Tadalafil relieves lower urinary tract symptoms secondary to benign prostatic hyperplasia

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

OBJECTIVE

• To review the evidence in support of the effectiveness of phosphodiesterase 5 inhibitors in lower urinary tract symptoms (LUTS) caused by benign prostatic hyperplasia (BPH).

METHODS

• Relevant studies were identified by performing a literature search using MEDLINE® and The Cochrane Library®. The criteria used during the search included randomized, placebo-controlled trials of treatment for LUTS secondary to BPH using the International Prostate Symptom Score as an outcome measure.

RESULTS

• Four trials that included a total of 1928 patients met the inclusion criteria. All four studies showed a statistically significant difference in the International Prostate Symptom Score, quality of life and erectile function in favour of phosphodiesterase 5 inhibitors. • No study showed a statistically significant improvement of the maximum urinary flow. • Meta-analysis of the results was not possible because of heterogeneity across the studies.

CONCLUSIONS

• Phosphodiesterase 5 inhibitors used in the clinical setting can significantly improve LUTS secondary to BPH, erectile function and quality of life. Maximum urinary flow improvement is not statistically significant. • Future research should focus on pathophysiological principles and cost analysis.

Efficacy and Safety of Tadalafil 5 mg Administered Once Daily in Korean Men with Erectile Dysfunction: A Prospective, Multicenter Study

PURPOSE

The aim of this study was to evaluate the efficacy of a daily dose of tadalafil 5 mg as well as its safety for the cardiovascular system in men with erectile dysfunction.

MATERIALS AND METHODS

This study included a total of 162 men who were administered a daily dose of tadalafil 5 mg between April and December of 2009. A total of 127 men completed the 8-week clinical trial. The International Index of Erectile Function (IIEF)-5, blood pressure, and heart rate were measured before treatment with tadalafil (V1) and 4 (V2) and 8 weeks (V3) after treatment with tadalafil. Adverse effects were assessed at V1, V2, and V3. In cases in which the International Prostate Symptom Score (IPSS) was ≥8 at V1, maximal flow rate (Qmax) and postvoid residual volume (PVR) were measured.

RESULTS

The IIEF-5 values were 11.25±3.18, 14.56±3.79, and 16.91±3.56 at V1, V2, and V3, respectively, with significant improvement (V1 vs. V2, p<0.001; V1 vs. V3, p<0.001). The IPSS values were 10.59±5.56, 9.07±6.06, and 8.15±6.10 at V1, V2, and V3, respectively, and the differences were statistically significant (V1 vs. V2, p<0.001; V1 vs. V3, p<0.001). There were no significant differences in blood pressure or heart rate. Adverse effects were observed in 7 men (5.51%) at V2 and in 5 men (3.94%) at V3.

CONCLUSIONS

Tadalafil 5 mg administered once-a-day may be effective in improving erectile function. Adverse effects on the cardiovascular system may be minimal. In addition, it is believed that this may also be effective in improving voiding symptoms.

Expression of cAMP-dependent protein kinase isoforms in the human prostate: functional significance and relation to PDE4

OBJECTIVES

To investigate the expression of isoforms of the cyclic AMP (cAMP)-dependent protein kinase (cAK) in the transition zone of the human prostate and the functional significance of the enzyme in the control of prostate smooth muscle.

METHODS

Using Western blot analysis and immunohistochemistry, the expression and distribution in the prostate of cAKIalpha, cAKIbeta, cAKIIalpha, and cAKIIbeta in relation to alpha-actin and the phosphodiesterase PDE4 (types A and B) were investigated. The effects of the cAK inhibitor Rp-8-CPT-cAMPS on the reversion of the adrenergic tension of isolated prostate tissue induced by forskolin, rolipram, sodium nitroprusside (SNP), and tadalafil were examined by means of the organ bath technique.

RESULTS

Immunosignals specific for cAKIalpha, cAKIIalpha, and cAKIIbeta were observed in the smooth musculature and glandular structures of the prostate. Double stainings revealed the colocalization of alpha-actin and PDE4 with the cAK isoforms. The expression of the cAK isoforms was confirmed by Western blot analysis. The relaxation of the tension induced by norepinephrine brought about by forskolin, rolipram, SNP, and tadalafil was significantly attenuated by Rp-8-CPT-cAMPS.

CONCLUSIONS

The colocalization of smooth muscle alpha-actin and PDE4 with cAK, as well as the results from the organ bath experiments, provide further evidence for a pivotal role of the cAMP-dependent signaling in the regulation of prostate smooth muscle contractility. Compounds interacting with the cAMP/cAK pathway might represent a new therapeutic avenue to treat symptoms of benign prostatic hyperplasia and lower urinary tract symptomatology.

Benign prostatic hyperplasia

This article reviews the epidemiology of benign prostatic hyperplasia (BPH), evaluation of patients with lower urinary tract symptomatology (LUTS), and management of patients with BPH and LUTS. The evaluation includes history and physical examination, laboratory testing, and specialized studies. The management includes medical and surgical options. Medical options include alpha-1-adrenergic receptor blockers, 5alpha-reductase inhibitors, and combinations of these and other medications. Surgical options include endoscopic procedures, open procedures, and laser procedures.

