Phosphodiesterase-5 inhibitors and benign prostatic hyperplasia:

Activation of the cGMP/PKG/ERK signaling pathway associated with PDE5Is inhibits fibroblast activation by downregulating autophagy in early progressive benign prostatic hyperplasia

PURPOSE

Benign prostatic hyperplasia (BPH) is one of the most prevalent diseases affecting aging males. However, approximately, 8% of the BPH patients under 50-year-old experience remarkably early progression, for reasons that remain elusive. Among the various factors implicated in promoting BPH advancement, the activation of fibroblasts and autophagy hold particular importance. Our research endeavors to explore the mechanisms behind the accelerated progression in these patients.

METHODS

Immunohistochemistry and immunofluorescence were performed to detect the expression levels of LC3, p62, PDE5, and α-SMA in diverse BPH tissues and prostate stromal cells. The autophagy activator rapamycin, the autophagy suppressor chloroquine, and siRNA transfection were used to identify the impact of autophagy on fibroblast activation.

RESULTS

Prostatic stromal fibroblasts in early progressive BPH tissues displayed activation of autophagy with an upregulation of LC3 and a concurrent downregulation of p62. After starvation or rapamycin treatment to a heightened level of autophagy, fibroblasts exhibited activation. Conversely, chloroquine treatment and ATG-7-knockdown effectively suppressed the level of autophagy and fibroblast activation. High expression of PDE5 was found in early progressive BPH stromal cells. The administration of PDE5 inhibitors (PDE5Is) hindered fibroblast activation through suppressing autophagy by inhibiting the ERK signaling pathway.

CONCLUSION

Our findings suggest that autophagy plays a pivotal role in promoting BPH progression through fibroblast activation, while PDE5Is effectively suppress autophagy and fibroblast activation via the ERK signaling pathway. Nevertheless, further investigations are warranted to comprehensively elucidate the role of autophagy in BPH progression.

Phosphodiesterase as a Target for Cognition Enhancement in Schizophrenia

Schizophrenia is a severe mental disorder that affects more than 1% of the population worldwide. Dopamine system dysfunction and alterations in glutamatergic neurotransmission are strongly implicated in the aetiology of schizophrenia. To date, antipsychotic drugs are the only available treatment for the symptoms of schizophrenia. These medications, which act as D2-receptor antagonist, adequately address the positive symptoms of the disease, but they fail to improve the negative symptoms and cognitive impairment. In schizophrenia, cognitive impairment is a core feature of the disorder. Therefore, the treatment of cognitive impairment and the other symptoms related to schizophrenia remains a significant unmet medical need. Currently, phosphodiesterases (PDEs) are considered the best drug target for the treatment of schizophrenia since many PDE subfamilies are abundant in the brain regions that are relevant to cognition. Thus, this review aims to illustrate the mechanism of PDEs in treating the symptoms of schizophrenia and summarises the encouraging results of PDE inhibitors as anti-schizophrenic drugs in preclinical and clinical studies.

New drugs are not enough‑drug repositioning in oncology: An update

Drug repositioning refers to the concept of discovering novel clinical benefits of drugs that are already known for use treating other diseases. The advantages of this are that several important drug characteristics are already established (including efficacy, pharmacokinetics, pharmacodynamics and toxicity), making the process of research for a putative drug quicker and less costly. Drug repositioning in oncology has received extensive focus. The present review summarizes the most prominent examples of drug repositioning for the treatment of cancer, taking into consideration their primary use, proposed anticancer mechanisms and current development status.

Efficacy of Tadalafil Therapy and Changes in Oxidative Stress Levels in Male Patients with Lower Urinary Tract Symptoms and Overactive Bladder

Objective

To evaluate the effects of tadalafil monotherapy on lower urinary tract symptoms, urodynamic parameters, and oxidative stress levels in male patients.

Methods

This prospective study included 53 male patients with urinary symptoms, who met the criteria for overactive bladder (OAB) (≥ 2 points for Q3 [urgency] in the OAB symptom score [OABSS] assessment and ≥ 3 points for the total score). The patients received 5 mg tadalafil orally once daily, and their symptoms were assessed before and after the 12‐week treatment. The OABSS and international prostate symptom score (IPSS) were used to evaluate the subjective symptoms. The objective findings were assessed using uroflowmetry. Oxidative stress was assessed by determining urinary levels of 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG) levels with an adjustment for urinary creatinine (CR) concentration.

Results

After tadalafil administration, total and individual indices of the OABSS assessment showed significant improvement. In addition, total storage and voiding symptoms that contributed to the IPSS were also significantly improved. The voided volume was increased, and the maximum flow rate was improved after tadalafil treatment (P = .002 and < 0.001, respectively). Urinary 8‐OHdG/CR decreased from 12.4 ± 9.7 ng/mg CR to 7.6 ± 11.6 ng/mg CR (P < .001). In patients who showed OAB improvement and did not meet the criteria for OAB after the treatment (44 patients, 83.0%), the urinary 8‐OHdG/CR level was significantly decreased from 11.6 ± 8.4 ng/mg CR to 6.4 ± 10.3 ng/mg CR (P < .001).

Conclusions

Tadalafil treatment improves OAB symptoms and urodynamic parameters by decreasing oxidative stress level.

