Effects of the phosphodiesterase 5 inhibitor Tadalafil on bladder function in a rat model of partial bladder outlet obstruction

Effects of tadalafil versus silodosin on voiding function in male patients with non-neurogenic detrusor underactivity: A comparative study using propensity score matching

OBJECTIVES

To investigate and compare the effects of tadalafil and silodosin on lower urinary tract symptoms and voiding functions in men with non-neurogenic detrusor underactivity.

METHODS

A total of 126 treatment-naive men with lower urinary tract symptoms diagnosed as non-neurogenic detrusor underactivity received tadalafil (5 mg/day) or silodosin (8 mg/day) for 12 months. After propensity score matching, parameter changes from before administration to 12 months since treatment initiation were assessed based on subjective symptoms and urodynamic findings, including bladder contractility index and maximum urinary flow rate, and were compared between the tadalafil treatment group and the silodosin group. Detrusor underactivity was defined as bladder contractility index <100 and bladder outlet obstruction index <40.

RESULTS

After propensity score matching, the final analysis included 48 patients each in the tadalafil and silodosin groups. No significant differences in prostate volume, subjective symptoms or urodynamic parameters were detected between the groups at baseline. Compared with baseline, significant improvements in subjective symptoms and storage and voiding functions were observed at month 12 in both groups. Maximum urinary flow rate significantly improved by 1.7 mL/s in the silodosin group and by 3.0 mL/s in the tadalafil group. In addition, the mean bladder contractility index increased from 80.0 to 86.1 in the silodosin group and from 77.9 to 97.6 in the tadalafil group. Improvements in maximum urinary flow rate and bladder contractility index were significantly superior in the tadalafil group.

CONCLUSIONS

Both tadalafil and silodosin significantly improve lower urinary tract symptoms and voiding function in patients with non-neurogenic detrusor underactivity. Furthermore, tadalafil is more effective than silodosin in improving bladder contractility index and maximum urinary flow rate.

Changes in the expression and function of the PDE5 pathway in the obstructed urinary bladder

Our study aims to explore changes in bladder contractility and the phosphodiesterase type 5 (PDE5) signalling pathway in response to partial bladder outlet obstruction (PBOO). A surgically induced male rat PBOO model and human obstructed bladder tissues were used. Histological changes were examined by H&E and Masson's trichrome staining. Bladder strip contractility was measured via organ bath. The expressions of nitric oxide synthase (NOS) isoforms, PDE5, muscarinic cholinergic receptor (CHRM) isoforms and PDE4 isoforms in bladder were detected by RT‐PCR and Western blotting. The immunolocalization of the PDE5 protein and its functional activity were also determined. PBOO bladder tissue exhibited significant SM hypertrophy and elevated responsiveness to KCl depolarization and the muscarinic receptor agonist carbachol. NOS isoforms, PDE5, CHRM2, CHRM3 and PDE4A were up‐regulated in obstructed bladder tissue, whereas no change in PDE4B and PDE4D isoform expression was observed. With regard to PDE5, it was expressed in the SM bundles of bladder. Interestingly, obstructed bladder exhibited less relaxation responsiveness to sodium nitroprusside (SNP), but an exaggerated PDE5 inhibition effect. The up‐regulation of PDE5 could contribute to the lack of effect on Q_max for benign prostatic hyperplasia/lower urinary tract symptom (BPH/LUTS) patients treated with PDE5 inhibitors. Moreover, PDE5 (with presence of NO) and PDE4 may serve as new therapeutic targets for bladder diseases such as BPH‐induced LUTS and overactive bladder (OAB).

Estrogen replacement is protective to the effect of in vitro hypoxia on female rabbit bladder and pelvic floor contractile response

Purpose

To explore the effect of estrogen replacement on pelvic floor and bladder contractile response to electrical field stimulation, following in vitro hypoxia in an animal model of surgical menopause.

Materials and Methods

Twelve female adult rabbits were divided into three groups: control, ovariectomy, and ovariectomy with estradiol replacement. At 4 weeks animals were euthanized. Bladder, coccygeus, and pubococcygeus were isolated. Tissues were equilibrated with oxygenated Tyrodes containing glucose and stimulated with electrical field stimulation. Tissues were then stimulated under hypoxic conditions for 1 hour using nitrogenated Tyrodes without glucose. Tissues were then re-oxygenated for 2 hours and stimulated.

