An updated systematic review and statistical comparison of standardised mean outcomes for the use of botulinum toxin in the management of lower urinary tract disorders

Therapeutic modulation of urinary bladder function: multiple targets at multiple levels

Storage dysfunction of the urinary bladder, specifically overactive bladder syndrome, is a condition that occurs frequently in the general population. Historically, pathophysiological and treatment concepts related to overactive bladder have focused on smooth muscle cells. Although these are the central effector, numerous anatomic structures are involved in their regulation, including the urothelium, afferent and efferent nerves, and the central nervous system. Each of these structures involves receptors for—and the urothelium itself also releases—many mediators. Moreover, hypoperfusion, hypertrophy, and fibrosis can affect bladder function. Established treatments such as muscarinic antagonists, β-adrenoceptor agonists, and onabotulinumtoxinA each work in part through their effects on the urothelium and afferent nerves, as do α1-adrenoceptor antagonists in the treatment of voiding dysfunction associated with benign prostatic hyperplasia; however, none of these treatments are specifically targeted to the urothelium and afferent nerves. It remains to be explored whether future treatments that specifically act at one of these structures will provide a therapeutic advantage.

Efficacy and safety of intravesical onabotulinumtoxinA injection on elderly patients with chronic central nervous system lesions and overactive bladder

PURPOSE

Intravesical injection of onabotulinumtoxinA is an effective treatment for overactive bladder (OAB). Nonetheless, the treatment outcome is unclear in OAB patients with central nervous system (CNS) lesions. This study evaluated the efficacy and safety of intravesical onabotulinumtoxinA treatment in elderly patients with chronic cerebrovascular accidents (CVAs), Parkinson's disease (PD) and dementia.

MATERIALS AND METHODS

Patients with CVA, PD, dementia, and OAB refractory to antimuscarinic therapy were consecutively enrolled in the study group. Age-matched OAB patients without CNS lesions were selected to serve as a control group. OnabotulinumtoxinA (100 U) was injected into the bladder suburothelium at 20 sites. The clinical effects, adverse events, and urodynamic parameters were assessed at baseline and 3 months post-treatment. The Kaplan-Meier method was used to compare long-term success rates between groups.

RESULTS

A total of 40 patients with OAB due to CVA (23), PD (9), dementia (8) and 160 control patients were included in this retrospetive analysis. Improvement of urgency severity scale, increased bladder capacity and increased post-void residual volume were comparable between the groups at 3 months. Patients with CNS lesions did not experience increased risks of acute urinary retention and urinary tract infection; nonetheless, patients with CVA experienced a higher rate of straining to void. Long-term success rates did not differ between the patients with and without CNS lesions.

CONCLUSION

Intravesical injection of 100 U of onabotulinumtoxinA effectively decreased urgency symptoms in elderly OAB patients with CNS lesions. The adverse events were acceptable, and long-term effects were comparable to OAB patients in general. Nonetheless, the possibility of longstanding urinary retention and chronic catheterization need careful evaluation for this very vulnerable population before choosing intravesical onabotulinumtoxinA treatment.

Chapter 6: Practical aspects of administration of onabotulinumtoxinA

Candidates for onabotulinumtoxinA are generally patients with overactive bladder (OAB) or neurogenic detrusor overactivity (NDO) whose disease is inadequately controlled with behavioral therapy and oral medication. All patients must be willing and able to perform clean intermittent catheterization (CIC). Before the decision to administer onabotulinumtoxinA is made, the clinician should provide counseling to the patient regarding the agent's indications, proposed benefits, risks, and mode of administration. The patient should be aware that onabotulinumtoxinA takes effect after approximately 1-2 weeks and usually lasts for 4-10 months, after which repeat injections will be necessary to maintain effect. Patient preparation may include pre-treatment antibiotics and withdrawal of antiplatelet therapy or anticoagulants. Preparation of the product involves reconstitution in sterile saline and dilution according to the planned dose. Local anesthesia (e.g., bladder instillation of lidocaine) is usually administered, although general anesthesia may be used in certain cases. The injections are performed using a flexible or rigid cystoscope, and the procedure takes approximately 15 min. The initial follow-up visit occurs within 7-14 days, when evidence of adverse effects, including urinary retention, can be evaluated. Repeat injections can be scheduled as needed, but not sooner than 3 months. Currently, the total dose of onabotulinumtoxinA should not exceed 360 U in a 3-month period for all indications, including those outside the urinary tract (i.e., cosmetic, ophthalmologic, etc.). Overall, onabotulinumtoxinA is effective, generally well tolerated, safe, and is relatively simple to provide.

What is the feasibility of switching to 200IU OnabotulinumtoxinA in patients with detrusor overactivity who have previously received 300IU?

Introduction

To assess the feasibility of converting from 300IU to 200IU OnabotulinumtoxinA in patients diagnosed with either idiopathic detrusor overactivity (IDO) or neurogenic detrusor overactivity (NDO).

Material and methods

Retrospective case–notes review of patients who were converted from 300IU to 200IU OnabotulinumtoxinA. Subjective patient reported improvements at interview and bladder diary reported parameters of urgency, urgency incontinence, frequency and nocturia.