Links between lower urinary tract symptoms, intermittent hypoxia and diabetes: Causes or cures?

Bothersome lower urinary tract symptoms (LUTS) manifest as urinary frequency, urgency, incontinence and incomplete bladder emptying. Existing treatments ameliorate but do not eliminate most symptoms, leading to financial and personal burdens attributable to sustained medical therapies that may last a lifetime. The purpose of this review is to highlight evidence of causal associations between LUTS and several common comorbidities, including intermittent hypoxia (IH) concomitant with obstructive sleep apnea (OSA), obesity, metabolic syndrome and type 2 diabetes. Links between these conditions, including therapies targeted to co-occurring complications that have demonstrated benefits for LUTS, suggest compelling avenues of research and also underscore critical gaps in understanding the mechanisms underlying urinary dysfunction. These gaps are prominent in the IH field, where an acknowledged link between OSA and LUTS has gone largely uninvestigated. New tools, models, or reappropriation of existing ones, especially rodent models, is required to parse the associations between IH/OSA, LUTS and obesity/diabetes and to elucidate their underlying, and potentially shared, etiologies.

Investigation of Interactive Activity of Electro-Acupuncture on Pharmacokinetics of Sildenafil and Their Synergistic Effect on Penile Blood Flow in Rats

Erectile dysfunction (ED) is a disorder found in males throughout the world, which negatively affects relationships with partners with advancing age. Hence, in this study, we tested a combined novel treatment of electro-acupuncture (EA) and sildenafil citrate against ED. In addition to EA therapy, the sildenafil citrate, a phosphodiesterase 5 inhibitor, is a widely recognized drug that has achieved considerable success in the treatment of ED. However, the combined effect of both the EA and sildenafil has not yet been investigated. Hence, we aimed to examine the effect of EA on the pharmacokinetics and pharmacodynamics of sildenafil in rat plasma. The pharmacokinetic parameters were determined using ultra performance liquid chromatography (UPLC) after EA and sildenafil administration (10 mg/Kg). Following this, the pharmacodynamics was studied via blood flow pattern using developing Doppler images of the lower body and penis. The pharmacokinetic studies demonstrated that sildenafil significantly increases by administration of low-frequency EA. Further, the pharmacodynamic studies using Doppler imaging revealed an elevated blood flow in rat penis compared with lower body during combined treatment of sildenafil and low-frequency EA. These data indicate a synergistic therapeutic effect of EA and sildenafil for the treatment of ED.

Factors affecting the efficacy and safety of phosphodiesterase 5 inhibitor and placebo in treatment for lower urinary tract symptoms: meta-analysis and meta-regression

PURPOSE

We aimed to investigate the real benefit and safety of phosphodiesterase 5 inhibitor (PDE 5I) for benign prostatic hyperplasia/lower urinary tract symptoms (BPH/LUTS) by determining the affecting factors and to overcome the previous meta-analysis studies.

METHODS

We conducted a systematic review of improvements in LUTS using International Prostate Symptom Score (IPSS), voiding subscore of IPSS (voiding IPSS), storage subscore of IPSS (storage IPSS), quality of life (QoL), maximal urinary flow rate (Qmax), and post-voided residual volume (PVR), and also investigated adverse events and relevant withdrawal rate.

RESULTS

Final included studies were 28 studies with 19,820 subjects (9800 treatment group and 10,020 control group). The overall weighted mean differences of total IPSS, voiding IPSS, storage IPSS, and QoL showed significant improvement. Single placebo group showed significant improvement in all outcomes except PVR. The weighted prevalence of overall withdrawal rate and adverse event-specific withdrawal rate was 10 and 3%, respectively. Meta-regression showed that baseline IPSS, dosage of PDE 5I, and country affect clinical improvement compared with placebo.

CONCLUSIONS

This study clarifies the efficacy of PDE 5I on treatment of BPH/LUTS as an initial treatment strategy. However, baseline IPSS, dosage of PDE 5I and country affected the clinical improvement. Moreover, adverse event-specific withdrawal rate was not as high as suspected based on the overall withdrawal rate.

Phosphodiesterase type 5 and cancers: progress and challenges

Cancers are an extraordinarily heterogeneous collection of diseases with distinct genetic profiles and biological features that directly influence response patterns to various treatment strategies as well as clinical outcomes. Nevertheless, our growing understanding of cancer cell biology and tumor progression is gradually leading towards rational, tailored medical treatments designed to destroy cancer cells by exploiting the unique cellular pathways that distinguish them from normal healthy counterparts. Recently, inhibition of the activity of phosphodiesterase type 5 (PDE5) is emerging as a promising approach to restore normal intracellular cyclic guanosine monophosphate (cGMP) signalling, and thereby resulting into the activation of various downstream molecules to inhibit proliferation, motility and invasion of certain cancer cells. In this review, we present an overview of the experimental and clinical evidences highlighting the role of PDE5 in the pathogenesis and prevention of various malignancies. Current data are still not sufficient to draw conclusive statements for cancer patient management, but could provide further rational for testing PDE5-targeting drugs as anticancer agents in clinical settings.

