Muscarinic receptor antagonists for overactive bladder treatment: does one fit all?:

Current pharmacotherapy of overactive bladder

Overactive bladder is a symptom complex consisting of bothersome storage urinary symptoms that is highly prevalent among both sexes and has a significant impact on quality of life. Various antimuscarinic agents and the beta-3 agonists mirabegron and vibegron are currently available for the treatment of OAB. Each drug has specific pharmacologic properties, dosing schedule and tolerability profile, making it essential to individualize the medical treatment for the patient's characteristics and expectations. In this manuscript, we review the most important factors involved in the contemporary pharmacological treatment of OAB.

Factors Associated with Decisions for Initial Dosing, Up-Titration of Propiverine and Treatment Outcomes in Overactive Bladder Syndrome Patients in a Non-Interventional Setting

Two doses of propiverine ER (30 and 45 mg/d) are available for the treatment of overactive bladder (OAB) syndrome. We have explored factors associated with the initial dosing choice (allocation bias), the decision to adapt dosing (escalation bias) and how dosing relative to other factors affects treatment outcomes. Data from two non-interventional studies of 1335 and 745 OAB patients, respectively, receiving treatment with propiverine, were analyzed post-hoc. Multivariate analysis was applied to identify factors associated with dosing decisions and treatment outcomes. Several parameters were associated with dose choice, escalation to higher dose or treatment outcomes, but only few exhibited a consistent association across both studies. These were younger age for initial dose choice and basal number of urgency and change in incontinence episodes for up-titration. Treatment outcome (difference between values at 12 weeks vs. baseline) for each OAB system was strongly driven by the respective baseline value, whereas no other parameter exhibited a consistent association. Patients starting on the 30 mg dose and escalating to 45 mg after 4 weeks had outcomes comparable with those staying on a starting dose of 30 or 45 mg. We conclude that dose escalation after 4 weeks brings OAB patients with an initially limited improvement to a level seen in initially good responders. Analysis of underlying factors yielded surprisingly little consistent insight.

Assessment of inhibitory effects on major human cytochrome P450 enzymes by spasmolytics used in the treatment of overactive bladder syndrome

BACKGROUND

The objective of this study was to examine the inhibitory potential of darifenacin, fesoterodine, oxybutynin, propiverine, solifenacin, tolterodine and trospium chloride on the seven major human cytochrome P450 enzymes (CYP) by using a standardized and validated seven-in-one cytochrome P450 cocktail inhibition assay.

METHODS

An in vitro cocktail of seven highly selective probe substrates was incubated with human liver microsomes and varying concentrations of the seven test compounds. The major metabolites of the probe substrates were simultaneously analysed using a validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Enzyme kinetics were estimated by determining IC50 and Ki values via nonlinear regression. Obtained Ki values were used for predictions of potential clinical impact of the inhibition using a static mechanistic prediction model.

RESULTS

In this study, 49 IC50 experiments were conducted. In six cases, IC50 values lower than the calculated threshold for drug-drug interactions (DDIs) in the gut wall were observed. In these cases, no increase in inhibition was determined after a 30 min preincubation. Considering a typical dosing regimen and applying the obtained Ki values of 0.72 µM (darifenacin, 15 mg daily) and 7.2 µM [propiverine, 30 mg daily, immediate release (IR)] for the inhibition of CYP2D6 yielded a predicted 1.9-fold and 1.4-fold increase in the area under the curve (AUC) of debrisoquine (CYP2D6 substrate), respectively. Due to the inhibition of the particular intestinal CYP3A4, the obtained Ki values of 14 µM of propiverine (30 mg daily, IR) resulted in a predicted doubling of the AUC for midazolam (CYP3A4 substrate).

CONCLUSIONS

In vitro/in vivo extrapolation based on pharmacokinetic data and the conducted screening experiments yielded similar effects of darifenacin on CYP2D6 and propiverine on CYP3A4 as obtained in separately conducted in vivo DDI studies. As a novel finding, propiverine was identified to potentially inhibit CYP2D6 at clinically occurring concentrations.

