Darifenacin: a novel M3 muscarinic 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.     

Pharmacological agents for the treatment of urinary incontinence due to overactive bladder

Although the exact aetiology of overactive bladder is unknown to date, pharmacological therapy has been targeted to both the central and peripheral nervous systems. Potential CNS targets include GABA, opioid, serotonin (5-HT), dopamine and glutaminergic receptors as well as the α-adrenoceptors. Potential PNS targets include muscarinic receptors, calcium and potassium channels and α- and β-adrenergic receptors. Since acetylcholine is the primary excitatory neurotransmitter involved in bladder (detrusor) contraction and emptying, anticholinergic agents are the primary compounds used clinically to decrease involuntary detrusor contractions. Anticholinergic therapy has a stabilising effect on the bladder (detrusor muscle); increases bladder capacity; decreases frequency of involuntary detrusor contractions; and delays the initial urge to void, but does not affect warning time. However, the clinical utility of antimuscarinic therapy is limited by the lack of receptor selectivity, resulting in the classic anticholinergic side effects of dry mouth, blurred vision, constipation and potentially, CNS effects such as somnolence and impaired cognitive function. These unwanted side effects often result in premature discontinuation of therapy and poor compliance. Previous attempts to develop uroselective α-adrenergic receptor antagonists have not been successful and although research continues, the hope that this class of agents would be viable alternatives to the anticholinergics remains to be proven in the clinical setting. The recent demise of several potassium channel openers does not augur well for the future of this class of agent. The reasons for the discontinuation of trials with these agents have not been fully elucidated, but one must assume that they were not uroselective and the cardiovascular side effects rendered them less than useful clinically. The serotonin re-uptake inhibitors appear to be promising novel therapeutic agents aimed at controlling bladder over-activity through specific CNS pathways. The sensory side of the micturition reflex is a potential therapeutic target. Agents to desensitise afferent nerve endings involved in C-fibre afferent reflexes include capsaicin and resiniferatoxin. Their clinical applicability is currently being evaluated. Finally, the recent findings related to the role of the P2X3 receptor in the sensory aspects of bladder filling have created new interest in the future development of agents that will improve the management of this prevalent and debilitating condition.     

Fesoterodine: a novel muscarinic receptor antagonist for the treatment of overactive bladder syndrome

Background: Fesoterodine is a newly approved drug for the treatment of overactive bladder syndrome. Objective: The aim of this study was to review the preclinical and clinical data on fesoterodine. Methods: The study involved a search of the Medline database and the proceedings volumes of urological congresses. Results/conclusions: Fesoterodine functions as an orally active prodrug that is converted to the active metabolite 5-hydroxymethyltolterodine by non-specific esterases. 5-Hydroxymethyltolterodine is a muscarinic receptor antagonist. Fesoterodine is primarily eliminated as inactive metabolites along with significant renal excretion as the unchanged active metabolite 5-hydroxymethyltolterodine. Fesoterodine is indicated for use at doses of 4 and 8 mg once daily. In clinical studies both doses of fesoterodine were consistently superior to placebo in improving the symptoms of overactive bladder syndrome, with 8 mg/day having significantly greater effects than 4 mg/day.     

Oxybutynin gel for the treatment of overactive bladder

Benign prostatic hyperplasia is an increasingly prevalent condition affecting > 50% of men > 65 years of age. Although it is a condition that is unlikely to be life threatening, it can significantly affect quality of life with distressing lower urinary tract symptoms. Increasingly, medical therapy is being used as first-line treatment for men with moderate-to-severe lower urinary tract symptoms. Two main pharmacological classes of drugs are used: 5α-reductase inhibitors and α-1 selective blockers. Both these classes of drugs have shown good tolerability and clinical efficacy. This article examines the potential benefit of the use of combination therapy. In particular, what is the evidence for using doxazosin and finasteride therapy together?     

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 M₃ 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 M₂ receptors as these receptors are mainly responsible for muscarinic receptor-dependent bradycardia. We have investigated a novel antimuscarinic, SVT-40776, highly selective for M₃ over M₂ receptors (Ki = 0.19 nmol·L⁻¹ for M₃ 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 µg·kg⁻¹ i.v), without affecting arterial blood pressure.

