Predictive factors for the effect of the α1-D/A adrenoceptor antagonist naftopidil on subjective and objective criteria in patients with neurogenic lower urinary tract dysfunction

Effects of an alpha-1d adrenoreceptor antagonist (naftopidil) on bladder dysfunction after radiotherapy in female rats

PURPOSE

Storage-phase bladder dysfunction can develop after pelvic radiotherapy. As the alpha-1d adrenoreceptor (a1d-AR) is dominant in the human detrusor, we aimed to investigate the effect of an a1d-AR antagonist on bladder dysfunction after pelvic radiotherapy in a rat model.

MATERIALS AND METHODS

Twenty-four female Wistar rats were used. Eight rats (14-15 weeks, 250-300 g) were randomized to three groups (normal reference group, radiation alone group and radiation plus naftopidil group). An 18-Gy dose of radiotherapy was applied to the radiation alone and radiation plus naftopidil groups. Naftopidil (20 mg/kg) was administered daily to the radiation plus naftopidil group. Four weeks after radiation, all rats underwent cystometry and were killed for reverse transcription polymerase chain reaction to detect mRNAs [a1d-AR, brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF)], Western blot to detect proteins (a1d-AR, extracellular-signal-regulated kinase, BDNF and VEGF) and immunohistochemistry.

RESULTS

Compared to the radiation alone group, (1) the decrease in the mRNA and protein expression of a1d-AR and VEGF was ameliorated, (2) the increase in the expression of BDNF mRNA and proteins such as extracellular-signal-regulated kinase and BDNF was suppressed, (3) submucosal thickness and vascularity on immunohistochemistry were improved, and (4) the baseline intravesical pressure and intercontraction interval in cystometry were ameliorated in the radiation plus naftopidil group.

CONCLUSION

Administration of an a1d-AR antagonist could improve storage-phase bladder dysfunction after radiotherapy not only by upregulating a1d-AR, which might decrease bladder compliance, but also by enhancing vascularity, which might protect the urinary bladder from chronic ischemic inflammation.

Efficacy and Safety of Naftopidil in Patients With Neurogenic Lower Urinary Tract Dysfunction: An 8-Week, Active-Controlled, Stratified-Randomized, Double-Blind, Double-Dummy, Parallel Group, Noninferiority, Multicenter Design

Purpose

The aim of this study was to evaluate the efficacy and safety of naftopidil compared with tamsulosin in patients with neurogenic lower urinary tract dysfunction (LUTD).

Methods

This study was conducted as an 8-week, active-controlled, stratified-randomized, double-blind, double-dummy, parallel group, noninferiority, and multicenter clinical trial. After 2 weeks of screening, eligible subjects were randomly assigned to receive naftopidil (25 mg for 1 week followed by 75 mg for 7 weeks) or tamsulosin (0.2 mg for 8 weeks). Primary endpoint was a change of International Prostatic Symptom Score (IPSS) total score after 8 weeks of treatment.

Results

One hundred ninety-four subjects with neurogenic LUTD were included into this trial. There were no differences between the 2 groups in baseline characteristics, including urodynamic study results, subtype of LUTD, pretreatment and concomitant medication, and causes of neurogenic bladder. The medication compliance rate was 94.0% (naftopidil, 93.6%; tamsulosin, 94.4%). There was a statistically significant decrease of IPSS total score at 8 weeks versus baseline in both the naftopidil (-5.64±0.66) and tamsulosin (-6.53±0.65) groups (P<0.0001 each). The mean difference between both groups was 0.89 (upper limit of 95% confidential interval, 2.72), which was lower than the noninferiority limit of 3 points. A subgroup analysis of neurologic lesions and sex found no mean difference of IPSS total score in each group. There was also no difference in safety profiles, including treatment emergent adverse events.

Conclusions

Naftopidil was not inferior to tamsulosin as a therapeutic drug for patients with neurogenic LUTD and had a similar safety profile.

Combination treatment with naftopidil increases the efficacy of radiotherapy in PC-3 human prostate cancer cells

PURPOSE

Clinically, radiotherapy (RT) often leads to the development of prostate cancer (PCa) resistance because of protective responses in cancer cells. One of the mechanisms includes the upregulation of RT-induced antioxidant enzymes. Thus, combination therapy with RT and certain pharmaceutical drugs targeting antioxidant enzymes may be ideal for increasing the efficacy of RT with minimum side effects. Naftopidil is a subtype-selective α_1D-adrenoceptor antagonist used for the treatment of benign prostatic hyperplasia (BPH). In our drug repositioning study, naftopidil showed not only unique growth-inhibitory effects but also AKT phosphorylation-inhibitory effects in PC-3 human PCa cells. Here, we examined the efficacy of additive naftopidil treatment in combination with RT in PC-3 cells.

METHODS

The effects of combination therapy with RT plus naftopidil were analyzed using an animal model of PC-3 xenografts in BALB/c nude mice. The expression of the antioxidant enzyme manganese superoxide dismutase (MnSOD) was evaluated by western blotting.