The regulation of transient receptor potential canonical 4 (TRPC4) channel by phosphodiesterase 5 inhibitor via the cyclic guanosine 3'5'-monophosphate

The transient receptor potential (TRP) protein superfamily consists of a diverse group of cation channels that bear structural similarities to the fruit fly Drosophila TRP. The TRP superfamily is distinct from other groups of ion channels in displaying a large diversity in ion selectivity, modes of activation, and physiological functions. Classical TRP (transient receptor potential canonical (TRPC)) channels are activated by stimulation of Gq-PLC-coupled receptors and modulated by phosphorylation. The cyclic guanosine monophosphate (cGMP)-PKG pathway is involved in the regulation of TRPC3 and TRPC6 channels. Phosphodiesterase (PDE) 5 inhibitor induced muscle relaxation in corporal smooth muscle cells and was used to treat erectile dysfunction by inhibiting cGMP degradation. Here, we report the functional relationship between TRPC4 and cGMP. In human embryonic kidney (HEK) 293 cells overexpressing TRPC4, cGMP selectively activated TRPC4 channels and increased cytosolic calcium level through TRPC4 channel. We investigated phosphorylation sites in TRPC4 channels and identified S688 as an important phosphorylation site for the cGMP-PKG pathway. Cyclic GMP also activated TRPC4-like current with doubly rectifying current-voltage relationship in prostate smooth muscle cell lines. Taken together, these results show that TRPC4 is phosphorylated by the cGMP-PKG pathway and might be an important target for modulating prostate function by PDE5 inhibitors.

Do baseline estrogen and testosterone affect lower urinary tract symptoms (LUTS) prior to or after pharmacologic treatment with tadalafil?

Little is known about how total testosterone and estradiol-17β influence lower urinary tract symptoms (LUTS) in men with benign prostatic hypertrophy (BPH). We analyzed data from a subset of men aged ≥18 years randomized to tadalafil 5 mg once-daily or placebo who had ≥6 month history of LUTS and an International Prostate Symptom Score (IPSS)≥13 enrolled in one of three randomized, placebo-controlled tadalafil clinical trials (N = 958). Three specific aims were addressed, as follows: (i) To characterize enrolled men by treatment randomization and testosterone level; (ii) to assess cross-sectional associations of estradiol-17β, testosterone, and LUTS prior to treatment with tadalafil; and, (iii) to assess longitudinal associations between baseline estradiol-17β and testosterone and improvements or worsening of LUTS during a 12-week period of tadalafil or placebo administration. LUTS were assessed by total IPSS, IPSS voiding sub-score (IPSS-V) and IPSS storage sub-score (IPSS-S) for cross-sectional analyses, and change in total IPSS (ΔIPSS), ΔIPSS-V, and ΔIPSS-S between baseline and 12-week visit for longitudinal analyses. Correlation analyses and linear regression examined associations. Baseline testosterone was not significantly associated with IPSS. In contrast, estradiol-17β was inversely correlated with IPSS (r = -0.08; p < 0.05) and IPSS-S (r = -0.14; p < 0.05). Tadalafil treatment resulted in greater IPSS improvements in men with lower baseline estradiol-17β versus those with higher baseline estradiol-17β. Lower baseline estradiol-17β was significantly associated with modestly improved ΔIPSS-V (p = 0.04) and Δtotal IPSS (p = 0.05) but not with ΔIPSS-S, following treatment which may substantiate the role of bladder dysfunction because of nerve and smooth muscle changes in the bladder in addition to benign prostatic enlargement in LUTS. Circulating baseline testosterone did not predict ΔIPSS. Men with lower baseline estradiol-17β levels showed greater responsiveness to tadalafil 5 mg treatment than those with higher baseline estradiol-17β levels when responsiveness was measured using total IPSS and IPSS-V.

The role of phosphodiesterase-5 inhibitors in prostatic inflammation: a review

Clinical and basic experimental evidence indicates that chronic inflammation is the greatest factor in benign prostatic hyperplasia (BPH) progression, which is the most common cause of Lower Urinary Tract Symptoms (LUTS). The use of anti-inflammatory agents such as steroids, cyclooxygenase-2 (COX-2) and phytotherapics have been investigated as forms of treatment for various prostate diseases. Recent evidence has demonstrated that PDE5 inhibitors (PDE5Is) improve symptoms of BPH/LUTS, possibly as a result of the relaxing of the smooth muscle fibers of the bladder and prostate by NO/cGMPc signaling, or by improving RhoA/Rho-kinase (ROCK), and reduction of the hyperactivity of the autonomic nervous system. However, some results have suggested that besides vasodilatation and their anti-proliferative effect, PDE5Is exert a direct anti-inflammatory effect, by raising cGMP. Given that inflammation is major factor in benign prostatic hyperplasia (BPH) progression, PDE5Is could act also restore prostatic function as they act as potent anti-inflammatory drugs. This review aims to provide a comprehensive summary of the use of phosphodiesterase-5 inhibitors to treat prostatic inflammation.

