Clinical pharmacokinetics of trospium chloride

Detrusor overactivity: an overview

Detrusor overactivity (DO) is a common clinical problem having profound effects on the quality of life (QOL) of women. With the use of meshes in the antiincontinence surgery, a new onset of DO, de novo DO has become an important issue in postoperative QOL of women. A systematic review of English language literature was conducted from Pubmed and publications of the last 7 years were analyzed and presented in this review. Multiple pathological events in the urothelium, sub-urothelium and possibly in the detrusor muscle seem to underlie the pathophysiology of DO. A variety of approaches, from life style modification to minimal-invasive surgery are available to treat DO and it is the responsibility of the physician to properly select and apply these modalities with the ultimate aim in improving the QOL of the patients. It is imperative to know the various pathophysiological processes that underlie the causation of DO to select proper management approach.

Trospium chloride once-daily extended release is effective and well tolerated for the treatment of overactive bladder syndrome: an integrated analysis of two randomised, phase III trials

BACKGROUND

Trospium chloride is an antimuscarinic agent with a hydrophilic polar quaternary amine structure that is minimally metabolised by hepatic cytochrome P450 and is actively excreted in the urine, each of which confers a potential benefit with regard to efficacy and tolerability.

PURPOSE

We analysed pooled data from two identically designed phase III trials of a once-daily, extended-release (XR) formulation of trospium chloride (trospium XR 60-mg capsules) in subjects with overactive bladder syndrome (OAB).

METHODS

Adults with OAB of > or = 6 months' duration with urinary urgency, frequency and > or = 1 urge urinary incontinence (UUI) episode/day were enrolled in these multicentre, parallel-group, double-blind trials. Participants were randomised (1 : 1) to receive trospium XR 60 mg or placebo for 12 weeks. Primary efficacy variables were changes in urinary frequency and the number of UUI episodes/day. Adverse events (AEs) were recorded throughout.

RESULTS

In total, 1165 subjects were randomised (trospium XR, 578; placebo, 587). At baseline, subjects averaged 12.8 toilet voids/day and 4.1 UUI episodes/day. Compared with placebo, subjects treated with trospium XR had significantly greater reductions from baseline in the mean number of toilet voids/day (-1.9 vs. -2.7; p < 0.001) and UUI episodes/day (-1.8 vs. -2.4; p < 0.001) at week 12. The most frequent AEs considered possibly related to study treatment were dry mouth (trospium XR, 10.7%; placebo, 3.7%) and constipation (trospium XR, 8.5%; placebo, 1.5%). Notably, rates of central nervous system (CNS) AEs were lower with trospium XR vs. placebo (dizziness: 0.2% vs. 1.0%; headache: 1.4% vs. 2.4%).

CONCLUSIONS

Treatment with trospium XR resulted in statistically significant improvements in both of the dual primary and all of the secondary outcome variables. Trospium XR demonstrated favourable rates of AEs, particularly CNS AEs (numerically lower than with placebo) and dry mouth (lower than previously reported with trospium immediate-release, although not compared in a head-to-head study).

Trospium chloride treatment of overactive bladder

OBJECTIVE

To review the pharmacology, pharmacokinetics, safety, and clinical application of trospium chloride for the management of overactive bladder (OAB).

DATA SOURCES

Clinical literature including both primary sources and review articles was accessed through MEDLINE, International Pharmaceutical Abstracts, and Cochrane databases from 1980 through January 8, 2009. Search terms included overactive bladder, urge urinary incontinence, muscarinic receptor antagonists, and urinary frequency. Further data sources were identified from bibliographies of selected articles.

STUDY SELECTION AND DATA EXTRACTION

Basic pharmacology data were extracted from animal studies and pharmacokinetic data were gathered from human studies. Multicenter, parallel, randomized, double-blind, placebo-controlled studies were included to describe the efficacy and adverse effects of trospium.

