On the Site and Mechanism of Action of β3-Adrenoceptor Agonists in the Bladder

Update on Overactive Bladder Therapeutic Options

BACKGROUND

Millions of Americans are burdened by overactive bladder (OAB) syndrome and the psychogenic and economic hardships that accompany it. Several theories attempt to explain OAB as a neurogenic dysfunction, myogenic dysfunction, urothelial dysfunction, or decreased expression of a channel protein secondary to bladder outlet obstruction. Given that the etiology of OAB is a working theory, the management of OAB is also an evolving subject matter in medicine. There are uncertainties surrounding the pathophysiology of OAB, the strength of a clinical diagnosis, and accurate reporting because of the disease's stigma and decreased use of health care.

DATA SOURCES

This is a narrative review that used PubMed, Google Scholar, Medline, and ScienceDirect to review literature on current and future OAB therapies.

RESULTS

Currently, first-line treatment for OAB is behavioral therapy that uses lifestyle modifications, bladder-control techniques, and psychotherapy. Second-line therapy includes antimuscarinic agents or beta 3 adrenergic agonists, and studies have shown that combination therapy with antimuscarinics and beta 3 adrenergic agonists provides even greater efficacy than monotherapy. Third-line therapies discussed include onabotulinumtoxinA, posterior tibial nerve stimulation, and sacral neuromodulation. OnabotulinumtoxinA has been FDA-approved as a nonpharmaceutical treatment option for refractory OAB with minimal side effects restricted to the urinary tract. Posterior tibial nerve modulation and sacral neuromodulation are successful in treating refractory OAB, but the costs and complication rates make them high-risk procedures. Therefore, surgical intervention should be a last resort. Estrogen therapy is effective in alleviating urinary incontinence in postmenopausal women, consistent with the association between estrogen deficiency and genitourinary syndrome. Potassium channel activators, voltage-gated calcium channel blockers, and phosphodiesterase inhibitors look to be promising options for the future of OAB management. As new therapies are developed, individuals with OAB can better personalize their treatment to maximize their quality of life and cost-effective care.

Pathophysiology of Overactive Bladder and Pharmacologic Treatments Including β3-Adrenoceptor Agonists -Basic Research Perspectives

Overactive bladder (OAB) is a symptom-based syndrome defined by urinary urgency, frequency, and nocturia with or without urge incontinence. The causative pathology is diverse; including bladder outlet obstruction (BOO), bladder ischemia, aging, metabolic syndrome, psychological stress, affective disorder, urinary microbiome, localized and systemic inflammatory responses, etc. Several hypotheses have been suggested as mechanisms of OAB generation; among them, neurogenic, myogenic, and urothelial mechanisms are well-known hypotheses. Also, a series of local signals called autonomous myogenic contraction, micromotion, or afferent noises, which can occur during bladder filling, may be induced by the leak of acetylcholine (ACh) or urothelial release of adenosine triphosphate (ATP). They can be transmitted to the central nervous system through afferent fibers to trigger coordinated urgency-related detrusor contractions. Antimuscarinics, commonly known to induce smooth muscle relaxation by competitive blockage of muscarinic receptors in the parasympathetic postganglionic nerve, have a minimal effect on detrusor contraction within therapeutic doses. In fact, they have a predominant role in preventing signals in the afferent nerve transmission process. β3-adrenergic receptor (AR) agonists inhibit afferent signals by predominant inhibition of mechanosensitive Aδ-fibers in the normal bladder. However, in pathologic conditions such as spinal cord injury, it seems to inhibit capsaicin-sensitive C-fibers. Particularly, mirabegron, a β3-agonist, prevents ACh release in the BOO-induced detrusor overactivity model by parasympathetic prejunctional mechanisms. A recent study also revealed that vibegron may have 2 mechanisms of action: inhibition of ACh from cholinergic efferent nerves in the detrusor and afferent inhibition via urothelial β3-AR.

Comparison of add-on medications for persistent storage symptoms after α-blocker treatment in BPH patients - a network meta-analysis

BACKGROUND

Patients with benign prostatic hyperplasia (BPH) receive α-blockers as first-line therapy to treat lower urinary tract symptoms; however, some individuals still experience residual storage symptoms. Antimuscarinics, β3-agonists, and desmopressin are effective add-on medications. Nevertheless, there is currently no evidence for the appropriate choice of the first add-on medication. This systematic review aimed to investigate the clinical benefits of antimuscarinics, β3-agonists, and desmopressin, in addition to α-blockers, for persistent storage symptoms in BPH patients.

METHODS

A comprehensive literature search of randomized controlled trials (RCTs) comparing the efficacy of different add-on medications in BPH patients with persistent storage symptoms despite α-blocker treatment was conducted. Clinical outcomes included the International Prostate Symptom Score (IPSS), IPSS storage subscore, nocturia, micturition, and urgency. A network meta-analysis was performed to estimate the effect size. Surface under cumulative ranking curves (SUCRAs) were used to rank the included treatments for each outcome.

RESULTS

A total of 15 RCTs were identified. Add-on imidafenacin and mirabegron resulted in significant improvement in all outcomes assessed. Other add-on medications such as desmopressin, tolterodine, solifenacin, fesoterodine, and propiverine showed positive benefits for most, but not all, outcomes. Based on the SUCRA rankings, add-on desmopressin was the best-ranked treatment for IPSS and nocturia, and add-on imidafenacin was the best for the IPSS storage subscore and micturition.

CONCLUSIONS

BPH patients presenting with persistent storage symptoms despite α-blocker administration are recommended to include additional treatment. Desmopressin and imidafenacin may be considered high-priority add-on treatments because of their superior efficacy compared with other medications.

Treating LUTS in Men with Benign Prostatic Obstruction: A Review Article

Benign prostatic obstruction (BPO) is a prevalent condition that affects men, primarily toward their old age. The condition is often accompanied by lower urinary tract symptoms (LUTS), which can significantly impair a patient's quality of life and lead to other medical complications. Accurate diagnosis of BPO is essential for effective management of complications secondary to BPO, and treatment plans should be tailored patients, and occasionally according to surgeon experience. As such, this literature review aims to analyze the current available data on male LUTS secondary to BPO by providing a comprehensive overview of relevant studies, as well as the surgical and medical management guidelines from the Canadian Urological Association (CUA), American Urological Association (AUA), and European Association of Urology (EAU). By synthesizing the existing literature, this review purports to summarize the current body of knowledge surrounding BPO and male LUTS, and support healthcare providers in making informed decisions about the management of male LUTS secondary to BPO, ultimately improving patient outcomes and quality of life.

