Electrophysiological profile of propiverine--relationship to cardiac risk

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.

Cardiovascular effects of antimuscarinic agents and beta3-adrenergic receptor agonist for the treatment of overactive bladder

INTRODUCTION

Overactive bladder (OAB) syndrome is common in the general population, particularly in elderly patients. Antimuscarinic drugs (AMs) are considered the mainstay pharmaceutical treatment of OAB whereas β3-adrenoceptor agonists, such as mirabegron, represent a good alternative. Owing to the important role of muscarinic and β3 receptors in cardiovascular (CV) tissue and to the fact that OAB patients often have CV comorbidities, the safety-profile of these drugs constitute an important challenge.

AREAS COVERED

The aim of this review is to evaluate the CV effects of AMs and mirabegron in OAB. A systematic literature search from inception until December 2017 was performed on PubMed and Medline.

EXPERT OPINION

AMs are generally considered to have good CV safety profile but, however, they may cause undesirable adverse events, such as dry mouth, constipation. CV AEs are rare but noteworthy, the most common CV consequences related to the use of these drugs are constituted by an increase in HR and QT interval. Mirabegron has similar efficacy and tolerability to AMs but causes less adverse events, with either modest hypertension and modest increase in HR (<5 bpm) being the most commonly reported.

Results of a randomized, double-blind, active-controlled clinical trial with propiverine extended release 30 mg in patients with overactive bladder

OBJECTIVE

To compare the efficacy and safety of the 30 mg extended release (ER) formulation of propiverine hydrochloride with the 4 mg ER formulation of tolterodine tartrate in patients with overactive bladder (OAB) in a non-inferiority trial.

PATIENTS AND METHODS

Eligible patients, aged 18-75 years and with symptoms of OAB, were enrolled in this multicentre, randomized, double-blind, parallel-group, active-controlled study. After a 2-week screening period, patients were randomized at a 1:1 ratio to receive either propiverine ER 30 mg or tolterodine ER 4 mg daily during the 8-week treatment period. Efficacy was assessed using a 3-day voiding diary and patient's self-reported assessment of treatment effect. Safety assessment included recording of adverse events, laboratory test results, measurement of post-void residual urine and electrocardiograms.

RESULTS

A total of 324 patients (244 female and 80 male) were included in the study. Both active treatments improved the variables included in the voiding diary and in the patient's self-reported assessment. The change from baseline in the number of voidings per 24 h was significantly greater in the propiverine ER 30 mg group compared with the tolterodine ER 4 mg group after 8 weeks of treatment (full analysis set [FAS] -4.6 ± 4.1 vs -3.8 ± 5.1; P = 0.005). Significant improvements were also observed for the change of urgency incontinence episodes after 2 weeks (P = 0.026) and 8 weeks (P = 0.028) of treatment when comparing propiverine ER 30 mg with tolterodine ER 4 mg. Both treatments were well tolerated, with a similar frequency of adverse drug reactions in both the propiverine ER 30 mg and tolterodine ER 4 mg groups (FAS 40.7 vs 39.5%; P = 0.8). More patients treated with tolterodine ER 4 mg discontinued the treatment because of adverse drug reactions compared with propiverine ER 30 mg (7.4 vs 3.1%).

CONCLUSIONS

Propiverine ER 30 mg was confirmed to be an effective and well-tolerated treatment option for patients with OAB symptoms. This first head-to-head study showed non-inferiority of propiverine ER 30 mg compared with tolterodine ER 4 mg.

