Treatment of Overactive Bladder in the Older Patient: Pooled Analysis of Three Phase III Studies of Darifenacin, an M3 Selective Receptor Antagonist

Neurological safety and efficacy of darifenacin and mirabegron for the treatment of overactive bladder in patients with history of cerebrovascular accident: A prospective study

OBJECTIVES

To evaluate the neurological safety and clinical efficacy of darifenacin and mirabegron in patients with a history of cerebrovascular accident (CVA) who had overactive bladder (OAB) symptoms.

METHODS

This prospective randomized study, approved by the institute's ethics committee, was carried out at a tertiary care center from December 2018 to June 2020. Treatment naïve adult patients with a past history of CVA with stable neurological status for atleast past 3 months with symptoms of OAB for 3 or more months were included. Eligible patients received either darifenacin or mirabegron for a period of 3 months and various parameters on the 3-day International Consultation on Incontinence Questionnaire (ICIQ) bladder diary, the Montreal Cognitive Assessment-Basic score (MoCA-B), and the adverse events at 3 months posttreatment were compared to that at the baseline.

RESULTS

A total of 60 patients were included, 30 in each arm. After 3 months of treatment with darifenacin or mirabegron, the majority of the ICIQ bladder diary parameters improved and there was no deterioration in the cognitive function as noted on the MoCA-B score in either of the arms. On intergroup comparison, the mean change in bladder diary parameters and the MoCA-B scores was similar between the two groups.

CONCLUSION

Darifenacin and mirabegron, in the short term, do not adversely affect the cognitive function in patients with a history of CVA with OAB symptoms. Both are safe and effective treatment options in patients with OAB post-CVA.

Exploring Molecular Approaches in Amyotrophic Lateral Sclerosis: Drug Targets from Clinical and Pre-Clinical Findings

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease (MND) characterized by the death of upper and lower motor neurons (corticospinal tract) in the motor cortex, basal ganglia, brain stem, and spinal cord. The patient experiences the sign and symptoms between 55 to 75 years of age, which include impaired motor movement, difficulty in speaking and swallowing, grip loss, muscle atrophy, spasticity, and sometimes associated with memory and cognitive impairments. Median survival is 3 to 5 years after diagnosis and 5 to 10% of the patients live for more than 10 years. The limited intervention of pharmacologically active compounds, that are used clinically, is majorly associated with the narrow therapeutic index. Pre-clinically established experimental models, where neurotoxin methyl mercury mimics the ALS like behavioural and neurochemical alterations in rodents associated with neuronal mitochondrial dysfunctions and downregulation of adenyl cyclase mediated cAMP/CREB, is the main pathological hallmark for the progression of ALS in central as well in the peripheral nervous system. Despite the considerable investigation into neuroprotection, it still constrains treatment choices to strong care and organization of ALS complications. Therefore, this current review specially targeted the investigation of clinical and pre-clinical features available for ALS to understand the pathogenic mechanisms and to explore the pharmacological interventions associated with the up-regulation of intracellular adenyl cyclase/cAMP/ CREB and activation of mitochondrial-ETC coenzyme-Q10 as a future drug target in the amelioration of ALS mediated motor neuronal dysfunctions.

Comparative Safety and Efficacy of Treatments for Overactive Bladder Among Older Adults: A Network Meta-analysis

BACKGROUND

Cumulative exposure to one or more anticholinergic medications ("anticholinergic burden") is associated with an increased risk of adverse outcomes, particularly among older individuals. Mirabegron, an oral selective β3-adrenergic receptor agonist, has demonstrated efficacy in managing the symptoms of overactive bladder without contributing to anticholinergic burden. However, it is not known whether the favorable safety profile of mirabegron relative to antimuscarinics varies with increasing age among a patient population who may have a high anticholinergic burden.

OBJECTIVE

The primary objective of this study was to indirectly compare the safety and efficacy profile of mirabegron relative to antimuscarinics in older adults with overactive bladder.

METHODS

A systematic literature review was conducted to identify randomized controlled trials that reported safety and efficacy endpoints among patients aged ≥ 65 years. Identified randomized controlled trials were subsequently synthesized via a network meta-analysis. Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines in designing, performing, and reporting the literature review were followed. In line with current best practices, the network meta-analysis was conducted using a Bayesian approach and according to the overall general guidance for evidence synthesis developed by the National Institute for Health and Care Excellence decision support unit. Estimates of relative safety were assessed via the odds ratio and estimates of relative efficacy were assessed via means and credible intervals.

RESULTS

A total of 3078 abstracts, 300 of which underwent full-text screening, were identified using the search criteria. Twenty articles reporting on 21 randomized controlled trials were eligible for data extraction and synthesis. Following review, five safety and five efficacy endpoints were considered for inclusion in the network meta-analysis. Regarding findings typical of anticholinergic exposure in older adults, mirabegron was not associated with an increased odds of dry mouth (odds ratio 95% credible interval 0.76 [0.26-2.37]) or constipation (1.08 [0.39-3.02]) relative to placebo, whereas antimuscarinics were strongly associated with these events (odds ratio range 3.78-7.85 and 2.12-4.66, respectively). In this older population, mirabegron was associated with a similar odds of experiencing adverse event-related treatment discontinuations relative to placebo (0.99 [0.57-1.70]), while the odds of experiencing an adverse event-related treatment discontinuation for antimuscarinics had a range of 1.14-3.03 (in most cases, the association was mild). No increased odds of experiencing overall treatment-emergent adverse events was observed for mirabegron or antimuscarinics (odds ratio range 1.25-1.55), apart from fesoterodine (2.23 [1.37-3.37]). Finally, a similar treatment effect was observed across all efficacy endpoints between mirabegron and antimuscarinics in this older population.

CONCLUSIONS

This study indicates that the safety and efficacy profile of mirabegron remains favorable compared with antimuscarinics among older adults. This includes safety outcomes typically associated with anticholinergic burden, which were less frequently observed in patients treated with mirabegron.

Systematic literature review of clinical trials evaluating pharmacotherapy for overactive bladder in elderly patients: An assessment of trial quality

AIMS

Overactive bladder (OAB) disproportionately affects older-aged adults, yet most randomized controlled trials (RCTs) underrepresent patients ≥65. This systematic literature review (SLR) identified RCTs evaluating β-3 adrenergic agonists or muscarinic antagonists in elderly patients with OAB, and compared study quality across trials.

METHODS

MEDLINE^® , Embase^® , and Cochrane Collaboration Central Register of Clinical Trials databases were searched from inception through April 28, 2015 to identify published, peer-reviewed RCT reports evaluating β-3 adrenergic agonists or muscarinic antagonists in elderly OAB patients (either ≥65 years or study-described as "elderly"). To assess study quality of RCT reports, we focused on internal/external validity, assessed via two scales: the validated Effective Public Health Practice Project [EPHPP]): Quality Assessment Tool for Quantitative Studies, and a tool commissioned by the Agency for Healthcare Research and Quality (AHRQ).

RESULTS

Database searches yielded 1380 records that were then screened according to predefined inclusion/exclusion criteria. We included eight papers meeting study criteria. Despite scientific community efforts to improve RCT reporting standards, published reports still include incomplete and inconsistent reporting-of subject attrition, baseline patient characteristics, inclusion/exclusion criteria, and other important details. Only three of the eight OAB RCTs in this review received quality ratings of Strong (EPHPP) or Fair (AHRQ) and were multicenter with large samples.

