Drug therapy of overactive bladder--what is coming next?

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.

The efficacy of nebivolol on spontaneously hypertensive rats with overactive bladder - an experimental study

INTRODUCTION

Overactive bladder (OAB) is a disease that significantly decreases quality of life. Adverse effects of the drugs currently used in OAB treatment limit their use in patients with hypertension. Nebivolol (a β₁-adrenergic receptor blocker) is approved for hypertension treatment, but also shows agonistic activity on β₃-adrenergic receptor, located in the urinary bladder. The aim of this study was to assess the impact of nebivolol on OAB symptoms and cardiovascular parameters in spontaneously hypertensive rats (SHR) - an animal model of OAB and hypertension.

MATERIAL AND METHODS

Female Wistar-Kyoto (WHY) and SHR rats were used in the experiments. Nebivolol was administered intra-arterially at a single daily dose of 0.05 mg/kg for 14 days. Subsequently, cystometry and bladder blood flow assessment were performed. Then, 24-hour measurement of heart rate, blood pressure, and urine production was carried out. In addition, the bladders of experimental rats were removed and processed to conduct biochemical analyses.

RESULTS

The main finding of this study is that the treatment with nebivolol resulted in an improvement of cystometric parameters characteristic for OAB in SHR. Nebivolol normalised blood pressure in SHR, while in WHY the cardiovascular parameters remained unchanged. Biomarkers characteristic for OAB were elevated in SHR compared to WHY, and nebivolol decreased their values in SHR while it had no influence on WHY.

CONCLUSIONS

Nebivolol alleviates OAB symptoms and normalises blood pressure in SHRs. These results suggest that nebivolol may be a useful treatment alternative for OAB patients with pre-existing hypertension.

The Modulation Of Detrusor Contractility By Agents Influencing Ion Channel Activity

Background: This study specified the role of several significant ion channels regulating the metabolism of calcium ions in contraction and relaxation of human detrusor muscle in order to identify possible target for future drugs that are capable of treating diseases resulting from impaired detrusor activity, e.g. overactive bladder. Although this disease can be successfully treated with muscarinic receptor antagonists or β3 agonist, many patients may not be suitable for chronic therapy, especially due to the relatively high side effects of the treatment.

Material and Methods: The study used the isolated detrusor tissue samples, which were obtained from the macroscopic healthy tissue of urinary bladder from 19 patients undergoing a total prostatectomy because of localized prostate cancer. Each biological sample was prepared into 8 strips. We used oxybutynin and mirabegron as control drugs and several blockers of specific subtypes calcium and potassium ion channels as tested substances. The contractility of bladder was investigated by an organ tissue bath method in vitro and contraction was induced by carbachol.

Results: The amplitude of contraction was successfully decreased by positive control drugs and, from tested agents, the comparable effect had the substance capable of influencing IP3 receptors and Orai-STIM channels and combination consisting of drugs possessing an inhibitory effect on IP3 receptors, L- and T-type voltage-gated calcium channels and Orai-STIM channels.

Conclusion: The present work represents a new finding about handling Ca2+ in urinary bladder contraction and pointed to a dominant role of IP3 receptor-mediated pathway in the regulation of Ca2+ metabolism, which may represent a future strategy in pharmacotherapy of impaired detrusor activity.

Proteomic Analysis of Urothelium of Rats with Detrusor Overactivity Induced by Bladder Outlet Obstruction

Overactive bladder (OAB) syndrome is a condition that has four symptoms: urgency, urinary frequency, nocturia, and urge incontinence and negatively affects a patient's life. Recently, it is considered that the urinary bladder urothelium is closely linked to pathogenesis of OAB. However, the mechanisms of pathogenesis of OAB at the molecular level remain poorly understood, mainly because of lack of modern molecular analysis. The goal of this study is to identify a potential target protein that could act as a predictive factor for effective diagnosis and aid in the development of therapeutic strategies for the treatment of OAB syndrome. We produced OAB in a rat model and performed the first proteomic analysis on the mucosal layer (urothelium) of the bladders of sham control and OAB rats. The resulting data revealed the differential expression of 355 proteins in the bladder urothelium of OAB rats compared with sham subjects. Signaling pathway analysis revealed that the differentially expressed proteins were mainly involved in the inflammatory response and apoptosis. Our findings suggest a new target for accurate diagnosis of OAB that can provide essential information for the development of drug treatment strategies as well as establish criteria for screening patients in the clinical environment.