Combining structure- and ligand-based approaches for studies of interactions between different conformations of the hERG K+ channel pore and known ligands

Drug-induced insurgence of cardiotoxic effects signaled by the prolongation of the QT interval in the electrocardiogram, has the potential to evolve into a characteristic arrhythmic event named Torsade de Pointes (TdP). Although several different mechanisms can theoretically lead to prolonged QT interval, most of drugs showing this side effect, prolong the cardiac repolarization time through the inhibition of the rapid component of the delayed repolarizing current (IKr) which in humans is carried by a K(+) channel protein encoded by hERG. In this study, four 3D-models, representing different conformational states of hERG K(+) channel, were built by a homology-based technique. A dataset of 59 compounds was collected from the literature and rationally selected according to the availability of IC50 values derived from whole-cell patch clamp performed at 37 °C on HEK cells. Molecular docking was carried out on each one of the four conformations of the channel, hundreds of docking-based molecular descriptors were obtained and used, together with other 2D and 3D molecular descriptors, to develop QSAR models. The statistical parameters describing the accordance between predicted and experimental data and the interpretation of the QSAR models enabled us to assess the reliability of the four 3D-models of the channel pore, thus allowing to look in more depth at binding modes and key features of the interactions occurring between the hERG K(+) channel and ligands endowed of blocking activity.

Propiverine: a review of its use in the treatment of adults and children with overactive bladder associated with idiopathic or neurogenic detrusor overactivity, and in men with lower urinary tract symptoms

Propiverine is a well established antimuscarinic agent with a mixed mode of action in the treatment of symptoms associated with overactive bladder (OAB). As well as blocking muscarinic receptors in the detrusor muscle, the drug also inhibits cellular calcium influx, thereby diminishing muscle spasm. In patients with symptoms of OAB resulting from idiopathic detrusor overactivity (IDO) or neurogenic detrusor overactivity (NDO), propiverine demonstrated dose-dependent efficacy and tolerability, with adverse events consistent with those associated with all antimuscarinic agents. In adults with IDO, propiverine demonstrated similar efficacy to that of other antimuscarinic agents (including solifenacin, tolterodine, oxybutynin and imidafenacin) and, in adults with NDO, propiverine and oxybutynin demonstrated similar efficacy. Propiverine was generally well tolerated in these patient populations, with a lower incidence of dry mouth than that associated with oxybutynin. In men with lower urinary tract symptoms (LUTS), and in whom the presence of benign prostatic enlargement (BPE) was implicated, propiverine administered as add-on therapy to an α(1)-adrenoceptor antagonist demonstrated similar or superior efficacy to that achieved with an α(1)-adrenoceptor antagonist alone, and combination therapy was particularly effective in patients with urinary storage symptoms. Combination therapy was generally well tolerated, but was associated with a higher incidence of adverse events than an α(1)-adrenoceptor antagonist alone. In children and adolescents with IDO/OAB or NDO, propiverine was generally more effective and better tolerated than oxybutynin. In conclusion, propiverine provides a valuable option for the treatment of adults and children with OAB associated with IDO or NDO, and in men with storage LUTS.

Cardiovascular effects of antimuscarinic agents in overactive bladder

INTRODUCTION

The potential impact of antimuscarinics (AMs) on cardiac function is a major concern in the treatment of overactive bladder (OAB) patients, especially in older ones who are likely to present cardiovascular (CV) comorbidities and other risk factors that may predispose them to the adverse cardiac effects of this therapy.

AREAS COVERED

This article aims to review the literature on the impact on the CV system of AMs used in the treatment of OAB, giving a comprehensive explanation of the pathogenetic mechanisms of AMs' effects on CV system and the impact of each AM drug on cardiac function.

EXPERT OPINION

Although the CV safety of AM drugs seems to be good, evidence provided in this manuscript does not allow to exclude an increase in HR, QT prolongation or an increase in the CV risk due to drug-drug interactions in OAB patients who are usually elderly and have comorbidities. Clinical and electrocardiographic monitoring may be necessary throughout the administration period in selected populations such as patients aged > 80 years, those with coronary heart disease or congestive heart failure. Further studies are needed to understand whether the most recently developed AM drugs, such as imidafenacin, are safer than the old ones.

An overview on mixed action drugs for the treatment of overactive bladder and detrusor overactivity

OBJECTIVES

To provide an overview on the efficacy, tolerability, safety and health-related quality of life (HRQoL) of drugs with a mixed action used in the treatment of overactive bladder (OAB).

