication bias (P = .18). Current evidence also suggests the efficacy of dimethyl sulfoxide and amitryptyline therapy. Hydroxyzine, intravesical bacille Calmette-Guérin, and resiniferatoxin therapy failed to demonstrate efficacy, but evidence was inconclusive owing to methodological limitations.

CONCLUSIONS

Pentosan polysulfate may be modestly beneficial for symptoms of PBS/IC. There is insufficient evidence for other pharmacologic treatments. A consensus on standardized outcome measures is urgently needed.

Increased expression of transient receptor potential vanilloid subfamily 1 in the bladder predicts the response to intravesical instillations of resiniferatoxin in patients with refractory idiopathic detrusor overactivity

OBJECTIVES

To investigate the correlation of transient receptor potential vanilloid subfamily 1 (TRPV1) mRNA expression levels and the clinical outcome of intravesical resiniferatoxin treatment in patients with idiopathic detrusor overactivity (IDO), as such treatment with vanilloids can be effective for DO.

PATIENTS AND METHODS

In all, 28 patients with IDO refractory to anticholinergics were enrolled and treated with four weekly intravesical instillations of 10 nm resiniferatoxin. Eleven patients having ureteroscopic surgery served as controls. Two bladder wall biopsies were taken from the posterior wall by rigid cystoscopy. TRPV1 expression in the bladder wall samples was determined by individual quantitative reverse transcription-polymerase chain reaction, and immunohistochemical staining. Responders to the therapy were defined as those with an improvement in an urgency scale by >/=1, and with improved general satisfaction. Baseline TRPV1 expression was compared between responders, nonresponders and controls.

RESULTS

At 3 months, 14 patients (50%) were responders and in the other 14 the treatment failed (nonresponders). Bladder biopsies were available in seven responders and 11 nonresponders. Transcript levels before treatment correlated significantly with the therapeutic effect of resiniferatoxin (P = 0.004), with higher TRPV1 mRNA expression in responders (median 1.50, range 0.89-2.78) than nonresponders (0.74, 0.34-1.32). Responders also had higher TRPV1 expression levels than a control group (P = 0.067), but the TRPV1 transcript levels of nonresponders were not significantly different from those of the control (P = 0.367).

CONCLUSION

Successful intravesical resiniferatoxin treatment is closely associated with the over-expression of TRPV1 in the bladder mucosa and submucosa in patients with IDO.

TRPs in bladder diseases

This review attempts to provide an overview of the current knowledge of TRP proteins and their possible role in bladder function and disease. At present, there are 28 transient receptor potential (TRP) channels (subdivided into 7 categories or families) which are involved in a number of functions [G.A. Hicks, TRP channels as therapeutic targets: hot property, or time to cool down? Neurogastroenterology and Motility 18, (2006) 590-594., J.D. Levine, N. Alessandri-Haber, TRP channels: targets for the relief of pain, Biochimica et Biophysica Acta 1772, (2007) 989-1003.]. Of those belonging to the group 1 subfamily, a number of TRPV, TRPM and TRPA proteins associated with osmoregulation, thermal, chemical and mechanical signaling mechanisms have been shown to be expressed within the lower urinary tract. Though the biological role of many of these channels in urinary bladder function still remains elusive, TRPV1 is by far the best characterized and is thought to be involved in a number of bladder disorders [A. Szallasi, P.M. Blumberg, Vanilloid (Capsaicin) Receptors and Mechanisms, Pharmacological Reviews 51, (1999) 150-221., I. Nagy, P. Santha, G. Jansco, L. Urban, The role of the vanilloid (capsaicin) receptor (TRPV1) in physiology and pathology, European Journal of Pharmacology 500, (2004) 351-369.].