Results

Pelvic floor required 10 times the stimulation duration (power) to achieve maximum contraction at 2 g baseline tension (10 ms duration) when compared to bladder (1 ms duration). Maximal tension generated was significantly greater for bladder than pelvic floor. Coccygeus and pubococcygeus were significantly less sensitive to the effects of hypoxia and had stable contractile response to field stimulation throughout the hour of hypoxia. Hypoxia resulted in progressive and rapid decline of bladder contractile strength. Following hypoxia, pelvic floor contractile recovery was superior to bladder. Improvement in the contractile response of both bladder and pelvic floor, during the period of post-hypoxia re-oxygenation, was significantly greater in ovariectomy animals treated with estradiol replacement.

Conclusions

Replacement of estradiol at time of ovariectomy reduced oxidative stress on tissue and was protective to the effects of hypoxia on pelvic floor and bladder contractile function.

Long-term tadalafil administration can prevent functional and structural changes of the urinary bladder in male rats with partial bladder outlet obstruction

AIMS

There have been few reports on whether long-term oral phosphodiesterase 5 inhibitor administration can ameliorate bladder changes due to bladder outlet obstruction (BOO). Therefore, we clarified the chronological changes of the bladder using male BOO rats and evaluated the effects of tadalafil on these changes.

METHODS

Eight-week-old male Sprague-Dawley rats were used. BOO was created by placing a polyethylene catheter around the urethra. Then, the rats were orally treated with a vehicle, or tadalafil 2 or 10 mg/kg until each evaluation period. Cystometric measurements were performed and the degree of fibrosis in the smooth muscle layer was evaluated at 2, 4, and 16 weeks.

RESULTS

In BOO rats, a significant increase in the number of non-voiding contractions (NVCs) and a shortened intercontraction interval (ICI) were observed in the earlier phase (2 and 4 weeks) compared to Sham rats. In the chronic phase (16 weeks), markedly increased residual urine volume and an extended ICI were observed accompanied by enhanced smooth muscle fibrosis. These results indicated that the bladder in BOO rats represented the overactive phenotype in the earlier phase and changed into the underactive phenotype in the chronic phase. Even in Sham rats, an increased number of NVCs and enhanced fibrosis were observed with time. Tadalafil administration significantly prevented these bladder changes in both BOO and Sham rats.

CONCLUSIONS

Long-term oral administration of tadalafil can prevent functional and histological changes in the BOO rat bladder. This agent is also effective for the bladder functional change even in non-obstructed rats.

Persistence Rate with Tadalafil for Treatment of Male Lower Urinary Tract Symptoms

OBJECTIVES

We examined the persistence rate with tadalafil for treatment of male lower urinary tract symptoms (LUTS) and explored the factors relevant to withdrawal.

PATIENTS AND METHODS

We retrospectively collected the data of male patients who received tadalafil treatment for LUTS. The persistence rate and the reason for withdrawal were investigated.

RESULTS

A total of 155 patients were examined. Mean age and mean observation period were 71.9 (48-93) years and 15.1 (1-52) months, respectively. During the observation period, 74 patients (48%) withdrew tadalafil. The Kaplan-Meier curve indicated a 58% persistence rate at 1 year. The reasons for withdrawal included insufficient efficacy (31 patients, 42%), adverse events (21 patients, 28%), or symptom improvement (8 patients, 11%). Patients who continued tadalafil were significantly younger than those who withdrew it due to insufficient efficiency (71.4 ± 9.6 vs. 74.9 ± 9.1 years).

CONCLUSIONS

Most patients withdrew tadalafil due to insufficient efficacy. Older patients are likely to withdraw the treatment because of insufficient efficacy, thus, tadalafil for male LUTS could be more effective for younger patients.