Management of use of urinary antimuscarinics and alpha blockers for benign prostatic hyperplasia in older adults at risk of falls: a clinical review

PURPOSE

We aimed to outline the existing information and the underlying mechanisms of risk of falls associated with the use of urinary antimuscarinics for overactive bladder (OAB) or alpha-blockers for benign prostatic hyperplasia (BPH) in older adults. In addition, we aimed to provide assistance to clinicians in decision-making about (de-)prescribing these drugs in older adults.

METHODOLOGY

Based on a literature search in PubMed and Google Scholar, we reviewed the literature, and identified additional relevant articles from reference lists, with an emphasis on the most commonly prescribed drugs in OAB and BPH in older patients. We discussed the use of bladder antimuscarinics and alpha-blockers, their potential side effects related to falls, and the deprescribing of these drugs in older adults.

RESULTS

Urinary urgency or incontinence and lower urinary tract symptoms due to untreated OAB and BPH contribute to fall risk. On the other hand, the use of bladder antimuscarinics and alpha-blockers is also related to fall risk. They contribute to (or cause) falling through dizziness, somnolence, visual impairment, and orthostatic hypotension while they differ in their side-effect profiles regarding these problems. Falls are common and can cause a remarkable amount of morbidity and mortality. Thus, preventive measures should be taken to lower the risk. If the clinical condition allows, withdrawal of bladder antimuscarinics and alpha-blockers is recommended in fall-prone older adults. There are practical resources and algorithms that guide and assist clinicians in deprescribing these drug groups.

CONCLUSIONS

The decision to prescribe or deprescribe these treatments in patients at high risk of falls should be individualized. In addition to explicit tools that are helpful for clinical decision-making in (de-)prescribing these drugs, STOPPFall (a recently developed expert-based decision aid specifically aiming to prevent falls) is present to assist prescribers in attaining decisions.

Mirabegron is better tolerated than solifenacin in Sjogren's syndrome patients with overactive bladder symptoms-A randomized controlled trial

OBJECTIVES

This study investigates the efficacy and adverse events of beta-3 agonists and antimuscarinic agents for managing overactive bladder syndrome in Sjogren syndrome.

METHODS

Sjogren's syndrome patients with an Overactive Bladder Symptom Score (OABSS) >5 were enrolled and were randomly assigned to mirabegron 50 mg/day or solifenacin 5 mg/day. Patients were evaluated on the recruitment day and reassessed at Week 1, 2, 4, and 12. The study's primary endpoint was to have a significant change in OABSS at Week 12. The secondary endpoint was the adverse event and crossover rate.

RESULTS

A total of 41 patients were included in the final analysis, with 24 in the mirabegron group and 17 in the solifenacin group. The study's primary outcome was a change of the OABSS at Week 12. We found that both mirabegron and solifenacin significantly reduce patients' OABSS after 12 weeks of treatment. The evolution of the OABSS was -3.08 for mirabegron and -3.71 for solifenacin (p = .56). Six out of 17 patients from the solifenacin group crossed over to the mirabegron arm due to severe dry mouth or constipation, while none from the mirabegron arm crossed over to the solifenacin group. Sjogren's syndrome-related pain was also improved in the mirabegron group (4.96-1.67, p = .008) compared to the solifenacin group (4.39-3.4, p = .49).

CONCLUSIONS

Our study showed that mirabegron is equally effective as solifenacin in treating Sjogren's syndrome patients with overactive bladder. Mirabegron is superior to solifenacin in terms of treatment-related adverse events.

Inhibition of prejunctional parasympathetic pathways by β3-adrenoceptor agonists in the isolated pig detrusor: comparison with human detrusor studies

Adrenergic receptors of the β₃-subtype (β₃-ADRs) seem to represent a new target for a more effective pharmacological treatment of overactive bladder (OAB), a wide spread urinary disorder. A promising opportunity for OAB therapy might rely on the development of selective β₃-ADR agonists, but an appropriate preclinical screening, as well as investigation of their pharmacological mechanism(s), is limited by poor availability of human bladder samples and of translational animal models. In this study, we used the porcine urinary bladder as experimental tool to ascertain the functions of β₃-ADRs in the control the parasympathetic motor drive. Tritiated acetylcholine ([³H]-ACh), mainly originated from neural stores, was released by electrical field stimulation (EFS) in epithelium-deprived detrusor strips from pigs bred without estrogens. EFS produced simultaneously [³H]-ACh release and smooth muscle contraction allowing to asses neural (pre-junctional) and myogenic (postjunctional) effects in the same experiment. Isoprenaline and mirabegron produced on the EFS-evoked effects a concentration-dependent inhibition antagonized by L-748,337, a high selective β₃-ADR antagonist. The analysis of the resultant pharmacodynamic parameters supports the notion that in pig detrusors, as well as in previously described human detrusors, the activation of inhibitory β₃-ADRs can modulate neural parasympathetic pathways. In such inhibitory control, the involvement of membrane K⁺ channels, mainly of the SK type, seems to play a pivotal role similarly to what previously described in humans. Therefore, the isolated porcine detrusor can provide a suitable experimental tool to study the mechanisms underlying the clinical efficacy of selective β₃-ADR compounds for human use.

Vibegron shows high efficacy in pediatric patients with refractory daytime urinary incontinence

PURPOSE

Sparse published reports exist nowadays on vibegron and pediatric overactive bladder, so its usefulness of this agent remains unclear. The purpose of this study was to clarify the effectiveness of vibegron for pediatric cases of daytime urinary incontinence (DUI), including refractory cases.

METHODS

Participants comprised 57 patients treated with vibegron for DUI from March 2019 to April 2022. To investigate treatment outcomes and risk factors for pediatric patients with refractory DUI, the following factors were evaluated: age at initiatial administration; frequency of DUI; duration of vibegron treatment; presence of neurodevelopmental disorders (NDDs); presence of constipation; and anticholinergic medications before and after initiation of treatment.

RESULTS

Patients included 38 boys and 19 girls with a median age at initial administration of 111 months (range: 64-202 months) and a median administration term of 6 months (range: 1-33 months). With treatment for 6 months, the response rate (complete response + partial response) was 68.3%. A total of 24 cases with NDD showed a 72.0% response rate at 6 months. As for the relationship between anticholinergic agents and vibegron, 15 cases were treated with vibegron as the first choice without anticholinergics (First-choice cases), and 33 cases were treated with vibegron alone after switching from anticholinergics (Switch cases). Vibegron was used in combination with anticholinergic agents in 9 cases (Add-on cases). Response rates at 6 months were 85.0% in First-choice cases, 66.3% in Switch cases, and 40.7% in Add-on cases. Univariate analyses failed to identify any significant risk factors for refractory cases.

