Anticholinergic and calcium antagonistic activities of NS-21 contribute to the inhibition of rat urinary bladder contractions

Role of calcium channel blockers in lower urinary tract symptoms in benign prostatic hyperplasia: a literature review

Background

Benign prostatic hyperplasia (BPH) and the use of CCBs are common in older persons, and are also associated with lower urinary tract symptoms (LUTS). This review summarised and synthesised relevant information and recent advances to improve clinical knowledge on the role of CCBs in LUTS, BPH symptoms and health-related quality of life.

Main body of the abstract

A search of databases of PubMed, Web of science, Hinari, and Google scholar was performed using several keywords. Relevant studies were also extracted from references of identified studies. Selected studies were assessed for content related to CCBs, BPH and LUTS, and the most relevant reports were included. The inhibition of calcium channels by CCBs interferes with influx of extracellular Ca2+ into the detrusor muscle, which interferes with bladder contraction and relaxation. Hence, CCBs are associated with precipitation or aggravation of urinary storage and voiding symptoms, which are also common symptoms of BPH. This suggests a potential aggravation of BPH symptoms with the use of CCBs.

Short conclusion

Persons at high risk of LUTS such as in BPH, may benefit from other classes of antihypertensive drugs. Therefore, it is essential to identify persons with BPH prior to commencement of therapy with CCBs. Patients on CCBs should be routinely reviewed for any potential precipitation or aggravation of LUTS. Patients should also be counselled to notify their healthcare provider of unusual urinary symptoms during CCB use. This will facilitate enhanced quality of life in patients with BPH.

Intestinal, urinary and uterine antispasmodic effects of isoespintanol, metabolite from Oxandra xylopioides leaves

BACKGROUND

Isoespintanol is a monoterpene isolated from the leaves of Oxandra xylopioides Diels. (Annonaceae) with antioxidant and antiinflammatory effects. It was of interest to know whether it has antispasmodic effects such as other known drugs, phloroglucinol and trimethoxybenzene, used in therapeutics for treating biliary, urinary and uterine spasms.

PURPOSE

To assess whether isoespintanol possesses antispasmodic effects on intestine, uterus and bladder.

STUDY DESIGN

A preclinical study was performed in which isoespintanol, phloroglucinol and trimethoxybenzene were evaluated with concentration-contractile response curves (CRC) of carbachol in isolated rat intestine and bladder, and with CRC of serotonin (5-HT) in rat uterus. Moreover, it was assessed whether isoespintanol interferes with Ca²⁺ influx by making CRC of Ca²⁺ in high-K⁺ medium in intestine and bladder.

RESULTS

Isoespintanol non-competitively inhibited the CRC of carbachol with affinity constant (pK) of 4.78 ± 0.09 in intestine and 4.60 ± 0.09 in bladder. Phloroglucinol and trimethoxybenzene were also non-competitive antagonists, but isoespintanol was 8 times more potent than trimethoxybenzene and similarly potent than phloroglucinol in intestine. In bladder, isoespintanol resulted 8 times more potent than trimethoxybenzene. The maximal inhibition of contraction followed the order of isoespintanol > trimethoxybenzene > phloroglucinol in intestine, and isoespintanol > trimethoxybenzene in bladder. Moreover, isoespintanol also completely and non-competitively inhibited the CRC of Ca²⁺, with a pK of 5.1 ± 0.1 in intestine, and 4.32 ± 0.07 in bladder. In uterus isoespintanol reduced, completely and non-competitively, the contraction produced by 5-HT with pK of 5.05 ± 0.07.

CONCLUSION

Results demonstrate that isoespintanol is a very good intestinal, urinary and uterine antispasmodic, with higher potency than the other drugs used in therapeutics. The mechanism of action of isoespintanol is the interference with Ca²⁺ influx, at a difference of trimethoxybenzene and phloroglucinol.

Effect of Calcium Channel Blockers on Lower Urinary Tract Symptoms: A Systematic Review

Background

Numerous medications are known to be associated with the development of lower urinary tract symptoms (LUTS). One such medication group is calcium channel blockers (CCB).

Objective

To critically examine the literature regarding the involvement of CCB in manifestation of LUTS in humans.

Methods

A systematic literature search was conducted on PubMed, SciELO, Scopus, and OpenGrey databases to find all potentially relevant research studies before August 2016.

Results

Five studies met the inclusion criteria and were included in this review. Three out of five studies stated that CCB were involved in either precipitation or exacerbation of LUTS. As for the remaining two studies, one study found out that only the monotherapy of CCB was associated with increased prevalence of nocturia and voiding symptoms in young females, whereas the other study reported an inverse association of CCB with LUTS. The methodological quality of studies was considered high for four studies and low for one study.