Evaluation of combined therapeutic effects of hydrogen sulfide donor sodium hydrogen sulfide and phosphodiesterase type-5 inhibitor tadalafil on erectile dysfunction in a partially bladder outlet obstructed rat model

AIMS

To evaluate the impacts of hydrogen sulfide (H₂ S) donor, sodium hydrogen sulfide (NaHS), and phosphodiesterase type-5 inhibitor (PDE5i), tadalafil per se and their combination treatment on partial bladder outlet obstruction (PBOO)-induced erectile dysfunction (ED).

METHODS

Sprague-Dawley rats were equally divided into five groups: (a) sham-operated control; (b) PBOO; (c) PBOO-treated with NaHS (5.6 mg/kg/day, ip); (d) PBOO-treated with tadalafil (2 mg/kg/day, oral); and (e) PBOO-treated with combination of NaHS and tadalafil. The obstruction was created by urethral ligation for 6 weeks. In vivo erectile responses, in vitro relaxant and contractile responses in penile tissue as well as protein expression of nitric oxide synthases (NOS), H₂ S synthesis enzymes, oxidative stress, hypoxia, fibrosis markers, and the smooth muscle/collagen ratio and apoptosis were analyzed.

RESULTS

Combined treatment entirely returned increased bladder mass, reduced erectile responses, relaxation responses to acetylcholine, and electrical field stimulation in obstructed rats, while partial amelioration was observed after mono-treatment. Decreased neuronal NOS and 3-mercaptopiruvate transferase enzyme expressions in penile tissue from obstructed rats were also entirely restored by the combined treatment. Mono-treatment partially improved increased hypoxia, oxidative stress, fibrosis markers, decreased smooth muscle mass, and H₂ S levels, while combined therapy completely recovered.

CONCLUSIONS

The combination therapy with H₂ S donor and PDE5i had positive effects on erectile responses through the improvement of ischemia-induced morphological and functional penile alterations in obstruction. H₂ S and NO may likely play a synergistic role in the regulation of erectile function and have constructive effects on clinical outcomes in male patients with ED and benign prostatic hyperplasia/lower urinary tract symptoms.

Effects of silodosin and tadalafil on bladder dysfunction in spontaneously hypertensive rats: Possible role of bladder blood flow

OBJECTIVES

To investigate the effects of an alpha1-adrenoceptor antagonist, silodosin, or a phosphodiesterase type 5 inhibitor, tadalafil, on bladder overactivity in spontaneously hypertensive rats.

METHODS

Twelve-week-old male spontaneously hypertensive rats were perorally administered silodosin (100 µg/kg), tadalafil (2 or 10 mg/kg) or vehicle once daily for 6 weeks. Wistar rats were used as normotensive controls and were treated with the vehicle. At 18-weeks-old, the effects of silodosin or tadalafil on blood pressure, bladder blood flow, urodynamic parameters (i.e. micturition frequency, urine output, inter-contraction interval, maximum voiding pressure, single voided volume and post-voiding residual urine volume), and bladder tissue levels of malondialdehyde, interleukin-6 and tumor necrosis factor-alpha were measured.

RESULTS

A significant increase in blood pressure, micturition frequency and bladder tissue levels of malondialdehyde, interleukin-6 and tumor necrosis factor-alpha was noted in spontaneously hypertensive rats. The single voided volume, bladder capacity and bladder blood flow were significantly lower in the spontaneously hypertensive rats than in the Wistar rats. Treatment with silodosin and the higher dose of tadalafil improved the urodynamic parameters, bladder blood flow and bladder tissue levels of malondialdehyde in the spontaneously hypertensive rats without affecting the blood pressure and bladder tissue levels of interleukin-6 and tumor necrosis factor-alpha.

CONCLUSIONS

Treatment with silodosin or tadalafil might improve hypertension-related bladder overactivity, as shown in spontaneously hypertensive rats through an improvement in the bladder blood flow and bladder tissue levels of oxidative stress.

A phosphodiesterase 5 inhibitor, tadalafil, suppresses stromal predominance and inflammation in a rat model of nonbacterial prostatitis

BACKGROUND

Chronic inflammation is thought to be a major causative factor for the development of benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS). Tadalafil, a phosphodiesterase type 5 inhibitor (PDE5-I), which has been used for the treatment of BPH-LUTS in daily practice, is known to act at several urinary organs. In this study, focused on the prostate, we examined the effect of tadalafil on the pathological changes and inflammatory factors in a rat nonbacterial prostatitis (NBP) model.

