Preview of new drugs for overactive bladder and incontinence: darifenacin, solifenacin, trospium, and duloxetine

A small-animal pharmacokinetic/pharmacodynamic PET study of central serotonin 1A receptor occupancy by a potential therapeutic agent for overactive bladder

Serotonin 1A (5-HT1A) receptors have been mechanistically implicated in micturition control, and there has been a need for an appropriate biomarker surrogating the potency of a provisional drug acting on this receptor system for developing a new therapeutic approach to overactive bladder (OAB). Here, we analyzed the occupancy of 5-HT1A receptors in living Sprague-Dawley rat brains by a novel candidate drug for OAB, E2110, using positron emission tomography (PET) imaging, and assessed the utility of a receptor occupancy (RO) assay to establish a pharmacodynamic index translatable between animals and humans. The plasma concentrations inducing 50% RO (EC50) estimated by both direct and effect compartment models were in good agreement. Dose-dependent therapeutic effects of E2110 on dysregulated micturition in different rat models of pollakiuria were also consistently explained by achievement of 5-HT1A RO by E2110 in a certain range (≥ 60%). Plasma drug concentrations inducing this RO range and EC50 would accordingly be objective indices in comparing pharmacokinetics-RO relationships between rats and humans. These findings support the utility of PET RO and plasma pharmacokinetic assays with the aid of adequate mathematical models in determining the in vivo characteristics of a drug acting on 5-HT1A receptors and thereby counteracting OAB.

Pharmacoeconomic evaluation of antimuscarinic agents for the treatment of overactive bladder

STUDY OBJECTIVE

To compare the cost-effectiveness of various antimuscarinic agents for the treatment of overactive bladder (OAB).

METHODS

A decision-analysis model was developed and included clinical outcomes (i.e., therapy continued or discontinued, treatment success or failure, OAB-induced comorbidities) and costs for drugs and treatment of OAB-induced comorbidities (i.e., urinary tract infections, fractures, depression, and skin infections). Treatment success was defined as complete continence. A systematic MEDLINE literature search from January 1990-January 2006 identified English-language articles concerning the eight antimuscarinic drugs: darifenacin, solifenacin, trospium, immediate-release oxybutynin, extended-release oxybutynin, transdermal oxybutynin, immediate-release tolterodine, and extended-release tolterodine. Probabilities and cost data for these drugs were retrieved from the literature, and drug costs were based on 2005 average wholesale prices. The analysis was constructed from a payer's perspective. The time frame for the model was 3 months.

RESULTS

Expected costs for each patient with OAB ranged from $3373 when treated with solifenacin to $3769 when treated with immediate-release oxybutynin. The average cost/patient with continued and successful treatment was lowest for solifenacin ($6863). Solifenacin dominated all other antimuscarinic agents because they were associated with high costs and low effectiveness. Success rates were the key parameters driving the sensitivity analysis.

CONCLUSION

Among various antimuscarinic agents, solifenacin 5 mg had the lowest costs and highest effectiveness in the treatment of OAB.

Impact of overactive bladder on women in the United States: results of a national survey

BACKGROUND

Overactive bladder (OAB) may affect health-related quality of life. Few data have been gathered on the impact of OAB or on patient satisfaction with therapy. This 2002 survey examined the effects of OAB on participants; treatment-seeking behaviors, patient satisfaction with oral OAB therapies, and desirable characteristics of new treatments were investigated.

METHODS

An online questionnaire was administered to 1228 women aged 40-65 years with at least a high school education and minimum annual income of 35,000 dollars. Respondents were categorized as having no OAB symptoms (control group; n = 330) or as having OAB symptoms (n = 898). Those with symptoms were subdivided into treatment groups: current users of prescription OAB medications (n = 309), lapsed prescription medication users (n = 265), and those never treated (n = 324). The significance of between-group differences in response was assessed through 95% confidence levels.

RESULTS

Symptoms of OAB significantly affect self-esteem, family relations, sexual relations, lifestyle, professional life, and health perception. More than half of women who discussed OAB with a health care provider (56%) waited longer than 1 year to seek treatment; many attempted to self-manage symptoms. Health care providers rarely screen for OAB, leaving many conditions undiagnosed and patients untreated. Women treated for OAB expressed significant dissatisfaction with current OAB therapies and the desire for more effective, convenient treatments with fewer adverse effects.

CONCLUSIONS

Likely outcomes should be discussed with patients before treatment is initiated so that expectations are realistic and patients' overall satisfaction with treatment is enhanced.

Retrospective evaluation of outcomes in patients with overactive bladder receiving tolterodine versus oxybutynin

PURPOSE

The frequency, relative risk, resource utilization, and costs related to comorbidities associated with overactive bladder (OAB) were studied.

METHODS

A retrospective analysis of patients with OAB who initiated treatment with tolterodine extended release (ER), oxybutynin ER, or oxybutynin immediate release (IR) between January 2001 and December 2002 was conducted to evaluate the frequency, relative risk, resource utilization, and costs related to three specific comorbidities associated with OAB: urinary tract infections (UTIs), depression, and fracture. Two patient cohorts (tolterodine ER versus oxybutynin ER and tolterodine ER versus oxybutynin IR) were matched on a 1:1 basis according to their propensity to receive a prescription for tolterodine ER.

RESULTS

The frequency and relative risk of UTIs were significantly lower in the tolterodine ER group than in the oxybutynin ER and oxybutynin IR groups. The relative risk of depression was also lower in the tolterodine ER group than the oxybutynin ER and oxybutynin IR groups; however, the differences were only significant in the tolterodine ER versus oxybutynin IR comparison. The utilization of UTI- and depression-related services and the number of antiinfective and antidepressant prescriptions were significantly lower in the tolterodine ER group than in the oxybutynin ER group. UTI- and depression-related costs were generally lower in the tolterodine ER group than in the oxybutynin ER or oxybutynin IR group.