CONCLUSIONS

Despite the prevalence of OAB among older age individuals, relatively few RCTs evaluate OAB treatments explicitly among elderly subjects. The findings from this quality assessment suggest some areas for improvement in both conduct and reporting of future RCTs assessing OAB treatment in elderly.

Real-world characteristics of elderly patients with overactive bladder in the United States

OBJECTIVES

Although much has been published about the demographic and clinical characteristics of elderly patients with overactive bladder (OAB) who were enrolled in clinical trials, very little is known about the general population of elderly Americans with OAB. We update this gap in the literature by using real-world data to describe this population.

METHODS

We used Medicare claims and the Medicare Current Beneficiary Surveys from 2006 to 2011 to identify patients with OAB. We describe the demographic characteristics, functional impairment and physical limitations, concurrent medical conditions, Charlson Comorbidity Index (CCI) scores, and concomitant medication use of patients with OAB; these characteristics are also described by sex and age group (65-74 vs. ≥75 years). We also compare the characteristics of OAB with non-OAB patients.

RESULTS

We identified 415 elderly patients with OAB (average age 79 years; 71% female) and 6868 without OAB (average age 77 years; 62% female). Patients with OAB reported high levels of functional impairment as measured by the Activities of Daily Living (44% vs. 33% for non-OAB patients), Instrumental ADL (53% vs. 40% for non-OAB patients), and physical functioning limitation (90% vs. 81% for non-OAB patients) scales. Elderly patients with OAB also experienced high levels of comorbidity burden, as measured by the number of medical conditions (18 vs. 11 for non-OAB patients), CCI (2.1 vs. 1.4 for non-OAB patients), and number of non-OAB-related concomitant medications used (11 vs. 8 for non-OAB patients).

CONCLUSIONS

Elderly patients with OAB in the general population have high levels of functional impairment and physical limitations, comorbidity, and concomitant medication use. These characteristics should be taken into consideration when managing OAB symptoms and designing future clinical studies. These results, which are representative of elderly patients with OAB in the general US population, should, however, be interpreted in light of the key limitations of the data we used: patients may have been misclassified and medical conditions overestimated due to artifacts of diagnosis coding and our results can only be generalized to patients who were enrolled in Medicare Parts A, B, and D for at least 12 continuous months.

Adverse events and treatment discontinuations of antimuscarinics for the treatment of overactive bladder in older adults: A systematic review and meta-analysis

INTRODUCTION

Antimuscarinics should be used with caution in older adults with overactive bladder (OAB) due to anticholinergic adverse events (AEs). Systematic reviews and meta-analyses (SRMAs) have analyzed safety-related outcomes but have not specified risk in the elderly, the population at highest risk for AEs. The aim of this review is to explore and evaluate AEs and treatment discontinuations in adults 65 or older taking antimuscarinics for OAB.

METHODS

Keywords were searched in MEDLINE, EMBASE, SCOPUS, and Cochrane Central Register for Controlled Trials. Randomized controlled trials (RCTs) along with sub-analyses and pooled analyses that compared antimuscarinics to placebo or another antimuscarinic were performed in February 2015. Studies assessing AEs or treatment discontinuations in a population of adults 65 or older were included. The Jadad Criteria and McHarm Tool were used to assess the quality of the trials.

RESULTS

A total of 16 studies met the inclusion criteria. Eighty AEs and 27 reasons for treatment discontinuation were described in the included studies and further explored. Anticholinergic AEs were more common in antimuscarinics compared to placebo. Incidence of dizziness, dyspepsia, and urinary retention with fesoterodine, headache with darifenacin, and urinary tract infections with solifenacin were significantly higher compared to placebo. Treatment discontinuation due to AEs and dry mouth were higher in the antimuscarinics when compared to placebo in older adults.

CONCLUSIONS

Treatment for overactive bladder using antimuscarinics in adults aged 65 or older resulted in significant increases in risk for several AEs compared to placebo including anticholinergic and non-anticholinergic AEs.

Mechanisms Underlying Activation of α₁-Adrenergic Receptor-Induced Trafficking of AQP5 in Rat Parotid Acinar Cells under Isotonic or Hypotonic Conditions

Defective cellular trafficking of aquaporin-5 (AQP5) to the apical plasma membrane (APM) in salivary glands is associated with the loss of salivary fluid secretion. To examine mechanisms of α₁-adrenoceptor (AR)-induced trafficking of AQP5, immunoconfocal microscopy and Western blot analysis were used to analyze AQP5 localization in parotid tissues stimulated with phenylephrine under different osmolality. Phenylephrine-induced trafficking of AQP5 to the APM and lateral plasma membrane (LPM) was mediated via the α_1A-AR subtype, but not the α_1B- and α_1D-AR subtypes. Phenylephrine-induced trafficking of AQP5 was inhibited by ODQ and KT5823, inhibitors of nitric oxide (NO)-stimulated guanylcyclase (GC) and protein kinase (PK) G, respectively, indicating the involvement of the NO/ soluble (c) GC/PKG signaling pathway. Under isotonic conditions, phenylephrine-induced trafficking was inhibited by La³⁺, implying the participation of store-operated Ca²⁺ channel. Under hypotonic conditions, phenylephrine-induced trafficking of AQP5 to the APM was higher than that under isotonic conditions. Under non-stimulated conditions, hypotonicity-induced trafficking of AQP5 to the APM was inhibited by ruthenium red and La³⁺, suggesting the involvement of extracellular Ca²⁺ entry. Thus, α_1A-AR activation induced the trafficking of AQP5 to the APM and LPM via the Ca²⁺/ cyclic guanosine monophosphate (cGMP)/PKG signaling pathway, which is associated with store-operated Ca²⁺ entry.

Oral pharmacotherapy for overactive bladder in older patients: mirabegron as a potential alternative to antimuscarinics

OBJECTIVE

Overactive bladder (OAB) is a particular challenge to treat in older adults with co-morbid conditions taking multiple medications. Antimuscarinics (e.g., solifenacin, fesoterodine) and β3-adrenergic receptor agonists (mirabegron) are similarly efficacious; however, antimuscarinics may be associated with side effects that result in poor persistence and contribute to anticholinergic burden, particularly in those taking other medications with anticholinergic properties. With a mechanism of action distinct from antimuscarinics, mirabegron has a different tolerability profile and does not contribute to anticholinergic burden. The objective of this review was to compare and contrast the tolerability profiles of antimuscarinics and mirabegron in older patients to inform practice.

METHODS

Prospective trials or retrospective subgroup analyses of antimuscarinics for the treatment of OAB in older patients were identified through a search of PubMed. Tolerability data and results of subgroup analyses of mirabegron in patients aged ≥65 and ≥75 years from a pooled analysis of three trials each of 12 weeks and a 1 year trial are described.

RESULTS

Anticholinergic adverse events (AEs) including dry mouth and constipation were more frequent with antimuscarinics versus mirabegron. In patients aged ≥65 years, dry mouth occurred with a six-fold higher incidence with tolterodine extended-release (ER) 4 mg than with mirabegron 25 mg or 50 mg over 12 weeks, and a three-fold higher incidence with tolterodine ER than mirabegron 50 mg over 1 year. Mirabegron had a low incidence of central nervous system effects. A systematic review of the cardiovascular safety profile of mirabegron has not identified any clinically significant effects on blood pressure or pulse rate at therapeutic doses amongst patients aged ≥65 years.