METHODS

Forty ten-month-old male Wistar rats were divided into nonbacterial prostatitis (NBP), NBP with tadalafil treatment (NBP-tadalafil), control, and control treated with tadalafil (control-tadalafil) groups (n = 10 per group). The NBP and NBP-tadalafil groups were castrated and then received daily subcutaneous 17β-estradiol for 30 days. The control-tadalafil and NBP-tadalafil groups were administered daily oral tadalafil for 30 days. All rats were then sacrificed and pathological changes and inflammatory factors were assessed in the prostatic tissues.

RESULTS

In the NBP group, the stroma-to-epithelium (S/E) ratio in the ventral prostate was significantly higher than in the control group (P < 0.001). In the NBP-tadalafil group, the S/E ratio was significantly lower than in the NBP group (P < 0.001). The macrophage levels and the extent of T-cell infiltration in the NBP-tadalafil group were significantly lower than in the NBP group (P < 0.005; P < 0.001, respectively). Compared with the NBP group, tissue concentrations of inflammatory cytokines, such as tumor necrosis factor-α, interleukin-8, and interleukin-1β, were significantly downregulated in the NBP-tadalafil group (P < 0.01; P < 0.05; P < 0.005, respectively).

CONCLUSIONS

Tadalafil suppressed stromal predominance and showed anti-inflammatory effects in a rat NBP model in association with downregulation of inflammatory cytokines.

Combination phosphodiesterase type 4 inhibitor and phosphodiesterase type 5 inhibitor treatment reduces non-voiding contraction in a rat model of overactive bladder

Introduction

Current treatments for overactive bladder (OAB) are often discontinued due to side effects or lack of efficacy. The goal of this study was to determine if combining a phosphodiesterase type 4 inhibitor (PDE4i); with a type 5 inhibitor (PDE5i); would have a beneficial effect on OAB symptoms and if a reduced dose of PDE4i in combination with PDE5i could also provide a beneficial effect in OAB. We hypothesized that PDE5i and PDE4i combination treatment could be utilized to reduce non-voiding contractions and smooth muscle disruption in a rat model of OAB.

Methods

Fifty-eight age-matched Sprague-Dawley rats underwent PBOO and daily gavage with PDE4i alone (roflumilast; 1mg/kg), PDE5i alone (tadalafil;10mg/kg), high dose combination (PDE4i 1mg/kg, PDE5i 10mg/kg), low dose combination (PDE4i 0.2mg/kg, PDE5i 10mg/kg), or vehicle for 28 days. Fourteen animals underwent sham PBOO with vehicle. Rats underwent conscious and anesthetized cystometry 28 days after PBOO and were euthanized for qualitative bladder histology. One-way ANOVA on ranks with a Dunn’s post hoc test was used to indicate statistically significant differences between groups (p<0.05).

Results

Bladder & urethral weight was significantly increased after PBOO with vehicle, PDE4i alone, and PDE5i alone, but not with either combination treatment. Frequency of non-voiding contractions during both conscious and anesthetized cystometry increased significantly after PBOO with vehicle, but not after PDE4i or high dose combination treatments compared to sham PBOO. Threshold pressure for voiding was significantly decreased with high dose combination compared to vehicle. PBOO treated with PDE4i alone or high dose combination showed less bladder smooth muscle fibrosis than vehicle, PDE5i alone, or low dose combination treatments.

Conclusion

A PDE4i and PDE5i combination treatment has potential benefit in reducing OAB symptoms, but future research is needed.