EVIDENCE ACQUISITION

MEDLINE database and abstract books of the major conferences were searched for relevant publications from 1966 to 2011 and using the key words 'overactive bladder', 'detrusor overactivity', 'oxybutynin', 'propiverine', and 'flavoxate'. Two independent reviewers considered publications for inclusion and extracted relevant data, without performing a meta-analysis.

EVIDENCE SYNTHESIS

Old and conflicting data do not support the use of flavoxate, while both propiverine and oxybutynin were found to be more effective than placebo in the treatment of OAB. Propiverine was at least as effective as oxybutynin but with a better tolerability profile even in the pediatric setting. Overall, no serious adverse event for any product was statistically significant compared to placebo. Improvements were seen in HRQoL with treatment by the oxybutynin transdermal delivery system and propiverine extended release.

CONCLUSIONS

While there is no evidence to suggest the use of flavoxate in the treatment of OAB, both oxybutynin and propiverine appear efficacious and safe. Propiverine shows a better tolerability profile than oxybutynin. Both drugs improve HRQoL of patients affected by OAB. Profiles of each drug and dosage differ and should be considered in making treatment choices.

Cardiac effects of muscarinic receptor antagonists used for voiding dysfunction

Antimuscarinic agents are the main drugs used to treat patients with the overactive bladder (OAB) syndrome, defined as urgency, with or without urgency incontinence, usually with increased daytime frequency and nocturia. Since the treatment is not curative and since OAB is a chronic disease, treatment may be life-long. Antimuscarinics are generally considered to be ‘safe’ drugs, but among the more serious concerns related to their use is the risk of cardiac adverse effects, particularly increases in heart rate (HR) and QT prolongation and induction of polymorphic ventricular tachycardia (torsade de pointes). An elevated resting HR has been linked to overall increased morbidity and mortality, particularly in patients with cardiovascular diseases. QT prolongation and its consequences are not related to blockade of muscarinic receptors, but rather linked to inhibition of the hERG potassium channel in the heart. However, experience with terodiline, an antimuscarinic drug causing torsade de pointes in patients, has placed the whole drug class under scrutiny. The potential of the different antimuscarinic agents to increase HR and/or prolong the QT time has not been extensively explored for all agents in clinical use. Differences between drugs cannot be excluded, but risk assessments based on available evidence are not possible.

The muscarinic receptor antagonist propiverine exhibits α(1)-adrenoceptor antagonism in human prostate and porcine trigonum

Purpose

Combination therapy of male lower urinary tract symptoms with α₁-adrenoceptor and muscarinic receptor antagonists attracts increasing interest. Propiverine is a muscarinic receptor antagonist possessing additional properties, i.e., block of L-type Ca²⁺ channels. Here, we have investigated whether propiverine and its metabolites can additionally antagonize α₁-adrenoceptors.

Methods

Human prostate and porcine trigone muscle strips were used to explore inhibition of α₁-adrenoceptor-mediated contractile responses. Chinese hamster ovary (CHO) cells expressing cloned human α₁-adrenoceptors were used to determine direct interactions with the receptor in radioligand binding and intracellular Ca²⁺ elevation assays.

Results

Propiverine concentration-dependently reversed contraction of human prostate pre-contracted with 10 μM phenylephrine (−log IC₅₀ [M] 4.43 ± 0.08). Similar inhibition was observed in porcine trigone (−log IC₅₀ 5.01 ± 0.05), and in additional experiments consisted mainly of reduced maximum phenylephrine responses. At concentrations ≥1 μM, the propiverine metabolite M-14 also relaxed phenylephrine pre-contracted trigone strips, whereas metabolites M-5 and M-6 were ineffective. In radioligand binding experiments, propiverine and M-14 exhibited similar affinity for the three α₁-adrenoceptor subtypes with −log K_i [M] values ranging from 4.72 to 4.94, whereas the M-5 and M-6 did not affect [³H]-prazosin binding. In CHO cells, propiverine inhibited α₁-adrenoceptor-mediated Ca²⁺ elevations with similar potency as radioligand binding, again mainly by reducing maximum responses.