Conclusions and implications:

SVT-40776 is a potent inhibitor of M₃ 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.British Journal of Pharmacology (2009) doi:10.1111/j.1476-5381.2008.00082.x     

Transdermal oxybutynin: a new treatment for overactive bladder

Overactive bladder has been successfully treated with oral anticholinergic drugs such as oxybutynin chloride. Although oral oxybutynin has been effective in controlling urinary urge incontinence and in decreasing incontinence episodes, adverse events, particularly dry mouth, often cause patients to discontinue oral therapy and to endure incontinence. Transdermal oxybutynin (Oxytrol^®, Watson Pharmaceuticals) is applied twice-weekly to maintain the efficacy of oral oxybutynin while significantly minimising side effects (e.g., dry mouth) that complicate therapy. By avoiding hepatic and gastrointestinal metabolism of oxybutynin, less N-desethyloxybutynin (N-DEO), the compound thought to be responsible for anticholinergic side effects, such as dry mouth, is produced. The new transdermal oxybutynin formulation offers patients with urinary incontinence an effective, safe and well-tolerated option for managing the symptoms of overactive bladder.     

Evidence for the efficacy and safety of tolterodine in the treatment of overactive bladder

Overactive bladder (OAB) is a chronic and prevalent condition, the symptoms of which (urinary frequency and urgency, with or without urge incontinence) can exert a profound negative effect on a person’s daily life activities. Tolterodine (Detrol^® in North America and Detrusitol^® in the rest of the world, Pharmacia), a competitive muscarinic antagonist, is the first agent of this class to be specifically developed for the treatment of OAB. This agent displays in vivo functional selectivity for the bladder over other tissues that contain muscarinic receptors (e.g., salivary glands, eye), which translates into good efficacy and tolerability in patients with OAB (including the elderly). Comparative, randomised, double-blind studies show that tolterodine (administered as immediate-release [IR] tablets 2 mg b.i.d.) is as effective as oxybutynin (5 mg t.i.d.) in improving all of the troublesome symptoms of OAB but with a significantly lower incidence and severity of dry mouth. The advent of a new extended-release (ER) capsule formulation of tolterodine (4 mg) for convenient once-daily treatment builds upon these findings, with significantly improved efficacy for reducing urge incontinence episodes and a lower frequency of dry mouth relative to the existing IR tablet (2 mg b.i.d.). Tolterodine can therefore be considered a valuable, well-tolerated treatment option for patients with OAB, providing improvements in symptoms that are both clinically meaningful to patients and sustained during long-term treatment.     

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.     

Oxybutynin for treatment of urge urinary incontinence and overactive bladder: an updated review

Urge urinary incontinence (UUI) and overactive bladder are common conditions often associated with profound impairment of the health and quality of life of the patient. Antimuscarinic medications have been the mainstay of treatment for these disorders. Oxybutynin hydrochloride, one of the most widely used antimuscarinic agents, has attracted considerable interest from both clinicians and pharmacologists over the last three decades. Although efficacy of this drug has been proven to be high, its use is limited by antimuscarinic adverse effects, possibly related to its active metabolite N-desethyloxybutynin (N-DEO). The extended-release form of oxybutynin uses a push-pull osmotic release system which has significantly improved its tolerability and safety profile. A transdermal transport system has also been developed, bypassing the first-pass metabolism in the liver and gut. This system is associated with significant reduction in the production of the primary metabolite and additional improvement in the tolerability profile of the drug. Intravesical instillation of oxybutynin has been reported although the efficacy and safety of this delivery system has yet to be determined. This article comprehensively reviews the contemporary literature on the pharmacology, clinical efficacy and adverse reactions of oxybutynin in its various delivery forms, and compares them to other frequently used medications for UUI and overactive bladder.     

Tolterodine for the treatment of overactive bladder

Background: The overactive bladder syndrome is a common condition affecting ～ 12% of men and women. It is extremely disturbing with a great impact on quality of life. Its treatment involves a combination of behavioural and pharmacological therapy. The latter includes antimuscarinic drugs such as tolterodine. Objective: To review the safety and efficacy of tolterodine in the treatment of overactive bladder in comparison with other available antimuscarinic agents. Methods: A Pubmed search was carried out differentiating randomised, clinical trials; longitudinal, retrospective studies; and metanalysis on the use of tolterodine for overactive bladder treatment. In the comparison with other antimuscarinic agents, only randomised, clinical trials were considered. Results/conclusion: Tolterodine is available as immediate- or extended-release formulations. It has been extensively evaluated with long-term, randomised trials for safety and efficacy showing a significant improvement in overactive bladder symptoms with an excellent tolerability profile.     