CONCLUSIONS

Vibegron was effective in pediatric cases of DUI, with efficacy demonstrated within a short time in many cases. Vibegron is expected to play a significant role in the treatment of DUI in pediatric cases.

Effect of β3-adrenoceptor agonist on the micromotion of bilateral major pelvic ganglion-excised rat bladder

AIMS

Micromotion is an autonomous intramural movement of the bladder, and is believed to be an initial step in the generation of urinary urgency. Therefore, controlling micromotion may be a novel target in overactive bladder (OAB) treatment. However, developing micromotion treatment has been limited by the absence of a standardized animal model. We attempted to create a micromotion animal model and investigated the effectiveness of a β₃ -adrenoceptor agonist (CL316,243) on micromotion.

METHODS

Bilateral major pelvic ganglia (MPGs) were excised in 18 male Sprague-Dawley rats, resulting in an almost completely denervated bladder. On postoperative Day 7, cystometry was performed. Rats were divided into three treatment groups: CL316,243; β_3- adrenoceptor antagonist (SR59230A) pretreated CL316,243; and a nonselective antimuscarinic agent (oxybutynin). Changes in micromotion were evaluated after the intra-arterial administration of each agent.

RESULTS

Low-amplitude oscillations in intravesical pressure (micromotion) were observed 1 week after MPGs excision. Micromotion frequency significantly (p = 0.003) decreased (2.17 ± 3.54 times/5 min) with CL316,243 compared with vehicle (6.33 ± 1.97 times/5 min). Micromotion amplitude also decreased with CL316,243 (1.15 ± 1.93 cmH₂ O) compared with vehicle (5.96 ± 5.12 cmH₂ O), approaching conventional significance (p = 0.090). No significant decreases in frequency or amplitude were observed with oxybutynin treatment.

CONCLUSIONS

Systemic administration of the β₃ -adrenoceptor agonist CL316,243 effectively controlled micromotion in bilateral MPGs-excised, almost completely denervated rat bladders. This result indicates that β₃ -adrenoceptor agonist may affect the bladder directly, suggesting that it might be effective for overall OAB, regardless of the presence or level of neurological deficits. Bilateral MPGs-excised rats are considered a plausible micromotion animal model suitable for future research.

The large part German medicine has played in the development of experimental pharmacology in Japan

The history of hitherto existing pharmacology in Japan presented here is authored in commemoration of the 150th anniversary of Naunyn-Schmiedeberg's Archives of Pharmacology. After the publication of the new book of anatomy "Anatomische Tabellen" translated into Japanese in 1774, the foundation of understanding the medical science was gradually formed in Japan under seclusion policy, and, since the Meiji Restoration of 1868, the modernization of Japanese medicine was rapidly fostered on the basis of German medicine. Thus, the Japanese government officially adopted German medicine, and the philosophy and practice of German medical schools were incorporated. Most of the medical texts used in Japan were of German origins, often in Dutch translations, and many Japanese physicians and medical researchers studied abroad in Germany. The start of experimental pharmacology in Japan was also made up by Japanese disciples of Oswald Schmiedeberg, who was the one of founders of the Archives in 1873. Additionally, it was customary for professor candidates in charge of pharmacology in medical faculties in Japan to go to Germany and study pharmacology. Through such historical circumstances, the Japanese Pharmacology Society has been established to fulfill the responsibility for contributing internationally to world-class research achievements in the field of medical sciences by supplying numerous talented pharmacologists. During the course of the development of experimental pharmacology in Japan, the Archives has provided an excellent stage for many Japanese pharmacologists to publish their research outcomes to proliferate them internationally. Without German medicine influence, Japanese pharmacology would not have been what it is today.

Novel botulinum neurotoxin-A tibial nerve perineural injection to alleviate overactive bladder symptoms in male rats

Although tibial nerve modulation has shown to induce positive changes in the overactive bladder (OAB), prolonged therapeutic effects using percutaneous stimulation have not yet been achieved. Intradetrusor onabotulinum toxin A injection can provide prolonged therapeutic effects; however, its delivery requires invasive measures. By applying local relief of tibial nerve neural entrapment with onabotulinum toxin A injection, this study investigated the feasibility and efficacy of combining the abovementioned two therapeutic strategies. An OAB animal model was developed using 12 adult Sprague-Dawley rats with cyclophosphamide intraperitoneal injection. A perineural injection site comparable to the tibial nerve perineural injection site and corresponding to that in humans was identified and developed in rats. The toxin was injected five days after establishing the OAB. The incision was made in the skin on the lateral surface of the thigh. The biceps femoris muscle was cut across, exposing the sciatic nerve and its three terminal branches: the sural, common peroneal, and tibial nerves, and 100 units of onabotulinum toxin A was injected into the surrounding tissue. Five days following injection, cystometry was performed. Inter-contraction time, contraction pressure, and interval of the disease state improved with statistical significance. The OAB animal model showed significant improvement with the tibial nerve perineural injection of botulinum toxin, thereby suggesting the possibility of a comparable treatment adaptation in humans.

β3 Relaxant Effect in Human Bladder Involves Cystathionine γ-Lyase-Derived Urothelial Hydrogen Sulfide

It is now well established that the urothelium does not act as a passive barrier but contributes to bladder homeostasis by releasing several signaling molecules in response to physiological and chemical stimuli. Here, we investigated the potential contribution of the hydrogen sulfide (H2S) pathway in regulating human urothelium function in β3 adrenoceptor-mediated relaxation. The relaxant effect of BRL 37344 (0.1–300 µM), a selective β3 adrenoceptor agonist, was evaluated in isolated human bladder strips in the presence or absence of the urothelium. The relaxant effect of BRL 37344 was significantly reduced by urothelium removal. The inhibition of cystathionine-γ-lyase (CSE), but not cystathionine-β-synthase (CBS), significantly reduced the BRL 37344 relaxing effect to the same extent as that given by urothelium removal, suggesting a role for CSE-derived H2S. β3 adrenoceptor stimulation in the human urothelium or in T24 urothelial cells markedly increased H2S and cAMP levels that were reverted by a blockade of CSE and β3 adrenoceptor antagonism. These findings demonstrate a key role for urothelium CSE-derived H2S in the β3 effect on the human bladder through the modulation of cAMP levels. Therefore, the study establishes the relevance of urothelial β3 adrenoceptors in the regulation of bladder tone, supporting the use of β3 agonists in patients affected by an overactive bladder.

