Antidiuretic effect of antimuscarinic agents in rat model depends on C-fibre afferent nerves in the bladder

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.

Urinary reabsorption in the rat kidney by anticholinergics

Anticholinergics, therapeutic agents for overactive bladder, are clinically suggested to reduce urine output. We investigated whether this effect is due to bladder or kidney urine reabsorption. Various solutions were injected into the bladder of urethane-anesthetized SD rats. The absorption rate for 2 h was examined following the intravenous administration of the anticholinergics imidafenacin (IM), atropine (AT), and tolterodine (TO). The bilateral ureter was then canulated and saline was administered to obtain a diuretic state. Anticholinergics or 1-deamino-[8-D-arginine]-vasopressin (dDAVP) were intravenously administered. After the IM and dDAVP administrations, the rat kidneys were immunostained with AQP2 antibody, and intracellular cAMP was measured. The absorption rate was ~ 10% of the saline injected into the bladder and constant even when anticholinergics were administered. The renal urine among peaked 2 h after the saline administration. Each of the anticholinergics significantly suppressed the urine production in a dose-dependent manner, as did dDAVP. IM and dDAVP increased the intracellular cAMP levels and caused the AQP2 molecule to localize to the collecting duct cells' luminal side. The urinary reabsorption mechanism through the bladder epithelium was not activated by anticholinergic administration. Thus, anticholinergics suppress urine production via an increase in urine reabsorption in the kidneys' collecting duct cells via AQP2.

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.

Imidafenacin exerts the antidiuretic effect by enhancing vasopressin-related responses in orally water-loaded rats

Imidafenacin, an antimuscarinic agent for treating overactive bladder, has an antidiuretic effect, but the detailed mechanisms of action remain unclear. The cholinergic and vasopressin systems are known to interact, for example, in the suppression of vasopressin-induced water reabsorption through muscarinic stimulation in the renal collecting duct. We, therefore, investigated whether vasopressin signaling pathway would participate in the antidiuretic effect of imidafenacin. In female Sprague-Dawley rats, urine production was measured by collecting urine from cystostomy chatheter using a Bollman restraining cage for 2h after drug i.v. injection and water load (25ml/kg p.o.). Both imidafenacin and a vasopressin V₂ receptor agonist desmopressin acetate (desmopressin) dose-dependently suppressed urine production. The combination of imidafenacin and desmopressin at the minimum effective doses suppressed the urine production more strongly than each alone. Mozavaptan hydrochloride (mozavaptan, 3mg/kg), a vasopressin V₂ receptor antagonist, completely inhibited the antidiuretic effects of imidafenacin and desmopressin at their respective minimum effective doses. The antidiuretic effect of desmopressin emerged at the maximum antidiuretic dose level (0.1µg/kg) even under mozavaptan-treatment, whereas that of imidafenacin (300µg/kg) was still kept suppressed by mozavaptan. When 300µg/kg imidafenacin was added to the combination of mozavaptan 3mg/kg and desmopressin 0.1µg/kg, the antidiuretic effect was further enhanced. The present study suggests that vasopressin signaling pathway participates in the antidiuretic effect of imidafenacin, and that imidafenacin exerts its antidiuretic effects by enhancing some part of the vasopressin signaling pathway in orally water-loaded rats.

Add-on anticholinergic therapy for residual nocturia in patients with lower urinary tract symptoms receiving α1-blocker treatment: a multi-centre, prospective, randomised study

PURPOSE

To evaluate the efficacy and safety of imidafenacin (IM), a novel short half-life anticholinergic, as add-on therapy for male LUTS with nocturia and nocturnal polyuria.

MATERIALS AND METHODS

This multicenter, prospective, randomized, open-labelled study was conducted and involved men who had frequency, urgency, and nocturia despite receiving a stable dose of α1-blocker for ≥1 month. Subjects were randomised to control (α1-blocker alone), IM twice/day (α1-blocker +0.1 mg imidafenacin twice daily), or IM nightly (α1-blocker plus 0.1 mg imidafenacin nightly) group; the treatment period was 8 weeks. Primary endpoints included improvements in night-time frequency and Nocturia Quality of Life Questionnaire (N-QOL) scores. Secondary endpoints included changes from the baseline in frequency volume chart variables, and post-void residual volume.

