Potential Benefits of Muscarinic M3 Receptor Selectivity

Darifenacin Self-assembled Liquid Crystal Cubic Nanoparticles: a Sustained Release Approach for an Overnight Control of Overactive Bladder

The current study is regarding the development and characterization of Darifenacin-loaded self-assembled liquid crystal cubic nanoparticles (LCCN). An anhydrous approach was used for the preparation of these cubic nanoparticles using a hydrotropic agent (propylene glycol), with minimal energy input. Upon dispersion in aqueous medium, the system was successfully transformed to cubosomal nanoparticles counterpart as depicted by transmission electron micrographs. A Box-Behnken design was used to optimize formulation variables, namely A: amount of GMO, B: amount of Pluronic F127, C: amount of PG, and D: amount of HPMC. The design has generated 29 formulae which were tested regarding drug content uniformity, dispersibility in water, particle size, zeta potential, polydispersity index, and in vitro release behavior. The numerical optimization algorithms have generated an optimized formula with high desirability ≈ 1. The optimized formula displayed small particle size, good homogeneity, and zeta potential along with controlled in vitro release profile and ex vivo permeation through rabbit intestine. Thus, self-assembled LCCN might offer an alternative anhydrous approach for the preparation of cubosomal nanoparticles with controlled release profile for a possibly better control of overactive bladder syndrome which tremendously affect the overall life quality.

Antimuscarinic use among older adults with dementia and overactive bladder: a Medicare beneficiaries study

OBJECTIVES

This study examined the incidence and predictors of antimuscarinic medication use including non-selective antimuscarinics among older adults with dementia and overactive bladder (OAB).

METHODS

The study used a new-user cohort design involving older adults (≥65 years) with dementia and OAB based on 2013-2015 Medicare data. Antimuscarinics included non-selective (oxybutynin, tolterodine, trospium, fesoterodine) and selective (solifenacin, darifenacin) medications. Descriptive statistics and multivariable logistic regression models were used to determine the incidence and predictors of new antimuscarinic use including non-selective antimuscarinics, respectively.

RESULTS

Of the 3.38 million Medicare beneficiaries with dementia, over one million (1.05) had OAB (31.03%). Of those, 287,612 (27.39%) were reported as prevalent antimuscarinics users. After applying continuous eligibility criteria, 21,848 (10.34%) incident antimuscarinic users were identified (77.6% non-selective; 22.4% selective). Most frequently reported antimuscarinics were oxybutynin (56.3%) and solifenacin (21.4%). Multivariable analysis revealed that patients ≥75 years, of black race, and those with schizophrenia, epilepsy, delirium, and Elixhauser's score were less likely to initiate antimuscarinics. Women, those with abnormal involuntary movements, bipolar disorder, gastroesophageal reflux disease, insomnia, irritable bowel syndrome, muscle spasm/low back pain, neuropathic pain, benign prostatic hyperplasia, falls/fractures, myasthenia gravis, narrow-angle glaucoma, Parkinson's disease, syncope, urinary tract infection and vulvovaginitis were more likely to initiate antimuscarinics. Further, patients with muscle spasms/low back pain, benign prostatic hyperplasia and those taking higher level anticholinergics had lower odds of receiving non-selective antimuscarinics, whereas white patients, black patients and those with schizophrenia and delirium were more likely to receive them.

CONCLUSIONS

Nearly one-third of dementia patients had OAB and over one-fourth of them used antimuscarinics. Majority of the incident users were prescribed non-selective antimuscarinics with several demographic and clinical factors contributing to their use. Given the high prevalence of OAB among dementia patients, there is a need to optimize their antimuscarinic use, considering their vulnerability for anticholinergic adverse effects.

The clinical pharmacology of the medical treatment for overactive bladder in adults

INTRODUCTION

Overactive bladder is a prevalent symptom complex that affects the patient's quality of life. Any disruption between the neuronal micturition pathway can lead to bladder overactivity. Neurogenic causes, myogenic causes, aging, bladder outlet obstruction, sex, and psychological factors are some of the factors contributing to bladder overactivity. The complaint of any symptoms of OAB, which is highly prevalent and affects overall QOL, often needs therapeutic interventions. When conservative therapy methods fail, the addition of medications is recommended. The most commonly used agents for the treatment of OAB are antimuscarinic drugs. New classes of drugs, such as beta-3 agonists, have enriched our pharmacologic armamentarium.

AREAS COVERED

In this review, with a special focus on oral pharmacological treatments, we discussed the definition, etiology, symptoms, diagnosis, and management of OAB.

EXPERT OPINION

OAB is a multifactorial condition with every patient presenting with a different collection of symptoms and signs. Medical therapies should be given in conjunction with behavioral therapies. Using high or low doses, flexible doses, and stopping or changing the medications are interchangeable strategies based on the level of treatment efficacy and patient satisfaction.

Study of the pharmacokinetics of eriodictyol-6-C-β-d-glucoside, a flavonoid of rooibos (Aspalathus linearis) extract, after its oral administration in mice

Systemic dry syndrome affects quality of life, and various effective methods are being developed for its treatment. We recently found that rooibos (Aspalathus linearis) extract activates muscarinic M₃ receptor and improves dryness in mice and humans. We identified eriodictyol-6-C-β-_D-glucoside (E6CG) as the active component affecting the secretory functions of exocrine glands; however, the pharmacokinetics and distribution of E6CG in exocrine glands have not been elucidated in mice receiving rooibos extract. We have developed a quantification method using LC-MS/MS to detect E6CG without an internal standard. Experiments on C57BL/6 mice administered rooibos extract showed that E6CG was transferred into blood plasma, with its concentration levels peaking 19.3 min after treatment. Substantial levels of E6CG were detected in the submandibular, sublingual, parotid, and lacrimal glands and in the sweat glands in palm skin. This study reports that rooibos extracts containing E6CG can be used as functional foods for improving systemic dryness.