DATA SYNTHESIS

Trospium chloride is an antimuscarinic agent indicated for the treatment of OAB with symptoms of urge urinary incontinence, urgency, and urinary frequency. Trospium has 3 chemical and pharmacokinetic properties unique among antimuscarinic agents: it is a positively charged quaternary ammonium compound with minimal central nervous system penetration; it is not metabolized by the cytochrome P450 system, resulting in a lower tendency for drug interactions; and it is excreted mainly unchanged in the urine as the active parent compound, providing local activity to achieve early onset of clinical effect and prolonged efficacy. In two 12-week, randomized, placebo-controlled clinical studies in adults with OAB, trospium 20 mg twice daily was more effective than placebo in reducing the number of micturitions per 24 hours, reducing the number of urge incontinence episodes per week, and increasing the volume of urine voided per micturition. Placebo-controlled trials report efficacy with trospium in treatment of OAB; comparative trials with other anticholinergic agents are limited. Current therapy of OAB consists primarily of anticholinergic drugs such as oxybutynin, which are associated with therapy-limiting adverse effects. Because the prevalence of OAB is greatest among the elderly, safety considerations regarding renal function must be noted, with dosage adjustment required in patients with severe renal impairment.

CONCLUSIONS

Whether the pharmacodynamic properties of trospium make it superior to other therapies will require considerable additional experience with the drug. For now, it appears to be a feasible alternative for patients who cannot tolerate oxybutynin.

The effects of reformulation: improved therapeutic index

Antimuscarinic agents are the treatment of choice for overactive bladder syndrome. Due to the development of novel delivery systems, extended-release formulations of oxybutynin, tolterodine, and trospium chloride are now available. In addition to the convenience of once-daily dosing, the new formulations of these commonly prescribed agents have improved their therapeutic index, striking a better balance between efficacy and tolerability.

Urothelial effects of oral agents for overactive bladder

The cholinergic system of the bladder includes muscarinic receptors distributed to detrusor myocytes and structures within mucosa including bladder afferent (sensory) nerves. The receptors have been shown to be involved in afferent signaling from the bladder, but it has not been established to what extent effects on this mucosal signaling pathway contribute to the therapeutic efficacy of the clinically used antimuscarinics. Mucosa can be influenced by antimuscarinics via the bloodstream. However, some antimuscarinics and their active metabolites are excreted in urine in amounts that may affect the mucosal muscarinic receptors from the luminal side. This has not yet been demonstrated to imply superior clinical efficacy. Nevertheless, mucosal afferent signaling pathways are therapeutically interesting targets that should be further explored.

Once daily trospium chloride is effective and well tolerated for the treatment of overactive bladder: results from a multicenter phase III trial

PURPOSE

An extended release formulation of trospium chloride was recently developed for the once daily treatment of overactive bladder. We investigated the safety, efficacy and tolerability of 60 mg trospium chloride once daily.

MATERIALS AND METHODS

Subjects with overactive bladder were randomized 1:1 to receive 60 mg trospium chloride once daily or placebo in this 12-week multicenter, parallel, double-blind, placebo controlled trial. Primary end points were calculated changes in diary recorded daily urinary frequency and daily urgency urinary incontinence episodes. Secondary end points were urgency severity, volume voided per void and the number of urgency voids per day. Safety was assessed by clinical examination, adverse event monitoring, clinical laboratory values and resting electrocardiograms.

RESULTS

Overall 601 subjects were prescribed trospium once daily (298) or placebo (303). Trospium once daily treatment resulted in significant improvements over placebo in all primary and key secondary efficacy outcomes at weeks 1 through 12. The most common adverse events were dry mouth (trospium 8.7% vs placebo 3%) and constipation (trospium 9.4% vs placebo 1.3%). Central nervous system adverse events were rare (headache with trospium 1.0% vs placebo 2.6%). No clinically meaningful changes in laboratory, physical examination or electrocardiogram parameters were noted.