CONCLUSIONS

Mirabegron has a more favorable tolerability profile than antimuscarinics amongst older patients and may provide an improved benefit-to-risk ratio and therefore be considered as an alternative to antimuscarinics for older patients.

Electronic bladder diaries of differing duration versus a paper diary for data collection in overactive bladder

AIMS

This observational study compared data values, reliability, consistency and compliance collected by electronic and paper diaries of differing durations.

METHODS

Subjects ≥18 years with overactive bladder (OAB) on stable antimuscarinic treatment for ≥12 weeks were assigned to one of five, 15-week diary schedules in this randomized, parallel-group observational study. Sample size was sufficient to assess reliability and consistency of diary data with adequate precision. Reliability was assessed via intraclass correlation coefficients, variability with ANCOVAs, and consistency using Cronbach's alpha.

RESULTS

Demographic characteristics of randomized subjects were representative of OAB trial populations. For mean volume voided, reliability was comparable across diary groups. For incontinence, reliability improved with increasing diary duration. For micturition frequency, electronic 7-day diary results had highest reliability and lowest variability. Lowest overall reliability was observed in the 3-day paper diary. Consistency was highest in the electronic continuous groups; Cont A (daily measurements throughout the study period [fully Continuous]) and Cont B (daily measurements for some but not all endpoints of interest [Partially Continuous]). Compliance was generally high; across groups ≥90% of diaries had at least one entry per day. There was no significant change in average micturition frequency with diary duration, suggesting no diary fatigue. One-third of subjects in the electronic Cont B group also reported micturitions as incontinence when they only needed to report incontinence; they also reported lowest satisfaction with the study. The electronic 7-day and electronic Cont A schedules (who reported incontinence and micturitions throughout the study) had lowest residual errors.

CONCLUSIONS

For future OAB trials, 7-day or continuous electronic diaries may improve accuracy and reliability of micturition and incontinence frequency data compared with shorter collection periods and paper diaries. Neurourol. Urodynam. 35:743-749, 2016. © 2015 Wiley Periodicals, Inc.

A review and additional post-hoc analyses of the incidence and impact of constipation observed in darifenacin clinical trials

Background

Constipation is a common side effect of antimuscarinic treatment for overactive bladder (OAB). This review evaluates the incidence and impact of constipation on the lives of patients with OAB being treated with darifenacin.

Methods

Constipation data from published Phase III and Phase IIIb/IV darifenacin studies were reviewed and analyzed. Over 4000 patients with OAB (aged 18–89 years; ≥80% female) enrolled in nine studies (three Phase III [data from these fixed-dose studies were pooled and provide the primary focus for this review], three Phase IIIb, and three Phase IV). The impact of constipation was assessed by discontinuations, use of concomitant laxatives, patient-reported perception of treatment, and a bowel habit questionnaire.

Results

In the pooled Phase III trials, 14.8% (50/337) of patients on darifenacin 7.5 mg/day and 21.3% (71/334) on 15 mg/day experienced constipation compared with 12.6% (28/223) and 6.2% (24/388) with tolterodine and placebo, respectively. In addition, a few patients discontinued treatment due to constipation (0.6% [2/337], 1.2% [4/334], 1.8% [4/223], and 0.3% [1/388] in the darifenacin 7.5 mg/day or 15 mg/day, tolterodine, and placebo groups, respectively), or required concomitant laxatives (3.3% [11/337], 6.6% [22/334], 7.2% [16/223], and 1.5% [6/388] in the darifenacin 7.5 mg/day or 15 mg/day, tolterodine, and placebo groups, respectively). Patient-reported perception of treatment quality was observed to be similar between patients who experienced constipation and those who did not. During the long-term extension study, a bowel habit questionnaire showed only small numerical changes over time in frequency of bowel movements, straining to empty bowels, or number of days with hard stools.

Conclusion

While constipation associated with darifenacin was reported in ≤21% of the patient population, it only led to concomitant laxative use in approximately one-third of these patients and a low incidence of treatment discontinuation. These data suggest that constipation did not impact patient perception of treatment quality.

Darifenacin for the treatment of overactive bladder

Overactive bladder is a debilitating disorder affecting 16.5% of adults and increasing in prevalence with age. Symptoms, including urgency, urge incontinence and frequency can result from detrusor overactivity with contraction of the bladder mediated primarily by activation of muscarinic M(3) receptors. Antimuscarinic agents are therefore an important approach to treating overactive bladder, but a lack of M(3) receptor subtype selectivity with these agents can generate a range of side effects that limits their effectiveness. This review describes an alternative approach to treating overactive bladder using the selective muscarinic M(3) receptor antagonist darifenacin. The M(3) receptor selectivity of darifenacin improves the symptoms of overactive bladder while reducing the potential for deleterious effects of non-M(3) muscarinic receptor antagonism in the brain or heart. The pharmacology and pharmacokinetics of darifenacin are summarized, and the its clinical efficacy and demonstrated safety profile are described.

Efficacy and tolerability of fesoterodine versus tolterodine in older and younger subjects with overactive bladder: a post hoc, pooled analysis from two placebo-controlled trials

AIMS

To assess the efficacy and tolerability of fesoterodine 8 mg versus tolterodine extended release (ER) 4 mg in subjects with overactive bladder (OAB) stratified by age (<65, 65-74, and ≥75 years).

METHODS

This was a post hoc analysis of data from two double-blind trials. Subjects reporting ≥1 urgency urinary incontinence (UUI) episode and ≥8 micturitions/24 hr at baseline were randomized to fesoterodine (4 mg for 1 week, 8 mg for 11 weeks), tolterodine ER 4 mg, or placebo. Subjects completed 3-day bladder diaries, Urgency Perception Scale (UPS), Patient Perception of Bladder Condition (PPBC), and OAB questionnaire (OAB-q) at baseline and week 12. The primary endpoint in both studies was change from baseline to week 12 in UUI episodes.

RESULTS

Among subjects <65 years (n = 2,670), improvements in UUI episodes, micturitions, urgency episodes, severe urgency episodes, frequency-urgency sum, UPS, PPBC, and all OAB-q scales and domains were significantly greater with fesoterodine versus tolterodine ER, and diary-dry rates were significantly higher. Among subjects 65-74 years (n = 990), improvements in mean voided volume per void, PPBC, and OAB-q Symptom Bother and Coping were significantly greater with fesoterodine versus tolterodine ER. Among subjects aged ≥75 years (n = 448), improvements in urgency episodes, severe urgency episodes, frequency-urgency sum, UPS, and OAB-q Symptom Bother were significantly greater with fesoterodine versus tolterodine ER. Both active treatments produced significant improvements in most outcomes versus placebo across age groups. Adverse event rates were similar among age groups.

CONCLUSIONS

Fesoterodine 8 mg consistently improved several OAB-related variables versus tolterodine ER 4 mg in subjects aged <65, 65-74, and ≥75 years, with some differences reaching statistical significance, and was generally well tolerated.