Conclusion

Healthcare providers should make efforts for an earlier identification of the individuals at risk of LUTS prior to the commencement of CCB therapy. Moreover, patients should be counselled to notify their healthcare provider if they notice urinary symptoms after the initiation of CCB.

Emerging drugs for treatment of overactive bladder and detrusor overactivity

BACKGROUND

Overactive bladder (OAB) signifies the presence of urinary urgency and can have major effects on quality of life and social functioning. Standard antimuscarinic drugs have good initial response rates but substantial adverse effects and long-term compliance problems.

OBJECTIVES

To review the complexities of the mechanisms underlying OAB and the current drugs available for treating its symptoms.

METHODS

The literature was reviewed to define current therapies and drugs in clinical trials. Articles were identified by means of a computerised PubMed and Cochrane Library search (using the following keywords: overactive bladder, detrusor overactivity, urgency and bladder), supported by a search of the PharmaProjects database.

CONCLUSIONS

New drug classes, such as beta-3 adrenergic agonists, may work by reducing contractility or excitability of bladder muscle. Moderation of afferent activity may allow improved OAB symptoms, with lower risk of affecting voiding function. Agents acting on the CNS could influence OAB favourably, but target selection and adverse effects are an issue. The recognition of the functional contribution of the urothelium and the diversity of nerve transmitters has sparked interest in both peripheral and central modulation of OAB pathophysiology.

Acetylcholine Release from Urinary Bladder Smooth Muscles of Non-Insulin-Dependent Diabetic Rats

INTRODUCTION

To investigate the mechanism of voiding dysfunction in non-insulin-dependent diabetes mellitus, we attempted to measure the acetylcholine (ACh) release using an in vivo microdialysis technique and measuring the detrusor pressure after electrical field stimulation (EFS) of the pelvic nerve.

MATERIALS AND METHODS

Eight- and 32-week-old female Goto-Kakizaki (GK) rats (non-insulin-dependent diabetes mellitus model) and age-matched female Wistar rats (controls) were used in this study. The pelvic nerve was exposed on a bipolar platinum electrode to EFS, and a cannula was inserted into the bladder to measure the detrusor pressure. The microdialysis probe was inserted into the bladder wall and was connected to a microinfusion syringe pump. Dialysate was constantly perfused, collected in a microtube, and then injected into the ACh assay system. Histological examinations were performed by staining with hematoxylin and eosin and S-100 immunohistochemical staining in bladder preparations of both GK and control rats.

RESULTS

In 8-week-old rats, both detrusor pressures and amounts of ACh release of GK rats were not significantly different from those of control rats. In 32-week-old rats, both detrusor pressures and ACh releases were only significantly increased at 5 and 10 Hz of EFS. In the histological study, the number of nerve fibers or bundles of 32-week-old GK rats was significantly decreased as compared with control rats.

CONCLUSION

The present data suggest that the decrease in EFS-induced ACh release in GK rats, which may be caused by the decreased number of nerve fibers, may contribute to the decrease in bladder contractions.

Effect of herbal extract mixture on menopausal urinary incontinence in ovariectomized rats

The decline of estrogen production after menopause is contributing factor to urinary incontinence (UI), and particularly stress urinary incontinence (SUI). We determined the preventive effects of herbal extract mixture (HEM) on UI in ovariectomized Sprague Dawley rats. Female 9-weeks old rats were ovariectomized and treated with HEM (2.2, 11, or 55 mg/kg/day) for 8 weeks. The index of urinary bladder weight to body weight in the HEM and non-ovariectomized and non-treated (SHAM) groups were slightly higher than the ovariectomized, non-treated group (OVX). The contraction index of acetylcholine to KCl on detrusor smooth muscle strips in the HEM groups showed a dose-dependent recovery. HEM treatment also significantly improved collagen levels, as shown by Masson trichrome staining, as well as hydroxyproline levels in the urinary bladder. Serum estradiol levels in the HEM groups were higher than the OVX group. In conclusion, HEM increased estradiol levels in serum and improved factors related to urinary incontinence. The improvements in estradiol levels were related to changes in urinary incontinence.