Mirabegron and solifenacin are effective for the management of the increased urinary frequency induced by psychological stress in female mice

Evidence to support the effectiveness of β3-adrenoceptor agonist mirabegron and anti-muscarinic solifenacin in the management of bladder dysfunction caused by psychological stress is lacking. This study investigates whether mirabegron or solifenacin reduces the bladder overactivity caused by water avoidance stress (WAS) in mice. Female mice were exposed to WAS for 1 h/day for 10 days and received either placebo, solifenacin or mirabegron in drinking water. Controls were age-matched without stress exposure. Voiding behaviour and functional isolated whole bladder responses during distension and in response to pharmacological agents and electrical field stimulation was investigated. Urinary frequency was significantly increased following stress. Mice treated with mirabegron or solifenacin displayed significantly fewer voiding events compared to the stressed mice, and voiding frequency in drug-treated animals was comparable to unstressed controls. The maximal contractile responses of bladders to carbachol were significantly enhanced by stress and reduced by mirabegron but not solifenacin. The frequency of phasic bladder contractions following stimulation with carbachol was significantly enhanced following stress and remained elevated in the mirabegron treated group. However, treatment with solifenacin significantly reduced the frequency of phasic contractions to unstressed control levels. Solifenacin and mirabegron are beneficial in reducing the overall voiding dysfunction caused by WAS in mice.

Continuous administration of mirabegron has advantages in inhibition of central sensitization compared with short-term treatment cessation in a mouse model of overactive bladder

AIMS

There is no clear pathophysiologic evidence determining how long overactive bladder (OAB) medication should be continued. We, therefore, investigated the effect of mirabegron using cessation (CES) or continuation (CON) treatment in an OAB animal model.

METHODS

Female C57BL/6 mice were divided into four groups (N = 8 each): Sham, OAB, CES, and CON groups. The OAB-like condition was induced by three times weekly intravesical instillations of KCl mixture with hyaluronidase. After the last intravesical instillation for inducing OAB, mirabegron (2 mg/kg/day) was administered in CES and CON groups for 10 and 20 days, respectively. Final experiments were carried out on 20 days from the last intravesical instillation in all groups. After cystometry, mRNA levels of bladder muscarinic, β-adrenergic, and P2X purinergic receptors were measured to investigate bladder efferent and afferent activity. In addition, mRNA levels of CCL2 and CCR2 in L6-S1 dorsal root ganglia (DRG) were measured to assess afferent sensitization. Immunofluorescent staining of CX3CR1, GFAP, and CCR2 in the L6 spinal cord was also conducted to investigate glial activation and central sensitization.

RESULTS

OAB mice showed bladder overactivity evidenced by decreased intercontraction interval (3.56 ± 0.51 vs. 5.76 ± 0.95 min in sham mice), increased non-voiding contractions (0.39 ± 0.11 vs. 0.13 ± 0.07/min in sham mice), and inefficient voiding (72.1 ± 8.6% vs. 87.1 ± 9.5% in sham mice). Increased M2, M3, β2, β3, P2X₂ , P2X₃ , P2X₄ , and P2X₇ levels in the bladder and increased CCL2 and CCR2 in DRG indicate bladder efferent and afferent hyperexcitability. In addition, CX3CR1, GFAP, and CCR2 in the L6 spinal cord were upregulated in OAB mice. However, the CON group exhibited reduced β2, β3, P2X₂ , P2X₃ , P2X₄ , and P2X₇ levels in the bladder, reduced CCL2 and CCR2 in DRG, which are markers of afferent hyperexcitability, and reduced immunoreactivities of CX3CR1, GFAP, and CCR2 in the L6 spinal cord, which are markers of the central sensitization. Moreover, the CON group showed better improvements in nonvoiding contractions (0.16 ± 0.09 vs. 0.44 ± 0.17/min) and voiding efficiency (93.9 ± 7.4% vs. 76.5 ± 13.1%) and reductions in bladder β3 receptors and CCL2 of L6-S1 DRG, and immunoreactivities of CX3CR1 and GFAP in the L6 spinal cord compared to the CES group.

CONCLUSIONS

Continuous mirabegron treatment seems to prevent central sensitization and, thus, might be desirable for long-term disease control of OAB.

Mirabegron has longer treatment persistence than antimuscarinics: Real-world data from a Korean national cohort database

AIMS

To descriptively evaluate treatment persistence among adults who received mirabegron or antimuscarinics in South Korea.

METHODS

This study involved a retrospective analysis of the Health Insurance Review and Assessment (HIRA) database. Patients (≥18 years) who had a new prescription for an overactive bladder (OAB) target medication (mirabegron/antimuscarinic) within an 8-month index period (July 1, 2015-February 29, 2016) were included. The date when the target (index) medication was dispensed was the index date. The 6-month period before the index date was used to assess patient eligibility. A 12-month post-index period was used to assess medication persistence, which was defined as the time to discontinuation. Overall data were analyzed and the results were also stratified by age group (≤65, >65 years), sex, or prior OAB medication experience. Persistence rates were calculated after the 1st, 3rd, 6th, 9th, and 12th months.

RESULTS

A data set of 52 722 cases was obtained (mirabegron: 11 424, antimuscarinics: 41 298). The mean age was 60.9 ± 16.1 years and the majority of the patients were female (30 862 [58.5%] patients). Median persistence was longer with mirabegron (51 days) versus antimuscarinics (25 days). The persistence rate with mirabegron was higher throughout the study compared with all the antimuscarinics (12-month data: 13.5% and 4.9%, respectively). Longer treatment persistence was noted in older, male, and treatment-experienced patients.

CONCLUSION

The results from the HIRA database showed that persistence was longer with mirabegron than with antimuscarinics in South Korea. This finding may help inform clinical decision-making within the South Korean healthcare system.

Potential of Mirabegron and its Extended-release Formulations for the Treatment of Overactive Bladder Syndrome

BACKGROUND

Overactive bladder syndrome is a broadly occurring urological disorder with a distressing impact on the quality of life. The commonly used antimuscarinic drugs show poor patient compliance because of unsatisfactory potency, tolerability and high occurrence of adverse effects such as dry mouth, blurred vision, constipation, dizziness etc. Mirabegron is the first approved β3-adrenoreceptor agonist, used as mono or in combination therapies for overactive bladder syndrome.

OBJECTIVE

The present review provides an insight into the mechanism, pharmacokinetics, toxicokinetics, clinical trials and the development of various conventional and modified-release dosage forms of mirabegron for the treatment of overactive bladder syndrome.