Pharmacokinetics and toxicity of antimuscarinic drugs for overactive bladder treatment in females

INTRODUCTION

Antimuscarinics (AMs) are the mainstay of pharmacological treatment of overactive bladder (OAB), a symptom complex defined by the presence of urinary urgency, usually associated with frequency and nocturia, with or without urgency urinary incontinence. The AMs used to treat OAB differ in their pharmacological profiles, which may affect their potential for causing adverse effects (AEs).

AREAS COVERED

The present article aims to review the literature about pharmacokinetics (PK) of the different AMs used in the treatment of OAB. Furthermore, the AEs related to the use of these drugs and their incidence are presented. This systematic review is based on material searched and obtained via Medline, Pubmed and EMBASE up to March 2012 using the search terms "adverse events, pharmacokinetics, tolerability" in combination with "darifenacin, fesoterodine, imidafenacin, oxybutynin, propiverine, solifenacin, tolterodine, and trospium."

EXPERT OPINION

Antimuscarinics are the first-line pharmacological treatment for OAB. Despite the development of new molecules that improve their efficacy/safety profile, there are some drugs that are pharmacokinetically more appropriate to be prescribed in specific populations such as patients with neurological disease or the elderly. Moreover, research should be encouraged in evaluating antimuscarinics in conjunction with other drugs such as estrogens or beta-agonists. The identification of prognostic criteria for pharmacological therapy would be helpful.

Muscarinic agonists and antagonists: effects on the urinary bladder

Voiding of the bladder is the result of a parasympathetic muscarinic receptor activation of the detrusor smooth muscle. However, the maintenance of continence and a normal bladder micturition cycle involves a complex interaction of cholinergic, adrenergic, nitrergic and peptidergic systems that is currently little understood. The cholinergic component of bladder control involves two systems, acetylcholine (ACh) released from parasympathetic nerves and ACh from non-neuronal cells within the urothelium. The actions of ACh on the bladder depend on the presence of muscarinic receptors that are located on the detrusor smooth muscle, where they cause direct (M₃) and indirect (M₂) contraction; pre-junctional nerve terminals where they increase (M₁) or decrease (M₄) the release of ACh and noradrenaline (NA); sensory nerves where they influence afferent nerve activity; umbrella cells in the urothelium where they stimulate the release of ATP and NO; suburothelial interstitial cells with unknown function; and finally, other unidentified sites in the urothelium from where prostaglandins and inhibitory/relaxatory factors are released. Thus, the actions of muscarinic receptor agonists and antagonists on the bladder may be very complex even when considering only local muscarinic actions. Clinically, muscarinic antagonists remain the mainstay of treatment for the overactive bladder (OAB), while muscarinic agonists have been used to treat hypoactive bladder. The antagonists are effective in treating OAB, but their precise mechanisms and sites of action (detrusor, urothelium, and nerves) have yet to be established. Potentially more selective agents may be developed when the cholinergic systems within the bladder are more fully understood.

Antimuscarinic drugs: review of the cognitive impact when used to treat overactive bladder in elderly patients

The blockade of muscarinic receptors in the management of overactive bladder (OAB) symptoms provides beneficial as well as adverse effects. The cognitive changes observed are caused by the drugs' ability to cross the blood-brain barrier and bind to muscarinic receptors within the central nervous system (CNS). To date, while not specifically testing for CNS side effects, most of the controlled efficacy trials of multiple OAB medications have not shown significant adverse effects on cognitive function. However, elderly individuals, in whom OAB is more prevalent, often are excluded from these studies. The few trials that have performed cognitive testing in healthy elderly people taking antimuscarinics have clearly shown that oxybutynin can adversely affect cognition. Darifenacin, trospium, solifenacin, and tolterodine appear to have little to no risk of causing CNS side effects in this population. However, caution needs to be used in elderly patients with preexisting dementia.

Persistence and adherence in the treatment of overactive bladder syndrome with anticholinergic therapy: a systematic review of the literature

Overactive bladder syndrome (OAB) is a chronic condition that has an impact on patients' daily activities and health-related quality of life (HRQL). Anticholinergic therapy is often prescribed following insufficient results with behaviour modification alone; however, rates of treatment discontinuation are consistently high. This study systematically reviewed persistence and adherence data in patients with OAB treated with anticholinergic therapy. A search focused on the intersection of OAB, persistence/adherence, and anticholinergic therapy was conducted in MEDLINE and EMBASE. Articles published after 1998 were reviewed and selected for inclusion based on prespecified criteria. A total of 147 articles and two abstracts were included in the review. Results from 12-week clinical trials showed high rates of discontinuation, ranging from 4% to 31% and 5% to 20% in treatment and placebo groups, respectively. Unsurprisingly, rates of discontinuation found in medical claims studies were substantially higher, with 43% to 83% of patients discontinuing medication within the first 30 days and rates continuing to rise over time. Findings from medical claims studies also suggest that over half of patients never refill their initial prescription and that adherence levels tend to be low, with mean/median medication possession ratio (MPR) values ranging from 0.30 to 0.83. The low levels of persistence and adherence documented in this review reveal cause for concern about the balance between the efficacy and tolerability of anticholinergic agents. Strategies should be identified to increase persistence and adherence. New agents and non-pharmacologic alternatives with good efficacy and minimal side effects should be explored.

Anticholinergics for overactive bladder therapy: central nervous system effects

The mainstay of pharmacological treatment of overactive bladder (OAB) is anticholinergic therapy using muscarinic receptor antagonists (tertiary or quaternary amines). Muscarinic receptors in the brain play an important role in cognitive function, and there is growing awareness that antimuscarinic OAB drugs may have adverse central nervous system (CNS) effects, ranging from headache to cognitive impairment and episodes of psychosis. This review discusses the physicochemical and pharmacokinetic properties of OAB antimuscarinics that affect their propensity to cause adverse CNS effects, as observed in phase III clinical trials and in specific investigations on cognitive function and sleep architecture. PubMed/MEDLINE was searched for "OAB" plus "muscarinic antagonists" or "anticholinergic drug." Additional relevant literature was identified by examining the reference lists of papers identified through the search. Preclinical and clinical trials in adults were assessed, focusing on the OAB antimuscarinics approved in the United States. The blood-brain barrier (BBB) plays a key role in protecting the CNS, but it is penetrable. The lipophilic tertiary amines, particularly oxybutynin, are more likely to cross the BBB than the hydrophilic quaternary amine trospium chloride, for which there are very few reports of adverse CNS effects. In fact, in 2008 the US product labels for oral oxybutynin were modified to include the potential for anticholinergic CNS events and a warning to monitor patients for adverse CNS effects. Even modest cognitive impairment in the elderly may negatively affect independence; therefore, selection of an antimuscarinic OAB drug with reduced potential for CNS effects is advisable.

Trospium chloride once-daily extended release is efficacious and tolerated in elderly subjects (aged ≥ 75 years) with overactive bladder syndrome

OBJECTIVE

• To evaluate the safety and efficacy of once-daily trospium chloride extended release (ER) in overactive bladder syndrome (OAB) in subjects aged ≥ 75 years.