Influence of Daytime or Nighttime Dosing with Solifenacin for Overactive Bladder with Nocturia: Impact on Nocturia and Sleep Quality

We compared changes in nocturia and sleep-related parameters between daytime and nighttime solifenacin dosing in patents with overactive bladder (OAB) and nocturia. We comparatively analyzed the data of a 12-week prospective, open-label, multicenter, randomized study. All 127 patients who presented to 5 centers in Korea for the treatment of OAB with nocturia between January 2011 and December 2013 were enrolled in this study. The patients were divided into 2 groups by medication timing: group 1, daytime (n = 62); and group 2, nighttime (n = 65). The International Prostate Symptom Score (IPSS), Overactive Bladder Symptom Score (OABSS), and Athens Insomnia Scale (AIS) were used to assess OAB symptoms and sleep quality. We evaluated the parameter changes before and 12 weeks after daytime or nighttime solifenacin administration. Baseline data, which included sex, age, body mass index (BMI), total AIS, IPSS, and OABSS, did not differ between the 2 groups. Total IPSS, OABSS, and total AIS significantly improved after solifenacin administration regardless of timing (P < 0.001). After solifenacin administration, the number of nocturia episodes decreased in the group 1 and 2 (P < 0.001). There were no significant intergroup differences in changes in AIS, IPSS, OABSS, and number of nocturia episodes 12 weeks after solifenacin administration. Treating OAB with solifenacin may improve nocturia and sleep quality, but advantages did not differ significantly by medication timing.

Expected Next-Generation Drugs Under Development in Relation to Voiding Symptoms

New drug development is a high-risk venture, but if successful, will bring great revenues to those willing to accept the risk. In the field of urology, in particular for lower urinary tract symptoms (LUTS), the recent successful landing of drugs (e.g., mirabegron, botulinum toxin A, and tadalafil) has resulted in increased interest in new drug development. Benign prostatic hyperplasia and overactive bladder syndrome, representative LUTS diseases, are attractive targets because of their prevalence and market size in the field of urology. Additionally, the awareness about new stream of research is very important not only because of the market size and economic factors, but also because to keep steady attention to these research for the researcher’s. We have reviewed a selection of new drugs currently under development for the treatment of the two aforementioned diseases and hope to offer urologists an overview of the current situation and future directions in the field of urology.

A short review of drug-food interactions of medicines treating overactive bladder syndrome

Background Overactive bladder syndrome is a condition where one or more of the symptoms such as pollakiuria, urgent need to urinate, nocturia and urinary incontinence is observed. Its prevalence ranges between 7 and 27 % in men and 9–43 % in women. The role of a pharmacist is to educate the patient on medications administration scheme, and drug interactions with particular food or food components. Aim of the review To assess a potential impact of food and fruit juice on the pharmacokinetic and therapeutic effects of medications used in treating overactive bladder syndrome. This information will enhance pharmaceutical care and is vital and helpful for pharmacists counseling their patients. Method In order to gather information on interactions of medications employed in bladder dysfunctions, the English language reports published in the PubMed, Embase, Cochrane and CINAHL database over the years 1996–2015 were studied. Additionally, other resources, namely drugs.com, Medscape, UpToDate, Micromedex, Medical Letter, as well as Stockley Drugs Interaction electronic publication were included in the study. The analysis also covered product data sheets for particular medicinal products. Results Meals and the consumption of grapefruit juice were found to exert a diversified effect on the pharmacokinetics of drugs employed in overactive bladder syndrome therapy. Neither tolterodine, nor mirabegron interact with food and citrus fruit juice, whereas darifenacin, fesoterodine, oxybutynin and solifenacin do interact with grapefruit and others citrus fruit juice. The effects of such interactions may potentially be negative to patients. Trospium absorption is significantly decreased by food. Conclusion For selected medicines used in treating bladder dysfunctions food and grapefruit juice consumption may significantly affect efficacy and safety of the therapy. All information on the topic is likely to enhance the quality of pharmaceutical care.