Mirabegron elicits rat corpus cavernosum relaxation and increases in vivo erectile response

Mirabegron is the first β3-adrenoceptor agonist approved on the market and may offer beneficial pharmacological action in patients with overactive bladder and erectile dysfunction. Here, we further investigate the mechanisms by which mirabegron induces rat corpus cavernosum (CC) relaxation. Adult male Wistar rats were used. The CC were isolated for in vitro functional assays and β-adrenoceptors subtypes mRNA expression evaluation. Animals were treated orally with mirabegron (30 mg/kg, 3 h), tadalafil (10 mg/kg, 3 h) or both for intracavernous pressure (ICP). Intracellular levels of cAMP and cGMP were also determined. The β₁-, β₂- and β₃-adrenoceptors subtypes were expressed in rat CC. Mirabegron produced concentration-dependent CC relaxations that were unaffected by the β₁-, β₂- or β₃-adrenoceptor antagonists atenolol (1 μM), ICI-118,551 (1 μM) and L748,337 (10 μM), respectively. Mirabegron-induced relaxations were not affected by the phosphodiesterase type 4 inhibitor, rolipram, or the adenylyl cyclase selective inhibitor, SQ 22,536. Potassium channel- or calcium influx-blockade are not involved in mirabegron-induced relaxations. In contrast, mirabegron produced rightward shifts in the contractile response induced by the α1-adrenoceptor agonist, phenylephrine. Finally, cavernous nerve stimulation caused frequency-dependent ICP increases, which were significantly increased in rats treated with mirabegron in a similar degree of tadalafil-treated rat, without promoting a significant cAMP or cGMP accumulation. Together, our results demonstrate that mirabegron induced CC relaxation through α1-adrenoceptor blockade. Care should be taken to translate the effect of mirabegron into the clinic, especially when using rat as an animal model of erectile dysfunction.

Effect of Sulforaphane on Bladder Compliance in a Rat Model of Partial Bladder Outlet Obstruction

Aims

To investigate the effect of Nrf2 activator sulforaphane (SFN) on bladder compliance and the underlying mechanisms in a rat model of partial bladder outlet obstruction (BOO).

Methods

Male 8-week-old Sprague-Dawley rats were divided into three groups. BOO rats were given daily 0.5 mg/kg sulforaphane (BOO+SFN) or vehicle (BOO) intraperitoneally for 4 weeks, while sham-operated rats were treated with vehicle (Sham). Bladder compliance, histological alteration, and collagen deposition were evaluated. The expression levels of collagen I, collagen III, MMP-1, and TIMP-1 were measured by immunohistochemistry and western blotting.

Results

BOO led to a significant decrease in bladder compliance. The change was partially restored by SFN treatment. The expression of MMP-1 was significantly decreased accompanying with increased TIMP-1 expression in BOO rats compared with that in Sham rats, which was ameliorated by SFN treatment. Moreover, the increased collagen I/collagen III ratio in the BOO group was reversed by SFN treatment.

Conclusions

Sulforaphane suppressed collagen deposition by regulating the MMP-1 and TIMP-1 expression and decreasing the collagen I/III expression ratio in BOO rats and improved bladder compliance.

Urine miR-21-5p as a potential biomarker for predicting effectiveness of tadalafil in benign prostatic hyperplasia

Aim:

To investigate whether urine levels of miRNAs that regulate the function of endothelial cells are associated with effectiveness in benign prostatic hyperplasia (BPH) patients treated with a phosphodiesterase type 5 inhibitor, tadalafil.

Patients & methods:

We measured urine levels of three miRNAs (miR-21-5p, miR-126-5p & miR-155-5p) in 55 BPH patients before and after tadalafil administration to understand its effectiveness.

Results:

Baseline urine miR-21-5p level was an independent predictor of response to tadalafil in multivariate regression analysis (odds ratio: 0.28; 95% CI: 0.10–0.77; p = 0.014). Receiver operator curve analysis revealed that baseline urine miR-21-5p could serve as a predictor of response (area under curve: 0.85; 95% CI: 0.75–0.95; p < 0.001).

Conclusion:

Urine miR-21-5p could serve as a biomarker in predicting response of tadalafil for BPH.

Tadalafil, a phosphodiesterase type 5 inhibitor, has a high potential for treating male lower urinary tract symptoms; however, there are few reports regarding which portion of the population is appropriate for treatment with tadalafil. This study showed that the baseline urine levels of miR-21-5p, an endothelium-associated miRNA, strongly correlates with response to tadalafil and have the potential to be a predictive biomarker of whether treatment with tadalafil is suitable.

