The effects of duloxetine on urethral function and sphincter morphology

Diagnosis and Non-Surgical Management of Urinary Incontinence - A Literature Review with Recommendations for Practice

Urinary incontinence (UI) is a bothersome symptom with population studies suggesting a prevalence of 13.1% in women and 5.4% in men. While a significant cohort of patients with this complaint may ultimately require surgical management to achieve complete continence, a number of non-surgical measures exist to improve symptoms and quality of life. A range of guidelines exist on this topic, including those published by the European Association of Urology (EAU), the International Continence Society (ICS), the American Urological Association (AUA) and the UK's National Institute for Health and Care Excellence (NICE). The aim of our study is to provide an overview of the initial assessment of patients with UI including history taking, examination and basic investigations. Our review outlines non-surgical management strategies for UI, including conservative measures, behavioral and physical therapies and drug treatment. We shall also examine the above guidelines and present a narrative overview of the literature surrounding the diagnosis and non-surgical management of urinary incontinence.

Urethral sphincter volume and urodynamic diagnosis

AIM

To compare urethral sphincter measurements in women with different urodynamic diagnoses using three-dimensional transperineal ultrasound (TPU).

METHODS

Women with lower urinary tract dysfunction having urodynamic studies (UDS) were prospectively recruited to this study. A detailed history and vaginal examination were conducted. Saline cystometry was performed and the women were divided into groups according to their urodynamic diagnosis, which were nondiagnostic urodynamics (NUDS), pure detrusor overactivity (PureDO), pure urodynamic stress incontinence (PureUSI) and mixed urinary incontinence (MUDS). Three-dimensional TPU was performed to measure total urethral sphincter volume, striated sphincter volume, core volume, sphincter length and maximum cross-sectional area. The ultrasound measurements were compared with the diagnostic urodynamics.

RESULTS

One hundred fifty women were included in the study. There were 37, 53, 22 and 38 women in the groups of NUDS, PureDO, PureUSI and MUDS respectively. The average striated sphincter volumes in these groups were 1.84 ml, 2.24 ml, 1.32 ml and 1.98 ml respectively. There was no difference in average age, body mass index or presence of prolapse in these groups. All measurements were larger in the PureDO and smaller in the PureUSI group compared with the NUDS group. The measurements in the MUDS group were larger than in the NUDS group and smaller than in the PureDO group but this difference was not statistically significant.

CONCLUSION

The urethral sphincter of women with PureDO is larger than in women with PureUSI. The value in women with MUDS was between the two. The size of the urethral sphincter appears to be related to the pathophysiology.

Urodynamic investigation by telemetry in Beagle dogs: validation and effects of oral administration of current urological drugs: a pilot study

Background

Vesico-urethral function may be evaluated in humans and dogs by conventional urodynamic testing (cystometry and urethral pressure profilometry) or by electromyography. These techniques are performed under general anaesthesia in dogs. However, anaesthesia can depress bladder and urethral pressures and inhibit the micturition reflex. The primary objective of this pilot study was to evaluate the use of telemetry for urodynamic investigation in dogs. We also aimed to determine the applicability of telemetry to toxicologic studies by assessing the repeatability of telemetric recordings.

Results

Conventional diuresis cystometry was performed in six continent adult female Beagle dogs prior to surgical implantation of telemetric and electromyographic devices. In the first phase of the telemetric study, continuous recordings were performed over 8 days and nights. Abdominal, intravesical and detrusor threshold pressures (Pdet th), voided volume (Vv), urethral smooth muscle electrical activity and involuntary detrusor contractions (IDC) were measured during the bladder filling phase and during micturition episodes.

Vv recorded during telemetry was significantly lower than bladder volume obtained by diuresis cystometry. Repeatability of telemetric measurements was greater for observations recorded at night. IDC frequency and Pdet th were both lower and Vv was higher at night compared to values recorded during daytime.