SUBJECTS AND METHODS

• The analysis included subjects ≥ 75 years of age with OAB. • A subgroup analysis of pooled data was performed for subjects aged ≥ 75 years from two randomized, double-blind, multicenter studies of subjects with OAB receiving once-daily trospium 60 mg extended release (ER) or placebo for 12 weeks, followed by 9-month open-label extension periods during which all subjects received trospium ER. A total of 143 of the 1165 subjects from two phase III registration trials who were aged ≥ 75 years (85 trospium ER, 58 placebo; mean age 79 years and ranging up to 90 years; 73% female) were evaluated. • Dual primary efficacy variables were the changes from baseline in the average number of toilet voids per day and urge urinary incontinence episodes per day.

RESULTS

• At week 12 of the double-blind period, trospium ER produced greater improvements from baseline than placebo in voiding diary parameters, OAB Patient Global Assessment, and quality of life. • Efficacy and tolerability persisted among subjects receiving open-label trospium ER for up to 1 year.

CONCLUSIONS

• Once-daily trospium chloride 60 mg ER demonstrated efficacy vs placebo and was tolerated in subjects aged ≥ 75 years with OAB. • For subjects who continued into the open-label treatment period, efficacy and tolerability were observed for up to 1 year.

Do gender, age or lifestyle factors affect responses to antimuscarinic treatment in overactive bladder patients?

AIMS

Gender, age, obesity, smoking and alcohol or caffeine intake have been shown or proposed to be risk factors for the prevalence and/or severity of the overactive bladder symptom complex (OAB) or related parameters. We have explored whether any of these factors affect the therapeutic response to a muscarinic receptor antagonist during routine clinical use.

METHODS

Data were analysed from 3766 OAB patients (77.1% woman, age 62.6 +/- 12.8 years) participating in an observational, open-label postmarketing surveillance study of the safety and efficacy of darifenacin. Multiple logistic regression models were applied to explore the effect of potential OAB risk factors on the darifenacin treatment-associated improvement of OAB symptoms, patient's subjective rating of bladder problems and global efficacy and tolerability.

RESULTS

Age and (less consistently) gender were statistically significantly correlated with efficacy parameters, but the extent of their impact was judged to be too small to be clinically relevant. Except for a very small effect of body mass index on urgency episode improvement, none of the lifestyle-associated factors had significant effects on the efficacy of darifenacin. Except for a very small age effect, none of the potential risk factors had significant effects on global tolerability.

DISCUSSION AND CONCLUSIONS

We conclude that the efficacy and tolerability of a muscarinic receptor antagonist, such as darifenacin is largely independent of potential OAB risk factors, such as gender, age, obesity, smoking and alcohol or caffeine intake.

Review of cognitive impairment with antimuscarinic agents in elderly patients with overactive bladder

Overactive bladder (OAB) will become an increasingly prevalent problem as the proportion of older people in the population increases over the next 20 years. In addition to the urological symptoms (urinary urgency, with or without urgency incontinence, usually with increased daytime frequency and nocturia), OAB is associated with other problems in older patients, especially an increased risk of falls and fractures. The bother caused by OAB needs not be an inevitable consequence of ageing, because the symptoms can usually be alleviated, even in frail older people. Pharmacological treatment for OAB involves the use of antimuscarinic agents, whose efficacy and safety profiles depend on their interactions with muscarinic receptors that are widely distributed throughout the body. Interactions between antimuscarinics and M(1) receptors in the central nervous system may have the potential to cause cognitive impairment in older people, depending on muscarinic receptor binding profiles, lipophilicity and the ability to cross the blood brain barrier. Concerns over the possibility of cognitive impairment have contributed to an under-utilisation of antimuscarinics in the geriatric population, despite the high prevalence and severity of OAB in older subjects. Antimuscarinic agents should be actively considered for elderly patients with OAB, but it is desirable to establish the cognitive risk for every type of antimuscarinic, using robust cognition assessment methods.

Behavioral intervention versus pharmacotherapy or their combinations in the management of overactive bladder dysfunction

Overactive bladder syndrome (OAB) refers to individuals with the following symptoms: urinary urgency, increased urinary frequency, and urge incontinence. These symptoms are not life threatening but can cause embarrassment and significantly impact quality of life. There are numerous treatment options for OAB, including behavioral therapy, traditional pharmacological therapy or a combination of the two. These options are considered the mainstay of treatment for OAB. We carried out a comprehensive systematic review of the available literature on the effectiveness of behavioral intervention, anticholinergic drugs, and their combination in the management of adults with overactive bladder, with emphasis on results from clinical trials and primary literature. Each treatment intervention is efficacious, and the choice should be based on the patient's severity of symptoms, tolerability, compliance and satisfaction with the treatment. Based on available literature, management of OAB using a combination of behavioral therapy and drug intervention is the most efficacious in terms of patient satisfaction, perceived improvement, and reduction of bladder symptoms. It is also the most practical and cost effective for optimal management of patients with OAB. Pharmacological treatment, in addition to behavioral therapy, remains important in the management of adults with OAB syndrome.

Current and novel therapeutic options for irritable bowel syndrome management

Irritable bowel syndrome is a functional gastrointestinal disorder affecting up to 3-15% of the general population in western countries. It is characterised by unexplained abdominal pain, discomfort, and bloating in association with altered bowel habits. The pathophysiology of irritable bowel syndrome is multifactorial involving disturbances of the brain-gut axis. The pathophysiology provides the rationale for pharmacotherapy: abnormal gastrointestinal motor functions, visceral hypersensitivity, psychosocial factors, autonomic dysfunction, and mucosal immune activation. Understanding the mechanisms, and their mediators or modulators including neurotransmitters and receptors have led to several therapeutic approaches including agents acting on the serotonin receptor or serotonin transporter system, antidepressants, novel selective anticholinergics, alpha-adrenergic agonists, opioid agents, cholecystokinin-antagonists, neurokinin-antagonists, somatostatin receptor agonists, corticotropin releasing factor antagonists, chloride channel activators, guanylate cyclase-c agonists, melatonin, atypical benzodiazepines, antibiotics, immune modulators and probiotics. The mechanisms and current evidence regarding efficacy of these agents are reviewed.

Trospium chloride treatment of overactive bladder

OBJECTIVE

To review the pharmacology, pharmacokinetics, safety, and clinical application of trospium chloride for the management of overactive bladder (OAB).

DATA SOURCES

Clinical literature including both primary sources and review articles was accessed through MEDLINE, International Pharmaceutical Abstracts, and Cochrane databases from 1980 through January 8, 2009. Search terms included overactive bladder, urge urinary incontinence, muscarinic receptor antagonists, and urinary frequency. Further data sources were identified from bibliographies of selected articles.

STUDY SELECTION AND DATA EXTRACTION

Basic pharmacology data were extracted from animal studies and pharmacokinetic data were gathered from human studies. Multicenter, parallel, randomized, double-blind, placebo-controlled studies were included to describe the efficacy and adverse effects of trospium.