The Impact of Gene Polymorphisms on the Success of Anticholinergic Treatment in Children with Overactive Bladder

AIM

To determine the impact of gene polymorphisms on detrusor contraction-relaxation harmony in children with lower urinary tract symptoms (LUTS).

MATERIALS AND METHODS

Toilet trained children older than 5 years of age with LUTS and normal neurological examination underwent videourodynamic study. The control group was composed of age matched children with no voiding complaints. The study group who filled out the voiding dysfunction symptom score before and after the treatment received standard oxybutynin treatment and was reevaluated 1 year after treatment. Genomic DNA was isolated from all patients and subjected to PCR for amplification. Genotyping of ARGHEF10, ROCK2, ADRB3, and CYP3A4 was carried out with Polymerase Chain Reaction- Restriction Fragment Length Polymorphism (PCR-RFLP) method.

RESULTS

34 (45%) and 42 (55%) patients were enrolled in the study and control group, respectively. ARGEF10 GG, ADRB3 TC, and CYP3A4 AG genotype patients displayed insignificant difference between pre- and posttreatment voiding dysfunction symptom score and bladder volumes.

CONCLUSIONS

The polymorphism of genes in the cholinergic pathway did not significantly differ clinical parameters. On the other hand, polymorphic patients in the adrenergic pathway seemed to suffer from clinical disappointment. For this reason, we think that the neglected adrenergic pathway could be a new therapeutic target for the treatment of anticholinergic resistant LUTS in children.

Lower urinary tract symptoms in patients with liver cirrhosis

PURPOSE

To evaluate the prevalence of lower urinary tract symptoms (LUTS) in men with liver cirrhosis.

METHODS

In total, 128 men with known liver cirrhosis were prospectively evaluated using the validated German version of the International Prostate Symptom Score (IPSS) questionnaire. In parallel, all men underwent a detailed examination including medical history; physical examination; Child-Pugh liver function score (CPS) assessment; and measurement of blood levels of prostate-specific antigen (PSA), total and free testosterone, sexual hormone-binding globulin (SHBG), prolactin, luteotropic hormone (LH), and follicle-stimulating hormone (FSH).

RESULTS

Mean patient age and mean IPSS was 56 ± 9 years and 8 ± 6, respectively. Mild (IPSS: 1-7), moderate (IPSS: 8-19), and severe (IPSS: 20-35) LUTS were present in 60.2 % (77/128), 31.3 % (40/128), and 7.0 % (9/128) of the patients, respectively. Storage symptoms increased with the CPS (p = 0.04). Voiding symptoms and overall IPSS did not differ between the CPS groups (p = 0.93 and p = 0.67). No correlation was found between ascites volume and IPSS, storage symptoms, voiding symptoms, or quality of life (QoL) (p = 0.46, p = 0.26, p = 0.81, p = 0.87). From CPS groups A to C, mean PSA levels (p = 0.04), total and free testosterone levels (p < 0.001 and p < 0.001), and SHBG levels decreased (p = 0.03); however, prolactin levels increased (p = 0.03). LH and FSH levels did not differ between the CPS groups (p = 0.15 and p = 0.35).

CONCLUSIONS

Men with liver cirrhosis commonly have LUTS, with a predominance of storage symptoms. Liver cirrhosis may also affect PSA-based prostate cancer risk assessment. Accurate diagnosis and therapy strategies are warranted to improve the QoL of these patients.

Rationale for the use of anticholinergic agents in overactive bladder with regard to central nervous system and cardiovascular system side effects

PURPOSE

Central nervous system (CNS) and cardiovascular system (CVS) side effects of anticholinergic agents used to treat overactive bladder (OAB) are underreported. Hence, this review aimed to focus on the mechanisms of CNS and CVS side effects of anticholinergic drugs used in OAB treatment, which may help urologists in planning the rationale for OAB treatment.