Nitric oxide/cyclic guanosine monophosphate signalling mediates an inhibitory action on sensory pathways of the micturition reflex in the rat

BACKGROUND

Overactive bladder can be associated with a hyperexcitability of bladder afferent C-fibres. Several studies have suggested that nitric oxide (NO) or its downstream signalling could modulate the micturition reflex (MR) by reducing the excitability of bladder afferents.

OBJECTIVES

To evaluate the role of the NO/cyclic guanosine monophosphate (cGMP) signalling pathway on the MR in a model of bladder hyperactivity (BHA) associated with C-fibre activation in the rat.

DESIGN, SETTING, AND PARTICIPANTS

Adult female Sprague Dawley rats were used.

MEASUREMENTS

Cystometry was performed in anaesthetised rats. The effects of 0.1 mg/kg of sodium nitroprusside (SNP), an NO donor; 10 mg/kg of 8Br-cGMP, a cGMP analogue; 3 mg/kg of sildenafil and 1 mg/kg of vardenafil, two phosphodiesterase type 5 inhibitors (PDE5-I); 10 mg/ml of L-N(G)-nitroarginine methyl ester (L-NAME), an NO synthase inhibitor; and 1 mg/kg of LY-83583, a guanylate cyclase inhibitor, were investigated on BHA during intravesical capsaicin (30 micromol/l) instillation. All drugs were delivered intravenously except for L-NAME, which was intravesically administered.

RESULTS AND LIMITATIONS

SNP, 8Br-cGMP, and PDE5-I increased the intercontraction interval (ICI), while SNP and PDE5-I increased the micturition pressure threshold (MPT). L-NAME and LY-83583 decreased MPT, and L-NAME decreased ICI. 8Br-cGMP decreased the maximum intravesical pressure (MP), contrary to L-NAME and LY-83583. SNP and PDE5-I had no effect on MP. SNP increased the voided volume (VV). PDE5-I and 8Br-cGMP also increased VV, although not significantly. In contrast, L-NAME tended to decrease VV. Although 8Br-cGMP decreased the baseline intravesical pressure, LY-83583 increased it. Neither SNP nor PDE5-I nor L-NAME had any effect on baseline pressure.

CONCLUSIONS

Compounds activating the NO/cGMP pathway inhibited BHA, whereas compounds inhibiting the NO/cGMP pathway increased it. These results indicate that the NO/cGMP signalling pathway is involved in the regulation of the MR, with an action that seems more predominant on the sensory rather on the motor component of the MR in a rat model of BHA associated with C-fibre afferent activation.

Signalling pathways involved in sildenafil-induced relaxation of human bladder dome smooth muscle

BACKGROUND AND PURPOSE

The mechanism(s) of action responsible for the beneficial effects of phosphodiesterase 5 (PDE5) inhibitors including sildenafil on lower urinary tract symptoms suggestive of benign prostate hyperplasia are unclear. In particular, the role of the NO-cGMP signalling pathway in regulating human bladder dome smooth muscle relaxation is questionable. Thus, we assessed the ability of a PDE5 inhibitor, sildenafil, to relax such tissue, and identified the signalling pathways involved in this relaxation.

EXPERIMENTAL APPROACH

Human bladder samples were obtained from 20 patients with no overactive bladder undergoing cystectomy for bladder cancer. Detrusor strips were mounted isometrically in Krebs-HEPES solution. Concentration-response curves for sildenafil (10 nM-30 microM) were generated in the presence of various inhibitors on carbachol-induced pre-contraction.

KEY RESULTS

Sildenafil relaxed carbachol-pre-contracted human detrusor strips, starting at 3 microM. This effect was not modified by NO donors, S-nitroso-N-acetylpenicillamine (10 microM) or sodium nitroprusside (300 nM), but was significantly inhibited by inhibition of guanylate cyclase (with ODQ, 10 microM) or adenylyl cyclase (with MDL-12,330A, 10 microM), by the ATP-sensitive potassium channel inhibitor, glibenclamide (10 microM), or inhibition of the large (with iberiotoxin, 30 nM) or small (with apamin, 100 nM) conductance calcium-activated potassium channels.

CONCLUSIONS AND IMPLICATIONS

Sildenafil-induced relaxation of human detrusor smooth muscle involved cGMP-, cAMP- and K(+) channel-dependent signalling pathways, with a minor contribution from NO. The effect of this sildenafil-induced relaxation on the clinical benefit of PDE5 inhibitors on urinary storage symptoms in men deserves further investigation.

Sexual impact of treatment of lower urinary tract symptoms associated with benign prostatic hyperplasia

Lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS/BPH) and the treatment of these conditions are commonly associated with sexual dysfunction. The effects on sexual function of common medical and surgical therapies used in the treatment of LUTS/BPH are reviewed. Also discussed is the emerging use of phosphodiesterase inhibitors in the treatment of LUTS/BPH.