RESULTS

Combination therapy with RT plus naftopidil induced a more efficacious delay in PC-3 xenograft tumor growth as compared with monotherapy with naftopidil or RT. In PC-3 tumors, combination therapy with RT plus naftopidil suppressed the upregulation of RT-induced MnSOD expression. In vitro, neither AKT inhibitor IV nor naftopidil directly altered MnSOD expression. Upregulation of RT-induced MnSOD expression was markedly suppressed by combination treatment with RT plus AKT inhibitor IV or naftopidil.

CONCLUSIONS

These results suggest that additive naftopidil treatment in combination with RT may increase the efficacy of RT for the treatment of PCa.

[Neurology and the bladder: how to assess and manage neurogenic bladder dysfunction. With particular references to neural control of micturition]

Bladder dysfunctions are one of the most common features seen in the failure of the autonomic nervous system. Among those, overactive bladder (urinary urgency and frequency) worsens quality of life of the patients, and a large amount of post-voiding residual urine or urinary retention causes urinary tract infection, kidney dysfunction, and may bring renal failure. In the present paper we discussed neural control of micturition and how to assess it. Also, we proposed appropriate management of bladder dysfunction in elderly white matter lesions (a common cause of OAB) and diabetic neuropathy (a usual pathology underlying urinary retention). For OAB, anti-cholinergics are the mainstay, whereas for the pathological post-voiding residual urine or urinary retention, alpha-blockers, cholinergic agents and clean, intermittent self-catheterization are the choice. Treatment of bladder dysfunctions is the important target for maximizing patients' quality of life.

A 12-Week, Open Label, Multi-Center Study to Evaluate the Clinical Efficacy and Safety of Silodosin on Voiding Dysfunction in Patients with Neurogenic Bladder

OBJECTIVES

The purpose of this study is to evaluate clinical effect and safety of α1A -adrenoceptor blocker, silodosin, in patients with voiding dysfunction caused by neurogenic bladder.

METHODS

From April 2011 to January 2012, patients who were diagnosed as potential voiding dysfunction associated with neurogenic bladder, aged ≥ 20 years were enrolled. Silodosin (8 mg/day) was administered once daily in the morning with food. The efficacy was assessed at the baseline and after 12 weeks of the treatment having following parameters of international prostate symptom score and other measures including the maximum flow rate and the postvoid residual urine volume.

RESULTS

A total of 97 patients were screened and 95 were enrolled. Of these 95 patients, 82 patients were completed and included in analysis. After 12-weeks of treatment, mean total international prostate symptom score decreased significantly from 22.23 ± 6.80 to 14.98 ± 9.48 (P = 0.0002). Voiding symptoms and storage symptoms were also improved by decreasing in international prostate symptom score-QoL from 4.62 ± 0.92 to 3.48 ± 1.63 (P < 0.0001). Maximum flow rate increased significantly from 10.72 ± 2.66 to 15.14 ± 6.63 (P < 0.0001). The main adverse event was ejaculation disorder. No serious adverse events related to silodosin were noted.

CONCLUSIONS

This study indicates that silodosin was significantly effective, well tolerated and safe in patients who have voiding dysfunction associated with neurogenic bladder.

The role of naftopidil in the management of benign prostatic hyperplasia

Naftopidil, which to a certain extent shows an affinity to α1D-adrenoceptor subtype in addition to a high affinity to α1A-adrenoceptor, has been used for the treatment of benign prostatic obstruction and benign prostatic hyperplasia (BPH) associated lower urinary tract symptoms (LUTS). The aim of the present review is to systematically refer to the published studies on this unique agent for BPH. Based on a randomized prazosin-controlled study and another double-blind placebo-controlled study, which verified the dose-dependent effects of naftopidil, the Japanese Ministry of Health, Labor and Welfare approved naftopidil for treating men with BPH in 1996. Several tamsulosin-controlled studies have suggested treatment effects of naftopidil similar to those of tamsulosin and potentially higher efficacy for alleviating storage symptoms by naftopidil. Although well-designed, randomized studies are warranted to confirm the long-term outcomes and effector/target of naftopidil, the α1A-antagonist naftopidil, which also blocks α1D-adrenoceptor, improves voiding symptoms, and may also be useful for the management of men with storage symptoms represented by nocturia, retrieving their quality of life impaired by BPH-associated LUTS.

Bladder contractility and urethral resistance relation: what does a pressure flow study tell us?

Hydrodynamic analysis of a pressure flow study is the only reliable method to determine the presence or absence of a bladder outlet obstruction, especially benign prostatic obstruction. To interpret the results of pressure flow study in benign prostatic obstruction, understanding the outlines of the basic theory about evaluation of the relationship between bladder contractility and urethral resistance relation is of paramount importance. In contrast, hydrodynamic analysis of pressure flow study in conditions other than benign prostatic obstruction is complicated by the limits of theories about the hydrodynamics of the lower urinary tract. In this review, the proposed hydrodynamic theories about the relationship between bladder contractility and urethral resistance relation are outlined. Then, problems encountered in the application of hydrodynamic analysis of pressure flow study to diseases other than benign prostatic obstruction are discussed.