RESULTS

The clinical trials of phase II and phase III of mirabegron demonstrated symptomatic relief from the overactive bladder without disturbing the micturition cycle. To date, mirabegron showed promising results for safety, tolerability and efficacy in patients with overactive bladder syndrome. The modified-release tablet dosage form of mirabegron appear to be a proficient and suitable replacement for antimuscarinics and revealed the tremendous potential to overcome the adverse effects of conventional antimuscarinic drugs like Oxybutyline chloride ER, Detrol LA, VESIcare, etc. Conclusion: Mirabegron shows a distinct mode of action, i.e., targeting β3-adrenoreceptors and improving bladder storage without altering void contractions. The limited side effects, high safety, efficacy and tolerability of mirabegron present an adequate substitute to antimuscarinics. However, long-term analysis and clinical studies are prerequisites for assessing the safety, tolerability and efficacy profile of mirabegron.

Fluoxetine, a selective serotonin reuptake inhibitor used clinically, improves bladder function in a mouse model of moderate spinal cord injury

After spinal cord injury, the upward conduction of the spinal cord is lost, resulting in the loss of micturition control, which manifests as detrusor sphincter dyssynergia and insufficient micturition. Studies have shown that serotonergic axons play important roles in the control of the descending urination tract. In this study, mouse models of moderate spinal cord contusions were established. The serotonin agonists quipazine (0.2 mg/kg), 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DAPT, 0.1 mg/kg), buspirone (1 mg/kg), sumatriptan (1 mg/kg), and rizatriptan (50 mg/kg), the serotonin reuptake inhibitors fluoxetine (20 mg/kg) and duloxetine (1 mg/kg), and the dopamine receptor agonist SKF-82197 (0.1 mg/kg) were intraperitoneally administered to the model mice 35 days post-injury in an acute manner. The voided stain on paper method and urodynamics revealed that fluoxetine reduced the amount of residual urine in the bladder and decreased bladder and external urethral sphincter pressure in a mouse model of moderate spinal cord injury. However, fluoxetine did not improve the micturition function in a mouse model of severe spinal cord injury. In contrast, the other serotonergic drugs had no effects on the micturition functions of spinal cord injury model mice. This study was ethically approved by the Institutional Animal Care and Use Committee of Jiangsu Province Hospital of Chinese Medicine (approval No. 2020DW-20-02) on September 11, 2020.

Validated spectrofluorimetric method for determination of mirabegron by utilizing its quenching effect on acetoxymercuric fluorescein reagent

A reliable, sensitive, simple and inexpensive spectrofluorimetric method has been developed for assay of mirabegron in bulk powder and in its tablets. The method depends on the quenching effect of mirabegron on the fluorescence intensity of acetoxymercuric fluorescein (AMF) reagent at ƛem of 520 nm and ƛex of 498 nm. Parameters that may affect the reaction such as pH, AMF solution concentration, temperature, time and diluting solvents were studied and optimized. Under the optimized conditions, the proposed method was applied over the concentration range of 1-5 μg mL^-1 with acceptable linearity (r = 0.9997). The developed method was validated according to ICH guidelines in terms of accuracy, precision, linearity, range, LOD and LOQ. The proposed method was applied to analyze mirabegron in Bladogra® 50 mg tablets with acceptable recovery% of 100.41 and RSD% of 1.72. The results obtained were compared to those obtained by a previously reported TLC method.

β3 Adrenoceptor-induced cholinergic inhibition in human and rat urinary bladders involves the exchange protein directly activated by cyclic AMP 1 favoring adenosine release

BACKGROUND AND PURPOSE

The mechanism by which β₃ receptor agonists (e.g. mirabegron) control bladder overactivity may involve adenosine release from human and rat detrusor smooth muscle. Retrograde activation of adenosine A₁ receptors reduces ACh release from cholinergic bladder nerves. β₃ -Adrenoceptors usually couple to adenylyl cyclase. Here we investigated, which of the cAMP targets, protein kinase A or the exchange protein directly activated by cAMP (EPAC) could be involved in this cholinergic inhibition of the bladder.

EXPERIMENTAL APPROACH

[³ H]ACh and adenosine release from urothelium-denuded detrusor strips of cadaveric human organ donors and rats were measured by liquid scintillation spectrometry and HPLC, respectively. In vivo cystometry was also performed in urethane-anaesthetized rats.

KEY RESULTS

The exchange protein directly activated by cAMP (EPAC) inhibitor, ESI-09, prevented mirabegron- and isoprenaline-induced adenosine release from human and rat detrusor strips respectively. ESI-09, but not the PKA inhibitor, H-89, attenuated inhibition of [³ H]ACh release from stimulated (10 Hz) detrusor strips caused by activating β₃ -adrenoceptors, AC (forskolin) and EPAC1 (8-CTP-2Me-cAMP). Isoprenaline-induced inhibition of [³ H]ACh release was also prevented by inhibitors of PKC (chelerythrine and Go6976) and of the equilibrative nucleoside transporter 1 (ENT1; dipyridamole and NBTI), but not by PLC inhibition with U73122. Pretreatment with ESI-09, but not with H-89, prevented the reduction of the voiding frequency caused by isoprenaline and forskolin in vivo.

CONCLUSION AND IMPLICATIONS

Data suggest that β₃ -adrenoceptor-induced inhibition of cholinergic neurotransmission in human and rat urinary bladders involves activation of an EPAC1/PKC pathway downstream cAMP production resulting in adenosine outflow via ENT1.

Pharmacological properties of β-adrenoceptors mediating rat superior mesenteric artery relaxation and the effects of chemical sympathetic denervation

AIMS

β-Adrenoceptors (β-ADRs) mediating the relaxation of rat superior mesenteric arteries (SMAs) were pharmacologically identified, and the effects of chemical sympathetic denervation on β-ADR-mediated relaxation were examined.

MAIN METHODS

The tension changes of endothelium-denuded SMAs were isometrically recorded and the mRNA of endothelium-denuded SMA β-ADR was detected using RT-PCR.

KEY FINDINGS

In endothelium-denuded SMAs contracted with ≥10^-7 M phenylephrine (an α₁-ADR agonist), isoprenaline (a β-ADR agonist)-induced relaxation was competitively inhibited by 3 × 10^-9-10^-8 M propranolol (a β_1,2-ADR antagonist), but not further affected by ≥10^-8 M propranolol. Although isoprenaline-induced relaxation was not affected by ICI-118,551 (10^-9-10^-8 M; a β₂-ADR antagonist), it was competitively inhibited by atenolol (10^-7-3 × 10^-7 M; a β₁-ADR antagonist) in the presence of ICI-118,551. In the presence of 10^-7 M propranolol, isoprenaline- and CGP-12177A (a β₃-ADR partial agonist)-induced relaxation was competitively inhibited by high concentrations of bupranolol (a β_1,2,3-ADR antagonist), with pA₂ values of 6.49 and 5.76, respectively. We detected the mRNA of β₁- and β₃-ADRs in endothelium-denuded SMAs. Treatment with 6-hydroxydopamine (a catecholaminergic neurotoxin) reduced maximal isoprenaline-induced relaxation in the presence and absence of 10^-7 M propranolol, but not CGP-12177A-induced relaxation.