Basic and clinical aspects of antimuscarinic agents used to treat overactive bladder

Antimuscarinic agents are now widely used as the pharmacological therapy for overactive bladder (OAB) because neuronal (parasympathetic nerve) and non-neuronal acetylcholine play a significant role for the bladder function. In this review, we will highlight basic and clinical aspects of eight antimuscarinic agents (oxybutynin, propiverine, tolterodine, solifenacin, darifenacin, trospium, imidafenacin, and fesoterodine) clinically used to treat urinary dysfunction in patients with OAB. The basic pharmacological characteristics of these eight antimuscarinic agents include muscarinic receptor subtype selectivity, functional bladder selectivity, and muscarinic receptor binding in the bladder and other tissues. The measurement of drug-receptor binding after oral administration of these agents allows for clearer understanding of bladder selectivity by the integration of pharmacodynamics and pharmacokinetics under in vivo conditions. Their central nervous system (CNS) penetration potentials are also discussed in terms of the feasibility of impairments in memory and cognitive function in elderly patients with OAB. The clinical aspects of efficacy focus on improvements in the daytime urinary frequency, nocturia, bladder capacity, the frequency of urgency, severity of urgency, number of incontinence episodes, OAB symptom score, and quality of life (QOL) score by antimuscarinic agents in patients with OAB. The safety of and adverse events caused by treatments with antimuscarinic agents such as dry mouth, constipation, blurred vision, erythema, fatigue, increased sweating, urinary retention, and CNS adverse events are discussed. A dose-dependent relationship was observed with adverse events, because the risk ratio generally increased with elevations in the drug dose of antimuscarinic agents. Side effect profiles may be additive to or contraindicated by other medications.

QT and QTc Interval With Standard and Supratherapeutic Doses of Darifenacin, a Muscarinic M3Selective Receptor Antagonist for the Treatment of Overactive Bladder

Prolongation of QT interval on an electrocardiogram is a valuable predictor of a drug's ability to cause potentially fatal ventricular tachyarrhythmia (torsades de pointes). Darifenacin is a muscarinic M3 selective receptor antagonist developed for the treatment of overactive bladder, a debilitating condition that is particularly prevalent in the older population. This 7-day, randomized, parallel-group study (n=188) measured QT/QTc interval in healthy volunteers receiving once-daily darifenacin at steady-state therapeutic (15 mg) and supratherapeutic (75 mg) doses, alongside controls receiving placebo or moxifloxacin (positive control, 400 mg) once daily. There was no significant increase in QTcF interval with darifenacin treatment compared with placebo. Mean changes from baseline at pharmacokinetic Tmax versus placebo were -0.4 and -2.2 milliseconds in the darifenacin 15 mg and 75 mg groups, respectively, compared with +11.6 milliseconds in the moxifloxacin group (P<.01). This study demonstrates that darifenacin does not prolong QT/QTc interval.

Characterization of bladder selectivity of antimuscarinic agents on the basis of in vivo drug-receptor binding

The in vivo muscarinic receptor binding of antimuscarinic agents (oxybutynin, solifenacin, tolterodine, and imidafenacin) used to treat urinary dysfunction in patients with overactive bladder is reviewed. Transdermal administration of oxybutynin in rats leads to significant binding of muscarinic receptors in the bladder without long-term binding in the submaxillary gland and the abolishment of salivation evoked by oral oxybutynin. Oral solifenacin shows significant and long-lasting binding to muscarinic receptors in mouse tissues expressing the M₃ subtype. Oral tolterodine binds more selectively to muscarinic receptors in the bladder than in the submaxillary gland in mice. The muscarinic receptor binding of oral imidafenacin in rats is more selective and longer-lasting in the bladder than in other tissues such as the submaxillary gland, heart, colon, lung, and brain, suggesting preferential muscarinic receptor binding in the bladder. In vivo quantitative autoradiography with (+)N-[¹¹C]methyl-3-piperidyl benzilate in rats shows significant occupancy of brain muscarinic receptors with the intravenous injection of oxybutynin, solifenacin, and tolterodine. The estimated in vivo selectivity in brain is significantly greater for solifenacin and tolterodine than for oxybutynin. Imidafenacin occupies few brain muscarinic receptors. Similar findings for oral oxybutynin were observed with positron emission tomography in conscious rhesus monkeys with a significant disturbance of short-term memory. The newer generation of antimuscarinic agents may be advantageous in terms of bladder selectivity after systemic administration.

Antimuscarinics for the treatment of overactive bladder: understanding the role of muscarinic subtype selectivity

INTRODUCTION AND HYPOTHESIS

Antimuscarinic agents appear to exert their therapeutic activity in overactive bladder (OAB) via blockade of the M(3) muscarinic receptor subtype. Antimuscarinics are broadly similar in efficacy, but their safety and tolerability profiles vary, which may reflect differences in muscarinic receptor selectivity profiles.

METHODS

This review of available literature aims to determine whether antimuscarinic agents with greater M(3) selectivity have clinical advantages over less selective drugs.

RESULTS

Antimuscarinic agents differ widely in their propensity to cause cognitive and cardiovascular (CV) effects, which appear mainly to be related to differences in their relative selectivity for binding to non-M(3) receptors, including M(1) receptors in the brain and cardiac M(2) receptors.

CONCLUSIONS

Cognitive and CV effects are especially pertinent for the OAB patient who tends to be older with various comorbidities and is often taking multiple medications. Hence, it is important to consider the risk/benefit balance of antimuscarinic agents when selecting OAB treatment.

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.