The emerging role of solifenacin in the treatment of overactive bladder

Although antimuscarinic drug therapy has been proven to be effective in the management of patients with symptoms of the overactive bladder syndrome, compliance with medication is often affected by the antimuscarinic adverse effects of dry mouth, constipation, somnolence and blurred vision. The development of bladder-selective M₃-specific antagonists offers the possibility of increasing efficacy whilst minimising adverse effects. At present there are no M₃-specific antagonists currently available although solifenacin and darifenacin are both under development and are due to be launched in 2004. The purpose of this article is to review the pharmacology and clinical trial data available for solifenacin, in addition to examining its role in the treatment of the overactive bladder syndrome.     

Muscarinic receptor function, density and G-protein coupling in the overactive diabetic rat bladder

1 Bladder smooth muscle sensitivity to muscarinic agonists is increased in the overactive bladder. Treatment of rats with streptozotocin induces a diabetic state in which the bladder muscle is overactive and also supersensitive to muscarinic agonists. This study has examined bladder contraction, muscarinic receptor density and receptor/G-protein coupling in the streptozotocin-induced overactive bladder of the rat. 2 Diabetes was induced by a single intraperitoneal dose of streptozotocin. Seven days later contraction of isolated detrusor muscle strips was assessed in tissue bath experiments, while receptor density was assayed in saturation experiments with [3H]-QNB (quinuclidinyl benzilate, L-[benzilic-4,4'-3H]) and receptor/G-protein coupling was determined in agonist displacement experiments with this radioligand. 3 Isolated detrusor strips from diabetic animals displayed an enhanced degree of spontaneous activity (0.060 +/- 0.016 g mg(-1), compared with 0.015 +/- 0.004 g mg(-1), P < 0.05). Carbachol produced contractile responses in tissues from both control and diabetic rats, but the diabetic tissues were more sensitive to this agonist, the pEC50 being 6.52 +/- 0.17 compared with 5.93 +/- 0.06 in controls (P < 0.001). Maximum responses to carbachol were similar in both groups of animals. The increase in carbachol potency was accompanied by a 40% increase in receptor density from 158 +/- 5 to 221 +/- 22 fmol mg(-1) protein (P < 0.05), but this was not enough to fully account for the change in tissue sensitivity. 4 In the absence of GTP-gamma-S, carbachol displaced [3H]-QNB from two binding sites, the high-affinity site (pKi = 7.06 +/- 0.26) which represents the receptors coupled to G-proteins made up 43.1 +/- 5.9% of the total binding sites in control tissues and this value was similar (41.0 +/- 4.0%) in the diabetic tissues (pKi = 6.64 +/- 0.31). In the presence of GTP-gamma-S, carbachol displaced [3H]-QNB from a single binding site which had a low-affinity, similar to the low-affinity site observed in the absence of GTP-gamma-S. 5 These data demonstrate that detrusor supersensitivity is observed after only 1 week of untreated diabetes in the rat. The overactivity is associated with an enhanced sensitivity to carbachol, which is partly explained by an increase in receptor density, but there appears to be no change in receptor/G-protein coupling.     

Oxybutynin chloride topical gel: a new formulation of an established antimuscarinic therapy for overactive bladder

Background: Oxybutynin, a cholinergic-muscarinic receptor antagonist, is established as a safe and effective pharmacological treatment for patients with overactive bladder syndrome (OAB). Oxybutynin is available in multiple immediate- and extended-release oral and two transdermal formulations. Oxybutynin chloride topical gel (OTG) (Gelnique^®, Watson Pharmaceuticals, Corona, CA, USA) was approved in January 2009 by the US FDA. OTG was designed to provide consistent plasma oxybutynin levels with daily application, favorably altering the circulating N-desethyloxybutynin metabolite:oxybutynin ratio, and to utilize a biocompatible delivery system, thus minimizing both the anticholinergic adverse effects of oral formulations and the application-site skin reactions associated with other available forms of transdermal delivery. Objective/methods: This review summarizes the pharmacological properties and the clinical efficacy and safety profile of OTG based on the published literature and unpublished data provided by the manufacturer upon request. Results/conclusion: OTG represents an efficacious, safe, and convenient alternative to other oxybutynin formulations and other oral anticholinergic medications for the treatment of OAB. Future studies and broad clinical experience should confirm the promising early experience observed with this formulation.     