Pharmacological agents for the treatment of urinary incontinence due to overactive bladder

Although the exact aetiology of overactive bladder is unknown to date, pharmacological therapy has been targeted to both the central and peripheral nervous systems. Potential CNS targets include GABA, opioid, serotonin (5-HT), dopamine and glutaminergic receptors as well as the alpha-adrenoceptors. Potential PNS targets include muscarinic receptors, calcium and potassium channels and alpha- and beta-adrenergic receptors. Since acetylcholine is the primary excitatory neurotransmitter involved in bladder (detrusor) contraction and emptying, anticholinergic agents are the primary compounds used clinically to decrease involuntary detrusor contractions. Anticholinergic therapy has a stabilising effect on the bladder (detrusor muscle); increases bladder capacity; decreases frequency of involuntary detrusor contractions; and delays the initial urge to void, but does not affect warning time. However, the clinical utility of antimuscarinic therapy is limited by the lack of receptor selectivity, resulting in the classic anticholinergic side effects of dry mouth, blurred vision, constipation and potentially, CNS effects such as somnolence and impaired cognitive function. These unwanted side effects often result in premature discontinuation of therapy and poor compliance. Previous attempts to develop uroselective alpha-adrenergic receptor antagonists have not been successful and although research continues, the hope that this class of agents would be viable alternatives to the anticholinergics remains to be proven in the clinical setting. The recent demise of several potassium channel openers does not augur well for the future of this class of agent. The reasons for the discontinuation of trials with these agents have not been fully elucidated, but one must assume that they were not uroselective and the cardiovascular side effects rendered them less than useful clinically. The serotonin re-uptake inhibitors appear to be promising novel therapeutic agents aimed at controlling bladder over-activity through specific CNS pathways. The sensory side of the micturition reflex is a potential therapeutic target. Agents to desensitise afferent nerve endings involved in C-fibre afferent reflexes include capsaicin and resiniferatoxin. Their clinical applicability is currently being evaluated. Finally, the recent findings related to the role of the P2X3 receptor in the sensory aspects of bladder filling have created new interest in the future development of agents that will improve the management of this prevalent and debilitating condition.

Comparison of the effects of novel antimuscarinic drugs on human detrusor smooth muscle

OBJECTIVE

To evaluate the effects of tolterodine, vamicamide and temiverine, novel antimuscarinic drugs developed for the treatment of frequency and urinary incontinence, on human detrusor smooth muscle. Materials and methods Specimens of human urinary bladder were obtained from 20 patients who underwent total cystectomy for malignant bladder tumour. Using an organ-bath technique, the effects of various drugs on the contractions induced by carbachol, KCl, CaCl2 and electrical field stimulation in the detrusor strips were investigated.

RESULTS

Carbachol (0.001-10000 micromol/L) caused concentration-dependent contractions in human detrusor smooth muscles. Tolterodine (0.01-10 micromol/L), vamicamide (0.01-10 micromol/L), temiverine (0.01-1 micromol/L) and atropine (0.001-1 micromol/L) caused parallel shifts to the right of the concentration-response curves to carbachol. All slopes for the regression line of Schild plots were close to unity, and the rank order of pA2 values was atropine = tolterodine > vamicamide > temiverine. Tolterodine, vamicamide and atropine did not inhibit the maximum contractile responses to carbachol, while temiverine (10 micromol/L) significantly inhibited the maximum contractions. Tolterodine (0.001-1 micromol/L) and vamicamide (0.01-10 micromol/L) did not inhibit the KCl- (80 mmol/L) and CaCl2-induced (5 mmol/L) contractions, while temiverine (0.01-10 micromol/L) significantly inhibited the contractions. Electrical field stimulation (2-60 Hz) caused frequency-dependent contractions in human detrusor smooth muscles, which were significantly inhibited by various drugs. In the presence of 1 micromol/L atropine, tolterodine and vamicamide did not inhibit the contractions induced by electrical field stimulation at all frequencies, while temiverine (10 micromol/L) significantly inhibited the contractions.

CONCLUSION

Tolterodine and vamicamide inhibited contractions of human detrusor smooth muscles only through their antimuscarinic action, while temiverine had both antimuscarinic and calcium-antagonist actions. Furthermore, these novel drugs have different efficacies and potencies for inhibiting human detrusor smooth muscle.

Pharmacologic actions of temiverine (p-INN) and its active metabolite, RCC-36, on isolated human urinary bladder muscle

BACKGROUND

Temiverine (p-INN) is a newly synthesized drug that is expected to have anticholinergic action. We investigated the pharmacologic actions of temiverine and its active metabolite, RCC-36, on isolated human bladder.

METHODS

Effects of temiverine and RCC-36 on the detrusor contractions induced by acetylcholine, potassium chloride (KCl), calcium chloride (CaCl2), and electric field stimulation were evaluated using the muscle-bath technique, and compared with the effects of atropine and oxybutynin.