Urinary incontinence: pharmacotherapy options

The impact of incontinence is felt by millions of people worldwide, with tremendous decrement in quality of life and enormous cost reaching billions of dollars. Urinary incontinence is defined as 'involuntary leakage of urine' and is categorized into two main types: urgency urinary incontinence (UUI) and stress urinary incontinence (SUI). Behavioral modifications and pharmacologic therapies, primarily antimuscarinic agents, are the mainstay of treatment for UUI. These drugs are moderately efficacious but have troublesome side-effects, the combination resulting in poor compliance and persistence with therapy. There are several agents on the market today, each with some variation in pharmacologic properties. Whether these translate into meaningful differences in clinical efficacy and tolerability remains a matter of debate. Treatment of SUI has seen little success with pharmacologic therapy. In Europe, duloxetine is approved for treatment of SUI with marginal success rates; this drug, although available in the United States for treatment of depression, is not approved for SUI. The search for newer and better pharmacologic options and novel therapies is on-going, fueled primarily by the high prevalence of bothersome incontinence and the tremendous number of health care dollars spent on current therapy. This review addresses pharmacologic options for treatment of urinary incontinence.

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.

Ratiometric Ca+2 measurement in human recombinant muscarinic receptor subtypes using the Flexstation scanning fluorometer

In modern drug discovery, numerous assay formats are available to screen and quantitate receptor-ligand interactions. Radioactive assays are "gold standard" because they are fast, easy, and reproducible; however, they are hazardous, produce radioactive waste, require special lab conditions, and are expensive on a large scale. Thus, it provides a lot of importance to the "mix & measure" assays that have an optical readout. Fluorescence techniques are likely to be among the most important detection approaches used for high throughput screening due to their high sensitivity and amenability to automation. The aim of the present study was to determine the functional antagonistic affinities of standard muscarinic antagonists in CHO cells over expressing m1, m3, and m5 receptors and to compare them with the respective binding affinities. This study was further extended to elucidate that Ca+2 measurement assays can serve as a functional screening tool for GPCRs. For this purpose, standard muscarinic receptor antagonists, namely, tolterodine, oxybutynin, and atropine were used. We determined and compared the IC50 values of these three standard inhibitors in fura 2 AM loaded m1, m3, and m5 overexpressing CHO cells and in radioligand binding assay. Both the assays exhibited comparable rank order potencies of the standard inhibitors. This study suggests that Ca+2 mobilization assays can be an alternate to radioligand binding assays.

In vivo and in vitro pharmacological characterization of SVT-40776, a novel M3 muscarinic receptor antagonist, for the treatment of overactive bladder

BACKGROUND AND PURPOSE

Highly selective M(3) muscarinic receptor antagonists may represent a better treatment for overactive bladder syndrome, diminishing side effects. Cardiac side effects of non-selective antimuscarinics have been associated with activity at M(2) receptors as these receptors are mainly responsible for muscarinic receptor-dependent bradycardia. We have investigated a novel antimuscarinic, SVT-40776, highly selective for M(3) over M(2) receptors (Ki = 0.19 nmol.L(-1) for M(3) receptor affinity). This study reports the functional activity of SVT-40776 in the bladder, relative to its activity in atria.

EXPERIMENTAL APPROACH

In vitro and ex vivo (oral dosing) inhibition of mouse detrusor and atrial contractile responses to carbachol were used to study the functional activity of SVT-40776. The in vivo efficacy of SVT-40776 was characterized by suppression of isovolumetric spontaneous bladder contractions in anaesthetized guinea pigs after intravenous administration.

KEY RESULTS

SVT-40776 was the most potent in inhibiting carbachol-induced bladder contractions of the anti-cholinergic agents tested, without affecting atrial contractions over the same range of concentrations. SVT-40776 exhibited the highest urinary versus cardiac selectivity (199-fold). In the guinea pig in vivo model, SVT-40776 inhibited 25% of spontaneous bladder contractions at a very low dose (6.97 microg.kg(-1) i.v), without affecting arterial blood pressure.

CONCLUSIONS AND IMPLICATIONS

SVT-40776 is a potent inhibitor of M(3) receptor-related detrusor contractile activity. The absence of effects on isolated atria preparations represents an interesting characteristic and suggests that SVT-40776 may lack unwanted cardiac effects; a feature especially relevant in a compound intended to treat mainly elderly patients.

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.

Anticholinergic drugs versus other medications for overactive bladder syndrome in adults

BACKGROUND

Overactive bladder syndrome is defined as "urgency with or without urge incontinence, usually with frequency and nocturia". It is a common condition with significant economic and quality of life implications. While the condition's pathophysiology remains to be fully elucidated, pharmacotherapy is the main treatment option. Despite uncertainty as to drug treatment of choice, anticholinergics are increasingly being used in primary and secondary care settings. This review compares anticholinergic drugs with other types or classes of drugs for treating overactive bladder syndromes.

OBJECTIVES

To compare anticholinergic drugs with other types or classes of drugs for treating overactive bladder symptoms.

SEARCH STRATEGY

We searched the Cochrane Incontinence Group Specialised Trials Register (searched 20 December 2006) and the reference lists of relevant articles. No language or other limits were imposed.

SELECTION CRITERIA

All randomised and quasi-randomised controlled trials comparing anticholinergic drugs with other drugs for the treatment of overactive bladder symptoms. At least one arm of the study used an anticholinergic drug and at least one other arm used a non-anticholinergic drug.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed the identified studies for eligibility and methodological quality and independently extracted data from the included studies. Data analysis was performed using RevMan software (version 4.2.8).