Open-label, Intermittent Dose, Prospective Study Evaluating the Effects of Tadalafil on Lower Urinary Tract Symptoms and Erectile Function in Patients with Benign Prostatic Hyperplasia: Continuation and Durability of Effects

PURPOSE

Benign prostatic hyperplasia is often accompanied by age-related comorbidity, such as erectile dysfunction (ED). Recent data suggest an association between ED and lower urinary tract symptoms (LUTS), and increasing evidence indicates that the clinical use of phosphodiesterase type 5 (PDE5) inhibitors provides relief from LUTS. The aim of the present study was to investigate the effects of tadalafil (20 mg once every 3 days for 12 weeks, p.o.) in men with moderate-to-severe ED and LUTS and to investigate the duration of the effects of tadalafil beyond treatment cessation.

MATERIALS AND METHODS

Men with an International Index of Erectile Function-5 (IIEF-5) score of less than 11 (representing "moderate-to-severe" ED status) and with an International Prostate Symptom Score (IPSS) of more than 8 (representing "moderate-to-severe" LUTS status) were enrolled. IPSS (total score, storage subscore, and voiding subscore) and IIEF-5 scores before treatment (baseline), during treatment (weeks 4 and 12 after treatment commencement), and after treatment (weeks 16 and 20after treatment commencement) were compared.

RESULTS

IPSS and IIEF-5 scores were significantly different between baseline and week 12 after treatment commencement. Furthermore, these scores were significantly different between baseline and week 20 after treatment commencement. However, except for IIEF-5 scores, no significant differences were observed between week 12 and week 20.

CONCLUSIONS

Treatment with 20 mg tadalafil (once every 3 days) had beneficial effects on LUTS and ED beyond treatment cessation in patients with moderate-to-severe ED and LUTS.

Detrusor myocyte activity and afferent signaling

AIMS

To discuss (1) mechanisms involved in the generation and control of myocyte contractions and consequent afferent nerve activity and (2) these mechanisms as targets for drugs aimed for treatment of overactive bladder (OAB) symptoms and detrusor overactivity (DO).

METHODS

Literature review of myocyte activation, bladder afferent nerves, mediators in the bladder, and translational aspects of the findings.

RESULTS

During bladder filling, there is normally no parasympathetic outflow from the spinal cord. Despite this, the bladder develops tone during filling and also exhibits non-synchronized local contractions and relaxations that are caused by a basal myogenic mechanical activity that may be reinforced by release of, for example, acetylcholine from non-neuronal and/or neuronal sources or local mediators, such as prostaglandins and endothelins. It is suggested that these spontaneous contractions are able to generate activity in afferent nerves ("afferent noise") that may contribute to DO and OAB.

CONCLUSIONS

Spontaneous bladder myocyte contractions and factors that are able to modulate them, as well as the consequent afferent nerve activity, may be targets for drugs meant for treatment of OAB/DO.

Recent advances in management of bladder overactivity

Pharmacologic therapies, primarily antimuscarinic agents, have been the mainstay of treatment for overactive bladder. These drugs produce variable efficacy, a moderate rate of side effects, and rare occurrences of cure. The search for newer and better formulations and derivatives of this class of medication as well as novel therapies is ongoing and primarily fueled by the high prevalence of overactive bladder and the tremendous number of health care dollars spent on current therapy. Surgical options for overactive bladder have evolved slowly and are currently reserved for medical treatment failures and drug intolerance. This article will highlight the new drugs and therapies brought into clinical use for the treatment of overactive bladder over the last few years as well as a promising new agent in the advanced stages of development.

The forefront for novel therapeutic agents based on the pathophysiology of lower urinary tract dysfunction: pathophysiology of voiding dysfunction and pharmacological therapy

Normal lower urinary tract function consists of voiding and storage. During voiding, the pontine micturition reflex center orders the sacral parasympathetic nucleus to increase parasympathetic activity, resulting in urinary bladder detrusor contraction via activation of post-synaptic muscarinic receptors (M2/3) and in the relaxation of both urethral and prostatic smooth muscle by nitric oxide (NO). In addition, the rhabdosphincter relaxes by inhibition of the pudendal nucleus at the sacral portion. During the storage phase, increase in sympathetic activity relaxes the urinary bladder via activation of post-synaptic beta(3)-receptors and in the contraction of both urethral and prostatic smooth muscles via alpha(1)-adrenoceptor. Many factors influence voiding function, including lower urinary tract disorders (benign prostatic hyperplasia in males, urethral stricture) and neurological disorders (central and peripheral). Theories of pharmacotherapy for voiding dysfunction are 1) increase detrusor contractility and 2) decrease urethral resistance. The former includes agonists for muscarinic receptors and cholinesterase inhibitor; and the latter includes alpha(1)-adrenoceptor antagonists, NO donors, benzodiazepines, baclofen, dantrolene, and boturinum toxin.

Urodynamic effects of once daily tadalafil in men with lower urinary tract symptoms secondary to clinical benign prostatic hyperplasia: a randomized, placebo controlled 12-week clinical trial

PURPOSE

We explored the impact of once daily tadalafil on urodynamic measures in men with lower urinary tract symptoms secondary to clinical benign prostatic hyperplasia via invasive and noninvasive urodynamic studies.

MATERIALS AND METHODS

We conducted a multicenter, randomized, double blind, placebo controlled clinical trial comparing once daily tadalafil 20 mg vs placebo during 12 weeks in men with lower urinary tract symptoms secondary to clinical benign prostatic hyperplasia with or without bladder outlet obstruction. Invasive and noninvasive urodynamics, International Prostate Symptom Score and general safety were assessed. The primary study end point was change in detrusor pressure at maximum urinary flow rate.