In the second phase of the telemetric study, phenylpropanolamine, oestriol, bethanechol, oxybutynin or duloxetine were administered orally for 15 days. For each drug, continuous recordings were performed overnight for 12 hours on days 0, 1, 8 and 15. Electromyographic urethral activity was significantly increased 8 days after oestriol or duloxetine administration. No significant changes in bladder function were observed at any time point.

Conclusions

In dogs, the high repeatability of nocturnal telemetric recordings indicates that this technique could provide more informative results for urologic research. Urethral smooth muscle electrical activity appears to be modified by administration of drugs with urethral tropism. In this pilot telemetric study, bladder function was not affected by oral administration of urological drugs at their recommended clinical dosages. Experimental studies, (pharmacokinetic and pharmacodynamic) and clinical studies are warranted to further define the effects of these drugs on vesico-urethral function in dogs.

A nonhuman primate model of stable urinary sphincter deficiency

PURPOSE

The pathophysiology of urinary sphincter deficiency in women remains incompletely understood and current treatment options have limitations. Female nonhuman primates may represent a relevant animal model for studies of pathophysiology and treatment interventions because of their human-like reproductive and age associated stages of life (premenopause, perimenopause and postmenopause), lower urinary tract structure and bipedal posture. We developed and characterized a nonhuman primate model of defined injury to the urethral sphincter complex.

MATERIALS AND METHODS

We used 22 adult female cynomolgus monkeys in which injury to the sphincter complex was created by cauterizing and then transecting its pudendal innervation. Urodynamic studies were performed before and during pudendal and hypogastric nerve stimulation at baseline, and 3, 6 and 12 months after injury. We also analyzed sphincter structure in vivo by cystourethrography, and ex vivo by quantitative histology and immunohistochemistry at these time points.

RESULTS

Injury produced a 47% to 50% decrease in maximal urethral pressure (vs baseline p <0.05). It also abolished the increase in maximal urethral pressure in response to pudendal and hypogastric nerve stimulation (vs baseline p >0.05), which persisted more than 12 months after injury. Urodynamic changes were consistent with decreased skeletal and smooth muscle content, decreased nerve responses and an associated decrease in somatic and adrenergic innervation in the sphincter complex.

CONCLUSIONS

These structural and urodynamic changes are consistent with those in patients with stress urinary incontinence. They support the usefulness of nonhuman primates as translatable surrogates for pathophysiological studies of urinary sphincter deficiency and testing novel therapies for that condition.

The effect of solifenacin on urethral sphincter morphology

INTRODUCTION AND HYPOTHESIS

The aim of the study was to determine whether a 6-week course of 5 mg of solifenacin succinate used to treat mixed incontinence, produces measurable changes in the appearance of the urethral sphincter.

METHODS

Twenty-six women undergoing treatment for mixed incontinence were recruited from a urogynaecology unit after failing to improve with conservative treatments and bladder drill. All underwent dual channel subtracted cystometry, which showed mixed urodynamic stress incontinence and detrusor overactivity. All patients underwent a 3D transperineal ultrasound before solifenacin therapy was started and after 6 weeks of treatment. The urethral length, width and volume of the smooth muscle and total sphincter volume were compared before and after the treatment.

RESULTS

Clinically, 13 reported no improvement in either stress or urge incontinence. Eight women reported improvement in their urgency symptoms but no benefit in their stress leakage. Four women reported resolution of both stress and urge incontinence. One woman reported worsening of her bladder symptoms. There was no significant change in the urethral length (p = 0.27), width (p = 0.50), volume of smooth muscle (p = 0.87) or total sphincter volume (p = 0.60) before and after treatment with solifenacin.

CONCLUSIONS

A 6-week course of solifenacin resulted in no measurable changes in the appearance of the urethral sphincter.

Measurement of urethral closure function in women with stress urinary incontinence

PURPOSE

We assessed the use of urethral pressure reflectometry in detecting pressure increases in the female urethra and compared the usefulness of urethral pressure reflectometry vs urethral pressure profilometry in a pharmacodynamic intervention study.