MAIN RESULTS

Twelve trials were included in the review. There were seven crossover trials and five parallel group studies. For the comparisons between anticholinergic drugs with tricyclic antidepressants, alpha adrenergic agonists, afferent nerve inhibitors, and calcium channel blocker a single trial was identified for each. Nine trials compared flavoxate with anticholinergics. There was no evidence of a difference in cure rates between anticholinergics and flavoxate. Adverse effects were more frequent in anticholinergic groups versus flavoxate groups (RR 2.28 95% CI 1.45 to 3.56). There was no strong evidence to favour either anticholinergic drugs or the comparators.

AUTHORS' CONCLUSIONS

Many of the drugs considered in trials in this review are no longer used in clinical practice (and this includes the most commonly tested - flavoxate). There is inadequate evidence as to determine whether any of the available drugs are better or worse than anticholinergic medications. Larger randomised controlled trials in clinical settings are required to further establish the role of these medications in the management of overactive bladder syndrome.

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.

Anticholinergic drugs versus other medications for overactive bladder syndrome in adults

BACKGROUND

Overactive bladder syndrome is defined as "urgency with or without urge incontinence, usually with frequency and nocturia". It is a common condition with significant economic and quality of life implications. While the condition's pathophysiology remains to be fully elucidated, pharmacotherapy is the main treatment option. Despite uncertainty as to drug treatment of choice, anticholinergics are increasingly being used in primary and secondary care settings. This review compares anticholinergic drugs with other types or classes of drugs for treating overactive bladder syndromes.

OBJECTIVES

To compare anticholinergic drugs with other types or classes of drugs for treating overactive bladder symptoms.

SEARCH STRATEGY

We searched the Cochrane Incontinence Group Specialised Trials Register (searched 20 December 2006) and the reference lists of relevant articles. No language or other limits were imposed.

SELECTION CRITERIA

All randomised and quasi-randomised controlled trials comparing anticholinergic drugs with other drugs for the treatment of overactive bladder symptoms. At least one arm of the study used an anticholinergic drug and at least one other arm used a non-anticholinergic drug.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed the identified studies for eligibility and methodological quality and independently extracted data from the included studies. Data analysis was performed using RevMan software (version 4.2.8).

MAIN RESULTS

Thirteen trials were included in the review. There were eight crossover trials and five parallel group studies. For the comparisons between anticholinergic drugs with tricyclic antidepressants, alpha adrenergic agonists, afferent nerve inhibitors, and calcium channel blocker a single trial was identified for each. Ten trials compared flavoxate with anticholinergics. There was no evidence of a difference in cure rates between anticholinergics and flavoxate. Adverse effects were more frequent in anticholinergic groups versus flavoxate groups (RR 2.28 95% CI 1.45 to 3.56). There was no strong evidence to favour either anticholinergic drugs or the comparators.

AUTHORS' CONCLUSIONS

Many of the drugs considered in trials in this review are no longer used in clinical practice (and this includes the most commonly tested - flavoxate). There is inadequate no evidence as to whether any of the available is better or worse than anticholinergic medications. Larger randomised controlled trials in clinical settings are required to further establish the role of these other medications in the management of overactive bladder syndrome.

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.

Development and validation of bioanalytical methods for imidafenacin (KRP-197/ONO-8025) and its metabolites in human urine by using liquid chromatography-tandem mass spectrometry

New bioanalytical methods have been developed for the determination of imidafenacin (KRP-197/ONO-8025, IM), a novel antimuscarinic drug developed for the treatment of overactive bladder, and its metabolites, M-2, M-3, M-4, M-6 and M-8 (method 1), M-5 and M-9 (method 2) in human urine by using liquid chromatography-tandem mass spectrometry. In each method, the urine sample was extracted by solid-phase extraction, separated on a semi-micro high-performance liquid chromatography column using gradient elution and detected by tandem mass spectrometer with an atmospheric pressure chemical ionization or ionspray interface. Extraction recoveries of IM and metabolites were 81.4% or more. Calibration curves had good linearity in the concentration ranges 0.2-50 ng/mL for IM, M-2, M-3, M-4, M-6 and M-8 (method 1) and 1-250 ng/mL for M-5 and M-9 (method 2), respectively. The accuracy and precision in the intra-day and inter-day reproducibility tests were within +/-17.0 and 16.1% at the lowest concentrations, and within +/-12.8 and 11.1% at higher concentrations, respectively. Using these analytical methods, excretion profiles of IM and its metabolites in human urine were successfully determined after oral administration of IM at the therapeutic dosage of 0.1 mg.

Trospium Chloride: Distinct Among Other Anticholinergic Agents Available for the Treatment of Overactive Bladder

Trospium chloride is an antimuscarinic agent indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency. It has been available in Europe for over 20 years and in the United States since May 2004. Trospium has pharmacologic properties that are distinct from other antimuscarinic agents. The safety and efficacy profiles of trospium and how its pharmacologic properties contribute to these profiles form the basis for this review. The low incidence of adverse event of central nervous system effects and the efficacy parameters of "urgency" and "onset of action" are highlighted.