CONCLUSIONS

Trospium once daily provided significant improvements in overactive bladder symptoms (frequency, urgency urinary incontinence and urgency). Efficacy was similar to that seen previously with trospium chloride twice daily, while class effect anticholinergic adverse events occurred at comparatively low levels. Dry mouth was elicited at the lowest reported rate in the oral antimuscarinic drug class.

Muscarinic receptors in the bladder: from basic research to therapeutics

Muscarinic receptor antagonists (antimuscarinics) serve as the cornerstone in the pharmacological management of overactive bladder (OAB) by relieving the symptoms of urgency, frequency and incontinence. These drugs operate primarily by antagonizing post-junctional excitatory muscarinic receptors (M(2)/M(3)) in the detrusor. The combination of pharmacological and gene knockout studies has greatly advanced our understanding of the functional role of muscarinic receptors in the bladder. M(3) receptors produce direct smooth muscle contraction by a mechanism that relies on entry of extracellular calcium through L-type channels and activation of a rho kinase. M(2) receptors, which predominate in number, appear to facilitate M(3)-mediated contractions. M(2) receptors can also produce bladder contractions indirectly by reversing cAMP-dependent beta-adrenoceptor-mediated relaxation, although the physiological role of beta-adrenoceptors in detrusor relaxation is controversial. Emerging evidence suggests that muscarinic receptors in the urothelium/suburothelium can modulate the release of certain factors, which in turn may affect bladder function at the efferent or afferent axis. Currently, oxybutynin, tolterodine, darifenacin, solifenacin and trospium are the five major antimuscarinics approved for the treatment of OAB. Comparative clinical studies have shown that oxybutynin and solifenacin may be marginally more effective than tolterodine, although the latter seems to be better tolerated. Pharmacokinetic-pharmacodynamic analyses using plasma concentrations of 'total drug' indicate that, at therapeutic doses, the clinical efficacy of darifenacin and solifenacin may be driven primarily by selective M(3) receptor occupation, whereas the pharmacodynamic effects of pan-selective molecules (such as tolterodine, trospium) may potentially involve multiple receptors, including M(2) and M(3). Furthermore, high M(3) receptor occupation is the likely explanation for the greater propensity of darifenacin and oxybutynin to cause dry mouth and/or constipation. Although the recently introduced drugs represent a significant improvement over older drugs, especially with respect to the convenience of dosing schedule, their overall efficacy and tolerability profile is still less than optimal and patient persistence with therapy is low. Recent advances in basic research have not yet offered a clear discovery path for improving the therapeutic index of antimuscarinic molecules. There is still an unmet need for an antimuscarinic medicine with superior clinical effectiveness that can translate into better persistence on therapy.

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.

Treatment of the overactive bladder syndrome with muscarinic receptor antagonists - a matter of metabolites?

Antagonists of muscarinic acetylcholine receptors, such as darifenacin, oxybutynin, propiverine, solifenacin, tolterodine, and trospium, are the mainstay of the treatment of the overactive bladder syndrome. Fesoterodine is a newer drug awaiting regulatory approval. We briefly review the pharmacological activity of their metabolites and discuss how active metabolites may contribute to their efficacy and tolerability in vivo. Except for trospium, and perhaps solifenacin, all of the above drugs form active metabolites, and their presence and activity need to be taken into consideration when elucidating relationships between pharmacokinetics and pharmacodynamics of these drugs. Moreover, the ratios between parent compounds and metabolites may differ depending on genotype of the metabolizing enzymes, concomitant medication, and/or drug formulation. Differential generation of active metabolites of darifenacin or tolterodine are unlikely to influence the overall clinical profile of these drugs in a major way because the active metabolites exhibit a similar pharmacological profile as the parent compound. In contrast, metabolites of oxybutynin and propiverine may behave quantitatively or even qualitatively differently from their parent compounds and this may have an impact on the overall clinical profile of these drugs. We conclude that more comprehensive studies of drug metabolites are required for an improved understanding of their clinical effects.

