Emerging drugs for treatment of overactive bladder and detrusor overactivity

Vitamin D levels and the risk of overactive bladder: a systematic review and meta-analysis

CONTEXT

Overactive bladder is treated mainly with behavioral and drug therapy, and symptoms of urinary frequency and incontinence are challenging to eliminate. There is thus a continuous unmet need for new drugs with a substitution effect mechanism.

OBJECTIVE

It not known whether vitamin D deficiency can lead to overactive bladder or urinary incontinence or whether vitamin D supplementation alleviates bladder symptoms. This comprehensive systematic review with meta-analysis was conducted to determine whether overactive bladder is associated with vitamin D deficiency.

DATA SOURCES

The PubMed and Cochrane Library databases were searched systematically up to July 3, 2022.

DATA EXTRACTION

Initially, 706 articles were identified in the literature search, of which 13 were included in the systematic review: 4 randomized controlled trials, 3 cohort studies, 3 cross-sectional studies, and 3 case-control studies.

DATA ANALYSIS

An increased risk of overactive bladder and urinary incontinence was observed with vitamin D deficiency (odds ratio [OR] = 4.46; 95%CI, 1.03-19.33; P = 0.046 and OR = 1.30; 95%CI, 1.01-1.66; P = 0.036, respectively). Vitamin D levels were relatively low in patients with overactive bladder or urinary incontinence (SMD = -0.33; 95%CI, -0.61 to -0.06, P = 0.019). On the basis of existing data, the risk of urinary incontinence was reduced by 66% after vitamin D supplementation (OR = 0.34; 95%CI, 0.18-0.66; P = 0.001). Egger test was conducted to assess publication bias, and the results were tested for robustness using a sensitivity analysis.

CONCLUSIONS

Vitamin D deficiency increases the risk of overactive bladder and urinary incontinence, and vitamin D supplementation reduces the risk of urinary incontinence. The development of new strategies to prevent or alleviate bladder symptoms is crucial. Vitamin D supplementation may be gaining recognition as an effective strategy for prevention or alleviation of bladder symptoms such as overactive bladder and incontinence.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022351443.

Emerging drugs for overactive bladder

INTRODUCTION

Overactive bladder (OAB) is a common problem which can have disastrous effects on the quality of life of the sufferer. There are established treatments for the problem but they have significant adverse effects. Better drugs and new treatment modalities are necessary to deal with OAB.

AREA COVERED

Antimuscarinics, mirabegron and intravesical injection of botulinum toxin A are established treatments for OAB. Sacral neuromodulation is more invasive but has been successful in treating OAB. Phase II and III trials are in progress for newer β3-agonists and various combinations of antimuscarinics, β3-agonists and antidiuretics. Targeted secretion inhibitors (TSI) can increase efficacy and reduce adverse effects. Liposome integrated botulinum toxin A has an advantage of effective administration by intravesical instillation. Both medicines are in Phase II trials. Many other drugs which have promising results are discussed.

EXPERT OPINION

Newer antimuscarinics have better tolerability. Long-term data for mirabegron has shown that it is more effective in severe OAB. Combination drugs may prove to be more effective with less adverse effects. Emerging treatments with TSI, lipotoxin and gene therapy appear promising.

Voltage-gated Na+ channel blockers reduce functional bladder capacity in the conscious spontaneously hypertensive rat

OBJECTIVE

To evaluate the consequence of pharmacologic inhibition of voltage-gated Na(+) channels (Nav) in the conscious rat, based on Nav having been implicated as modulators of rodent urodynamics using knockout as well as antisense oligodeoxynucleotide approaches.

METHODS

The urodynamic response to standard Nav blockers, lamotrigine, amitriptyline, mexiletine, and carbamazepine were evaluated using conscious, continuous-filling cystometry in spontaneously hypertensive rats (SHRs). As a selectivity evaluation, the activity of the Nav blockers at muscarinic receptors was assessed via effect on carbachol-evoked bladder contractions.

RESULTS

Lamotrigine, amitriptyline, mexiletine, and carbamazepine decreased peak micturition pressure, micturition interval, and void volume. These effects were markedly similar to observations with muscarinic antagonists. Therefore, we evaluated the selectivity of these agents against bladder muscarinic receptors. Lamotrigine, mexiletine, and carbamazepine had no effect on muscarinic bladder contractions, whereas amitriptyline displayed a robust antagonism of carbachol-induced contractility.

CONCLUSION

Three Nav blockers--lamotrigine, mexiletine, and carbamazepine--demonstrated a reduction in micturition pressure and functional bladder capacity, similar to previous observations with muscarinic antagonists. These 3 Nav blockers are free of muscarinic antagonism, consistent with their cystometric effects being mediated via their Nav blocking activities. The negative findings reported here with Nav blockers suggest that Nav channel blockade is unlikely to reflect an improved treatment strategy for bladder disorders over currently prescribed muscarinic antagonists.

Onabotulinum toxin a (botox®) in the treatment of neurogenic bladder overactivity

Botulinum toxin (BT) is a potent presynaptic neuromuscular blocking agent which induces selective, reversible muscle weakness for months when injected intramuscularly. During recent years BT has revolutionized the treatment of previously intractable symptoms of detrusor overactivity. Based on a systematic search of the PubMed database, a review of the current literature on the use of onabotulinum toxin A (Botox®) in the treatment of neurogenic detrusor overactivity is presented.