MATERIALS AND METHODS

In this randomized, double-blind, placebo controlled, crossover study 17 women with stress urinary incontinence or mixed urinary incontinence received 4 mg esreboxetine or placebo for 7 to 9 days followed by a washout period before crossing over treatments. Urethral pressure reflectometry and urethral pressure profilometry were performed before and at the end of each treatment period.

RESULTS

The urethral opening pressure measured with urethral pressure reflectometry increased significantly compared to placebo by 13.7 cm H(2)O (p <0.0001) with an observed within subject standard deviation of 5.4. The increase in maximum urethral closure pressure was 8.4 cm H(2)O compared to placebo (p = 0.06) and for maximum urethral pressure the increase was 9.9 cm H(2)O (p = 0.04). However, the within subject SD for these parameters was higher at 11.4 and 12.2, respectively, implying lower power for these analyses. While receiving esreboxetine patients had significantly fewer incontinence episodes and reported a treatment benefit (global impression of change) compared to placebo.

CONCLUSIONS

The opening pressure measured with urethral pressure reflectometry was less variable compared to the parameters measured with urethral pressure profilometry (maximum urethral closure pressure and maximum urethral pressure). Consequently using urethral pressure reflectometry would result in a more efficient study design when investigating pharmacological effects on the urethra in future studies. We also found that esreboxetine was well tolerated, and had a positive and clinically relevant effect on urethral closure function and symptoms of stress urinary incontinence.

A canine model of irreversible urethral sphincter insufficiency

OBJECTIVE

To develop a canine model of external urinary sphincter insufficiency by creating irreversible damage to the sphincter, because there is a need for a reliable and reproducible large animal model for the study of stress urinary incontinence (SUI) caused by deficient sphincter function.

MATERIALS AND METHODS

About a quarter of the total external sphincter muscle was removed microsurgically from seven female dogs; three age-matched dogs served as normal controls. The dogs had standard urodynamic and radiographic studies before and at 1, 2, 3, 4 and 7 months after surgery. Three dogs were killed at 4 months and four at 7 months after surgery for tissue analyses.

RESULTS

The interventions produced a consistent outcome. Urodynamic studies showed a significant and sustained decrease in sphincter function, which included a static urethral pressure profile, stress urethral profile and detrusor leak-point pressure. Furthermore, in vivo pudendal nerve stimulation and organ-bath studies of the retrieved tissue strips confirmed the loss of sphincter tissue function. Histologically, absence of functional sphincter muscle was evident in the damaged sphincter region.

CONCLUSIONS

These results show that a reliable and reproducible canine model of irreversible sphincter insufficiency can be created by microsurgical removal of sphincter muscle tissue. This model of external sphincter insufficiency could be used for evaluating methods (e.g. cell therapies) for treating SUI.

The treatment of urinary incontinence with Duloxetine

Duloxetine is a Serotonin and Noradrenaline reuptake inhibitor, and is the first drug licensed for medical treatment of urodynamic stress incontinence. In this paper, we will briefly review the pharmacology, current evidence and controversies in relation to the use of duloxetine.

The effect of duloxetine on urethral sphincter morphology

OBJECTIVES

This was a pilot study to identify whether a course of duloxetine had any effect on urethral sphincter morphology.

METHODS

Fifteen women with urodynamic stress incontinence were treated with duloxetine. The pretreatment condition of the bladder was assessed with the Patient Global Impression of Severity scale. A transperineal ultrasound scan was performed before therapy and again after 4-8 weeks of treatment. The urethral length and the width of the hypoechogenic core (longitudinal smooth muscle, vascular plexus and urothelium) were assessed.

RESULTS

Baseline incontinence symptoms were moderate or severe in 87% of women and an improvement following treatment was reported in 80% of women. Poor views were obtained of the striated muscle. There was a statistically significant increase in the mean width of the hypoechogenic core of the urethra from 5.0 mm to 6.3 mm (P < 0.01). There was no statistically significant change in the length of the urethra (mean 29.4 mm before and 28.0 mm after treatment).

CONCLUSIONS

Duloxetine appears to result in an alteration of the smooth muscle component of the urethral sphincter.