In vivo demonstration of M3 muscarinic receptor subtype selectivity of darifenacin in mice

A novel muscarinic receptor antagonist, darifenacin, inhibited specific binding of [N-methyl-(3)H]scopolamine ([(3)H]NMS) in the mouse bladder, submaxillary gland and heart in a concentration-dependent manner. The inhibitory effect was most potent in the submaxillary gland, followed by the bladder and heart. In addition, darifenacin inhibited specific [(3)H]NMS binding in the membranes of CHO-K1 cell lines expressing muscarinic M(2) and M(3) receptor subtypes, and the potency was significantly (22-fold) greater at the M(3) than at the M(2) subtype. At 0.5 to 12 h after oral administration of darifenacin, a significant increase in K(d) values for specific [(3)H]NMS binding was seen in the bladder, submaxillary gland and lung of mice, compared with control values. Also, there was a sustained decrease in the B(max) values in the submaxillary gland. These data suggest that muscarinic receptor binding of oral darifenacin is rapid in onset and of a long duration. On the other hand, oral darifenacin exerted only temporary or little binding of muscarinic receptors in the heart and colon. Pilocarpine-induced salivary secretion in mice was continuously suppressed by oral darifenacin. The time-course of suppression coincided well with that for the muscarinic receptor binding in the submaxillary gland. The antagonistic effect of darifenacin against the dose-response curves for pilocarpine appeared to be insurmountable. In conclusion, the present study has shown that oral darifenacin may exert a pronounced and long-lasting binding of muscarinic receptors in tissues expressing the M(3) subtype.

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.

Urinary incontinence: economic burden and new choices in pharmaceutical treatment

In the year 2000, an estimated 17 million community-dwelling adults in the United States had daily urinary incontinence (UI), and an additional 33 million suffered from the overlapping condition, overactive bladder. Estimates of the total annual cost of these conditions range up to 32 billion US dollar; the largest components are management costs and the expenses associated with nursing home admissions attributable to UI. In most cases, patients with UI can be treated with pharmaceutical agents, in addition to behavioral therapy. Until recently, pharmaceutical therapy for UI has been limited, especially because the adverse effects of available agents resulted in poor adherence to treatment regimens. Recent innovations in molecular design and new dosage forms of UI medications offer the promise of fewer and less severe adverse effects and, thus, better treatment outcomes for patients. Additionally, the availability of multiple agents within a therapeutic class offers health care providers a spectrum of choices with which to personalize treatment for each individual patient. New pharmacologic treatment options for UI have the potential to allow greater independence for older persons who reside at home and to delay or avoid the costs of admission to long-term care facilities. Alternate dosage forms, which include patches and sustained-release formulations, may benefit patients who have difficulty chewing, swallowing, or remembering to take medications. Although these newer products are generally more expensive than older forms of therapy, they typically have more favorable cost-effectiveness ratios. Access to these new medications for patients enrolled in public and private health care plans may help to reduce the economic and social burden of UI care.

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.

The overactive bladder: review of current pharmacotherapy in adults. Part 1: pathophysiology and anticholinergic therapy

Overactive bladder is a syndrome characterised by urinary urgency, with or without urge incontinence, and usually with frequency and nocturia. It affects millions of people of all ages worldwide and causes significant morbidity, especially in terms of health-related quality of life. It poses a huge economic burden on health resources. Managing such patients involves a thorough history, physical examination and the use of pertinent investigations before the initiation of treatment. Therapy consists of lifestyle changes, bladder training, anticholinergics, second-line agents such as resiniferatoxin instillation or botulinum toxin injections into the bladder in refractory cases and, finally, in intractable cases, surgery. In the first part of this review of pharmacotherapy for the treatment of this condition, the focus is on the pathophysiological factors potentially involved in overactive bladder and covers the wide range of currently available first-line anticholinergic agents. Treatment algorithms are suggested on the basis of current literature.

Pharmacodynamic effects of darifenacin, a muscarinic M3 selective receptor antagonist for the treatment of overactive bladder, in healthy volunteers

OBJECTIVE

To evaluate the pharmacodynamic effects of darifenacin (a muscarinic M(3) selective receptor antagonist) and dicyclomine (an M(1) selective receptor antagonist) in healthy male volunteers.

SUBJECTS AND METHODS

In this double-blind, four-way crossover study, 27 healthy men (aged 19-44 years) were randomized to receive darifenacin 7.5 mg or 15 mg once daily, dicyclomine 20 mg four times daily or matching placebo. Each 7-day treatment period was separated by a 7-day washout. Multiple assessments of cognitive function, quantitative electroencephalogram (EEG) recordings, salivation, visual nearpoint, heart rate and heart rate variability were made on day 7 in each treatment period.

RESULTS

Compared with placebo, neither dose of darifenacin affected cognitive function, whereas dicyclomine impaired performance on five of the 12 variables 2 h after dosing; simple reaction time (P = 0.009), speed of numeric (P = 0.012) and spatial (P = 0.048) working memory, and speed (P = 0.04) and sensitivity (P = 0.03) of picture recognition. These cognitive changes were accompanied by slowing of the EEG for dicyclomine. Darifenacin showed no clinically relevant effect on EEG. Darifenacin 7.5 and 15 mg once daily did not differ from placebo in effects on visual nearpoint, heart rate or heart rate variability. By contrast, dicyclomine significantly increased the maximum visual nearpoint, decreased heart rate and increased heart rate variability, relative to placebo. Both agents decreased salivary flow rate vs placebo. Treatment-related adverse events were comparable in all groups, the most common being dry mouth; none led to treatment discontinuation.

CONCLUSIONS

Darifenacin did not affect cognitive, cardiac or visual function in healthy volunteers, a profile that may reflect its relative M(3) receptor selectivity and M(1)/M(2) sparing properties.

Comparison of darifenacin and oxybutynin in patients with overactive bladder: assessment of ambulatory urodynamics and impact on salivary flow

OBJECTIVES

To evaluate the effects of darifenacin, an M3 selective receptor antagonist, compared with oxybutynin, on ambulatory urodynamics, salivary flow, heart rate and visual nearpoint in patients with overactive bladder (OAB).

METHODS

A double-blind, randomized, crossover study (n=65) with three treatment cohorts: darifenacin immediate release (IR) 2.5 mg three times a day (t.i.d.) or oxybutynin 2.5 mg t.i.d.; darifenacin controlled release (CR) 15 mg once daily (q.d.) or oxybutynin 5 mg t.i.d.; darifenacin CR 30 mg q.d. or oxybutynin 5 mg t.i.d. Within cohorts, patients received 7 days' treatment with each agent separated by 14 days' washout.