RESULTS

Urodynamic measures remained largely unchanged during the study with no statistically significant or clinically adverse difference between tadalafil and placebo in change in detrusor pressure at maximum urinary flow rate (mean difference between treatments -2.2 cm H(2)O, p = 0.33) or any other urodynamic parameter assessed including maximum urinary flow rate, maximum detrusor pressure, bladder outlet obstruction index or bladder capacity (all measures p > or = 0.13). Treatment with tadalafil resulted in significant improvements in International Prostate Symptom Score (mean difference between treatments -4.2, p < 0.001). Tadalafil was generally well tolerated with the majority of adverse events being mild to moderate in severity and few patients discontinuing due to adverse events (tadalafil 2.0%, placebo 1.0%).

CONCLUSIONS

Treatment with tadalafil once daily for lower urinary tract symptoms secondary to clinical benign prostatic hyperplasia showed no negative impact on bladder function as measured by detrusor pressure at maximum urinary flow rate or on any other urodynamic parameter assessed. Nonetheless men receiving tadalafil reported significant improvements in International Prostate Symptom Score with an adverse events profile similar to other recent studies of tadalafil for lower urinary tract symptoms secondary to clinical benign prostatic hyperplasia.

Therapeutic options in the treatment of benign prostatic hyperplasia

Current theraputic options for the treatment of symptomatic benign prostatic hyperplasia (BPH) are reviewed. Therapeutic options for mild lower urinary tract symptoms (LUTS), as defined by the American Urological Association, are generally treated medically. Moderate to severe LUTS can be treated medically or with surgical therapy. Current medical and surgical treatments for LUTS secondary to BPH are reviewed and evolving treatments are explored.

Sildenafil citrate and tamsulosin combination is not superior to monotherapy in treating lower urinary tract symptoms and erectile dysfunction

PURPOSE

To evaluate the efficacy of sildenafil citrate only, 25 mg. Four times/week, tamsulosin only, 0.4 mg once daily, and the combination of both on lower urinary tract symptoms (LUTS) suggestive of benign prostate hyperplasia (BPH) and erectile dysfunction.

METHODS

A total of 60 men with BPH-related LUTS were randomized to receive sildenafil citrate only (n = 20), tamsulosin only (n = 20), and the combination of both (n = 20) for 8 weeks. Changes from baseline in International Prostate Symptom Score (IPSS), maximum urinary flow rate (Q (max)), post voiding residual urine volume (PRV), Sexual Health Inventory for Male (SHIM) score, 3rd and 4th questions of International Index of Erectile Function (IIEF) were assessed at the end of the treatment.

RESULTS

The mean age was 58 years. IPSS, Q (max), PRV, SHIM scores, and 3rd and 4th questions in IIEF significantly improved in each group. Improvement of IPSS was more remarkable in combination (40.1%) and tamsulosin only (36.2%) groups in comparison with sildenafil citrate only group (28.2%; p < 0.001). Improvement of Q (max) and PRV were greater in tamsulosin only and combination than sildenafil citrate only group. SHIM scores significantly improved in sildenafil citrate only (65%) and combination (67.4%) than tamsulosin only (12.4%; p < 0.001). Increases in the 3rd and 4th questions of IIEF were greater in sildenafil only and combination than tamsulosin only (p < 0.001).

CONCLUSIONS

Treatment with the combination of tamsulosin only and sildenafil citrate only was not superior to tamsulosin only to enhance voiding symptoms. Also, sexual function improvement was similar for both the combination and sildenafil citrate only treatments.

Pharmacological management of benign prostatic hypertrophy with phosphodiesterase-5 inhibitors

Benign prostatic hypertrophy (BPH) and its associated lower urinary-tract symptoms (LUTS) commonly result in a significant decrease in the quality of life (QOL) of aging men. Although several safe and effective medications are currently available for the management of this disease, newly emerging research has focused on the exploration of unconventional pharmacological therapy. In particular, multiple clinical trials published within the past two years have explored the use of phosphodiesterase-5 (PDE-5) inhibitors for the alleviation of LUTS secondary to BPH. Although this class of medication has traditionally been used in men with erectile dysfunction (ED), the preliminary results from these studies have offered promising evidence for use of PDE-5 inhibitors in BPH.

[Significance of phosphodiesterase isoenzymes in the control of human detrusor smooth muscle function. An immunohistochemical and functional study]

OBJECTIVES

The use of inhibitors of phosphodiesterase (PDE) isoenzymes 1 and 5 to treat overactive bladder has been suggested. To further evaluate the significance of PDE isoenzymes in detrusor smooth muscle relaxation, we investigated the effects of selective PDE inhibitors on the tension induced by carbachol of isolated human detrusor tissue. Using immunohistochemical methods, the expression of PDE1, PDE4, and PDE5 in human detrusor was also investigated.

MATERIAL AND METHODS

The expression of PDE1, PDE4, and PDE5 was evaluated by means of conventional immunohistochemistry (IHC). Using the organ bath technique, the effects of the PDE inhibitors vinpocetine, rolipram, sildenafil, tadalafil, and vardenafil on the tension induced by the muscarinic agonist carbachol (1 microM) were investigated.