Phosphodiesterase sequence variants may predispose to prostate cancer

We hypothesized that mutations that inactivate phosphodiesterase (PDE) activity and lead to increased cAMP and cyclic guanosine monophosphate levels may be associated with prostate cancer (PCa). We sequenced the entire PDE coding sequences in the DNA of 16 biopsy samples from PCa patients. Novel mutations were confirmed in the somatic or germline state by Sanger sequencing. Data were then compared to the 1000 Genome Project. PDE, CREB and pCREB protein expression was also studied in all samples, in both normal and abnormal tissue, by immunofluorescence. We identified three previously described PDE sequence variants that were significantly more frequent in PCa. Four novel sequence variations, one each in the PDE4B,PDE6C, PDE7B and PDE10A genes, respectively, were also found in the PCa samples. Interestingly, PDE10A and PDE4B novel variants that were present in 19 and 6% of the patients were found in the tumor tissue only. In patients carrying PDE defects, there was pCREB accumulation (P<0.001), and an increase of the pCREB:CREB ratio (patients 0.97±0.03; controls 0.52±0.03; P-value <0.001) by immunohistochemical analysis. We conclude that PDE sequence variants may play a role in the predisposition and/or progression to PCa at the germline and/or somatic state respectively.

Effects of chronic administration of tamsulosin and tadalafil, alone or in combination, in rats with bladder outlet obstruction induced by chronic nitric oxide deficiency

PURPOSE

The aim of this study was to define if tadalafil causes detrusor muscle impairment and to observe the effect of combination of tadalafil with tamsulosin on the lower urinary tract of rats with bladder outlet obstruction (BOO) induced by chronic nitric oxide deficiency.

MATERIALS AND METHODS

Thirty-one male rats were randomized to following groups: 1 - control; 2 - L-Nitroarginine methyl ester (L-NAME); 3 - Tamsulosin + L-NAME, 4 Tadalafil+L-NAME; and 5 - Tamsulosin + Tadalafil + L-NAME. At the end of the treatment period (30 days), all animals were submitted to urodynamic study.

RESULTS

The administration of L-NAME increased the number of non-voiding contractions (NVC) (1.04 ± 0.22), volume threshold (VT) (1.86 ± 0.35), and micturition cycle (MC) (1.34 ± 0.11) compared with control (0.52 ± 0.06, 0.62 ± 0.06, and 0.67 ± 0.30), respectively. The administration of tamsulosin reduced the number of NVC (0.57 ± 0.42) and VT (0.76 ± 0.24 ) compared with L-NAME group. Co-treatment with tadalafil decreased the number of VT (0.85 ± 0.53) and MC (0.76 ± 0.22) compared with L-NAME group. The combination of tamsulosin with tadalafil improved the number of NVC (0.56 ± 0.18), VT (0.97 ± 0.52) and MC (0.68 ± 0.30) compared with L-NAME group.

CONCLUSION

In rats with BOO induced by chronic nitric oxide deficiency, tadalafil did not cause impairment in detrusor muscle and seems to have an addictive effect to tamsulosin because the combination decreased non voiding contractions as well the number of micturition cycles.

Effect of chronic Sildenafil treatment on the prostate of C57Bl/6 mice

Sildenafil is a potent and selective inhibitor of phosphodiesterase-5 (PDE5) and is considered first-line therapy for erectile dysfunction. Nowadays, Sildenafil is used extensively throughout the world on patients with pulmonary hypertension. However, few studies have evaluated the possible side effects of chronic Sildenafil treatment on the male reproductive system, specifically in the prostate. In the present study, it was demonstrated via morphological and ultrastructural analysis that chronic treatment with Sildenafil induced an enhancement of the glandular activity of the prostate. In addition, mice treated with Sildenafil showed a significant increase in testosterone serum levels. However, no statistically significant differences were observed in nitric oxide serum levels, or in sGC, eNOS, PSA and TGF-β prostatic expression. In conclusion, the present study suggests that chronic use of Sildenafil does not cause evident prostatic damage, and therefore, can be used pharmacologically to treat a variety of disorders.

[New treatment strategies for male lower urinary tract symptoms]

For patients with lower urinary tract symptoms (LUTS), α1-adrenoreceptor inhibitors and 5-alpha reductase inhibitors as well as their combination are considered the gold standard. In addition, anticholinergic agents are being introduced as monotherapy or in combination with α1-adrenocepetor inhibitors for patients with predominant storage disorders. Phosphodiesterase 5 (PDE5) inhibitors are often the best option for patients with LUTS who also suffer from erectile dysfunction. Recently, novel treatment options have been presented and intraprostatic injection of various agents, such as botulinum toxin A, NX-1207 and PRX302 has shown promising initial results. In addition, innovative minimally invasive treatment options, such as UroLift® appear to be efficacious and safe in this patient cohort. Particular emphasis should be laid on patients with LUTS and concomitant sexual disorders.

Evaluating the significance of cyclic adenosine monophosphate-mediated signaling in human prostate: a functional and biochemical study

OBJECTIVE

To investigate further the potential significance of the cyclic adenosine monophosphate (cAMP) pathway in the control of prostate smooth muscle. The cAMP pathway has been assumed to be an alternative pharmacologic target to treat dysfunctions of the human lower urinary tract. To date, only a few studies have addressed the physiologic relevance of cAMP signal transduction in the control of human prostate function.