RESULTS

All active treatments improved urodynamic parameters. Both darifenacin CR doses had significantly less effect on salivary flow than oxybutynin. Effects on urodynamic parameters, heart rate and visual nearpoint were comparable.

CONCLUSION

Ambulatory urodynamics appears to be an innovative and potentially useful investigative tool in the evaluation of the efficacy of new therapeutic agents. Darifenacin CR is an efficacious therapy for OAB with comparable effects on urodynamic parameters but producing significantly less dry mouth than oxybutynin.

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

AIM

To evaluate the efficacy, tolerability and safety of darifenacin, an M(3) selective receptor antagonist, in the subgroup of older patients from a pooled analysis of three phase III, multicentre, randomized, double-blind clinical trials in patients with overactive bladder (OAB).

PATIENTS AND METHODS

317 patients aged > or =65 years with OAB symptoms (urge incontinence, urgency and frequency) received up to 12 weeks' oral treatment with darifenacin 7.5 mg or 15 mg once daily or matching placebo. Efficacy was evaluated from daily electronic diary records. Safety endpoints included withdrawal rates and treatment-related adverse events.

RESULTS

Darifenacin treatment of patients aged > or =65 years was associated with a dose-related, significant improvement of all the major symptoms of OAB. At week 12, the median reduction in incontinence episodes/week was greater with darifenacin 7.5 mg or 15 mg than in the corresponding placebo arms (66.7% vs. 34.8% and 75.9% vs. 44.8%, respectively, both p < 0.001). Both doses were also significantly superior to placebo in improving micturition frequency (both p < 0.001), bladder capacity (volume voided) (darifenacin 7.5 mg, p = 0.018, darifenacin 15 mg, p < 0.001), and the frequency of urgency episodes (both p < 0.001). Darifenacin was well tolerated. The most common treatment-related adverse events were dry mouth (7.5 mg, 20.6%; 15 mg, 30.9%; placebo, 4.5%) and constipation (7.5 mg, 18.6%; 15 mg, 23.6%; placebo, 6.4%), typically mild or moderate. Use of constipation remedies (laxatives, stool softeners or fibre supplements) was low and similar between groups (7.5 mg, 10.3%; 15 mg, 16.4%; placebo, 10.0%). There were few withdrawals due to treatment-related adverse events (7.5 mg, 1.0%; 15 mg, 9.1%; placebo, 2.7%), and no nervous system or cardiovascular safety concerns.

CONCLUSIONS

The results demonstrate excellent efficacy, tolerability and safety with darifenacin 7.5 mg and 15 mg once-daily treatment for OAB in older patients.

Efficacy and tolerability of darifenacin, a muscarinic M3 selective receptor antagonist (M3 SRA), compared with oxybutynin in the treatment of patients with overactive bladder

A randomized, double-blind, placebo-controlled, four-way crossover, safety study of darifenacin versus oxybutynin was carried out on 76 patients with overactive bladder (OAB). Adults with OAB received 2 weeks each of darifenacin 15 and 30 mg once daily (q.d.), oxybutynin 5 mg three times daily (t.i.d.) and placebo, in random sequence at 10-day intervals. Darifenacin and oxybutynin significantly reduced incontinence episodes, and the number/severity of urgency episodes (all P<0.05 versus placebo). Improvements in OAB symptoms with darifenacin were dose-dependent. Dry mouth was less common with darifenacin 15 mg than oxybutynin (13% and 36%; P<0.05), while constipation was comparable (10% and 8%, respectively). Corresponding rates for darifenacin 30 mg were 34% and 21%, respectively. Patients only reported blurred vision or dizziness with oxybutynin (3% and 2%, respectively). Darifenacin (15 mg q.d.) provides comparable efficacy with improved tolerability versus oxybutynin (5 mg t.i.d.) in the treatment of patients with OAB.

Dose response with darifenacin, a novel once-daily M3 selective receptor antagonist for the treatment of overactive bladder: results of a fixed dose study

This study evaluated the efficacy, tolerability, and safety of darifenacin, an M3 selective receptor antagonist (M3 SRA), in patients with overactive bladder (OAB). In a multicenter, double-blind, placebo-controlled dose-ranging study, 439 adult OAB patients (85.4% female) were randomized to darifenacin controlled-release tablets 7.5 mg (n = 108), 15 mg (n = 107) or 30 mg (n = 115) qd, or placebo (n = 109) for 12 weeks. Darifenacin significantly reduced the median number of incontinence episodes/week (-68.7, -76.5, and -77.3% from baseline at 7.5, 15, and 30 mg, respectively, vs -46% with placebo, all p < 0.01) and dose relatedly improved micturition frequency, frequency and severity of urgency, nocturia, and bladder capacity. Darifenacin was well tolerated. Adverse events were commonly mild to moderate dry mouth and constipation. There were no safety concerns. Darifenacin is effective and well tolerated in the treatment of OAB, with 7.5 and 15 mg doses offering flexibility of dosing for optimal treatment outcome.

Darifenacin in the treatment of overactive bladder

Antimuscarinic drug therapy has been shown to be effective in the management of patients with symptoms of the overactive bladder syndrome (OAB), but the bothersome antimuscarinic adverse effects of dry mouth, constipation, somnolence and blurred vision often affect compliance with medication. The development of bladder selective M3 specific antagonists offers the possibility of increasing efficacy whilst minimising adverse effects. The M3 specific antagonist solifenacin has recently been marketed, and darifenacin will soon be available. The purpose of this article is to review the pharmacology and clinical trial data available for darifenacin, in addition to examining its role in the treatment of the OBS.