SIGNIFICANCE

Isoprenaline-induced relaxation of rat SMAs is mediated by β₁- and β₃-ADRs. β-ADR-mediated relaxation of rat SMAs is shown to be attenuated by chemical sympathetic denervation. The differences in the effects of bupranolol and chemical sympathetic denervation on the responses to isoprenaline and CGP-12177A in rat SMAs might be explained by the possible presence of multiple β₃-ADRs with different pharmacological properties.

Cardiovascular safety of antimuscarinic add-on therapy in patients with overactive bladder who had a suboptimal response to mirabegron monotherapy: A post hoc analysis from the Japanese MILAI II study

Objective

This analysis was conducted to investigate the cardiovascular (CV) safety outcomes from the MILAI II study. MILAI II was conducted to evaluate the long‐term safety and efficacy of antimuscarinic add‐on therapy to mirabegron over 52 weeks in patients with overactive bladder (OAB) symptoms.

Methods

MILAI II consisted of a 2‐week screening period (patients received mirabegron 50 mg once daily) plus a 52‐week treatment period (patients were randomized to receive a combination of mirabegron 50 mg/d plus solifenacin 5 mg/d, propiverine 20 mg/d, imidafenacin 0.2 mg/d, or tolterodine 4 mg/d). CV safety was assessed using treatment‐emergent adverse events (TEAEs), vital signs, and 12‐lead electrocardiograms (ECGs). Vital signs and ECG data were evaluated for each patient using worst post‐baseline values reported.

Results

Of 647 patients, 570 (88.1%) were female with a mean age of 65 years. CV history at baseline and CV‐related concomitant medication use throughout the study were balanced between groups. The incidences of overall and drug‐related CV TEAEs were ≤8.1% and ≤6.2%, respectively, for all groups. The most common TEAEs were ECG T wave amplitude decreased, ECG QT prolonged, and ventricular extrasystoles. Overall, 36 TEAEs of interest related to the CV system that were possibly/probably related to treatment were reported with similar incidences for each group. For the worst post‐baseline vital signs and ECGs, no relationships were noted in terms of either timing or treatment group.

Conclusion

A favorable CV safety profile was observed following long‐term combination treatment with mirabegron and an antimuscarinic in patients with OAB symptoms.

Contractile elements and their sympathetic regulations in the pig urinary bladder: a species and regional comparative study

Contractile behaviour of the urinary bladder and its sympathetic inhibition during storage phases are not well understood. Here, we explore muscularis mucosae (MM) as a predominant mucosal contractile element and the capability of sympathetic nerves to relax detrusor smooth muscle (DSM) or MM. Distribution of α-smooth muscle actin (α-SMA)-immunoreactive cells was compared in pig, human, guinea pig, rat and mouse bladders by immunohistochemistry, while contractility of the bladder mucosa was compared in these species by isometric tension recordings. In pig, human and guinea pig bladders, DSM and MM located in the lamina propria expressed α-SMA immunoreactivity, while both rat and mouse bladders lacked a MM. Consistent with this presence or absence of MM, bladder mucosa of pig, human and guinea pig but not rat and mouse developed spontaneous phasic contractions (SPCs). Distribution of tyrosine hydroxylase (TH)-immunoreactive sympathetic nerve fibres was compared in pig DSM, MM, trigone and urethra, as were their sympathetic nerve-evoked contractile/relaxing responses examined. In pig DSM or MM, where TH-immunoreactive sympathetic fibres exclusively projected to the vasculature, sympathetic relaxations were difficult to demonstrate. In contrast, sympathetic contractions were invariably evoked in pig trigone and urethra where the smooth muscle cells receive TH-immunoreactive sympathetic innervations. Thus, SPCs of bladder mucosa appear to predominantly arise from the MM displaying species differences. Despite the currently accepted concept of sympathetic nerve-mediated DSM relaxation during the storage phase, it is unlikely that neurally released noradrenaline acts on β-adrenoceptors to relax either DSM or MM due to the anatomical lack of sympathetic innervation.

Updating the evidence on drugs to treat overactive bladder: a systematic review

Introduction

Overactive bladder (OAB) is a common condition, increasing with age and affecting quality of life. While numerous OAB drugs are available, persistence is low. We evaluated evidence published since 2012 to determine if newer drugs provided better efficacy and harm profiles.

Methods

We searched MEDLINE and the Cochrane Library from 2012 to September 2018 using terms for included drugs and requested information from manufacturers of included drugs. We performed dual review of all systematic review processes, evaluated study quality, and conducted meta-analyses using random effects models.

Results

In addition to 31 older studies, we included 20 trials published since 2012 (N = 16,478; 4 good, 11 fair, and 5 poor quality). Where statistical differences were found, they were clinically small (reductions of < 0.5 episodes/day). Solifenacin plus mirabegron improved efficacy outcomes over monotherapy with either drug, but significantly increased constipation compared with solifenacin and dry mouth compared with mirabegron. Solifenacin reduced incontinence over mirabegron and tolterodine and urgency episodes over tolterodine. Mirabegron did not differ from tolterodine in efficacy but had significantly lower incidence of dry mouth than solifenacin or tolterodine. Fesoterodine showed significant improvements but also anticholinergic effects vs. tolterodine. Oxybutynin, solifenacin, and tolterodine had similar efficacy, but dry mouth led to greater discontinuation with oxybutynin. Blurred vision, cardiac arrhythmia, and dizziness were uncommon.

Conclusion

New evidence confirms small, but clinically uncertain, differences among monotherapies and also between combination and monotherapy, regardless of statistical significance. While drugs mainly differed in incidence of dry mouth or constipation, none provided improved efficacy without increased harms.

Electronic supplementary material

The online version of this article (10.1007/s00192-019-04022-8) contains supplementary material, which is available to authorized users.