METHODS

Phosphodiesterase activity was isolated from microsomal fractions prepared from prostatic tissue and subjected to biochemical analysis. Using the organ bath technique, the effects of the phosphodiesterase type (PDE)4 inhibitors Ro 20-1724, rolipram, and RP 73401 on the tension induced by norepinephrine of isolated prostatic tissue were investigated and compared with the PDE5 inhibitor sildenafil and BAY 13-1197, a nitric oxide-independent activator of the soluble guanylyl cyclase. Statistical analysis was conducted using the Gosset t test.

RESULTS

Biochemical analysis of the microsomal fraction revealed only a single peak of PDE activity that was sensitive to papaverine and the PDE4 inhibitors rolipram and Ro 20-1724. The tension induced by norepinephrine was reversed by the drugs with the following order of efficacy: Ro 20-1724, RP 73401, rolipram, sildenafil, and BAY 13-1197. Pre-exposure of the tissue to a threshold concentration (0.05 μM) of forskolin (adenlyl cyclase activator) increased the reversion of tension induced by rolipram and RP 73401 and the PDE5 inhibitor sildenafil.

CONCLUSION

These results have provided evidence for the significance of cAMP signaling in the control of prostate smooth muscle.

Comparison of efficacy for erectile function and lower urinary tract symptoms of tadalafil 20 mg on-demand and 5 mg once daily in patients with erectile dysfunction

Aim:  To compare the improvement in erectile dysfunction (ED) and lower urinary tract symptoms (LUTS) as well as safety of tadalafil dosed at 20 mg on-demand and 5 mg once daily among ED patients. Materials and methods:  A total of 194 ED patients visited between March 2010 and June 2011 were recruited. Out of 194 individuals, 168 (86.6%) met inclusion criteria after completing the two-week screening period (V0). The Patients were randomly allocated into two groups: (i) 20 mg of tadalafil as needed (Group 1: n = 84, 50.0%) and (ii) 5 mg of tadalafil once daily (Group 2: n = 84, 50.0%). Blood pressure (BP), heart rate (HR) and the five-item version of the International Index of Erectile Function (IIEF-5) were assessed immediately before initiation of treatment (V1) and after four (V2) and twelve weeks of treatment (V3). In men with an IPSS of ≥ 8 at V1, IPSS, maximal flow rate (Qmax) and post-void residual volume (PVR) were also assessed. Results:  Of the 168 patients, 134 (79.8%; Group 1: n = 68, 81.0%; Group 2: n = 66, 78.6%) patients completed the trial. IIEF-5 improved in both groups, and the mean change was larger in Group 2 at V3 (4.9 ± 4.2 vs. 6.5 ± 4.5; p = 0.032) Similarly, though IPSS (with ≥ 8, n = 88, 65.7%; Group 1: n = 44, 64.7%; Group 2: n = 44, 66.7%) improved in both groups, the mean change was larger in Group 2 at V3 (-2.8 ± 4.3 vs. -4.8 ± 4.1; p = 0.026). Qmax and PVR did not differ significantly in either group. Conclusions:  Once daily tadalafil was more efficacious in treating both ED and LUTS than on-demand dosing. However, no differences were observed between the two dosing schedules with regard to the improvement in LUTS when stratified by improvement in ED. The side effects were insignificant for both dosing schedules.

ADMET considerations for phosphodiesterase-5 inhibitors

INTRODUCTION

ADMET (absorption, distribution, metabolism, excretion, and toxicity) profiling is an important aspect of all drug developments. The pharmaceutical industry must always consider ADMET properties in order to optimize drug candidates and to introduce new formulations against existing marketed drugs. Consequently, candidate drug development may be halted early in the discovery phase or during the more costly drug development process because of their poor ADMET properties.

AREAS COVERED

The main focus of this article is ADMET profiling, pharmacokinetic (PK) drug interactions, mechanisms and possible adverse drug reactions (ADRs) for approved phosphodiesterase-5 inhibitors (PDE5Is). The authors also look at the efficacy and non-erectogenic benefits of current PDE5Is, which are widely used by patients with erectile dysfunction (ED). The authors also discuss other unapproved PDE5Is such as aildenafil and udenafil, which are currently in use in clinical trials.

EXPERT OPINION

The authors believe that the enhancing effect of PDE5Is on the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway means that PDE5Is could be used to treat various conditions. An important issue in their development is 'cross-talk' between PDE5 and other PDEs and thus their specificity for other PDEs. But while it might be difficult to achieve the ideal ADMET profile, it should not necessarily prevent further development of a lead PDE5I. The risk assessment of PDE5Is, with respect to their ADMET properties, is therefore very important for predicting drug-drug interactions, possible side effects, ADRs and its future clinical applications.

A randomized, placebo-controlled study to assess safety and efficacy of vardenafil 10 mg and tamsulosin 0.4 mg vs. tamsulosin 0.4 mg alone in the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia

INTRODUCTION

Safety and efficacy of tamsulosin and vardenafil are well established: however, there is no report regarding combined therapy with these drugs for lower urinary tract symptoms (LUTSs) secondary to benign prostatic hyperplasia (BPH).

AIM

To compare the safety and efficacy of tamsulosin 0.4 mg/day vs. tamsulosin 0.4 mg/day plus vardenafil 10 mg/day in patients with LUTS/BPH in a randomized trial with 12-week follow-up.