Add-on Therapy With the α-Blockers Tamsulosin and Naftopidil Improves Voiding Function by Enhancing Neuronal Activity in Prostatic Hyperplasia Rats

Purpose

Benign prostatic hyperplasia (BPH) impacts quality of life in men by causing lower urinary tract symptoms. α1-Adrenoceptor (α1-AR) blockers improve lower urinary tract symptoms. We investigated the efficacy of add-on therapy with α1-AR blockers on BPH rats.

Methods

Rats in the drug-treated groups were orally administered each drug once a day for 30 days after orchiectomy. To induce BPH, rats were castrated and testosterone (20 mg/kg) was injected subcutaneously once per day for 30 days. Cystometry was conducted to measure voiding contraction pressure and the interval contraction time, immunohistochemistry was performed to measure c-Fos and nerve growth factor (NGF) expression in the neuronal voiding centers, and nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry was used to measure nitric oxide synthase (NOS) expression.

Results

Orchiectomy and testosterone injection decreased voiding contraction pressure and the interval contraction time, suggesting BPH symptoms. Voiding contraction pressure and the interval contraction time were greater in the group that received the combination treatment (tamsulosin with naftopidil) than in the tamsulosin monotherapy or naftopidil monotherapy groups. c-Fos, NGF, and NOS expression in the neuronal voiding centers was enhanced by BPH induction. c-Fos, NGF, and NOS expression was suppressed by the combination treatment (tamsulosin with naftopidil) to a greater extent than was the case for tamsulosin monotherapy or naftopidil monotherapy.

Conclusions

Combination therapy of tamsulosin and naftopidil showed greater efficacy for the treatment of BPH than tamsulosin monotherapy or naftopidil monotherapy; therefore, combination therapy can be considered as a novel therapeutic method for BPH.

Effects of varying degrees of partial bladder outlet obstruction on urinary bladder function of rats: A novel link to inflammation, oxidative stress and hypoxia

OBJECTIVES

The aim of the present study was to investigate the effects of different degrees of obstruction, and the roles of inflammation, oxidative stress, and hypoxia parameters on bladder function.

METHODS

Thirty male Sprague-Dawley rats were divided into 3 groups (n = 10 in each group): (i) sham-operated control; (ii) severe partial bladder outlet obstruction (PBOO); and (iii) moderate PBOO. Severe and moderate PBOO were induced by urethral ligation using 3-Fr and 4-Fr catheters, respectively, for 6 weeks. After 6 weeks, the in vitro contractile responses to carbachol, electrical field stimulation, ATP and KCl were measured in bladder strips. In addition, mRNA and protein expression of nuclear factor kappa B (NF-κB) hypoxia-inducible factor (HIF) and nuclear factor, erythroid 2-like 2 (Nrf2) in bladder were determined by real-time polymerase chain reaction and western blotting. Malondialdehyde (MDA) levels in bladder tissues were also determined.

RESULTS

Rats in the severe PBOO group had the highest bladder weight. Detrusor strips from rats in the severe PBOO group exhibited 61%-82% smaller contractile responses to all four stimuli than those from the sham-operated group. Activity of NF-κB as an inflammatory marker was increased in the severe PBOO group, whereas HIF-1α and HIF-2β protein levels were increased significantly in the moderate PBOO group. A master regulator of oxidative stress, Nrf2 expression was increased in all obstructed rats. MDA levels were higher in the severe PBOO group than in sham-operated group.

CONCLUSION

The results of the present study reveal the importance of oxidative stress-induced NF-κB signaling in bladder dysfunction with severe obstruction. Altered HIF signaling may contribute to the functional impairment after PBOO. Novel and evolving therapies targeting oxidative and/or inflammatory pathways may be a reasonable strategy for the management of lower urinary tract symptoms or benign prostatic hyperplasia.