RESULTS

The tension induced by carbachol was dose-dependently reversed by the PDE inhibitors; the maximum reversal of tension ranged from 7% (tadalafil) to 34% (vardenafil). IHC revealed that the expression of PDE isoenzymes was limited to the smooth musculature of the detrusor. While there was prominent expression of PDE4 and PDE5, immunoreactions indicating the presence of PDE1 were less abundant.

CONCLUSION

Despite the fact that inhibitors of PDE1, PDE4, and PDE5 exerted only a weak relaxant response on detrusor strips precontracted by carbachol, our findings indicate that both the cAMP and cGMP pathways might be involved in the relaxation mechanism of human detrusor smooth muscle.

Characterization of phosphodiesterase type 5 expression and functional activity in the human male lower urinary tract

INTRODUCTION

Phosphodiesterase type 5 (PDE5) inhibitors ameliorate low urinary tract (LUT) symptoms in men with ED and symptomatic benign prostatic hyperplasia (BPH). PDE5 is highly expressed in rat and human bladder, where it regulates cyclic guanosine monophosphate (cGMP) degradation, muscle tone, and proliferation.

AIM

To investigate PDE5 tissue distribution and activity in human LUT tissues (urethra, prostate, and bladder).

MAIN OUTCOME MEASURES

PDE5 expression and activity were analyzed and compared within the same BPH patient in LUT tissues and in smooth muscle cells (SMCs) cultured from urethra, prostate, and bladder.

METHODS

In LUT tissues, PDE5 was localized by immunohistochemistry and mRNA expression by quantitative real-time polymerase chain reaction. Proliferation assay was used as readout of PDE5 activity, evaluated as ability of vardenafil to increase the antiproliferative effect of different nitric oxide (NO)/cGMP pathway activators [the PDE5-resistant cGMP analog Sp-8-Br-PET-cGMPS, the NO donor sodium nitroprusside (SNP), and the soluble guanylate cyclase (sGC) stimulator BAY 41-8543].

RESULTS

In all the LUT tissues, PDE5 was immunolocalized in blood vessels and in muscular fibres, but not in epithelium. PDE5 mRNA expression was higher in urethra and bladder than in prostate SMC. The antiproliferative effect of Sp-8-Br-PET-cGMPS was similar in all LUT SMC. In prostatic SMC, SNP and BAY 41-8543 show a dose-dependent antiproliferative effect that resulted marginally enhanced by vardenafil. Conversely, in urethra and bladder SMC the antiproliferative effect of SNP and BAY 41-8543 was lower than in prostatic SMC, but it was significantly enhanced by vardenafil. In urethral and bladder cells vardenafil half-maximal response inhibiting concentration was in the subnanomolar range, whereas in prostate cells it resulted significantly higher.

CONCLUSIONS

The highest expression and biological activity of PDE5 was found in bladder. However, a consistent PDE5 expression and activity was also found in prostatic urethra. In contrast, the prostate gland showed the lowest PDE5 abundance and cultures derived from this tissue were less sensitive to vardenafil.

Changes in peak urinary flow and voiding efficiency in men with signs and symptoms of benign prostatic hyperplasia during once daily tadalafil treatment

OBJECTIVE

To determine, by post hoc analysis, the effects of tadalafil (a long-acting phosphodiesterase 5 inhibitor) on peak urinary flow (Q(max)), bladder capacity, voiding efficiency and the obstructive symptoms of benign prostatic hyperplasia (BPH) in men with lower urinary tract symptoms secondary to BPH (BPH-LUTS), compared with placebo.

PATIENTS AND METHODS

After a 4-week placebo run-in period, 1058 men with BPH-LUTS were randomly allocated to receive once daily treatment with placebo or tadalafil (2.5, 5, 10, or 20 mg) for 12 weeks. Uroflowmetry, postvoid residual volume (PVR), and BPH symptom score measurements were assessed throughout the trial.

RESULTS

Increases in Q(max) were numerically greater for tadalafil (2.5, 5, 10, and 20 mg with percentage changes of 15%, 16%, 17%, 22%, respectively) vs placebo (12%), but did not reach statistical significance. Age, baseline Q(max), erectile dysfunction history, sexual activity, and previous alpha-blocker therapy significantly influenced the Q(max) response. Tadalafil was not associated with significant changes in PVR. Tadalafil had its greatest effects on bladder capacity and voiding efficiency in men with a Q(max) of <10 mL/s at baseline, but these changes were not significantly different from placebo responses. Tadalafil treatment significantly improved the IPSS obstructive subscores (tadalafil 2.5, 5, 10, 20 mg with percentage changes of 24%, 31%, 33%, 33%, respectively) vs placebo (13%).

CONCLUSIONS

Once daily tadalafil did not significantly change Q(max) or voiding efficiency compared with placebo in men with BPH-LUTS, although there were dose-dependent improvements. No subgroups were identified where tadalafil or placebo treatment had a deleterious effect on Q(max). Despite these minimal changes in uroflowmetric measures, tadalafil was associated with clinically meaningful and statistically significant improvements in the obstructive symptoms of BPH.