DATA SYNTHESIS

Trospium chloride is an antimuscarinic agent indicated for the treatment of OAB with symptoms of urge urinary incontinence, urgency, and urinary frequency. Trospium has 3 chemical and pharmacokinetic properties unique among antimuscarinic agents: it is a positively charged quaternary ammonium compound with minimal central nervous system penetration; it is not metabolized by the cytochrome P450 system, resulting in a lower tendency for drug interactions; and it is excreted mainly unchanged in the urine as the active parent compound, providing local activity to achieve early onset of clinical effect and prolonged efficacy. In two 12-week, randomized, placebo-controlled clinical studies in adults with OAB, trospium 20 mg twice daily was more effective than placebo in reducing the number of micturitions per 24 hours, reducing the number of urge incontinence episodes per week, and increasing the volume of urine voided per micturition. Placebo-controlled trials report efficacy with trospium in treatment of OAB; comparative trials with other anticholinergic agents are limited. Current therapy of OAB consists primarily of anticholinergic drugs such as oxybutynin, which are associated with therapy-limiting adverse effects. Because the prevalence of OAB is greatest among the elderly, safety considerations regarding renal function must be noted, with dosage adjustment required in patients with severe renal impairment.

CONCLUSIONS

Whether the pharmacodynamic properties of trospium make it superior to other therapies will require considerable additional experience with the drug. For now, it appears to be a feasible alternative for patients who cannot tolerate oxybutynin.

Choice of antimuscarinic agents for overactive bladder in the older patient: focus on darifenacin

Overactive bladder (OAB) is a difficult condition to live with and is very costly to the community. OAB affects 16% of the adult population and rises with increasing age. We describe the necessary steps in evaluation and behavioral therapy prior to initiating medical therapy. There are several medications that have been used for the treatment of patients who suffer from OAB. This manuscript discusses the popular agents used for OAB, with a focus on the recent clinical trials on darifenacin.

A systematic review and meta-analysis of randomized controlled trials with antimuscarinic drugs for overactive bladder

CONTEXT

Anticholinergic drugs are commonly used in patients with overactive bladder (OAB) who do not achieve symptom relief and quality of life improvement with conservative management. Several drugs, with different doses, formulations, and routes of administration are currently available, making the choice quite difficult.

OBJECTIVE

To evaluate efficacy and safety of different doses, formulations, and route of administration of the available anticholinergic drugs.

EVIDENCE ACQUISITION

A systematic review of the literature was performed in August 2007 using Medline, Embase, and Web of Science. Efficacy (micturitions per 24h, volume voided per micturition, urgency urinary incontinence episodes per 24h, incontinence episodes per 24h) and safety (mainly, adverse events and withdrawal rates) end points were evaluated in the randomized control trials (RCTs) assessing the role of anticholinergic drugs in non-neurogenic OAB. Meta-analysis of RCTs was conducted using the Review Manager software 4.2 (Cochrane Collaboration).

EVIDENCE SYNTHESIS

Our systematic search identified 50 RCTs and three pooled analyses. Tolterodine immediate release (IR) had a more favorable profile of adverse events than oxybutynin IR. Regarding different dosages of IR formulations, dose escalation might yield some limited improvements in the efficacy but at the cost of significant increase in the rate of adverse events. In the comparisons between IR and extended-release (ER) formulations, the latter showed some advantages, both in terms of efficacy and safety. With regard to the route of administration, use if a transdermal route of administration does not provide significant advantage over an oral one.

CONCLUSION

Many of the available RCTs have good methodological quality. ER formulations should be preferred to the IR ones. With regard to IR formulations, dose escalation might yield some improvements in the efficacy with significant increase in the AE. More clinical studies are needed to indicate which of the drugs should be used as first-, second-, or third-line treatment.

Treatment of overactive bladder in the aging population: focus on darifenacin

Anticholinergics are commonly used in primary and secondary care settings for the treatment of overactive bladder syndrome. The number of anticholinergic drugs available on the market is increasing and various studies, both observational and randomized controlled trials, have evaluated effectiveness of the different preparations available. When anticholinergic therapy is prescribed, there is still uncertainty about which anticholinergic drugs are most effective, at which dose, and by which route of administration. There is also uncertainty about the role of anticholinergic drugs in different patient groups, particularly in the elderly. The rationale for using anticholinergic drugs in the treatment of overactive bladder syndrome is to block the parasympathetic acetylcholine pathway and thus abolish or reduce the intensity of detrusor muscle contraction. There are currently five recognized subtypes of muscarinic receptor; the M₁, M₂, and M₃ subtypes are of interest in bladder activity. Muscarinic receptors are found in other parts of the body, eg, in the gut, salivary glands, tear ducts. Side effects associated with non-selective antimuscarinics can be particularly distressing in the elderly. The development of bladder selective M₃ specific antagonists has the advantage of providing increased efficacy with minimal side effects. Darifenacin is one such preparation. The aim of this review is to assess the pharmacology, interactions and the safety and tolerability of darifenacin in the treatment of overactive bladder in the elderly population with particular reference to clinical trial data available.

Long-term darifenacin treatment for overactive bladder in patients aged 65 years and older: analysis of results from a 2-year, open-label extension study

OBJECTIVES

This analysis evaluated the long-term safety, tolerability and efficacy of darifenacin, a muscarinic M3 selective receptor antagonist, in the treatment of overactive bladder (OAB) in patients > or = 65 years of age.

METHODS

Patients who completed one of two 12-week, placebo-controlled, double-blind, feeder studies received once-daily (o.d.) treatment with darifenacin 7.5 mg for the first 2 weeks of the 2-year, open-label extension study. The dose could be subsequently adjusted (7.5 or 15 mg o.d.) according to need. Safety and tolerability were assessed, and efficacy variables/endpoints were evaluated from patient diary data.

RESULTS

214 patients (65-89 years) entered and 137 (64.0%) completed the 2-year extension study, amounting to 308 patient-years' drug exposure. Darifenacin was well tolerated with no new safety concerns. The most common adverse events (AEs) were dry mouth and constipation, which infrequently resulted in discontinuation (2.3% and 4.2%, respectively). Darifenacin produced significant improvements in OAB symptoms that were maintained over the 2-year period (median reduction from feeder-study baseline to 2 years: -11.0 [-83.7%] for incontinence episodes/week and -1.2 [-12.4%] for micturitions/day, both p < 0.05), with 44.4% patients achieving > or = 90% reduction in incontinence episodes at 2 years.

CONCLUSIONS

Darifenacin demonstrated good tolerability and safety in older patients with OAB. The improvement in OAB symptoms was sustained throughout the 2-year extension, resulting in high treatment persistence rates. Results were comparable with those in the overall OAB population from this study, indicating that darifenacin treatment is effective and well tolerated irrespective of age.

Darifenacin treatment of patients >or= 65 years with overactive bladder: results of a randomized, controlled, 12-week trial

BACKGROUND

Overactive bladder (OAB) increases in prevalence with advancing age. This study specifically investigated patients >or= 65 years, evaluating the efficacy, tolerability, safety and quality of life (QoL) outcomes from darifenacin treatment.

METHODS

Patients (n = 400, mean age 72 years) with OAB were randomized (2:1) to receive 12 weeks of double-blind treatment with darifenacin (7.5 mg once daily for 2 weeks, then optional titration to 15 mg daily) or placebo (with sham titration). Efficacy, tolerability and safety were assessed from patient diary data, adverse events and discontinuations and QoL outcomes using specific questionnaires.