Treatment approaches for painful bladder syndrome/interstitial cystitis

Painful bladder syndrome/interstitial cystitis (PBS/IC) is a disease of unknown aetiology, characterised by severe pressure and pain in the bladder area or lower pelvis that is frequently or typically relieved by voiding, along with urgency or frequency of urination in the absence of urinary tract infections. PBS/IC occurs primarily in women, is increasingly recognised in young adults, and may affect as many as 0.1-1% of adult women. PBS/IC is often comorbid with allergies, endometriosis, fibromyalgia, irritable bowel syndrome and panic syndrome, all of which are worsened by stress. As a result, patients may visit as many as five physicians, including family practitioners, internists, gynaecologists, urologists and pain specialists, leading to confusion and frustration. There is no curative treatment; intravesical dimethyl sulfoxide, as well as oral amitriptyline, pentosan polysulfate and hydroxyzine have variable results, with success more likely when these drugs are given together. Pilot clinical trials suggest that the flavonoid quercetin may be helpful. Lack of early diagnosis and treatment can affect outcomes and leads to the development of hyperalgesia/allodynia.

Multiple Intravesical Instillations of Low-Dose Resiniferatoxin in the Treatment of Refractory Interstitial Cystitis

BACKGROUND

Current medications used in the treatment of interstitial cystitis (IC) have limited efficacy. This prospective study investigated the efficacy of multiple intravesical instillations of resiniferatoxin (RTX) at the concentration of 10 nM.

METHODS

Patients with proven IC previously treated with traditional medications for more than 6 months without clinical benefit were enrolled. They were excluded if bladder outlet obstruction or urinary tract infection was present. Intravesical instillation of low-dose RTX (10 nM) once weekly for 4 weeks was performed at the outpatient department. International Prostate Symptom Score (IPSS), 5-Point Pain Scale, and Quality of Life Index (QOL Index) were recorded. A videourodynamic study was done at baseline and 3 months after treatment.

RESULTS

The therapeutic results and urodynamic parameters were compared between baseline and 3 months. Thirteen patients, including 10 women and 3 men, were enrolled in this study. The mean duration of IC symptoms was 4.4 +/- 2.5 years. The mean duration of active treatment was 15.3 +/- 8.6 months. One female patient dropped out due to severe bladder pain after RTX instillation. Among the 12 patients who completed the study treatment, subjective assessment revealed that 2 had an excellent therapeutic result, 5 had an improved result and 5 remained unchanged from baseline. The overall satisfactory rate was 58.3%. IPSS, 5-Point Pain Scale, and QOL Index were significantly decreased after RTX treatment. There was no significant increase in mean functional bladder capacity or change in urodynamic parameters. No serious adverse event occurred after RTX treatment.

CONCLUSIONS

This study suggests that multiple intravesical instillations of RTX at the concentration of 10 nM are effective in relieving lower urinary tract symptoms in patients with refractory IC. The treatment is tolerable and suitable for use on an outpatient clinic basis.

TRPV1 (vanilloid receptor) in the urinary tract: expression, function and clinical applications

The transient receptor potential vanilloid subfamily 1 (TRPV1) is an ion channel activated by capsaicin, heat, protons and endogenous ligands such as anandamide. It is largely expressed in the urinary tract of mammals. Structures in which the receptor expression is firmly established include sensory fibers and urothelial cells, although the presence of TRPV1 in other cell types has been reported. As in other systems, pain perception was the first role attributed to TRPV1 in the urinary tract. However, it is now increasingly clear that TRPV1 also regulates the frequency of bladder reflex contractions, either through direct excitation of sensory fibers or through urothelial-sensory fiber cross talk involving the release of neuromediators from the epithelial cells. In addition, the recent identification of the receptor in urothelial and prostatic cancer cells raise the exciting hypothesis that TRPV1 is involved in cell differentiation. Desensitization of the receptor by capsaicin and resiniferatoxin has been investigated for therapeutic purposes. For the moment, lower urinary tract dysfunctions in which some benefit was obtained include painful bladder syndrome and overactive bladder of neurogenic and non-neurogenic origin. However, desensitization may become obsolete when non-toxic, potent TRPV1 antagonists become available.

[Afferent pathways arising from the lower urinary tract. Physiology, pathophysiology, and clinical implications]

Voluntary control of bladder function is mainly influenced by sensations arising from the lower urinary tract. Conscious perception of these sensations is imperative for appropriate urine storage and voiding at a socially accepted time and place and depends on the integrity of the afferent axis urothelium -- peripheral nerves -- spinal cord -- pons -- mesencephalon -- sensory cortex. This review considers the current knowledge about normal and impaired sensations arising from the bladder and the sphincter and addresses their clinical significance.