A pooled analysis of three phase III studies to investigate the efficacy, tolerability and safety of darifenacin, a muscarinic M3 selective receptor antagonist, in the treatment of overactive bladder

OBJECTIVE

To evaluate the efficacy, tolerability and safety of darifenacin, a muscarinic M3 selective receptor antagonist (M3 SRA), from an analysis of pooled data from three phase III, multicentre, double-blind clinical trials in patients with overactive bladder (OAB).

PATIENTS AND METHODS

After a 4-week washout/run-in period, 1059 adults (85% women) with symptoms of OAB (frequency and urgency with urge incontinence) for > or = 6 months were randomized to once-daily oral treatment with darifenacin (7.5 mg, 337; or 15 mg, 334) or matching placebo (388) for 12 weeks. Efficacy was evaluated using electronic patient diaries that recorded incontinence episodes (including those resulting in a change of clothing or pads), frequency and severity of urgency, voiding frequency, and bladder capacity (volume voided). Safety was evaluated by analysis of adverse events (AEs), withdrawal rates and laboratory tests.

RESULTS

Relative to baseline, 12 weeks of treatment with darifenacin resulted in a significant reduction in the median (% change, interquartile range) number of incontinence episodes per week; 7.5 mg (-8.8, -68.4%, -15.1 to -4.4); 15 mg; (-10.6, -76.8%, -17.3 to -5.8: both P < 0.01 vs placebo). There was a significant dose-response trend in each study for which darifenacin 7.5 and 15 mg were evaluated (P < 0.01). There were also significant decreases in the frequency and severity of urgency, voiding frequency, and number of significant leaks (incontinence episodes resulting in a change of clothing or pads; both P < or = 0.001 vs placebo), together with an increase in bladder capacity (both P < 0.01 vs placebo). Darifenacin was well tolerated; the most common AEs were dry mouth and constipation, although together these resulted in few discontinuations (darifenacin 7.5 mg 0.6% of patients; 15 mg 2.1%; placebo 0.3%). The incidence of peripheral/central nervous system and cardiovascular AEs were comparable with those on placebo.

CONCLUSIONS

Darifenacin (7.5 and 15 mg once daily) is effective in the treatment of patients with OAB. As predicted by its M3 selectivity and associated M1/M2-sparing profile, darifenacin was well tolerated with no central nervous system or cardiovascular safety concerns.

INCREASED WARNING TIME WITH DARIFENACIN: A NEW CONCEPT IN THE MANAGEMENT OF URINARY URGENCY

PURPOSE

We assessed the effect of darifenacin, an M3 selective receptor antagonist, on the warning time associated with urinary urgency.

MATERIALS AND METHODS

In this multicenter, double-blind study subjects with urinary urgency for 6 months or greater and episodes of urgency 4 times or greater daily were randomized to darifenacin controlled release tablets (30 mg once daily) or placebo. Warning time was defined as the time from the first sensation of urgency to voluntary micturition or incontinence. Data were collected using electronic event recorders during 6-hour clinic visits or 3 urge-void cycles, if shorter, at baseline and at treatment end.

RESULTS

A total of 72 subjects entered the study and 67 were included in the primary efficacy analysis (darifenacin in 32 and placebo in 35). Darifenacin treatment resulted in a significant increase in mean warning time with a median increase of 4.3 minutes compared with placebo (p = 0.003). Overall 47% of darifenacin treated subjects compared with 20% receiving placebo achieved a 30% increase or greater in mean warning time (OR 5.6, p = 0.009). Median and minimum warning times were also significantly increased following darifenacin treatment vs placebo (p = 0.004 and 0.017, respectively). The median difference in minimum warning time was 1.9 minutes in favor of darifenacin vs placebo.

CONCLUSIONS

To our knowledge this is the first study to evaluate change in warning time, which is potentially important to individuals with symptoms associated with overactive bladder. Darifenacin increases mean, median and minimum warning time compared with placebo, allowing subjects more time to reach a toilet and potentially avoiding the embarrassing experience of incontinence.

An investigation of dose titration with darifenacin, an M3-selective receptor antagonist

OBJECTIVES

To evaluate the efficacy, tolerability and safety of a flexible-dosing strategy with darifenacin, an M(3)-selective receptor antagonist, in patients with symptoms of overactive bladder (OAB).

PATIENTS AND METHODS

In this multicentre double-blind 12-week study, 395 patients (aged 22-89 years; 84% female) with OAB symptoms for >6 months were randomized (2 : 1) and received once-daily treatment with darifenacin controlled-release tablets 7.5 mg (268 patients) or matching placebo (127). After 2 weeks of treatment, the efficacy, safety and tolerability were assessed and the dose increased to 15 mg once daily (pseudo-increase for placebo recipients) if additional efficacy was required by both the patient and physician. In the week before clinic visits (at 2 and 12 weeks), patients recorded incontinence episodes (primary efficacy endpoint) and several secondary efficacy variables in an electronic daily diary. Safety and tolerability were evaluated from withdrawal rates and adverse-event reports.

RESULTS

The treatment groups had comparable baseline characteristics. Similar proportions of darifenacin (59%) and placebo (68%) recipients increased the dose at 2 weeks; at 12 weeks patients on darifenacin (overall group) had a significantly greater reduction in the median number of incontinence episodes per week than had those on placebo, at - 8.2 (-62.9%) and - 6.0 (-48.1%), respectively (P = 0.035). There were also significant improvements in voiding frequency (P = 0.001), bladder capacity (volume voided; P = 0.036), frequency of urgency (P < 0.001), severity of urgency (P = 0.013) and number of significant leaks/week (i.e. incontinence episodes needing a change of clothing or pads, per week; P = 0.010) for darifenacin over placebo. Subset analysis suggested that some patients (those remaining on darifenacin 7.5 mg) were more sensitive to darifenacin than those who increased the dose, based on both efficacy and adverse events. Continued treatment with 7.5 mg for 'sensitive' patients, and an increased dose (to 15 mg) for remaining patients, resulted in comparable outcomes by 12 weeks. The most common treatment-related adverse events were mild-to-moderate dry mouth and constipation, which led to discontinuation in < 3.0% of darifenacin-treated patients and < 1.0% of the placebo group. Central nervous system and cardiovascular adverse events were comparable to those with placebo.