Lower urinary tract symptoms/benign prostatic hypertrophy and vascular function: Role of the nitric oxide-phosphodiesterase type 5-cyclic guanosine 3',5'-monophosphate pathway

It is well known that there is an association of lower urinary tract symptoms/benign prostatic hypertrophy with cardiovascular disease, suggesting that lower urinary tract symptoms/benign prostatic hypertrophy is a risk factor for cardiovascular events. Vascular function, including endothelial function and vascular smooth muscle function, is involved in the pathogenesis, maintenance and development of atherosclerosis, leading to cardiovascular events. Vascular dysfunction per se should also contribute to lower urinary tract symptoms/benign prostatic hypertrophy. Both lower urinary tract symptoms/benign prostatic hypertrophy and vascular dysfunction have cardiovascular risk factors, such as hypertension, dyslipidemia, diabetes mellitus, aging, obesity and smoking. Inactivation of the phosphodiesterase type 5-cyclic guanosine 3',5'-monophosphate-nitric oxide pathway causes lower urinary tract symptoms/benign prostatic hypertrophy through an enhancement of sympathetic nervous activity, endothelial dysfunction, increase in Rho-associated kinase activity and vasoconstriction, and decrease in blood flow of pelvic viscera. Both endogenous nitric oxide and exogenous nitric oxide act as vasodilators on vascular smooth muscle cells through an increase in the content of cyclic guanosine 3',5'-monophosphate, which is inactivated by phosphodiesterase type 5. In a clinical setting, phosphodiesterase type 5 inhibitors are widely used in patients with lower urinary tract symptoms/benign prostatic hypertrophy. Phosphodiesterase type 5 inhibitors might have beneficial effects on vascular function through not only inhibition of cyclic guanosine 3',5'-monophosphate degradation, but also increases in testosterone levels and nitric oxide bioavailability, increase in the number and improvement of the function of endothelial progenitor cells, and decrease in insulin resistance. In the present review, the relationships between lower urinary tract symptoms/benign prostatic hypertrophy, the phosphodiesterase type 5-nitric oxide-cyclic guanosine 3',5'-monophosphate pathway, vascular function and cardiovascular outcomes are examined.

Latest Evidence on the Use of Phosphodiesterase Type 5 Inhibitors for the Treatment of Lower Urinary Tract Symptoms Secondary to Benign Prostatic Hyperplasia

CONTEXT

Several preclinical reports, randomized controlled trials, systematic reviews, and posthoc analyses corroborate the role of phosphodiesterase type 5 inhibitors (PDE5-Is) in the treatment of men with lower urinary tract symptoms (LUTS) associated with benign prostatic enlargement (BPE).

OBJECTIVE

Update of the latest evidence on the mechanisms of action, evaluate the current meta-analyses, and emphasize the results of pooled data analyses of PDE5-Is in LUTS/BPE.

EVIDENCE ACQUISITION

Literature analysis of basic researches on PDE5-Is, systematic literature search in PubMed and Scopus until May 2015 on reviews of trials on PDE5-Is, and collection of pooled data available on tadalafil 5mg.

EVIDENCE SYNTHESIS

Latest evidences on the pathophysiology of LUTS/BPE has provided the rationale for use of PDE5-Is: (1) improvement of LUT oxygenation, (2) smooth muscle relaxation, (3) negative regulation of proliferation and transdifferentiation of LUT stroma, (4) reduction of bladder afferent nerve activity, and (5) down-regulation of prostate inflammation are the proven mechanisms of action of PDE5-Is. Data from eight systematic reviews demonstrated that PDE5-Is allow to improve LUTS (International Prostate Symptom Score mean difference vs placebo: 2.35-4.21) and erectile function (International Index of Erectile Function mean difference vs placebo: 2.25-5.66), with negligible change in flow rate (Qmax mean difference vs placebo: 0.01-1.43). Pooled data analyses revealed that tadalafil 5mg once daily allows the clinically-meaningful improvement of LUTS and nocturnal voiding frequency independent of both erectile dysfunction severity and improvement.

CONCLUSIONS

PDE5-Is are safe and effective in improving both LUTS and erectile function in appropriately selected men with LUTS/BPE. Data on the reduction of disease progression, long-term outcomes, and cost-effectiveness analyses are still lacking.

PATIENT SUMMARY

We reviewed recent literature on phosphodiesterase type 5 inhibitors in men with lower urinary tract symptoms associated with prostatic enlargement. We found evidence to confirm that phosphodiesterase type 5 inhibitors are a valid treatment option for men affected by bothersome urinary symptoms with or without erectile dysfunction.