METHODS

We conducted a randomized, double-blind, placebo-controlled study on 60 men with persistent storage LUTS after 2-week run-in with tamsulosin.

MAIN OUTCOME MEASURES

International Prostate Symptom Score (IPSS), IPSS-bother, International Index of Erectile Function, Version 5 (IIEF-5) and Over Active Bladder questionnaire (OAB-q) scores, uroflowmetry data (Qmax, Qave), and postvoiding residual urine were recorded after run-in (baseline), and 2 and 12 weeks after treatment. Differences between vardenafil and placebo at different times were calculated with unpaired samples t-test. Between-group differences in change from baseline to 2 and 12 weeks were evaluated with analysis of variance.

RESULTS

We found a between-group significant difference from baseline to 12 weeks in the following: (i) Qmax (placebo: +0.07, vardenafil: +2.56, P = 0.034); (ii) Qave (placebo: -0.15, vardenafil: +1.02, P = 0.031); (iii) irritative-IPSS subscores (placebo: -1.67, vardenafil: -3.11, P = 0.039); and (iv) IIEF (placebo: +0.06, vardenafil: +2.61, P = 0.030). No patient reported any serious (grade ≥ 2) adverse event (AE). There were no differences in the incidence of common, treatment-related AEs between men undergoing combined therapy or tamsulosin alone.

CONCLUSIONS

The combination of tamsulosin and vardenafil for 12 weeks was well tolerated and more effective to improve both LUTS and erectile function, as compared with tamsulosin alone. Further studies are needed to assess the role of combined therapy of phosphodiesterase type 5 inhibitors and alpha blockers in treating LUTS/BPH.

An overview of prostate diseases and their characteristics specific to Asian men

In this paper, we reviewed the features of common prostate diseases, such as benign prostatic hyperplasia (BPH), prostate cancer (PCa) and chronic prostatitis (CP) that are specific to Asian men. Compared to the Westerners, Asians exhibit particular characteristics of prostate diseases. Through summarizing the epidemiology, symptomatology, diagnostics and therapeutics of these diseases, we find that Asians have a lower incidence of PCa than whites, but the incidences of BPH and CP are similar. Asian men with CP often suffer from fewer disease sites, but have a higher frequency of pain during urination rather than after sexual climax. Prostate-specific antigen (PSA) is a widely used marker for the diagnosis of PCa in both Asian and Western countries. Although the PSA level may be lower in Asians, the threshold used is based on whites. After reviewing the treatments available for these diseases, we did not find a fundamental difference between Asians and whites. Furthermore, the selection for the most appropriate treatment based on the individual needs of patients remains a challenge to urologists in Asia. After considering the traits of prostate diseases that are specific to Asian men, we hope to pave the way for the development of specific diagnostic and therapeutic strategies targeted specifically to Asian men.

Analysis of prescriptions of alpha-blockers and phosphodiesterase 5 inhibitors from the urology department and other departments

PURPOSE

We analyzed the prescriptions of alpha-blockers and phosphodiesterase 5 inhibitors (PDE5Is) in the urology department as well as in other departments of the general hospital.

METHODS

We investigated the frequency of prescription of alpha-blockers and PDE5Is from 3 general hospitals from January 1, 2007 to December 31, 2009. For alpha-blockers, data were collected from patients to whom alpha-blockers were prescribed from among patients recorded as having benign prostatic hyperplasia according to the 5th Korean Standard Classification of Diseases. For PDE5Is, data were collected from patients to whom PDE5Is were prescribed by the urology department and by other departments. Alpha-blockers were classified into tamsulosin, alfuzosin, doxazosin, and terazosin, whereas PDE5Is were classified into sildenafil, tadalafil, vardenafil, udenafil, and mirodenafil.

RESULTS

Alpha-blockers were prescribed to 11,436 patients in total over 3 years, and the total frequency of prescriptions was 68,565. Among other departments, the nephrology department had the highest frequency of prescription of 3,225 (4.7%), followed by the cardiology (3,101, 4.5%), neurology (2,576, 3.8%), endocrinology (2,400, 3.5%), pulmonology (1,102, 1.6%), and family medicine (915, 1.3%) departments in order. PDE5Is were prescribed to 2,854 patients in total over 3 years, and the total frequency of prescriptions was 10,558. The prescription frequency from the urology department was 4,900 (46.4%). Among other departments, the endocrinology department showed the highest prescription frequency of 3,488 (33.0%), followed by the neurology (542, 5.1%), cardiology (467, 4.4%), and family medicine (407, 3.9%) departments in order.

CONCLUSIONS

A high percentage of prescriptions of alpha-blockers and PDE5Is were from other departments. For more specialized medical care by urologists is required in the treatment of lower urinary tract symptoms and erectile dysfunction.