CONCLUSIONS

Darifenacin appears to be an effective, well-tolerated and flexible treatment for patients with OAB, allowing individualized dosing according to patient needs.

Darifenacin: a novel M3muscarinic selective receptor antagonist for the treatment of overactive bladder

Darifenacin is a novel M3 muscarinic selective receptor antagonist for once-daily treatment of overactive bladder (OAB), a highly prevalent, chronic and debilitating disease defined by urinary urgency with or without urge incontinence, usually with increased frequency of micturition and nocturia. In vitro, darifenacin is a potent and specific muscarinic receptor antagonist with </= 59-fold higher selectivity for muscarinic M3 receptors relative to other muscarinic receptor subtypes. This profile may, therefore, confer clinical efficacy in the treatment of OAB, with a lower propensity for adverse effects and safety issues related to blockade of other muscarinic receptor subtypes. Indeed, consistent with its low relative affinity for M1 and M2 receptors, no effects on cognitive function and heart-rate variability, respectively, have been observed with darifenacin. Subsequent large-scale clinical trials have confirmed that darifenacin (at doses of 7.5 and 15 mg/day) results in central nervous system and cardiac adverse events comparable to placebo, and provides early and meaningful improvement across a range of OAB symptoms including incontinence episodes, urgency and urinary frequency. On the basis of such findings, darifenacin would appear to meet the current need for an effective OAB pharmacotherapy that is efficacious, well-tolerated and, more importantly, minimises the risk of safety-related adverse effects.

Darifenacin, an M3 selective receptor antagonist, is an effective and well-tolerated once-daily treatment for overactive bladder

OBJECTIVES

To evaluate the efficacy, tolerability and safety of darifenacin, a once-daily M3) selective receptor antagonist (M3 SRA), in patients with overactive bladder (OAB).

METHODS

This multicentre, double-blind, placebo-controlled, parallel-group study enrolled 561 patients (19-88 years; 85% female) with OAB symptoms for >6 months, and included some patients with prior exposure to antimuscarinic agents. After washout and a 2-week placebo run-in, patients were randomised (1:4:2:3) to once-daily oral darifenacin controlled-release tablets (3.75 mg [n=53], 7.5 mg [229] or 15 mg [n=115]) or matching placebo (n=164) for 12 weeks. Patients recorded daily incontinence episodes, micturition frequency, bladder capacity (mean volume voided), frequency of urgency, severity of urgency, incontinence episodes resulting in change of clothing or pads and nocturnal awakenings due to OAB using an electronic diary during weeks 2, 6 and 12 (directly preceding clinic visits). Tolerability data were evaluated from adverse event reports.

RESULTS

Darifenacin 7.5 mg and 15 mg had a rapid onset of effect, with significant improvement compared with placebo being seen for most parameters at the first clinic visit (week 2). This effect was sustained through week 12. At this time the number of incontinence episodes per week was reduced from baseline by 67.7% with darifenacin 7.5 mg and 72.8% with darifenacin 15 mg compared with 55.9% with placebo (p=0.010 and p=0.017, respectively, versus placebo). The 3.75 mg group (null dose arm) was included for proof of concept of dose flexibility, therefore formal sample sizing and statistical analysis were not performed for this group. Darifenacin 7.5 mg and 15 mg, respectively, were significantly superior to placebo for improvements in micturition frequency (p<0.001, p<0.001), bladder capacity (p<0.040, p<0.001), frequency of urgency (p<0.001, p=0.005), severity of urgency (p<0.001, p=0.002) and number of incontinence episodes leading to a change in clothing or pads (p<0.001, p=0.002). There was no significant reduction in nocturnal awakenings due to OAB. The most common adverse events were mild-to-moderate dry mouth and constipation. However, no patients withdrew from the study as a result of dry mouth and discontinuation related to constipation was rare (0.6% placebo versus 0.9% darifenacin). In addition, there was a low need for laxative use, with no difference between the darifenacin groups and those taking placebo. There were no reports of blurred vision and the CNS and cardiac safety profile was comparable to placebo.

CONCLUSIONS

Darifenacin significantly improves the major symptoms of OAB. No significant CNS (primarily M1-receptor mediated) adverse events or cardiac (primarily M2-receptor mediated) adverse events were identified in this study, as may be predicted from the M3 selective receptor profile of darifenacin.

Antimuscarinics for treatment of overactive bladder

For many years, antimuscarinic drugs have been the first-line pharmacological treatment for urgency, frequency, and urge incontinence, all symptoms of the disorder termed overactive bladder. Antimuscarinic treatment is not always effective and is associated with side-effects that limit its clinical use. The clinical significance of the effects of antimuscarinic drugs has been questioned lately. In this review, the rationale for the use of these drugs in the management of overactive bladder is re-examined and the results of treatment are discussed. I conclude that these drugs are the only treatment with undisputed effectiveness in the treatment of overactive bladder. They may not be the perfect treatment for all patients with this disorder, but their value for individual patients should not be underestimated. Further clinical trials with improvement in quality of life as the primary endpoint are needed and may give a fair reflection of the clinical value of antimuscarinic drugs.