RESULTS

Mean urgency urinary incontinence episodes (UUIEs) decreased significantly from baseline to Week 12 with both darifenacin (-88.6%) and placebo (-77.9%; p > 0.05), with 70% and 58% patients responding with >or= 50% reductions, respectively (p = 0.021). This was accompanied by significant differences between groups in reductions in micturition frequency (-25.3% with darifenacin vs. -18.5% placebo; p < 0.01). QoL assessments revealed significant improvements with darifenacin versus placebo at Week 12 in OAB-q, Patient Perception of Bladder Condition, and patient and physician assessments of treatment benefit (all p < 0.001). The most commonly reported adverse events were dry mouth and constipation.

CONCLUSIONS

This study demonstrated that marked improvements in OAB symptoms can be achieved in patients >or= 65 years, with significant treatment differences in responder rates, micturition frequency and QoL. Reduction in UUIEs may not be the optimal endpoint in this population, whereas QoL appears to be a sensitive and relevant patient-oriented measure of treatment effect.

Effects of the M3 Receptor Selective Muscarinic Antagonist Darifenacin on Bladder Afferent Activity of the Rat Pelvic Nerve

OBJECTIVE

Previous studies have revealed that intravesical and systemic administration of oxybutinin suppress pelvic afferent nerves. This study evaluates the efficacy of a selective M3 antimuscarinic, darifenacin, on bladder afferent activity.

METHODS

Sixteen single bladder afferent fibers were isolated in nine female Sprague-Dawley rats. On the basis of their conduction velocities, they were grouped as Adelta or C fibers. The effect of repeat bladder filling was studied on the mechanosensitive properties of these units. The M3 receptor selective muscarinic antagonist darifenacin (0.1mg/kg) was administered intravenously. Unitary afferent activity was again analyzed 30, 60, 90, and 120 min after the drug administration.

RESULTS

Seven units corresponded to criteria for Adelta fibers, nine for C fibers. Repeat bladder filling did not change nerve activity in Adelta or C fibers. When nerve activity was expressed as a percent of control activity, afferent sensitivity changed after darifenacin in Adelta fibers: 86+/-27%, 30 min (p>0.05), 69 +/- 32%, 60 min (p<0.05), 56 +/- 36%, 90 min (p<0.05), and 61+/- 49%, 120 min (p>0.05), and in C fibers: 70+/-39%, 30 min (p<0.05), 57 +/- 49%, 60 min (p<0.05), 45 +/- 42%, 90 min (p<0.01), and 47 +/- 43%, 120 min (p<0.01).

CONCLUSIONS

In this study we show that darifenacin reduces bladder afferent activity in both Adelta and C fibers. The decrease in afferent spikes in C fibers may be more pronounced than that in Adelta fibers. These results may explain that the efficacy of darifenacin in overactive bladder symptoms is partly due to bladder afferent desensitization.

Die Therapie der Blasenüberaktivität bei älteren und alten Menschen

Overactive bladder syndrome is a widespread disorder that leads to considerable impairment of quality of life. Besides behavioural therapy (bladder training), methods used in physiotherapy, electrotherapy and instrumental biofeedback have also proved to be successful approaches to treatment. With their good clinical and urodynamic efficacy, substances with antimuscarinic action at M3 receptors in particular and possibly also at M2 receptors have proved successful as first-line agents for the treatment of overactive bladder (OAB). Despite the frequently high level of suffering and severe impairment of quality of life, however, compliance is poor. Muscarine receptors do have a significant effect on detrusor function, but numerous other mechanisms and receptor entities also play a role. Whether patient acceptance can be significantly increased by the development of selective M-receptor antagonists, improved bladder selectivity or formulating innovations remains to be proven by broad-based clinical testing and independent, comparative, scientific studies. At present, it is not possible to estimate with absolute certainty the risk of an anticholinergic-induced deterioration in cognitive abilities, in particular in elderly individuals. Initial data suggest that primarily M3-selective receptor blockage with darifenacin could be beneficial.

Overactive bladder syndrome in older people

The overactive bladder symptom complex (OAB) is the commonest cause of urinary incontinence in older people, and is usually due to underlying detrusor overactivity, and as such is a treatable condition. Older people are a heterogeneous group, which includes fit community-dwelling individuals and those with significant medical comorbidity; thus the requirements of care for this group are many and varied. The International Continence Society definition of the frail elderly, those aged >65 years with continence problems, who by virtue of comorbidity are house-bound or living in an institution, is clearly not applicable to all. However, many conditions begin to appear in later life and practitioners need to be aware of the need to manage these, and their treatment, when dealing with older people. Studies of medication for OAB have included the elderly and there is evidence of an equivalent benefit in younger people. The impact of treatment on the cognitively impaired and those receiving acetylcholinesterase inhibitors is discussed.

Darifenacin: a muscarinic M3-selective receptor antagonist for the treatment of overactive bladder

Darifenacin is a novel, muscarinic M(3)-selective receptor antagonist with up to 59-fold selectivity for M(3) receptors compared with other muscarinic receptor subtypes and a low relative affinity for M(1) and M(2) receptors. This profile may explain its clinical efficacy in overactive bladder (OAB), the observed absence of adverse effects on cognitive function and reduced cardiovascular risks. Large-scale clinical trials have confirmed that darifenacin 7.5 and 15 mg/day provide rapid and meaningful improvement across a range of OAB symptoms, but with CNS and cardiac adverse event rates comparable to placebo. On this basis, darifenacin seems to meet the standard for an effective OAB pharmacotherapy that is well-tolerated and, more importantly, minimises the risk of safety-related adverse effects.

New Options and Strategies for the Treatment of Urinary Incontinence

Urinary incontinence is a prevalent, although often unreported, disease within the elderly population, with consequences spanning many aspects of the patient's life. Treatments differ for each subtype of urinary incontinence: urge incontinence, stress incontinence, and incontinence associated with bladder outlet obstruction and lower urinary tract symptoms in men. Limitations in current therapies have negatively affected care for each of these subtypes, particularly in the vulnerable elderly population. An emergence of new treatment options and strategies has created opportunities to optimize care for the general population. These include the use of trospium, darifenacin, solifenacin, and duloxetine as well as the strategic use of antimuscarinic agents in conjunction with alpha adrenergic blockade in men with bladder outlet obstruction. Yet, the literature regarding use of these agents and strategies in the elderly should be carefully evaluated to determine the benefits and the unique risks posed by their use in this vulnerable population.

The Current and Future Burden and Cost of Overactive Bladder in Five European Countries

OBJECTIVE

To estimate and compare the current and future direct cost of overactive bladder (OAB) to the health care systems of five European countries.

METHOD

A health economic model was created to estimate the number of people currently affected by OAB symptoms, the expected number to be affected in the future, and the resultant economic burden on health care systems in Germany, Italy, Spain, Sweden, and the United Kingdom.

RESULTS

The model estimated that in 2000, 20.2 million people over age 40 in the five countries experienced the symptoms of OAB; 7 million of these had urgency with urge incontinence. This figure is expected to rise to 25.5 million by 2020, including 9 million who will have urgency with urge incontinence. Average annual direct costs of OAB management ranged from euro269 to euro706 per patient per year. The largest cost was the use of incontinence pads, accounting for an average of 63% of the annual per patient cost of OAB management. Total cost to health care systems across all five countries was estimated at euro4.2 billion in 2000, and by 2020, the expected total cost was estimated to be euro5.2 billion, an increase of euro1 billion (26%).