Expression and distribution of key enzymes of the cyclic GMP signaling in the human clitoris: relation to phosphodiesterase type 5 (PDE5)

The clitoris contributes to the normal female sexual response cycle. A significance of cyclic guanosine monophosphate (GMP) has been assumed in the control of clitoral vascular smooth muscle. As only a few investigations on the physiology of the vascular and non-vascular clitoral tissue have been carried out, knowledge on the mechanisms controlling this particular female genital organ is still vague. It has been suggested that human clitoral corpus cavernosum smooth muscle is regulated by nitric oxide (NO)/cyclic GMP and related key enzymes, such as NO synthases (NOSs) and the phosphodiesterase type 5 (PDE5). The present study evaluated in the human clitoris, by means of immunohistochemistry, the expression and distribution of key enzymes of the cyclic GMP pathway, such as the endothelial NOS, PDE2, PDE11 and cyclic GMP-dependent protein kinase type I (cGKI) in relation to the PDE5. Immunohistochemistry revealed the presence of PDE2, PDE5 and cGKI in the smooth muscle wall of blood vessels transversing the supepithelial and stromal space. Immunosignals specific for PDE2 were also identified in interstitial-like cells located in the basal epithelial layer. Staining for PDE11A was observed in single nerve trunks located in the clitoral stroma. The results are in favor of a role of the cyclic GMP signaling in the control of clitoral blood flow. It seems likely that PDE2 and PDE11 are also involved in the mechanism of local (neuro)transmission in the clitoris.

Cyclic GMP signaling in rat urinary bladder, prostate, and epididymis: tissue-specific changes with aging and in response to Leydig cell depletion

Aging of the male reproductive system leads to changes in endocrine signaling and is frequently associated with the emergence of prostate hyperplasia and bladder dysfunctions. Recent reports highlight prostate and bladder as promising targets for therapeutic interventions with inhibitors of the cyclic GMP (cGMP)-degrading phosphodiesterase 5 (PDE5). However, the cGMP signaling system in these organs is as yet poorly characterized, and the possibility of age-related alterations has not been addressed. This study investigates key proteins of cGMP pathways in bladder, prostate, and epididymis of young (3 months) and old (23-24 months) Wistar rats. Local differences in the abundance of PDE5, soluble guanylyl cyclase (sGC) and particulate guanylyl cyclases (GC-A, GC-B), endothelial nitric oxide synthase, and cGMP-dependent protein kinase I (PRKG1 (cGKI)) revealed pronounced tissue-specific peculiarities. Although cGMP-generating enzymes were not affected by age in all organs, we recognized age-related decreases of PDE5 expression in bladder and a selective diminishment of membrane-associated PRKG1 in epididymis. In disagreement with published data, all cGMP pathway proteins including PDE5 are poorly expressed in prostate. However, prostatic PRKG1 expression increases with aging. Androgen withdrawal during temporary Leydig cell elimination induced a massive (>12-fold) upregulation of PRKG1 in prostate but not in other (penis and epididymis) androgen-dependent organs. These findings identify PRKG1 as a key androgen-sensitive signaling protein in prostate of possible importance for growth regulation. The elucidated effects may have significance for age-associated pathologies in the male lower-urinary tract.

The role of antimuscarinics in the management of men with symptoms of overactive bladder associated with concomitant bladder outlet obstruction: an update

CONTEXT

This review focuses on the contemporary role of antimuscarinics in the management of men with symptoms of bladder outlet obstruction (BOO) and concomitant overactive bladder (OAB). Safety issues of antimuscarinics in this subpopulation of men are also reviewed.

OBJECTIVE

We reviewed the current literature and performed an analysis of the efficacy, suitability, and the safety of antimuscarinics in this subpopulation of men.

EVIDENCE ACQUISITION

We performed a systematic search of Medline/PubMed, Embase, Scopus, and the Cochrane Database of Systematic Reviews for relevant articles published between 1990 and September 2010, restricted to studies in humans published in English. In addition, published abstracts presented at the annual meetings of the European Association of Urology, the American Urological Association, and the International Continence Society in the last decade (2000-2010) were hand-searched and evaluated. Each article's title and abstract were reviewed for their appropriateness and relevance to the use of antimuscarinics in patients with BOO and concomitant OAB. Relevant articles were fully reviewed and included in the final data acquisition.

EVIDENCE SYNTHESIS

Treatment options include combination treatment with α-blockers and antimuscarinics, sequential use of α-blockers and antimuscarinics, monotherapy with antimuscarinics, and a combination of antimuscarinics and 5α-reductase inhibitors. The sequential use of α-blockers and antimuscarinics seems to be the most appropriate approach, and the use of antimuscarinics and α-blockers appears generally to be safe and efficacious. Data are insufficient for a possible stratification of patients for a specific sequence of the drugs reviewed.

CONCLUSIONS

This review infers that the existing data confirm the safety of antimuscarinics administered for the treatment of these patients. The efficacy of antimuscarinics has been proven in different trials regarding different storage symptom end points, but not all end points regarding OAB reached significance. All the reported trials are of short duration (4-12 wk) and include only men with low postvoid residual urine volumes at baseline (<200ml). Overall, the addition of an antimuscarinic to the treatment of a patient with BOO and concomitant OAB seems to offer an amelioration of the symptoms and a moderate improvement in quality of life.