Multiple intravesical instillation of low-dose resiniferatoxin is effective in the treatment of detrusor overactivity refractory to anticholinergics

OBJECTIVE

To examine the effectiveness and tolerability of multiple intravesical instillations of 10 nmol/L resiniferatoxin in patients with detrusor overactivity (DO) refractory to anticholinergic agents, as not all these patients are successfully treated by one such instillation.

PATIENTS AND METHODS

The study included 53 patients with DO from neurogenic (NDO, 10), previous bladder outlet obstruction (BOO, 20) or idiopathic cause (IDO, 23) and who were refractory to anticholinergic agents. Patients received three to four instillations of 10 nmol/L resiniferatoxin, as outpatients. The International Prostate Symptom Score and quality-of-life index were recorded, and a video-urodynamic study conducted at baseline and 3 months after treatment. The therapeutic results and urodynamic variables were compared among patients with different causes of DO.

RESULTS

Four patients withdrew from the study after the first instillation because of urinary tract infection or severe pain on urination, leaving 49 who completed at least three instillations. The overall results were an excellent response in 17 patients (35%), improvement in 13 (27%) and failure in 19 (39%); the treatment was deemed a success (excellent or improved) in 16 of 20 with previous BOO, 11 of 19 with IDO, and only three of 10 with NDO (P = 0.011). Patients had significant improvements in the storage symptom score, total symptom score and quality-of-life index after treatment. The cystometric capacity and the postvoid residual were significantly greater and voiding efficiency significantly less after treatment. DO during the urodynamic study was absent in 12 patients after treatment.

CONCLUSIONS

Multiple intravesical instillations of 10 nmol/L resiniferatoxin are effective in treating patients with DO refractory to anticholinergics.

Intravesical resiniferatoxin decreases spinal c-fos expression and increases bladder volume to reflex micturition in rats with chronic inflamed urinary bladders

OBJECTIVE

To evaluate the effect of intravesical resiniferatoxin on spinal c-fos expression and bladder volume at reflex micturition in rats with chronic urinary bladder inflammation.

MATERIALS AND METHODS

Of three groups of female Wistar rats, group 1 received cyclophosphamide (75 mg/kg body weight) intraperitoneally every third day (cyclophosphamide is an antitumoral agent that induces bladder inflammation after urinary excretion of its metabolite, acrolein); group 2 comprised sham-inflamed rats that received saline instead of cyclophosphamide, and group 3 received cyclophosphamide, as group 1, every third day but plus 10 nmol/L resiniferatoxin intravesically, through a urethral catheter, at 7 days. At 8 days, under urethane anaesthesia, a needle was inserted in the bladder dome and saline infused at 6 mL/h for 2 h. Finally the animals were perfusion-fixed through the ascending aorta with 4% paraformaldehyde. Transverse sections cut from L6 spinal cord segments were immunoreacted for Fos protein and positive cells in the dorsal horn counted. In a further set of equal groups the bladders were prepared in the same way under urethane anaesthesia and after 30-min of stabilization, saline was infused at 6 mL/h and the volume evoking reflex micturition determined.

RESULTS

The mean (SD) number of positive c-fos cells per spinal cord section was 85 (21), 42 (9) (P = 0.002) and 55 (10) in groups 1 to 3, respectively; the values for group 2 and 3 were similar (P = 0.22) and statistically less than that of group 1 (P = 0.02). Reflex micturition occurred at, respectively, 0.26 (0.09), 0.49 (0.18) and 0.52 (0.11) mL, being similar in group 2 and 3 (P = 0.74) but lower in group 1 (P = 0.003).

CONCLUSION

Intravesical resiniferatoxin decreases c-fos expression and increases bladder capacity in chronically inflamed rat bladders. These findings suggest that desensitizing the vanilloid receptor type 1 by intravesical resiniferatoxin is relevant to the treatment of pain and voiding frequency in patients with chronic inflammatory bladder conditions.