MATERIALS AND METHODS

PubMed/MEDLINE was searched for the key words "OAB," "anticholinergics," "muscarinic receptor selectivity," "blood-brain barrier," "CNS," and "CVS side effects." Additional relevant literature was determined by examining the reference lists of articles identified through the search.

RESULTS

CNS and CVS side effects, pharmacodynamic and pharmacokinetic properties, the metabolism of these drugs, and the clinical implications for their use in OAB are presented and discussed in this review.

CONCLUSIONS

Trospium, 5-hydroxymethyl tolterodine, darifenacin, and solifenacin seem to have favorable pharmacodynamic and pharmacokinetic properties with regard to CNS side effects, whereas the pharmacodynamic features of darifenacin, solifenacin, and oxybutynin appear to have an advantage over the other anticholinergic agents (tolterodine, fesoterodine, propiverine, and trospium) with regard to CVS side effects. To determine the real-life situation, head-to-head studies focusing especially on CNS and CVS side effects of OAB anticholinergic agents are urgently needed.

Antimuscarinic treatment in overactive bladder: special considerations in elderly patients

Overactive bladder is a common condition that increases in prevalence in association with age. Antimuscarinic therapy remains the mainstay of pharmacological treatment for the condition, and there is an increasing body of evidence that supports the use of these drugs. Despite this, and because of concerns about associated adverse effects, older people are less likely to receive active treatment for their condition. This review considers some of the factors that need to be taken into account when using these medications.

Overactive bladder, differential diagnosis, and clinical utility of fesoterodine

Overactive bladder is a symptom syndrome with urgency, frequency and, in many cases, nocturia. Urge incontinence is not present in all. There is no direct correlation with detrusor overactivity, an objective finding during urodynamic testing where involuntary contractions can be noticed. In the pathophysiology, much more attention has been given to the afferent/sensory arm of the micturition reflex in the last decade. Anatomical and infectious causes have to be diagnosed or ruled out. Diagnosis of overactive bladder is made mostly by history-taking, but other tests can be necessary in specific patients. Treatment consists of behavioral measures, a good explanation of the condition, training, and pelvic floor physiotherapy. Drugs are often used. Until recently, antimuscarinic drugs have been the mainstay of pharmacological therapy. Fesoterodine is a newer antimuscarinic agent which is more pharmacodynamically stable then tolterodine. Fesoterodine has been extensively researched using different dosages and compared with placebo and tolterodine, in different age groups, and under different conditions. Fesoterodine is superior to placebo and to tolterodine in the short term and long term. Its safety is very acceptable.

Antimuscarinic treatment in overactive bladder: special considerations in elderly patients

Overactive bladder is a common condition that increases in prevalence in association with age. Antimuscarinic therapy remains the mainstay of pharmacological treatment for the condition, and there is an increasing body of evidence that supports the use of these drugs. Despite this, and because of concerns about associated adverse effects, older people are less likely to receive active treatment for their condition. This review considers some of the factors that need to be taken into account when using these medications.

An overview of the clinical use of antimuscarinics in the treatment of overactive bladder

Overactive bladder is a common and bothersome condition. Antimuscarinic agents, as a class, are the cornerstone of medical treatment of overactive bladder. They offer significant improvements in symptoms and patients' quality of life. Antimuscarinics are generally well tolerated with mild and predictable side effects. Available antimuscarinics have small, yet statistically significant, differences in their efficacy and tolerability profiles. In clinical practice, finding the agent that offers the optimum balance of efficacy and side effects for an individual patient remains the major challenge.

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.

Fesoterodine for the treatment of overactive bladder

OBJECTIVE

To review pharmacologic, pharmacokinetic, efficacy, and safety data for fesoterodine and determine its role in the treatment of overactive bladder.

DATA SOURCES

A MEDLINE search (1966-July 2009) was conducted using the key words fesoterodine, tolterodine, muscarinic receptor antagonist, anticholinergic, overactive bladder, urge incontinence, efficacy, safety, adverse effect, pharmacology, pharmacokinetic, and receptor binding.