Vardenafil-induced relaxation and cyclic nucleotide levels in normal and obstructed rat urinary bladder

OBJECTIVE

To study the effects of the phosphodiesterase-5 inhibitor, vardenafil, on contraction and cyclic nucleotide levels in isolated detrusor preparations with and without mucosa, from control rats and rats with partial urethral obstruction (PUO) and intact mucosa.

MATERIALS AND METHODS

Female Sprague-Dawley rats were divided into groups subjected to PUO for 14 days (six), and sham-operated control rats (12). Detrusor preparations were mounted in organ baths and effects of increasing concentrations of vardenafil (1 nm to 100 microm) assessed on carbachol-activated (1 microm) preparations, and on contractions induced by transmural activation of nerves (electrical field stimulation, EFS). Levels of cGMP and cAMP were determined using radioimmunoassays.

RESULTS

Vardenafil caused concentration-dependent relaxations of carbachol-contracted detrusor, the mean (sd) of which at 100 microm was 91 (4)% in control and 100% in PUO rats. The -log 50% inhibitory concentration (IC(50)) was 4.41 (0.08) and 4.73 (0.05) (P < 0.01), respectively. Removing the mucosa increased the relaxant effect of vardenafil at 1-10 microm (P < 0.05) although -log IC(50) values were unaffected compared to the control. The cGMP levels ( pmol/mg protein) in control preparations increased from 2.5 (0.6) to 5.0 (0.8), and from 1.4 (0.2) to 7.2 (1.3) in obstructed bladders. In mucosa-denuded preparations the cGMP content increased from 0.6 (0.1) to 1.6 (0.4) in response to vardenafil. In control rats, the levels of cAMP increased from 12.8 (2.5) to 18.9 (0.9) (P < 0.05) after vardenafil. In mucosa-denuded preparations the cAMP levels after vardenafil increased from 16.5 (2.11) to 37.8 (3.4) (P < 0.01). In PUO bladders, the tissue content of cAMP increased from 12.6 (2.4) to 20.6 (3.4) (P < 0.01). Vardenafil concentration-dependently inhibited nerve-induced contractions in all groups studied. At 100 microm 19 (3)% of the control contraction remained, vs 8 (1)% for preparations from obstructed rats, and 11 (4)% in mucosa-denuded preparations.

CONCLUSION

In normal rats, vardenafil relaxed carbachol- and inhibited EFS-induced contractions of detrusor preparations with and without urothelium, and in PUO rats with urothelium. Relaxations were accompanied by increases in both cAMP and cGMP content. It is proposed that vardenafil-induced relaxation of rat detrusor, also in obstructed and mucosa-denuded preparations, is mediated via cAMP.

PDE5 inhibitors for LUTS

To review the current literature regarding the relationship between lower urinary tract symptoms (LUTS) and erectile dysfunction (ED), and the role of phosphodiesterase-5 (PDE5) inhibitors for the treatment of LUTS. Review of recently published (1990-2009) data regarding epidemiologic and pathophysiologic mechanisms are involved in LUTS-ED, focusing on PDE5 inhibitors particularly evidenced from level 1 clinical trials. Search terms included phosphodiesterase inhibitors, nitric oxide, autonomic hyperactivity, Rho-kinase, atherosclerosis, LUTS, benign prostatic hypertrophy, and ED. Results of several epidemiologic studies show a possible causal relationship between LUTS and ED. Four possible mechanisms have been proposed to explain this association. Multiple large clinical trials have shown a benefit in LUTS after PDE5-inhibitors treatment. PDE5 inhibitors show promise as a future treatment for LUTS, either in conjunction with existing therapies or as a primary treatment.

Association of lower urinary tract symptoms and the metabolic syndrome: results from the Boston Area Community Health Survey

PURPOSE

In this study we investigated the relationship between lower urinary tract symptoms as defined by the American Urological Association symptom index and the metabolic syndrome, and determined the relationship between individual symptoms comprising the American Urological Association symptom index and the metabolic syndrome.

MATERIALS AND METHODS

The Boston Area Community Health Survey used a 2-stage cluster design to recruit a random sample of 2,301 men 30 to 79 years old. Analyses were conducted on 1,899 men who provided blood samples. Urological symptoms comprising the American Urological Association symptom index were included in the analysis. The metabolic syndrome was defined using a modification of the Adult Treatment Panel III guidelines. The association between lower urinary tract symptoms and the metabolic syndrome was assessed using odds ratios and 95% confidence intervals estimated using logistic regression models.

RESULTS

Increased odds of the metabolic syndrome were observed in men with mild to severe symptoms (American Urological Association symptom index 2 to 35) compared to those with an American Urological Association symptom index score of 0 or 1 (multivariate OR 1.68, 95% CI 1.21-2.35). A statistically significant association was observed between the metabolic syndrome and a voiding symptom score of 5 or greater (multivariate adjusted OR 1.73, 95% CI 1.06-2.80) but not for a storage symptom score of 4 or greater (multivariate adjusted OR 0.94, 95% CI 0.66-1.33). Increased odds of the metabolic syndrome were observed even with mild symptoms, primarily for incomplete emptying, intermittency and nocturia. These associations were observed primarily in younger men (younger than 60 years) and were null in older men (60 years old or older).