Onabotulinum toxin A proved to be highly effective in the majority of studies, even though a wide range of injection techniques and dosages were described. The onset of the effect usually appeared before 2 weeks, and reached a peak within 2-6 weeks, with the clinical effect being maintained for approximately 6-8 months, or even longer. Depending on the dose, a number of patients developed high residual volume and clean intermittent self/helper catheterization (CIC) may become necessary. Only a few side effects were described, and intravesical onabotulinum toxin A injection seems to be well tolerated. However, details on injection technique, dose interval between injections, etc. are still under debate and only a few randomized, placebo controlled studies have been published.

A novel pathway underlying the inhibitory effects of melatonin on isolated rat urinary bladder contraction

The aim of the present study was to elucidate the direct effects of melatonin on bladder activity and to determine the mechanisms responsible for the detrusor activity of melatonin in the isolated rat bladder. We evaluated the effects of melatonin on the contractions induced by phenylephrine (PE), acetylcholine (ACh), bethanechol (BCh), KCl, and electrical field stimulation (EFS) in 20 detrusor smooth muscle samples from Sprague-Dawley rats. To determine the mechanisms underlying the inhibitory responses to melatonin, melatonin-pretreated muscle strips were exposed to a calcium channel antagonist (verapamil), three potassium channel blockers [tetraethyl ammonium (TEA), 4-aminopyridine (4-AP), and glibenclamide], a direct voltage-dependent calcium channel opener (Bay K 8644), and a specific calcium/calmodulin-dependent kinase II (CaMKII) inhibitor (KN-93). Melatonin pretreatment (10^-8~10^-6 M) decreased the contractile responses induced by PE (10^-9~10^-4 M) and Ach (10^-9~10^-4 M) in a dose-dependent manner. Melatonin (10^-7 M) also blocked contraction induced by high KCl ([KCl]_ECF; 35 mM, 70 mM, 105 mM, and 140 mM) and EFS. Melatonin (10^-7 M) potentiated the relaxation response of the strips by verapamil, but other potassium channel blockers did not change melatonin activity. Melatonin pretreatment significantly decreased contractile responses induced by Bay K 8644 (10^-11~10^-7 M). KN-93 enhanced melatonin-induced relaxation. The present results suggest that melatonin can inhibit bladder smooth muscle contraction through a voltage-dependent, calcium-antagonistic mechanism and through the inhibition of the calmodulin/CaMKII system.

Pharmacologic therapy for the neurogenic bladder

This article is a review of the current and past literature on medical management of the neurogenic bladder, with a particular focus on spinal cord injury and multiple sclerosis. The use of antimuscarinics, αα-blocker, and tricyclic antidepressants and their combined use are discussed along with new therapies in human and animal trials.

Effects of combined use of trospium chloride and melatonin on in vitro contractility of rat urinary bladder

OBJECTIVES

To examine the effects of combined use of trospium chloride and melatonin on in vitro contractility of rat urinary bladder.

METHODS

Isolated bladder strips from 20 male Wistar rats were examined in an organ bath. Contractions were evoked by acetylcholine (ACh). Initially, effective concentrations of trospium and melatonin to inhibit the contractions were determined. We subsequently tested the effects of combined use of melatonin and trospium on agonist-induced contractions.

RESULTS

Exposure of bladder strips to 10 microM ACh significantly increased the contractions. After cumulative administration of increasing concentrations of trospium (1, 3, and 5 microM), agonist-induced contractions decreased significantly (P <.05). Similarly, the mean peak amplitude of contractions evoked by ACh was significantly inhibited by melatonin in a concentration-dependent manner (100, 200, and 300 microM) (P <.05). Further evaluation of the effects of combined use of trospium and melatonin on ACh-induced contractions of bladder strips revealed that one-tenth of initially applied dose of trospium (500 nM) in addition to the lowest inhibitory dose of melatonin (100 microM) significantly lowered both the peak amplitude and area under the contractility curve of contractions (P <.05).

CONCLUSIONS

Our results showed that combined use of low dose trospium and melatonin had strong in vitro inhibitory capability on agonist-induced contractions of rat bladder strips. The present findings may offer an insight into lowering the dose of an antimuscarinic by combining it with an antioxidant and endogenous hormone, melatonin.

Pharmacologic management of urinary incontinence, voiding dysfunction, and overactive bladder

Most drugs used in the treatment of urinary incontinence and voiding dysfunction in women modulate neuromuscular transmission in the urethra and bladder. Pharmacotherapy is the mainstay of treatment for overactive bladder. Although several different antimuscarinic medications are available for the treatment of overactive bladder, most have similar efficacy and tolerability. Pharmacotherapy has a limited role in the management of stress incontinence and voiding dysfunction in women. Newer drugs that target different mechanisms of action are being developed for the treatment of urinary incontinence and voiding dysfunction in women.

Prospective pharmacologic therapies for the overactive bladder

Lower urinary tract symptoms (LUTS), overactive bladder syndrome (OAB) and detrusor overactivity (DO) are all conditions that can have major effects on quality of life and social functioning. Antimuscarinic drugs are first-line treatment-they often have good initial response rates, but adverse effects and decreasing efficacy cause long-term compliance problems, and alternatives are needed. The recognition of the functional contribution of the urothelium, the spontaneous myocyte activity during bladder filling, and the diversity of nerve transmitters has sparked interest in both peripheral and central modulation of LUTS/OAB/DO pathophysiology. There may be several new possibilities to treat LUTS/OAB/DO. β(3)-AR agonists (YM178), PDE 5 inhibitors (sildenafil, tadalafil, vardenafil), vitamin D analogs (elocalcitol), combinations (α(1)-AR antagonist + antimuscarinic), and drugs with a central mode of action (tramadol, aprepitant) all have Randomized controlled trial (RCT) documented efficacy. Which of these therapeutic principles will be developed to clinically useful treatments remains to be established.