STUDY SELECTION AND DATA EXTRACTION

All articles written in English that were identified from the data sources were evaluated, prioritizing randomized, controlled trials with human data. The references of published articles that we identified were examined for any additional studies appropriate for the review.

DATA SYNTHESIS

Fesoterodine, a competitive muscarinic receptor antagonist, is converted to its active metabolite, 5-hydroxymethyltolterodine, by nonspecific esterases, bypassing the cytochrome P450 system. Two randomized controlled Phase 3 trials examined the safety and efficacy of fesoterodine in the treatment of overactive bladder. Fesoterodine was found to produce significant improvements in the treatment of overactive bladder symptoms compared with placebo. Post hoc analysis of these trials demonstrated significant improvements in health-related quality of life in patients with overactive bladder. Only one study included tolterodine, and direct comparisons between fesoterodine and tolterodine were not conducted. The most common treatment-emergent adverse effects associated with fesoterodine included dry mouth, constipation, urinary tract infection, and headache.

CONCLUSIONS

Fesoterodine appears to be effective and generally safe for the treatment of overactive bladder. The efficacy and safety of fesoterodine in overactive bladder treatment seem to be at least similar to that of tolterodine. Although additional comparative trials are needed, based on available data, it does not appear that fesoterodine provides a substantial advantage over extended-release tolterodine in either efficacy or safety.

[Drug-drug interactions in urology]

Many patients concomitantly receive multiple urological and nonurological medications. This practice can lead to drug-drug interactions (DDIs). These interactions can be pharmacodynamic (acting on the same body function) or pharmacokinetic (affecting each other's concentrations) and are a frequent cause of adverse drug reactions. Examples of pharmacodynamic DDIs include the use of overactive bladder drugs together with those prescribed for psychiatric or neurological indications that also have anticholinergic properties, or the use of PDE5 inhibitors together with vasodilating drugs, particularly nitrates. Pharmacokinetic DDIs are mainly due to effects on drug metabolism, specifically that involving CYP3A4 and 2D6, or on drug transporters. Drugs can both inhibit and induce the activity of many of these enzymes and transporters. CYP3A4 inducers can lower levels of cyclosporine or tacrolimus so much that transplant rejection occurs, and CYP3A4 inhibitors can increase their levels, leading to nephrotoxicity. Levels of the anticholinergic darifenacin can be increased so much by potent CYP3A4 inhibitors that this combination is contraindicated. These examples show that knowledge of DDI can help patients avoid undesirable side effects of drugs.

Triple therapy in refractory detrusor overactivity: a preliminary study

PURPOSE

To evaluate in a prospective study the impact of the "three-drug therapy" (antimuscarinic, alpha-blocker and tricyclic antidepressants) on the treatment of refractory detrusor overactivity (DO).

METHODS

Data from 27 consented patients with refractory DO were available for study. They were asked to complete a daily urinary chart and underwent urodynamic evaluation (UD) before and 60 days after treatment. Response to treatment was considered the presence of one or less involuntary detrusor contractions (IDC) on post-treatment UD. Statistical analysis was performed with Fisher and Mann-Whitney tests, besides Spearman's correlation. P values <0.05 were considered significant.

RESULTS

The mean follow-up was 15 months. The comparison of the daily urinary chart before and after treatment showed significant increase on bladder capacity and decreases on urgency, urge-incontinence and frequency. Objective data from UD showed that the mean maximum bladder capacity (MBC) ranged from 200 to 300 mL (P < 0.001) with treatment. The same trend was observed with the other UD variables. When compared to baseline, the questionnaire OAB-v8 showed significant improvement (P < 0.01). Main side effects comprised dry mouth and constipation (40%), with average scores of 5.16 and 3.08, respectively (visual scale from 0 to 10).

CONCLUSIONS

Triple therapy may be an effective, easily employed and well-tolerated option to refractory DO treatment. More studies are necessary to achieve more consistent data on the matter.