Mammalian Cyclic Nucleotide Phosphodiesterases: Molecular Mechanisms and Physiological Functions

The superfamily of cyclic nucleotide (cN) phosphodiesterases (PDEs) is comprised of 11 families of enzymes. PDEs break down cAMP and/or cGMP and are major determinants of cellular cN levels and, consequently, the actions of cN-signaling pathways. PDEs exhibit a range of catalytic efficiencies for breakdown of cAMP and/or cGMP and are regulated by myriad processes including phosphorylation, cN binding to allosteric GAF domains, changes in expression levels, interaction with regulatory or anchoring proteins, and reversible translocation among subcellular compartments. Selective PDE inhibitors are currently in clinical use for treatment of erectile dysfunction, pulmonary hypertension, intermittent claudication, and chronic pulmonary obstructive disease; many new inhibitors are being developed for treatment of these and other maladies. Recently reported x-ray crystallographic structures have defined features that provide for specificity for cAMP or cGMP in PDE catalytic sites or their GAF domains, as well as mechanisms involved in catalysis, oligomerization, autoinhibition, and interactions with inhibitors. In addition, major advances have been made in understanding the physiological impact and the biochemical basis for selective localization and/or recruitment of specific PDE isoenzymes to particular subcellular compartments. The many recent advances in understanding PDE structures, functions, and physiological actions are discussed in this review.

Effect of combination treatment on patient-related outcome measures in benign prostatic hyperplasia: clinical utility of dutasteride and tamsulosin

BACKGROUND

Benign prostatic hyperplasia, the fourth most commonly diagnosed medical condition in the elderly, is a major underlying cause of lower urinary tract symptoms in men. Medical therapy is usually the first therapeutic option. Combination therapy is increasingly used for better symptom relief and outcome.

METHODS

We searched the literature using the MEDLINE database for the efficacy of combination therapy in men with benign prostatic hyperplasia in terms of symptom improvement and impact on quality of life.

RESULTS

Combination therapy with dutasteride and tamsulosin not only provides better symptom improvement and improved urinary flow rate, but is also associated with a more favorable impact on quality of life and patient satisfaction with treatment than monotherapy. Combination therapy also reduces the risk of events related to disease progression, such as acute urinary retention and benign prostatic hyperplasia-related surgery.

CONCLUSION

Combination therapy with dutasteride and tamsulosin is highly efficacious as medical therapy for benign prostatic hyperplasia in patients with moderate-to-severe lower urinary tract symptoms.

Urological Disorders in Men

Urinary incontinence (UI) and benign prostatic hyperplasia (BPH) are 2 common urogenital problems in men. UI is associated with involuntary leakage of urine and lower urinary tract symptoms (LUTS) of urgency, frequency, and nocturia. Types of UI include functional, urge, stress, and overflow. Treatment for UI is based on the type of incontinence, patient-specific factors, and treatment preferences of both patients and health care providers. Options for the management of UI include environmental modifications, disposable incontinence products, pelvic floor exercises, pharmacotherapy, surgically implanted devices, and intermittent catheterization. BPH may be also associated with LUTS. Patient symptoms, assessed with a measurement tool such as the American Urological Association Symptom Index (AUASI), serve as the basis for determining treatment. Management approaches for BPH include pharmacotherapy, surgery, and minimally invasive procedures. Anticholinergic drugs as well as α-receptor antagonists and 5-α reductase inhibitors, either alone or in combination, are effective and useful for LUTS unresponsive to traditional pharmacotherapy. Transurethral resection of the prostate (TURP) can eliminate symptoms of BPH but is associated with relatively more complications than other available surgical and minimally invasive procedures.

Phosphodiesterase-5 inhibitors for lower urinary tract symptoms secondary to benign prostatic hyperplasia: a systematic review and meta-analysis

OBJECTIVES

To evaluate the efficacy and safety of phosphodiesterase-5 (PDE-5) inhibitors for treating lower urinary tract symptoms secondary to benign prostatic hyperplasia.

METHODS

Randomized controlled trials were identified and extracted from MEDLINE, Embase, Cochrane Central, and relevant reference lists. The database search, quality assessment, and data extraction were independently performed by 2 reviewers. Heterogeneity was analyzed using the chi-square test and I(2) test. If lacking of heterogeneity, fixed-effects models were used for the meta-analysis, otherwise random-effects models were used.

RESULTS

A total of 5 studies (11 randomized controlled trials) were identified from the search strategy. Compared with placebo, short-term trials (≤12 weeks) indicated that PDE-5 inhibitors significantly improved the International Prostate Symptom Score (mean difference -2.60, 95% confidence interval [CI] -3.12 to -2.07; P < .00001), and statistical significance was observed in the International Prostate Symptom Score irritative and obstructive subscore, International Prostate Symptom Score quality of life and erectile function. However, no statistically significant difference was detected in maximal urinary flow rate (mean difference 0.21, 95% CI -0.21-0.64; P = .32) and postvoid residual urine volume (mean difference 0.09, 95% CI -4.71-4.89; P = .80). No statistically significant difference was found between the 2 groups in the incidence of serious adverse events (relative risk 0.52, 95% CI 0.25-1.07; P = .07), despite that adverse event with a greater incidence was detected in the PDE-5 group (relative risk 1.87, 95% CI 1.31-2.68; P = .0005).

CONCLUSIONS

As the first-line treatment of erectile dysfunction, the PDE-5 inhibitor is also effective and safe for lower urinary tract symptoms secondary to benign prostatic hyperplasia. It could be considered as the first-line treatment in the future for the treatment of patients with comorbid benign prostatic hyperplasia and erectile dysfunction.