CONCLUSION

Treatment of OAB patients with tolterodine ER was associated with reduced frequency, relative risk, medical and pharmacy resource utilization, and incurred costs related to selected OAB-associated comorbidities compared with treatment with oxybutynin ER or oxybutynin IR.

Current trends in the evaluation and management of female urinary incontinence

Despite its common occurrence and often seemingly obvious causes, female urinary incontinence requires a thorough and thoughtful evaluation for its proper diagnosis and treatment. With rare exceptions, urinary incontinence is the result of failure of the sphincter mechanism to resist bladder pressures encountered during daily activities. This may be the result of sphincter failure, overactivity of the bladder detrusor muscle or both. In uncomplicated cases, the diagnosis is usually based on an evaluation in the office. Urodynamic and cystoscopic study may be helpful in complex, resistant and recurring cases of urinary incontinence of any cause. Most cases of incontinence may be classified as stress, urge or mixed urinary incontinence. Treatment of stress urinary incontinence focuses on supplementing the urethral continence mechanisms, particularly the urethral supports and periurethral striated muscle function. The current paradigm for the treatment of urge incontinence centres on pharmacologic therapy, primarily by correcting detrusor overactivity with antimuscarinic drugs. Other therapies aimed at altering sensorimotor function may be used in resistant cases. The treatment of mixed urinary incontinence requires consideration of the contribution of each of its components. With proper diagnosis, effective treatment is possible for most patients.

Neurogenic bowel and bladder in the older adult

Special skills are needed in caring for an elderly patient with a neurogenic bowel and bladder. One not only has to take into account the age-related changes that occur, but also how these changes impact on a patient already struggling with bowel and bladder issues because of various neurogenic causes. Incontinence of bowel and bladder leads to a loss of quality of life and physicians should be educated on the treatment available to provide the best care for their patients.

The emergence of new drugs for overactive bladder

Overactive bladder is a common and distressing problem. Standard therapy is directed towards modifying the detrusor motor sensitivity and response via anticholinergic medication. Currently available medications are reviewed and alternative targets for treatment are presented.

Female neurogenic vesicourethral dysfunction: evaluation and management

This paper outlines the evaluation and management of neurogenic vesicourethral dysfunction (NVUD). The anatomy and neurophysiology involved with lower urinary tract functions are reviewed. Multiple sclerosis, diabetes, lumbar disc prolapse, and Parkinson's disease are specifically addressed. Proper evaluation of patients suspected of having NVUD, which is fundamental to making an accurate diagnosis, is discussed. This is followed by options for initiating individualized management plans that focus on protecting and preserving renal function, in addition to relieving the symptoms of NVUD.

Sexually dimorphic micturition in rats: relationship of perineal muscle activity to voiding pattern

In the present study we examined the possibility that striated muscle activity may underlie sexually dimorphic micturition in rats. Micturition dynamics, the gross anatomy of the external urethral sphincter, and the participation of the striated perineal muscles in micturition were compared in urethane-anesthetized adult male and female rats. Bladder contraction characteristics, particularly the magnitude of bladder high-frequency pressure waves during voiding, differed between sexes. Dissections indicated that the sphincter was more extensive and thicker in males than in females. Electromyography showed that in both sexes the sphincter discharged in bursts that correlated with the rising phase of high-frequency bladder pressure oscillations. Regional differences in discharge pattern were seen in the sphincters of males, with the proximal part of the sphincter showing components activated during bladder filling. Bulbospongiosus, ischiocavernosus, and cremaster muscles also were activated during bladder contraction in males. In both sexes transection of the motor branch of the lumbosacral plexus eliminated the bladder high-frequency oscillations and reduced voided volume. Neurectomy did not affect bladder pressure but reduced voiding efficiency by 45% in males. In females the bladder pressure was dramatically decreased, but voiding efficiency only decreased by 24%. Our findings suggest that, in rats, striated perineal muscles contribute to the sexually dimorphic micturition. Activity of the dimorphic perineal muscles may regulate genital and urinary urethra expulsive functions, helping to expel seminal plug and fluids through the long urethra in the male.

Improving the Tolerability of Anticholinergic Agents in the Treatment of Overactive Bladder

Pharmacological treatment for overactive bladder has centred around the interruption of the detrusor activity that is central to urge and incontinence symptoms. The majority of patients with this disorder are treated with antimuscarinic agents. These drugs have been demonstrated to improve urgency, frequency of micturition and urge incontinence, all of which are primary symptoms of overactive bladder; however, they are also commonly associated with anticholinergic adverse effects, most notably dry mouth. Attempts to increase tolerability have included the development of advanced formulations that regulate release of the active ingredient and the development of pharmacological agents that target the desired bladder receptors more specifically and accurately. Although all agents provide good efficacy, tolerability is greatly affected by the formulation used to deliver the active pharmacological agent, as well as the specificity of the targeted receptors. Clinical trials involving a transdermal formulation of oxybutynin have shown that this delivery method may be associated with a lower incidence of anticholinergic adverse events compared with both the immediate-release and the extended-release oral formulations of traditional agents, as well as the most recently approved agents - trospium chloride, solifenacin and darifenacin. Much is still being learned about the function and specificity of muscarinic receptors, which will support the development of agents with sustained efficacy and enhanced tolerability compared with the available formulations to date. These include the S-isomer of oxybutynin, as well as selective muscarinic M2 receptor antagonists.