RESULTS AND LIMITATIONS

Compared with the controls, IM twice/day and IM nightly patients had a significantly lower night-time frequency (changes from baseline: 0.1 ± 0.8 in control, -0.6 ± 0.9 in IM twice/day, and -0.4 ± 1.0 in IM nightly, p = 0.5227, 0.0006 and 0.0143, respectively). The hours of undisturbed sleep and N-QOL score were significantly improved in IM twice/day group, though not IM nightly group. Nocturnal urine volume was significantly reduced in IM nightly group, although total urine volume remained unchanged.

CONCLUSIONS

A short half-life anticholinergic is suggested to be safe and effective as an add-on therapy for residual nocturia in patients with male LUTS receiving α1-blocker treatment. Anticholinergic administration nightly could reduce the nocturnal urine volume.

Muscarinic receptors mediate cold stress-induced detrusor overactivity in type 2 diabetes mellitus rats

OBJECTIVES

This study determined if muscarinic receptors could mediate the cold stress-induced detrusor overactivity induced in type 2 diabetes mellitus rats.

METHODS

Ten-week-old female Goto-Kakizaki diabetic rats (n = 12) and Wister Kyoto non-diabetic rats (n = 12) were maintained on a high-fat diet for 4 weeks. Cystometric investigations of the unanesthetized rats were carried out at room temperature (27 ± 2°C) for 20 min. They were intravenously administered imidafenacin (0.3 mg/kg, n = 6) or vehicle (n = 6). After 5 min, the rats were transferred to a low temperature (4 ± 2°C) for 40 min where the cystometry was continued. The rats were then returned to room temperature for the final cystometric measurements. Afterwards, expressions of bladder muscarinic receptor M3 and M2 messenger ribonucleic acids and proteins were assessed by reverse transcription polymerase chain reaction and immunohistochemistry.

RESULTS

In non-diabetic Wister Kyoto rats, imidafenacin did not reduce cold stress-induced detrusor overactivity. In diabetic Goto-Kakizaki rats, just after transfer to a low temperature, the cold stress-induced detrusor overactivity in imidafenacin-treated rats was reduced compared with vehicle-treated rats. Within the urinary bladders, the ratio of M3 to M2 receptor messenger ribonucleic acid in the diabetic Goto-Kakizaki rats was significantly higher than that of the non-diabetic Wister Kyoto rats. The proportion of muscarinic M3 receptor-positive area within the detrusor in diabetic Goto-Kakizaki rats was also significantly higher than that in non-diabetic Wister Kyoto rats.

CONCLUSIONS

Imidafenacin partially inhibits cold stress-induced detrusor overactivity in diabetic Goto-Kakizaki rats. In this animal model, muscarinic M3 receptors partially mediate cold stress-induced detrusor overactivity.

Imidafenacin, an antimuscarinic agent, improves nocturia and reduces nocturnal urine volume

OBJECTIVE

To evaluate the efficacy of imidafenacin for nocturia and nocturnal polyuria in patients with overactive bladder.

MATERIALS AND METHODS

A stratified analysis was conducted on data from a phase III randomized, double-blind, controlled trial of imidafenacin performed at 158 centers in Japan. The subjects received imidafenacin (0.1 mg) twice daily (group I) or placebo twice daily (group P). The 24-hour urine volume, daytime and nighttime voiding frequency, and volume voided/micturition were evaluated from 3-day voiding diaries recorded every 4 weeks during the 12-week study period. Longitudinal data analysis was performed, with all values expressed as the least squares mean ± standard error.

RESULTS

A total of 46 patients (mean age 66.54 ± 9.38 years, 9 men and 37 women) with nocturia and nocturnal polyuria (>33% of urine production at night) were enrolled. Group I (n = 35) and group P (n = 11) showed no baseline differences in the daily voided volume, concomitant diseases, age, or body weight. However, the average daily number of micturitions differed (11.22 ± 2.17 vs 14.45 ± 2.85). Therefore, longitudinal data analysis was performed for each micturition pattern. After 12 weeks of treatment, nighttime micturition was significantly less frequent in group I than in group P (P = .0292), and the nocturnal percentage of 24-hour production was significantly smaller (P = .0053). The interval to the first nighttime void was significantly longer in group I than in group P, but no difference was found in the first nighttime voided volume.

CONCLUSION

The novel antimuscarinic agent, imidafenacin, decreases the number of urinations and reduces nocturnal urine production, thereby improving both nocturia and nocturnal polyuria.