CONCLUSIONS

The observed association between urological symptoms and the metabolic syndrome provides further evidence of common underlying factors between lower urinary tract symptoms and chronic conditions outside the urinary tract.

Activation of the nitric oxide-cGMP pathway reduces phasic contractions in neonatal rat bladder strips via protein kinase G

Nitric oxide (NO), a neurotransmitter in the lower urinary tract, stimulates soluble guanylyl cyclase (sGC) and in turn cGMP-dependent protein kinase G (PKG) to modulate a number of downstream targets. NO donors reduce bladder hyperactivity in some pathological models but do not affect normal bladder activity in the adult rat. In this study, the NO donor S-nitroso-N-acetyl-DL-penicillamine (SNAP; 100 microM) decreased the amplitude and frequency of spontaneous and carbachol-enhanced contractions in neonatal rat bladder strips, which are intrinsically hyperactive. This effect was blocked by inhibition of sGC and mimicked by application of a membrane-permeable cGMP analog (8-bromo-cGMP, 100 microM). Inhibition of PKG prevented or reversed the inhibitory effects of 8-bromo-cGMP. A portion of the SNAP-mediated inhibition was also dependent upon PKG; however, a short-lasting, sGC-dependent inhibitory effect of SNAP was still present after PKG inhibition. Inhibition of NO synthase with L-NAME (100 microM) did not change the amplitude or frequency of contractions. However, inhibition of endogenous phosphodiesterase (PDE)-5 with zaprinast (25 microM) reduced the amplitude and frequency of phasic contractions and increased the magnitude of inhibition produced by maximal concentrations of SNAP, suggesting that endogenous PDEs are constitutively active and regulate cGMP production. These results suggest that the NO-cGMP-PKG pathway may be involved in inhibitory control of the neonatal rat bladder.

Prospective pharmacologic therapies for the overactive bladder

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

Chronic treatment with a PDE5 inhibitor increases contractile force of normal bladder in rats

OBJECTIVES

We have previously shown that a phosphodiesterase 5 (PDE5) inhibitor, vardenafil, possesses bladder protective effects in bladder outlet obstruction (BOO) rats by preserving contractile force. In this study, we examined the effects of vardenafil to obtain clues for further research elucidating the mechanism of action of vardenafil on rat normal bladder.

MATERIALS AND METHODS

In all, twenty 12-week-old female Sprague-Dawley rats were divided into two equal groups: group 1, water-treated rats; and group 2, vardenafil-treated rats. Vardenafil (8 mg/kg/day) was given by drinking water. Four weeks after, vardenafil was washed out by giving water for 24-48 h, and then bladder was excised and dissected into four longitudinal strips for isometric organ bath assay. Contractile profile of bladder strips to electrical field stimulation (EFS), carbachol, and potassium chloride (KCl) was investigated.

RESULTS

Vardenafil had no effect on body and bladder weight. Contractile forces to EFS, carbachol, and KCl were all increased significantly in group 2 by chronic vardenafil treatment.

CONCLUSION

These effects were consistent with those observed in BOO rats for carbachol response, suggesting that effects of vardenafil are not limited to diseased condition, but also apply in normal condition. Chronic treatment with vardenafil increased contractile force of rat normal bladder strips.

Effects of once-daily tadalafil on erectile function in men with erectile dysfunction and signs and symptoms of benign prostatic hyperplasia

BACKGROUND

Lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH; BPH-LUTS) may be associated with erectile dysfunction (ED).

OBJECTIVE

To evaluate the effects of once-daily tadalafil on erectile function in men with ED and BPH-LUTS.

DESIGN, SETTING, AND PARTICIPANTS

Post hoc analysis of a phase 2-3, multinational, randomized, double-blind, placebo-controlled, parallel-group study of men with ED and moderate-to-severe LUTS secondary to BPH who reported being sexually active. In contrast to typical ED trials, no sexual activity threshold was required to participate.

INTERVENTIONS

Screening and 4-wk washout period for patients taking BPH and/or ED treatments; 4-wk placebo run-in period; then once-daily placebo or tadalafil 2.5, 5, 10, or 20 mg for 12 wk.

MEASUREMENTS

International Index of Erectile Function-Erectile Function (IIEF-EF) domain score, International Prostate Symptom Score (IPSS), peak urinary flow rate (Q(max)), and postvoid residual volume (PVR). Analyses were performed in men who reported being sexually active with a female partner and who expected to remain so throughout the study. IIEF-EF data are presented for the BPH/ED population overall and for subgroups stratified by baseline age group, body mass index, BPH-LUTS severity, prostate-specific antigen, prior alpha-blocker use, and prior ED therapy.

RESULTS AND LIMITATIONS

Overall, 581 men were included (placebo, n=115; tadalafil 2.5 mg, n=113; tadalafil 5 mg, n=117; tadalafil 10 mg, n=120; tadalafil 20 mg, n=116). IIEF-EF domain score improvements from baseline to end point with tadalafil were 5.4 (2.5 mg), 6.8 (5 mg), 7.9 (10 mg), and 8.2 (20 mg) versus 2.0 with placebo (least-squares means; all p values <0.001). IIEF-EF domain score improvements were observed with tadalafil for all subgroup analyses, with no significant differences between subgroup or subgroup-by-treatment interaction terms. IPSS improvements from baseline to end point were significantly greater for all tadalafil doses versus placebo (all p values <0.05). Changes in Q(max) and PVR were small and not clinically meaningful.