RESULTS

Atropine (10(-9) to 10(-6) mol/L), oxybutynin (10(-8) to 10(-5) mol/L), temiverine (10(-8) to 10(-5) mol/L), and RCC-36 (10(-8) to 3 x 10(-6) mol/L) caused a parallel shift to the right of the concentration-response curves to acetylcholine stimulation. The rank order of pA2 value was atropine > oxybutynin = RCC-36 > temiverine. Atropine did not suppress the maximum contractile response to acetylcholine, but the other drugs significantly suppressed this at the higher concentrations. Each drug caused a concentration-dependent inhibition of KCl (80 mmol/L)-, and CaCl2 (5 mmol/L)-induced contractile responses. Rank order of maximum inhibition was RCC-36 = temiverine > oxybutynin > atropine. Each drug caused a concentration-dependent inhibition of electric field-induced contraction with or without 10(-6) mol/L atropine pretreatment. Maximum inhibitions of temiverine and RCC-36 were significantly greater than that of oxybutynin.

CONCLUSION

Atropine, oxybutynin, temiverine, and RCC-36 have different efficacies and potencies of anticholinergic and calcium antagonistic activity on isolated human detrusor muscles. Furthermore, temiverine and RCC-36 have significant inhibitory actions toward the atropine-resistant part of contractions, which may be related to the calcium antagonistic actions of these compounds.

Comparison of the effects of NS-21 and terodiline on the QTc interval in dogs

1. NS-21 [(+/-)-4-diethylamino-1,1-dimethylbut-2-yn-1-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate monohydrochloride monohydrate], its active metabolite, RCC-36, and terodiline, are mixed anticholinergic-Ca2+ antagonistic drugs. Among them, terodiline has been shown to cause torsade de pointes, a serious polymorphic ventricular tachycardia. It remains unknown, however, whether NS-21 or its active metabolite, RCC-36, produces torsade de pointes. 2. In anesthetized dogs, terodiline (10 mg/kg i.v.) significantly prolonged the QTc interval by 6-8%, an effect thought to be associated with torsade de pointes. In contrast, neither NS-21 nor RCC-36 (10 mg/kg i.v.) prolonged the QTc interval; therefore NS-21 is unlikely to cause ventricular tachyarrhythmias, such as those associated with terodiline. 3. The effects of NS-21, RCC-36 and terodiline on the action potential were investigated in guinea pig papillary muscle. However, none of these drugs prolonged the duration of the action potential, although only terodiline caused the muscle preparation to lose its excitability.

Effect of NS-21, an anticholinergic drug with calcium antagonistic activity, on lower urinary tract function in a rat model of urinary frequency

BACKGROUND

NS-21 is under development for the treatment of urinary frequency and urinary incontinence. The purpose of this study was to investigate the effects of NS-21 and its active metabolite, RCC-36, on lower urinary tract function in an experimental rat model of urinary frequency.

METHODS

Cystometrograms were recorded in anesthetized rats with bilaterally transected hypogastric nerves. All drugs were administered intraduodenally.

RESULTS

In sham-operated rats, NS-21 (> or = 50 mg/kg) significantly increased the bladder capacity without significantly decreasing micturition pressure, while RCC-36 (100 mg/kg) significantly increased bladder capacity, and at a dose of > or = 30 mg/kg, also caused a decrease in micturition pressure. This increase in bladder capacity appeared at lower doses of both NS-21 and RCC-36 in the hypogastric nerve-transected rats. Propiverine (100 mg/kg) increased bladder capacity and at > or = 30 mg/kg, decreased micturition pressure in both sham-operated and nerve-transected rats. Oxybutynin (100 mg/kg) and atropine (30 mg/kg) decreased the micturition pressure in both sham-operated and nerve-transected rats without increasing the bladder capacity, while a similar anticholinergic calcium antagonist, terodiline (100 mg/kg) had no effect on bladder capacity in either sham-operated or nerve-transected rats. Flavoxate (500 mg/kg) significantly increased bladder capacity without significantly decreasing micturition pressure in both sham-operated and nerve-transected rats, while 50 mg/kg of verapamil significantly increased bladder capacity without significantly decreasing the micturition pressure in nerve-transected rats.

CONCLUSIONS

NS-21 and RCC-36 increased bladder capacity at lower doses in hypogastric nerve-transected rats than in sham-operated rats. Furthermore, NS-21 increased the bladder capacity without suppressing micturition pressure, suggesting that NS-21 may be a more effective therapeutic drug than propiverine, oxybutynin or flavoxate for the treatment of urinary frequency and urinary incontinence.