Food does not affect the pharmacokinetics of solifenacin, a new muscarinic receptor antagonist: results of a randomized crossover trial

AIM: To determine the effect of food ingestion on the pharmacokinetic profile of solifenacin succinate (YM905; Vesicare, a new bladder selective muscarinic receptor antagonist for the treatment of overactive bladder, a chronic disease usually caused by involuntary detrusor muscle contractions during bladder filling. METHODS: A randomized, two-period, crossover study in two groups of 12 healthy men (aged 18-45 years, body weight 60-100 kg, body mass index < or =30). A single 10-mg dose of solifenacin was administered to the first group in the fasting state during period 1 and in the fed state during period 2, and to the second group in the fed state during period 1 and in the fasting state during period 2 (10 mg is two times the suggested starting dose). There was a 14-day washout between treatment periods. Parameters obtained included C(max), AUC(last), and AUC(0-inf), as well as t(1/2), t(max), and t(lag). RESULTS: One subject withdrew during the first period for personal reasons. No statistically or clinically significant pharmacokinetic differences occurred between subjects in the fed and fasting states. All geometric mean ratios were close to 1 (C(max), 1.033; AUC(last), 1.068; AUC(0-inf), 1.040). The 90% confidence intervals (CIs) fell in the predefined no-food-effect boundaries of 0.8-1.25 (C(max), 0.953-1.120; AUC(last), 0.990-1.153; AUC(0-inf), 0.976-1.109). The mean difference in t(1/2) was -3.8 h (90% CI 7.6-0.0). There were no significant differences between the fed and fasting states with regard to t(max) and t(lag) (P > 0.05). CONCLUSIONS: The pharmacokinetics of oral solifenacin was not affected by food ingestion, suggesting that this drug may be administered with or without food. The results observed in this investigation are consistent with those of previous studies of solifenacin.     

Long-acting formulation of a new muscarinic receptor antagonist for the treatment of overactive bladder

A new muscarinic receptor antagonist, 5-hydroxymethyl tolterodine (5-HMT), was successfully encapsulated into PLGA microspheres. With an increase of PLGA concentration from 15% to 40%, encapsulation efficiency of 5-HMT increased from 55.39% to 76.32%, and the particle size of microsphere increased from 34.33 to 70.48?µm. Increasing the homogenisation speed from 850 to 2300?rpm, the particle size was reduced about 65%.The in vitro and in vivo studies in beagle dogs show that the release profile of 5-HMT-loaded microspheres (5-HMT MS) prepared with 503H is characterised by a low initial burst followed by slow release that lasted for 2 weeks. A C_max of 1.617?±?0.392?ng/mL was found on the sixth day. When evaluated for inhibition of the carbachol-induced contraction of rat urinary bladder, 5-HMT MS showed a much longer and more potent effect than tolterodine tablets. The mean urination time of the rats in the 5-HMT MS group was significantly decreased (p?<?0.05 or p?<?0.01) to less than 2 weeks.     

索利那新联合生物反馈治疗女性膀胱过度活动症的疗效

目的 观察索利那新(抗排尿功能障碍药)联合生物反馈治疗女性膀胱过度活动症(OAB)的疗效.方法 31例女性OAB患者,口服索利那新(28天,5mg/24 h )联合生物反馈(20天)进行治疗,3个月后评价疗效并追踪观察.结果 31例女性OAB患者中,治愈17例(58.1%),有效10例(32.3%),无效4例(12.9%),总有效率达87.1%.治疗后有效随访26例,3个月无复发.结论 索利那新联合生物反馈是治疗女性OAB的一种有效方法.     

ADX71441, a novel,potent and selective positive allosteric modulator of the GABAB receptor,shows efficacy in rodent models of overactive bladder

Background and Purpose

The GABA_B receptor agonist baclofen reduces urethral resistance and detrusor overactivity in patients with spasticity. However, baclofen''s side effects limit its use for the treatment of overactive bladder (OAB). Here, we tested a novel GABA_B positive allosteric modulator (PAM) {"type":"entrez-protein","attrs":{"text":"ADX71441","term_id":"323467756","term_text":"ADX71441"}}ADX71441 in models of OAB in mice and guinea pigs.