CONCLUSIONS

These data support the use of once-daily tadalafil in men with ED and BPH-LUTS.

TRIAL REGISTRATION

http://www.clinicaltrials.gov: NCT00384930.

Vardenafil modulates bladder contractility through cGMP-mediated inhibition of RhoA/Rho kinase signaling pathway in spontaneously hypertensive rats

INTRODUCTION

Phosphodiesterase type 5 inhibitors (PDE5i), the most widely used drugs for erectile dysfunction, could also improve lower urinary tract symptoms, essentially due to overactive bladder (OAB), a condition hypothesized to be a result of an increased RhoA/Rho-kinase (ROCK) signaling. Phosphorylation/inactivation of RhoA by cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG) activity has been described in vascular smooth muscle.

AIM

The aim of this paper was to investigate whether vardenafil-induced cGMP accumulation reduces RhoA/ROCK signaling in bladder.

METHODS

Spontaneously hypertensive rats (SHRs), a strain genetically prone to develop OAB, were treated with vardenafil (10 mg/kg/day) for 2 weeks. Wistar-Kyoto rats (WKY) were used as control. In vitro experiments were performed in human bladder smooth muscle cells (hBCs).

MAIN OUTCOME MEASURES

Urodynamic parameters were registered in vivo in anesthetized WKY and SHRs. RhoA/ROCK activity in bladder was evaluated by molecular and functional studies in tissues and cells.

RESULTS

The intercontraction interval and bladder capacity, and were decreased in SHRs and restored by vardenafil. The in vitro relaxant effect of the ROCK inhibitor Y-27632 was higher in bladder strips from SHR than from WKY and reduced by vardenafil. Nomega-nitro-L-arginine-methyl-ester (a NO-synthase inhibitor, 40 mg/kg/day during the last week of the 2-week treatment with vardenafil) partially antagonized vardenafil effect on Y-27632 responsiveness. Vardenafil prevented RhoA membrane translocation/activation, decreased ROCK activity, and increased cGMP levels in vivo (rat) and in vitro (hBCs). Exposing hBCs to vardenafil increased Ser(188) RhoA phosphorylation, to the same extent as the PDE5-insensitive PKG agonist Sp-8-Br-PET-cGMP. Moreover, vardenafil inhibited several RhoA-dependent functions in hBCs, including smooth muscle gene transcription and endothelin-1-induced migration. These effects were reverted by the PKG inhibitor KT 5823, further suggesting a cGMP/PKG-dependency. In hBCs, vardenafil was active in the low nanomolar range.

CONCLUSIONS

This is the first study demonstrating that the effect of vardenafil on OAB could be partially determined by a cGMP-dependent RhoA/ROCK signaling inhibition.

Pathology of benign prostatic hyperplasia

The epidemiology of benign prostatic hyperplasia (BPH) is complex and not fully understood. The androgenic hormones testosterones and dihydrotestosterone play at least a permissive and important role. Growth factors and other hormones including estrogens may also play a role. BPH is a truely hyperplastic process resulting in growth of glandular-epithelial and stromal/muscle tissue in the prostate, leading to often measurable growth taking on different shapes and configurations which may impact symptoms and secondary outcomes. It is important to recognize that BPH is a histological conditions, which is one but not the only cause of lower urinary tract symptoms, and may or may not be associated with prostate enlargement and bladder outlet obstruction. Recognizing the different entities and determining their presence in individual patients may help with therapeutic decision making.

Is there a rationale for the chronic use of phosphodiesterase-5 inhibitors for lower urinary tract symptoms secondary to benign prostatic hyperplasia?

OBJECTIVES

To critically review the physiological roles of phosphodiesterase-5 (PDE5), to explain and support the putative impact and clinical significance of PDE5 inhibitors (PDE5-Is) in the treatment of lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) and erectile dysfunction (ED), both highly prevalent in men aged > or =50 years, as PDE5-Is are very effective as a first-line therapy for ED, and attractive for further physiological functional investigations.

METHODS

We searched Medline for peer-reviewed articles in English, from 1991 to 2008, to provide a critical contemporary review of PDE5 pertaining to the potential interest of findings supporting a role for PDE5-Is in LUTS due to BPH. The selection of papers was based on the relevance of subject matter. A critical analysis of available fundamental and clinical data is reported.

RESULTS

Several studies assessed the role of the nitric oxide/cGMP signalling pathway in the regulation of the prostate tone, with the support of clinical observations. PDE5-Is can also represent a potential mode of action allowing the targeting of transcriptional activity implicated in the regulation of the progression of the inflammatory process involved in BPH. PDE5-Is can inhibit human stromal cell proliferation of the prostate mediated by cGMP accumulation. New targeting hypotheses of pathophysiological processes are also reported.

CONCLUSIONS

There is evidence that LUTS and ED are strongly linked. This analysis of the regulatory basis of PDE5 biology could indicate several directions of investigation. However, it is necessary to devise well-designed large prospective studies that would produce significant data before this approach becomes a standard of care.