Management of overactive bladder and urge urinary incontinence in the elderly patient

The symptoms of overactive bladder (OAB) and urge urinary incontinence may occur at any age but are particularly common among the elderly. These symptoms are associated with significant morbidity and often have a profound impact on patient quality of life. Urinary incontinence is an important contributor to the complications and economic cost of OAB for both community-dwelling and institutionalized elderly individuals. Many patients with OAB do not seek treatment because of embarrassment, fear of surgery, or the misperceptions that the problem is untreatable or is a normal and inevitable consequence of aging. Nonpharmacologic therapies improve bladder control by modifying lifestyle and behavior to prevent urine loss. This requires patient and caregiver motivation and can be time consuming. Improved results may be obtained by combining these strategies with pharmacotherapy or by means of pharmacotherapy alone. The most commonly used pharmacologic agents are the muscarinic receptor antagonists. These include oxybutynin, tolterodine, and three agents that have recently been approved for use in the United States: trospium, darifenacin, and solifenacin. In general, these therapies are well tolerated and safe; however, the selection of an optimal agent merits careful consideration. For elderly patients, important considerations include tolerability, absence of drug interactions, and the availability of a range of dosages to tailor treatment to individual patients. Primary care practitioners and geriatricians can have a key role in successful diagnosis and treatment of OAB. It is important for these physicians to realize that satisfactory outcomes may be achieved within the scope of a busy outpatient practice.

Overactive Bladder in the Elderly

Overactive bladder (OAB) is a common condition characterised by the symptoms of urinary frequency and urgency, with or without urge incontinence and nocturia. The prevalence of OAB increases markedly with age in both men and women. OAB can have a detrimental effect on physical functioning and psychological well-being, as well as significantly reducing quality of life. Antimuscarinic therapy -- with or without behavioural therapy -- represents the most common treatment for patients with OAB. Several antimuscarinic agents are currently available for the treatment of OAB in adults, including oxybutynin, tolterodine, trospium chloride, darifenacin and solifenacin. The antimuscarinics all appear to exert their clinical effect through inhibition of the bladder muscarinic receptors, but they vary both in structure and in their functional profile. While efficacy has been demonstrated in adult populations (including patients >65 years of age), few studies have been reported specifically in a geriatric population, and antimuscarinics are often underutilised in the elderly despite the marked increase in the prevalence of OAB in this age group. One explanation for this apparent underuse of an effective treatment option may be concerns about the frequency of anticholinergic adverse events, such as dry mouth; the likelihood of detrimental CNS effects, including cognitive impairment and sleep disturbances; and the potential for harmful interactions with existing pharmacotherapy. When selecting an antimuscarinic agent for the management of an elderly patient presenting with OAB, in addition to considering evidence of clinical efficacy and tolerability, issues of safety specific to an older population should be borne in mind. In particular, the likelihood of detrimental CNS effects should be considered, including cognitive impairment and sleep disturbances, secondary to anticholinergic load. Oxybutynin and tolterodine have both been associated with cognitive adverse events and effects on sleep architecture and quality. In contrast, trospium chloride and darifenacin do not appear to be associated with cognitive adverse events and trospium chloride does not negatively affect sleep architecture or quality. Biotransformation by the cytochrome P450 (CYP450) system is an important step in the activation or elimination of a large number of drugs, including oxybutynin, tolterodine, darifenacin and solifenacin, raising the possibility of clinically relevant and potentially serious drug interactions. In elderly patients, such interactions are of particular relevance given the potential for declining activity of certain members of the CYP450 family combined with decreased hepatic blood flow, which can reduce first-pass metabolism and thus the bioavailability of drugs metabolised via this route. Of the antimuscarinic agents used to treat OAB, only trospium chloride is not extensively metabolised in the liver by the CYP450 system and is excreted largely as the active parent compound in the urine. This paper provides an overview of the pathophysiology of OAB and reviews current approaches to achieving a differential diagnosis and selecting appropriate treatment for the older patient. The pharmacology and clinical effects of current medication for the treatment of OAB symptoms in patients defined by the OAB pharmacology literature as 'elderly' are also reviewed.