[Contribution of pharmacological research to the discovery of a first-in-class drug, mirabegron, for the treatment of overactive bladder]

Overactive bladder (OAB) is defined as urgency, with or without urge incontinence, usually with frequency and nocturia. Antimuscarinic drugs are often prescribed as a standard care; however, the treatment discontinuation due to the adverse events including dry mouth and constipation has been an issue. Taking these situations into account, we considered that a novel OAB drug having a different mechanism from antimuscarinics fills the unmet medical need. It has been known that, during bladder filling, activation of sympathetic nerves results in bladder smooth muscle relaxation via the β-adrenergic receptor (AR) stimulation. In 1999, three Japanese groups independently provided evidence for the existence of β₃-AR in human bladder smooth muscles and some of these groups showed that β₃-AR activation is mainly involved in the relaxation induced by β adrenergic stimulation. Therefore, we conducted pharmacological research focusing on β₃-AR as a novel target molecule for the treatment of OAB. A selective β₃-AR agonist mirabegron showed the relaxant effect in rat bladder smooth muscle and decreased resting intravesical pressure in anesthetized rats. Mirabegron also improved storage function in a rat detrusor overactivity model. Furthermore, in vitro isometric contraction study using human bladder tissues was conducted to predict the clinical efficacy and mirabegron showed the relaxant effect in human bladder smooth muscle. In clinical studies with OAB patients, mirabegron demonstrated promising efficacy and tolerability. These pharmacological evidences contributed to the approval of mirabegron as a first-in-class drug for OAB treatment in Japan ahead of other countries.

Design, synthesis and in vitro evaluation of a Dopa-organoboron compound that acts as a bladder relaxant through non-catecholamine receptors

Bladder relaxation through drug administration is an interesting topic in medicinal and combinatorial chemistry. In fact, compounds targeting catecholamine receptors [dopamine receptors and beta-adrenergic receptors (βAR) expressed in the bladder] are among the compounds commonly employed for this purpose. In particular, recent investigations have tended to focus on the β₃-adrenoceptor (β₃AR) as a target in the treatment of urinary incontinence and other disorders. However, organoboron compounds have been suggested as potent and efficient agents on these drug targets. In this work, through a docking study, we identified the parameters that induce a theoretical improvement in the affinity and activity of the organoboron compounds on the catecholamine receptors expressed in the bladder. Then, the identified potential drug, a boron-containing dopa-derivative named DPBX-L-Dopa, was synthesized and characterized. This compound induces a relaxation on the smooth muscle of the rat bladder, behaving as a weak relaxant compared to isoproterenol but with similar efficacy to BRL377, a selective β₃AR agonist. However, unexpectedly, this effect was not blocked by propranolol or haloperidol at the concentrations at which they are able to block the catecholamine receptors in bladder tissue. In view of these results, the effect of DPBX-L-Dopa compound on the alpha 1 adrenergic receptors (α₁AR) of aorta of the rats was also explored; however, no response of the tissue to this compound was obtained. The possible mechanisms of the action of this compound were explored and are discussed further.

β3-Adrenoceptor agonists inhibit purinergic receptor-mediated contractions of the murine detrusor

β₃-Adrenoceptor (β₃-AR) agonists are used to treat overactive bladder syndrome; however, their mechanism of action has not been determined. The aims of this study were to compare the effects of β₃-AR agonists on cholinergic versus purinergic receptor-mediated contractions of the detrusor and to examine the mechanisms underlying inhibition of the purinergic responses by β₃-AR agonists. Isometric tension recordings were made from strips of murine detrusor and whole cell current recordings were made from freshly isolated detrusor myocytes using the patch-clamp technique. Transcriptional expression of exchange protein directly activated by cAMP (EPAC) subtypes in detrusor strips was assessed using RT-PCR and real-time quantitative PCR. The β₃-AR agonists BRL37344 and CL316243 (100 nM) inhibited cholinergic nerve-mediated contractions of the detrusor by 19 and 23%, respectively, but did not reduce contractions induced by the cholinergic agonist carbachol (300 nM). In contrast, BRL37344 and CL316243 inhibited purinergic nerve-mediated responses by 55 and 56%, respectively, and decreased the amplitude of contractions induced by the P2X receptor agonist α,β-methylene ATP by 40 and 45%, respectively. The adenylate cyclase activator forskolin inhibited purinergic responses, and these effects were mimicked by a combination of the PKA activator N⁶-monobutyryl-cAMP and the EPAC activator 8-pCPT-2'-O-methyl-cAMP-AM (007-AM). Application of ATP (1 μM) evoked reproducible P2X currents in isolated detrusor myocytes voltage-clamped at -60 mV. These responses were reduced in amplitude in the presence of BRL37344 and also by 007-AM. This study demonstrates that β₃-AR agonists reduce postjunctional purinergic responses in the detrusor via a pathway involving activation of the cAMP effector EPAC.

Mirabegron induces relaxant effects via cAMP signaling-dependent and -independent pathways in detrusor smooth muscle

OBJECTIVE

We previously found that mirabegron exerts a relaxant effect in the presence of the β₃ -adrenoceptor antagonist SR58894A during carbachol-induced contraction in human and pig detrusor. The aim of this study was to explore the possible mechanism underlying the relaxant effects of mirabegron using detrusor smooth muscle.

METHODS

Human tissue was obtained from urinary bladders of patients undergoing radical cystectomy at Kyushu University and Harasanshin Hospital. Pig tissue was obtained from an abattoir. Tension force (organ bath experiments) was measured in intact or permeabilised (α-toxin or β-escin) detrusor smooth muscle strips. The contribution of cAMP-dependent signaling and the inhibition of Ca²⁺ sensitization to the relaxant effects of mirabegron were characterized using 1 μM SR58894A, 100 μM SQ22536 (an adenylyl cyclase inhibitor), 10 μM H-89 (a protein kinase [PK] A inhibitor), 10 μM Y-27632 (a selective Rho kinase inhibitor), and 10 μM GF-109203X (a selective PKC inhibitor).

RESULTS

30 μM Mirabegron impaired carbachol (0.03-1 μM)-induced contraction in human detrusor smooth muscle. SR58894A only partially attenuated the relaxant effects of mirabegron in human and pig detrusor strips precontracted with 1 μM carbachol. In α-toxin-permeabilized detrusor strips, tension force at 1 μM [Ca²⁺ ]_i was decreased by mirabegron in a concentration-dependent manner. The relaxant effect of mirabegron was only slightly attenuated by H-89 and not significantly affected by SQ22536. Y-27632 potentiated the relaxation response to mirabegron, but attenuated responses to cAMP; GF-109203X had little effect. Mirabegron but not cAMP had a notable relaxant effect in the pig detrusor smooth muscle permeabilized with β-escin.

CONCLUSIONS

Mirabegron-induced relaxation of pig and human detrusor smooth muscle occurs via both a β₃ -adrenoceptor/cAMP-dependent and -independent pathway.