Intravesical Vanilloids and Neurogenic Incontinence: Ten Years Experience

INTRODUCTION

In this study we critically review our '10-year' experience with intravesical vanilloids (capsaicin and resiniferatoxin) in the treatment of neurogenic incontinence, addressing the issue of their introduction into daily clinical practice.

MATERIALS AND METHODS

From July 1992 to June 2001, 54 patients suffering from detrusor hyperreflexia, due to spinal cord injuries, received intravesical instillation of capsaicin, and from January 1995 to June 2001, 47 patients received intravesical instillation of resiniferatoxin (RTX) in order to treat bladder dysfunction and symptoms. All patients presented detrusor hyperreflexia refractory to oral and/or intravesical oxibutynin and they displayed high-voiding pressure associated with frequent urine leakage. Capsaicin was used at a concentration of 10 mM; RTX was tested in two different concentrations: 10 nM and 10 microM. The outcome was considered according to simple parameters: (i) the number of patients who reported an improvement in clinical status (patient dry between clean intermittent catheterization) and urodynamic status (a bladder capacity 50% higher than pretreatment capacity, lasting more than 3 months after the instillation); (ii) the number of patients who continued intravesical therapy; (iii) the number of instillations they received; (iv) the length of the interval between 2 consecutive instillations, and (v) alternative therapies when vanilloids failed.

RESULTS

The topical intravesical instillation of capsaicin produced an improvement in symptoms and urodynamic parameters, in 29 patients (53.7%) after 3 months. In these 29 patients only 7 (24.13%) continued to received capsaicin in June 2001. The mean follow-up was 32.28 +/- 14.20 (range 8-52) months, the mean number of instillations was 6.14 +/- 2.54 (range 2-10) and the mean interval between the 2 consecutive instillations was 7.14 +/- 2.60 (range 4-12) months. The topical intravesical instillation of RTX produced an improvement in symptoms and urodynamic parameters in 73.33% of patients (a total of 45 patients) who received 10 microM. 18 of them (54.54%) continued to received RTX in June 2001. The mean follow-up was 27.88 +/- 10.95 (range 11-49) months, the mean number of instillations was 4.33 +/- 1.60 (range 2-8). The mean interval between 2 consecutive instillations was 9.61 +/- 2.99 (ranged 4-16) months.

CONCLUSION

The results obtained using RTX seem to be very promising with regard to efficacy and tolerance, particularly in comparison with capsaicin. Even if the number of patients who received capsaicin and RTX remains small, the intravesical vanilloid receptor agonist RTX could offer an attractive alternative to oral medications in the treatment of neurogenic incontinence.

The involvement of the tetrodotoxin-resistant sodium channel Na(v)1.8 (PN3/SNS) in a rat model of visceral pain

The present study investigated the effect of inhibiting the expression of Na(v)1.8 (PN3/SNS) sodium channels by an antisense oligodeoxynucleotide (ODN) on bladder nociceptive responses induced by intravesical acetic acid infusion in rats. Animals were injected intrathecally with either Na(v)1.8 antisense or mismatch ODN. Control cystometrograms under urethane anesthesia during intravesical saline infusion exhibited intercontraction intervals (ICIs) that were significantly longer in antisense-treated rats than in mismatch ODN-treated rats. Intravesical infusion of 0.1% acetic acid induced bladder hyperactivity as reflected by a 68% reduction in ICIs in mismatch ODN-treated rats but did not significantly reduce ICIs in antisense-treated rats. The number of Fos-positive cells after acetic acid administration were significantly reduced in the L6 spinal cord from antisense-treated animals, compared with mismatch ODN-treated animals. In addition, Na(v)1.8 immunoreactivity was reduced in L6 dorsal root ganglion neurons in the antisense-treated rat. In patch-clamp recordings, the conductance density of TTX-resistant sodium currents in dissociated bladder afferent neurons that were labeled by axonal transport of a fluorescent dye, Fast Blue, injected into the bladder wall was also smaller in antisense-treated rats than in mismatch ODN-treated rats, whereas no changes were observed in TTX-sensitive currents. These results indicate that the Na(v)1.8 TTX-resistant sodium channels are involved in the activation of afferent nerves after chemical irritation of the bladder. These channels represent a new target for the treatment of inflammatory pain from visceral organs such as the urinary bladder.