Conclusions

In contrast to other muscarinic receptor antagonists, propiverine exerts additional L-type Ca²⁺-channel blocking and α₁-adrenoceptor antagonist effects. It remains to be determined clinically, how these additional properties contribute to the clinical effects of propiverine, particularly in male voiding dysfunction.

Collation, assessment and analysis of literature in vitro data on hERG receptor blocking potency for subsequent modeling of drugs' cardiotoxic properties

The assessment of the torsadogenic potency of a new chemical entity is a crucial issue during lead optimization and the drug development process. It is required by the regulatory agencies during the registration process. In recent years, there has been a considerable interest in developing in silico models, which allow prediction of drug-hERG channel interaction at the early stage of a drug development process. The main mechanism underlying an acquired QT syndrome and a potentially fatal arrhythmia called torsades de pointes is the inhibition of potassium channel encoded by hERG (the human ether-a-go-go-related gene). The concentration producing half-maximal block of the hERG potassium current (IC(50)) is a surrogate marker for proarrhythmic properties of compounds and is considered a test for cardiac safety of drugs or drug candidates. The IC(50) values, obtained from data collected during electrophysiological studies, are highly dependent on experimental conditions (i.e. model, temperature, voltage protocol). For the in silico models' quality and performance, the data quality and consistency is a crucial issue. Therefore the main objective of our work was to collect and assess the hERG IC(50) data available in accessible scientific literature to provide a high-quality data set for further studies.

Effects of three metabolites of propiverine on voltage-dependent L-type calcium currents in human atrial myocytes

The non-selective muscarinic receptor antagonist propiverine impairs L-type Ca(2+) currents (I(Ca,L)) in human detrusor smooth muscle cells and atrial cardiomyocytes. Here, we have investigated the effects of three metabolites of propiverine on human cardiac I(Ca,L). Propiverine reduced I(Ca)(,L) with a -logIC(50) [M] value of 4.1, M-5 only showed minor effect on I(Ca)(,L) at high concentrations, M-6 did not influence I(Ca)(,L) at all. Like the parent compound M-14 also reduced I(Ca)(,L) (-logIC(50) [M]=4.6). We conclude, that propiverine and M-14 reduce cardiac I(Ca)(,L) at higher concentrations than in detrusor cells and therefore preferentially reduce I(Ca)(,L) in the urinary bladder than in the heart.

Predicting drug-induced changes in QT interval and arrhythmias: QT-shortening drugs point to gaps in the ICHS7B Guidelines

Background and purpose:

The regulatory guidelines (ICHS7B) recommending inhibition of the delayed rectifier K⁺ current (I_Kr), carried by human ether-a-go-go-related gene (hERG) channels in cardiac cells (the hERG test), as a ‘first line' test for identifying compounds inducing QT prolongation, have limitations, some of which are outlined here.

Experimental approach:

hERG current was measured in HEK293 cells, stably transfected with hERG channels; action potential duration (APD) and arrhythmogenic effects were measured in isolated Purkinje fibres and perfused hearts from rabbits.

Key results:

576 compounds were screened in the hERG test: 58% were identified as hERG inhibitors, 39% had no effect and 3% were classified as stimulators. Of the hERG inhibitors, 92 were tested in the APD assay: 55.4% of these prolonged APD, 28.3% had no effect and 16.3% shortened APD. Of the 70 compounds without effect on hERG channels, 54.3% did not affect APD, 25.7% prolonged, while 20% significantly shortened APD. Dofetilide (hERG inhibitor; IC₅₀, 29 nM) prolonged QT and elicited early after-depolarizations and/or torsade de pointes (TdP) in isolated hearts. Mallotoxin and NS1643 (hERG current stimulators at 3 μM), levcromakalim and nicorandil (no effect on hERG current), all significantly shortened APD and QT, and elicited ventricular fibrillation (VF) in isolated hearts.

Conclusion and implications:

The hERG assay alone did not adequately identify drugs inducing QT prolongation. It is also important to detect drug-induced QT shortening, as this effect is associated with a potential risk for ventricular tachycardia and VF, the latter being invariably fatal, whereas TdP has an ∼15–25% incidence of death.