Experimental Approach

Mice were left untreated or given (p.o.) vehicle (1= CMC), {"type":"entrez-protein","attrs":{"text":"ADX71441","term_id":"323467756","term_text":"ADX71441"}}ADX71441 (1, 3, 10 mg kg⁻¹) or oxybutynin (100 mg kg⁻¹; Experiment 1) or vehicle (1= CMC), baclofen (1, 3, 6 mg kg⁻¹) or oxybutynin (Experiment 2). Treated mice were then overhydrated with water, challenged with furosemide, before being placed into micturition chambers and monitored for urinary parameters. In anaesthetized guinea pigs, intravesical infusion of acetic acid was used to induce OAB and the effects of {"type":"entrez-protein","attrs":{"text":"ADX71441","term_id":"323467756","term_text":"ADX71441"}}ADX71441 (1, 3 mg kg⁻¹) or baclofen (1 mg kg⁻¹), administered i.v., on cystometric parameters were monitored.

Key Results

In mice, 10 mg kg⁻¹ {"type":"entrez-protein","attrs":{"text":"ADX71441","term_id":"323467756","term_text":"ADX71441"}}ADX71441 increased urinary latencies, reduced the number of urinary events and the total and average urinary volumes. In guinea pigs, {"type":"entrez-protein","attrs":{"text":"ADX71441","term_id":"323467756","term_text":"ADX71441"}}ADX71441 (1 and 3 mg kg⁻¹) increased the intercontraction interval (ICI) and bladder capacity (BC), and reduced micturition frequency (MF) compared to vehicle. At 3 mg kg⁻¹ {"type":"entrez-protein","attrs":{"text":"ADX71441","term_id":"323467756","term_text":"ADX71441"}}ADX71441 completely inhibited the micturition reflex and induced overflow incontinence in five out of 10 animals. Baclofen slightly increased ICI and BC and reduced MF.

Conclusion and Implications

Our findings demonstrate, for the first time, that a GABA_B PAM has potential as a novel approach for the treatment of OAB.     

Alfuzosin for the treatment of storage symptoms suggestive of overactive bladder

Introduction: Antimuscarinics are the mainstay of overactive bladder (OAB) pharmacotherapy although other agents, such as α-adrenergic receptor antagonists, might also be effective. Alfuzosin has α1-adrenoreceptor antagonist activity and is available worldwide for the treatment of lower urinary tract symptoms resulting from benign prostate hyperplasia. Alfuzosin may relieve storage symptoms suggestive of OAB in patients with or without bladder outlet obstruction (BOO).

Areas covered: This paper reviews the available literature on the use of alfuzosin in the treatment of storage symptoms suggestive of OAB. Additionally, the role of α-adrenoreceptor antagonists in the treatment of OAB is reviewed, based on pathophysiology.

Expert opinion: Although alfuzosin is effective against storage symptoms, it does not improve them in all patients with OAB. It is likely that alternative types of therapy, such as antimuscrarinics, need to be co-administered to patients with residual storage symptoms after alfuzosin administration. Alfuzosin can decrease the risk of adverse events associated with antimuscarinics. The sequential use of alfuzosin and antimuscarinics appears to be an appropriate strategy for the treatment of storage symptoms suggestive of OAB related to BOO.     

Tolterodine: a new antimuscarinic agent for the treatment of the overactive bladder

Bladder hyperactivity is a debilitating problem that affects many individuals. A plethora of therapeutic options have been investigated to combat this condition, antimuscarinic therapy being the most widely used. Nevertheless, this medication group has historically been of limited benefit, due to its side-effect profile. Tolterodine is a new muscarinic receptor antagonist that has been shown to be equally effective when compared to oxybutynin. However, the side-effect profile for tolterodine is much better than this commonly used anticholinergic. It has reduced affinity for the salivary glands in animal studies, and, in clinical trials, there has been a reduced incidence of dry mouth with this medication. In Phase III studies, tolterodine has been shown to decrease the number of micturitions per day, decrease the number of incontinence episodes per day and increase the mean volume voided per micturition. The maximal effect of this medication may not be seen for 6 - 8 weeks after initiation of the drug although the exact explanation for this finding has yet to be completely elucidated. The recommended dose is 2 mg b.i.d., which should be adjusted for those with liver failure or those on drugs that inhibit the cytochrome P450 isoenzyme known as CYP3A4. In summary, tolterodine is an effective well-tolerated antimuscarinic which should be considered as a first-line treatment due to its more favourable side-effect profile when than other available medications.