Results

Forty–four patients had received 300IU OnabotulinumtoxinA and were switched to 200IU after July 2008, 28 for IDO and 16 for NDO. Thirty–seven patients reported ongoing improvement with 200IU OnabotulinumtoxinA, six patients had worsening in their symptoms since down–titrating to 200IU and one patient did not attend follow–up. Improvement in urgency and urgency incontinence episodes per day were 82% and 72%, respectively, in patients who received 200IU. Of the 44 patients, 39 continued to receive 200IU, four requested up–titration to 300IU (due to decreased effect) and one did not attend after the 1st treatment. After converting from 300IU to 200IU, additional three patients were started on CISC for de novo voiding difficulty.

Conclusions

Seventy–nine percent of patients were satisfied with their symptoms after switching from 300IU to 200IU OnabotulinumtoxinA. Only 9% of patients (all with NDO) reverted back to receiving 300IU. This study showed similar efficacy and longevity in the majority of patients (90%) using 200IU in both NDO and IDO.

Development of an in vitro model to measure bioactivity of botulinum neurotoxin A in rat bladder muscle strips

Background

Botulinum toxin A (BoNT-A) is a new treatment modality in various causes of bladder dysfunction; like neurogenic detrusor overactivity and overactive bladder. The best technique of administrating BoNT-A in patients is unknown. A validated in vitro model could be used to investigate newer intravesical administration techniques of BoNT-A. In this study, we describe the development and validation of in vitro model to measure inhibitory effects of BoNT-A on bladder strip contractions.

Methods

Rat bladder strips were mounted in organ baths filled with Krebs’ solution. The strips were stimulated chemically (80 mM potassium chloride, 1 μM carbachol) and electrically (Electrical Field Stimulation (EFS) 100 shocks, 50 V, 20 Hz, every 3 minutes). The viability of the strips was measured by carbachol stimulation at the beginning and at the end of the experiments. The strips were incubated in various concentrations of BoNT-A (0.03, 0.2, 0.3 nM). Controls were incubated in Krebs’ solution only. The inhibition of strip contraction induced by EFS was measured. These measurements were statistically analyzed with a log-logistic model representing diffusion.

Results

All strips remained viable during the experiments. Inhibition of strip contraction was observed after incubation with 0.3 nM BoNT-A. The measurements fitted to a log-logistic model describing diffusion of BoNT-A in the bladder strip. The parameters of the log-logistic model representing diffusion were significant for 0.3 nM BoNT-A. Incubation with 0.2 nM BoNT-A showed insignificant results for 2 out of 3 runs. Incubation with 0.03 nM BoNT-A did not result in significant inhibition of strip contractions.

Conclusions

An in vitro model was developed and validated in which the inhibitory effect of low concentrations of BoNT-A on bladder strip contractions can be measured.

Single compartment drug delivery

Drug design is built on the concept that key molecular targets of disease are isolated in the diseased tissue. Systemic drug administration would be sufficient for targeting in such a case. It is, however, common for enzymes or receptors that are integral to disease to be structurally similar or identical to those that play important biological roles in normal tissues of the body. Additionally, systemic administration may not lead to local drug concentrations high enough to yield disease modification because of rapid systemic metabolism or lack of sufficient partitioning into the diseased tissue compartment. This review focuses on drug delivery methods that physically target drugs to individual compartments of the body. Compartments such as the bladder, peritoneum, brain, eye and skin are often sites of disease and can sometimes be viewed as "privileged," since they intrinsically hinder partitioning of systemically administered agents. These compartments have become the focus of a wide array of procedures and devices for direct administration of drugs. We discuss the rationale behind single compartment drug delivery for each of these compartments, and give an overview of examples at different development stages, from the lab bench to phase III clinical trials to clinical practice. We approach single compartment drug delivery from both a translational and a technological perspective.

Intravesical treatment of bladder pain syndrome/interstitial cystitis: from the conventional regimens to the novel botulinum toxin injections

INTRODUCTION

Bladder pain syndrome (BPS) includes interstitial cystitis (IC) and is often used as a synonym of it (i.e., BPS/IC). It is associated with lower urinary tract symptoms as well as with negative cognitive, behavioral, sexual and/or emotional consequences. Unfortunately, none of the numerous existing oral and intravesical treatments have been effective for all of the BPS subtypes and therefore relevant research is ongoing.

AREAS COVERED

In this review, the authors analyze the existing literature for the intravesical treatment of BPS/IC with focus on the novel administration of botulinum toxin (BTX). Several intravesical drugs have been studied in the past, including lidocaine, heparin, pentosan polysulfate sodium, dimethyl sulfoxide, chondroitin sulfate, hyaluronic acid as well as investigational drugs such as GM-0111. Recently, intravesical submucosal injections of BTX have been studied in patients with BPS/IC.

EXPERT OPINION

Most of the recent studies use BTX-A with no serious adverse effects and with satisfactory results in patients who do not respond to oral or standard intravesical therapy. Nevertheless, there is no consensus regarding the best dosage scheme of BTX, the injection sites and the treatment intervals. BTX intravesical administration in patients with BPS/IC is a safe and efficient treatment option; yet the level of evidence of the initial studies is not high. There is still the need for large randomized controlled studies so that a consensus can be reached for the ideal BTX dosage, injection sites and intervals between treatments.