Design, synthesis and in vitro evaluation of a Dopa-organoboron compound that acts as a bladder relaxant through non-catecholamine receptors

Bladder relaxation through drug administration is an interesting topic in medicinal and combinatorial chemistry. In fact, compounds targeting catecholamine receptors [dopamine receptors and beta-adrenergic receptors (βAR) expressed in the bladder] are among the compounds commonly employed for this purpose. In particular, recent investigations have tended to focus on the β₃-adrenoceptor (β₃AR) as a target in the treatment of urinary incontinence and other disorders. However, organoboron compounds have been suggested as potent and efficient agents on these drug targets. In this work, through a docking study, we identified the parameters that induce a theoretical improvement in the affinity and activity of the organoboron compounds on the catecholamine receptors expressed in the bladder. Then, the identified potential drug, a boron-containing dopa-derivative named DPBX-L-Dopa, was synthesized and characterized. This compound induces a relaxation on the smooth muscle of the rat bladder, behaving as a weak relaxant compared to isoproterenol but with similar efficacy to BRL377, a selective β₃AR agonist. However, unexpectedly, this effect was not blocked by propranolol or haloperidol at the concentrations at which they are able to block the catecholamine receptors in bladder tissue. In view of these results, the effect of DPBX-L-Dopa compound on the alpha 1 adrenergic receptors (α₁AR) of aorta of the rats was also explored; however, no response of the tissue to this compound was obtained. The possible mechanisms of the action of this compound were explored and are discussed further.

Mirabegron: potential off target effects and uses beyond the bladder

The β₃ -adrenoceptor was initially an attractive target for several pharmaceutical companies due to its high expression in rodent adipose tissue, where its activation resulted in decreased adiposity and improved metabolic outputs (such as glucose handling) in animal models of obesity and Type 2 diabetes. However, several drugs acting at the β₃ -adrenoceptor failed in clinical trials. This was thought to be due to their lack of efficacy at the human receptor. Recently, mirabegron, a β₃ -adrenoceptor agonist with human efficacy, was approved in North America, Europe, Japan and Australia for the treatment of overactive bladder syndrome. There are indications that mirabegron may act at other receptors/targets, but whether they have any clinical relevance is relatively unknown. Besides overactive bladder syndrome, mirabegron may have other uses such as in the treatment of heart failure or metabolic disease. This review gives an overview of the off-target effects of mirabegron and its potential use in the treatment of other diseases.

LINKED ARTICLES

This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.

β3-adrenoceptor agonists inhibit carbachol-evoked Ca2+ oscillations in murine detrusor myocytes

OBJECTIVE

To test if carbachol (CCh)-evoked Ca²⁺ oscillations in freshly isolated murine detrusor myocytes are affected by β3-adrenoceptor (β-AR) modulators.

MATERIALS AND METHODS

Isometric tension recordings were made from strips of murine detrusor, and intracellular Ca²⁺ measurements were made from isolated detrusor myocytes using confocal microscopy. Transcriptional expression of β-AR sub-types in detrusor strips and isolated detrusor myocytes was assessed using reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time quantitative PCR (qPCR). Immunocytochemistry experiments, using a β3-AR selective antibody, were performed to confirm that β3-ARs were present on detrusor myocytes.

RESULTS

The RT-PCR and qPCR experiments showed that β1-, β2- and β3-AR were expressed in murine detrusor, but that β3-ARs were the most abundant sub-type. The selective β3-AR agonist BRL37344 reduced the amplitude of CCh-induced contractions of detrusor smooth muscle. These responses were unaffected by addition of the BK channel blocker iberiotoxin. BRL37344 also reduced the amplitude of CCh-induced Ca²⁺ oscillations in freshly isolated murine detrusor myocytes. This effect was mimicked by CL316,243, another β3-AR agonist, and inhibited by the β3-AR antagonist L748,337, but not by propranolol, an antagonist of β1- and β2-ARs. BRL37344 did not affect caffeine-evoked Ca²⁺ transients or L-type Ca²⁺ current in isolated detrusor myocytes.

CONCLUSION

Inhibition of cholinergic-mediated contractions of the detrusor by β3-AR agonists was associated with a reduction in Ca²⁺ oscillations in detrusor myocytes.

Anti-cholinergic medications for bladder dysfunction worsen cognition in persons with multiple sclerosis

Bladder dysfunction is common in persons with MS (PwMS), often due to detrusor muscle overactivity. Anticholinergic medications are considered the first line treatment for bladder dysfunction and are known to worsen cognition in healthy older adults and in persons with dementia. Yet, it is not known if these medications have the same effect on PwMS. Thus, the Objective of this prospective matched-cohort study was to determine if anticholinergic medications affect objective measures of cognition in PwMS. We recruited PwMS starting either oxybutynin or tolterodine (cases). Cases and controls were tested with the Brief International Cognitive Assessment for MS (BiCAMS) battery prior to starting anticholinergic medications and 12weeks later. The primary outcome was change on the Symbol Digit Modalities Test (SDMT) between groups; secondary outcomes were changes on the other BiCAMS measures. Analysis of Covariance with baseline measures as covariates to assess the significance of between group differences was performed at 12weeks. Forty eight PwMS starting anticholinergic medications and 21 matched PwMS controls were recruited. There was a significant difference (p<0.001) in the change on the cognitive measures over 12weeks between groups. The controls demonstrated improvement, consistent with practice effect, while the cases remained unchanged. This study demonstrates that anticholinergic medications may have a negative effect on cognition in PwMS; further confirmatory studies are needed.

The Influence of Resiniferatoxin (RTX) and Tetrodotoxin (TTX) on the Distribution, Relative Frequency, and Chemical Coding of Noradrenergic and Cholinergic Nerve Fibers Supplying the Porcine Urinary Bladder Wall

The present study investigated the influence of intravesically instilled resiniferatoxin (RTX) or tetrodotoxin (TTX) on the distribution, number, and chemical coding of noradrenergic and cholinergic nerve fibers (NF) supplying the urinary bladder in female pigs. Samples from the bladder wall were processed for double-labelling immunofluorescence with antibodies against cholinergic and noradrenergic markers and some other neurotransmitter substances. Both RTX and TTX caused a significant decrease in the number of cholinergic NF in the urinary bladder wall (in the muscle coat, submucosa, and beneath the urothelium). RTX instillation resulted in a decrease in the number of noradrenergic NF in the submucosa and urothelium, while TTX treatment caused a significant increase in the number of these axons in all the layers. The most remarkable changes in the chemical coding of the NF comprised a distinct decrease in the number of the cholinergic NF immunoreactive to CGRP (calcitonin gene-related peptide), nNOS (neuronal nitric oxide synthase), SOM (somatostatin) or VIP (vasoactive intestinal polypeptide), and an increase in the number of noradrenergic NF immunopositive to GAL (galanin) or nNOS, both after RTX or TTX instillation. The present study is the first to suggest that both RTX and TTX can modify the number of noradrenergic and cholinergic NF supplying the porcine urinary bladder.