CONCLUSION

OAB is prevalent, with a substantial direct cost that is anticipated to increase in the future in line with aging populations. The overall burden, including indirect costs, may be considerably larger, and will fall predominantly on the elderly OAB population with urge incontinence. Recommended medical treatments could help manage those costs and should be evaluated.

The clinical pharmacokinetics of darifenacin

Darifenacin hydrobromide is a selective muscarinic M(3) receptor antagonist that is indicated for use in treatment of overactive bladder disorder. Darifenacin was found to have a short terminal elimination half-life after intravenous and immediate-release oral dosage forms (3-4 hours) but this increased with a prolonged-release (PR) formulation (14-16 hours). The absolute bioavailability of darifenacin from 7.5 and 15 mg PR tablets was estimated to be 15.4% and 18.6%, respectively. With repeated once-daily oral administration of the PR formulation, peak plasma concentrations of darifenacin are achieved approximately 7 hours post-dose. After oral administration, darifenacin is well absorbed from the gastrointestinal tract and very little unchanged drug (<2%) is recovered in the faeces. Steady state is achieved after 6 days of once-daily administration of the PR formulation. As expected, values of peak plasma concentration (C(max)) and area under the plasma concentration-time curve are dose dependent, although the increase in plasma concentrations is proportionally greater than the increase in dose owing to saturation of presystemic metabolism. From intravenous administration, it has been established that darifenacin possesses a moderate-to-high hepatic extraction ratio, with high plasma clearance (36-52 L/h) and a volume of distribution (165-276L) that exceeds total body water. It is highly protein bound (98%), primarily to alpha(1)-acid glycoprotein. Darifenacin is subject to extensive hepatic metabolism, with 3% of unchanged drug excreted in urine and faeces. Metabolism is mediated by hepatic cytochrome P450 2D6 and 3A4, the main metabolic routes being monohydroxylation in the dihydrobenzfuran ring, dihydrobenzfuran ring opening, and N-dealkylation of the pyrrolidine nitrogen. Several possibly important drug-drug interactions have been identified with darifenacin, including ketoconazole, erythromycin and fluconazole, each of which increases darifenacin mean C(max) by 9.52-, 2.28- and 1.88-fold, respectively. When given with imipramine, darifenacin causes 1.6-fold higher plasma concentrations of the antidepressant and its major metabolite. Moderate hepatic impairment, but not renal insufficiency, has been shown to increase plasma concentrations of the drug. The pharmacokinetic profile of darifenacin is not affected by food.

Irritable bowel syndrome: recent and novel therapeutic approaches

Irritable bowel syndrome (IBS) is a highly prevalent functional gastrointestinal disorder affecting up to 3-15% of the general population in Western countries. It is characterised by unexplained abdominal pain, discomfort and bloating in association with altered bowel habits. The pathophysiology of IBS is considered to be multifactorial, involving disturbances of the brain-gut-axis: IBS has been associated with abnormal gastrointestinal motor functions, visceral hypersensitivity, psychosocial factors, autonomic dysfunction and mucosal inflammation. Traditional IBS therapy is mainly symptom oriented and often unsatisfactory. Hence, there is a need for new treatment strategies. Increasing knowledge of brain-gut physiology, mechanisms, and neurotransmitters and receptors involved in gastrointestinal motor and sensory function have led to the development of several new therapeutic approaches. This article provides a systematic overview of recently approved or novel medications that show promise for the treatment of IBS; classification is based on the physiological systems targeted by the medication. The article includes agents acting on the serotonin receptor or serotonin transporter system, novel selective anticholinergics, alpha-adrenergic agonists, opioid agents, cholecystokinin antagonists, neurokinin antagonists, somatostatin receptor agonists, neurotrophin-3, corticotropin releasing factor antagonists, chloride channel activators, guanylate cyclase-c agonists, melatonin and atypical benzodiazepines. Finally, the role of probiotics and antibacterials in the treatment of IBS is summarised.

Long-term treatment with darifenacin for overactive bladder: results of a 2-year, open-label extension study

OBJECTIVE

To examine, in a 2-year, non-comparative, open-label extension study, the safety, tolerability and efficacy of darifenacin controlled-release (CR) 7.5/15 mg once daily in patients with overactive bladder (OAB) who completed two 12-week randomized, double-blind, placebo-controlled 'feeder' studies.

PATIENTS AND METHODS

Patients entering the extension received darifenacin 7.5 mg once daily for 2 weeks, after which a voluntary increase in dose to 15 mg was permitted. Thereafter, patients could adjust the dose (either 7.5 or 15 mg). Safety and tolerability were assessed from adverse events (AEs) and discontinuations. Efficacy was determined using various endpoints.

RESULTS

In all, 716 patients entered the extension (mean age 57.3 years; 85.1% women) and 475 (66.3%) completed it (1089.9 patient-years of exposure). Darifenacin was well tolerated with no significant safety concerns. The most commonly reported AEs were dry mouth and constipation (all-causality rates 23.3% and 20.9%, respectively), leading to discontinuation in 1.3% and 2.4% of patients, respectively. Constipation infrequently required intervention, and analysis of bowel-habit questionnaires revealed that the reporting of constipation was related to minor changes in bowel habit rather than true constipation. The efficacy of darifenacin was maintained, including significant improvements in the number of incontinence episodes/week (median change -84.4% at 2 years, P < 0.001 vs feeder-study baseline). After 2 years, > 40% of patients achieved a > or = 90% reduction in incontinence episodes/week.

CONCLUSION

In the first published 2-year, open-label study of a CR antimuscarinic agent, darifenacin 7.5/15 mg once daily had a favourable safety, tolerability and efficacy profile during the long-term treatment of OAB. As such, darifenacin represents a valuable therapeutic option for OAB.

Differential effects of the antimuscarinic agents darifenacin and oxybutynin ER on memory in older subjects

OBJECTIVES

To investigate the effects of darifenacin controlled-release (CR) and oxybutynin extended-release (ER) on cognitive function (particularly memory) in older subjects.

METHODS

Healthy subjects (n=150) >/=60 years were randomised to darifenacin, oxybutynin ER or placebo in a multicentre, double-blind, double-dummy, parallel-group, 3-week study. Doses were administered according to US labels: oxybutynin ER 10mg once daily (od), increasing to 15mg od then 20mg od by week 3; darifenacin 7.5mg od in weeks 1 and 2, then 15mg od in week 3. The primary end point was accuracy on the Name-Face Association Test (delayed recall) at week 3.

RESULTS

Results of the Name-Face Association Test at week 3 showed no significant difference between darifenacin and placebo on delayed recall (mean difference, -0.06, p=0.908). In contrast, oxybutynin ER resulted in memory impairment, with significantly lower scores than placebo and darifenacin (mean differences, -1.30, p=0.011 and -1.24, p=0.022, respectively) for delayed recall on the Name-Face Association Test at week 3. Additional tests of delayed recall indicated significant memory impairment with oxybutynin ER versus placebo at certain time points, whereas darifenacin was similar to placebo. No between-treatment differences were detected in self-rated memory, demonstrating that subjects were unaware of memory deterioration.

CONCLUSIONS

While darifenacin had no significant effects on memory versus placebo, oxybutynin ER caused significant memory deterioration (magnitude of effect comparable to brain aging of 10 years). The results also demonstrate that subjects may not recognise/report memory deterioration.