Efficacy and safety of tadalafil for the treatment of erectile dysfunction: results of integrated analyses

Treatment Outcomes of Diabetic Patients With Erectile Dysfunction Prescribed High-Dose Tadalafil

Objective: To assess the treatment outcome of diabetic patients with erectile dysfunction who are prescribed an alternate daily high dose of tadalafil over a 120-day treatment period. Methods: This was a single-site, retrospective, observational study of 63 diabetic men with erectile dysfunction prescribed an alternate daily dose of 30mg of tadalafil between January 1, 2021, and December 31, 2021. Treatment outcomes accessed medication compliance, adverse drug reactions, and patient treatment satisfaction at 60- and 120-days treatment. Results: Mean age of patients was 58.3 years and included patients who suffered from comorbidities ranging from hypertension (54.0%), dyslipidemia (52.3%), and depression (9.5%). At 60 days in the study, 69.8% were satisfied and continued the treatment. However, at the end of the 120-treatment period, a low number of men (17.5%) were satisfied with the treatment and therefore did not remain on the treatment protocol. These patients reported a lack of medication dose efficacy (86.5%), non-compliance with treatment as prescribed (65.4%), and adverse drug reactions (30.8%) as reasons for discontinuing treatment. None of the identified patient demographics were significantly associated with 120-day continuous treatment. Similarly, the odds ratio derived from the logistic regression did not demonstrate an association between the selected variables and the outcome of 120-day continuous treatment retention. Conclusion: This retrospective case series study found that 82.5% of diabetic patients were not satisfied with treatment with alternate dosing of 30mg tadalafil to treat their ED at the end of the 120-day treatment period suggesting an alternative treatment plan.

Advances in physical diagnosis and treatment of male erectile dysfunction

Erectile dysfunction (ED) is the most common male sexual dysfunction by far and the prevalence is increasing year after year. As technology advances, a wide range of physical diagnosis tools and therapeutic approaches have been developed for ED. At present, typical diagnostic devices include erection basic parameter measuring instrument, erection hardness quantitative analysis system, hemodynamic testing equipment, nocturnal erection measuring instrument, nerve conduction testing equipment, etc. At present, the most commonly used treatment for ED is pharmacological therapy represented by phosphodiesterase five inhibitors (PDE5i). As a first-line drug in clinical, PDE5i has outstanding clinical effects, but there are still some problems that deserve the attention of researchers, such as cost issues and some side effects, like visual disturbances, indigestion, myalgia, and back pain, as well as some non-response rates. Some patients have to consider alternative treatments. Moreover, the efficacy in some angiogenic EDs (diabetes and cardiovascular disease) has not met expectations, so there is still a need to continuously develop new methods that can improve hemodynamics. While drug have now been shown to be effective in treating ED, they only control symptoms and do not restore function in most cases. The increasing prevalence of ED also makes us more motivated to find safer, more effective, and simpler treatments. The exploration of relevant mechanisms can also serve as a springboard for the development of more clinically meaningful physiotherapy approaches. Therefore, people are currently devoted to studying the effects of physical therapy and physical therapy combined with drug therapy on ED. We reviewed the diagnosis of ED and related physical therapy methods, and explored the pathogenesis of ED. In our opinion, these treatment methods could help many ED patients recover fully or partially from ED within the next few decades.

Effect of low-dose tadalafil once daily on glycemic control in patients with type 2 diabetes and erectile dysfunction: a randomized, double-blind, placebo-controlled pilot study

BACKGROUND

Phosphodiesterase type 5 inhibitors restore nitric oxide signaling, that plays a significant role in erectile function, and appears to counteract insulin resistance in animal and human models. This study was aimed to evaluate the glycemic and metabolic effects of low-dose tadalafil once daily in patients with type 2 diabetes and erectile dysfunction.

METHODS

A 6-month, randomized, double-blind, placebo-controlled pilot trial was conducted. Eligible patients were randomly assigned in a ratio of 2:1 to the tadalafil 5 mg and placebo groups; all patients received either tadalafil or placebo once a day. The primary efficacy endpoint was the absolute change in glycated hemoglobin (HbA1c) levels during the 6-month study period. The secondary efficacy endpoints included metabolic parameters and erectile function.

RESULTS

Of the 68 patients who completed this study, 45 and 23 patients were allocated to the tadalafil and placebo groups, respectively. The mean HbA1c level was significantly different between the groups over the 6-month study period (P = 0.021). After 6 months of treatment, the HbA1c decrement in the tadalafil group was greater than that in the placebo group (- 0.14 ± 0.53% vs. 0.20 ± 0.69%, P = 0.030). The International Index of Erectile Function-5 scores improvement was significantly greater in the tadalafil group than in the placebo group at 6 months (P = 0.003).

CONCLUSION

This prospective pilot study showed that low-dose tadalafil administered once a day was effective in improving glycemic control and erectile function in patients with type 2 diabetes and erectile dysfunction. Trial registration KCT0005666.

Testosterone replacement therapy and erectile dysfunction

Testosterone (T) deficiency and erectile dysfunction (ED) are independently functionally and socially impairing, and their concurrence in men can be challenging to treat. Successful management requires an understanding of the mechanisms through which T underlies normal erectile function. While the literature elucidating some of these mechanisms is vast (e.g., androgen regulation of the activity of nitric oxygen synthase and phosphodiesterase type 5) for others it is scarce (e.g., catalysts of castration-induced corporal fibrosis). The randomized controlled trial data for the efficacy of T replacement as mono- or combination therapy to treat ED has been conflicting. Positive results were frequently not clinically meaningful. Meta-analyses have been helpful in illuminating trends that seem to be promising. Consensus is still lacking in several areas, such as the threshold of low T severity for which replacement therapy is most beneficial; the timing for initiating combination therapy; and the duration of treatment.

The Use of Vasoactive Drugs in the Treatment of Male Erectile Dysfunction: Current Concepts

It is widely accepted that disorders of the male (uro)genital tract, such as erectile dysfunction (ED) and benign diseases of the prostate (lower urinary tract symptomatology or benign prostatic hyperplasia), can be approached therapeutically by influencing the function of both the vascular and non-vascular smooth muscle of the penile erectile tissue or the transition zone/periurethral region of the prostate, respectively. As a result of the discovery of nitric oxide (NO) and cyclic guanosine monophosphate (GMP) as central mediators of penile smooth muscle relaxation, the use of drugs known to increase the local production of NO and/or elevate the intracellular level of the second messenger cyclic GMP have attracted broad attention in the treatment of ED of various etiologies. Specifically, the introduction of vasoactive drugs, including orally active inhibitors of the cyclic GMP-specific phosphodiesterase (PDE) 5, has offered great advantage in the pharmacotherapy of ED and other diseases of the genitourinary tract. These drugs have been proven efficacious with a fast on-set of action and an improved profile of side-effects. This review summarizes current strategies for the treatment of ED utilizing the application of vasoactive drugs via the oral, transurethral, topical, or self-injection route.

Effects of phosphodiesterase type 5 inhibitors on choroid and ocular vasculature: a literature review

To provide information on the effects of phosphodiesterase type 5 (PDE5) inhibitors on choroidal vessels and central serous chorioretinopathy (CSC) and possible implications for development of exudative age-related macular degeneration (AMD). Two independent investigators conducted a qualitative review of PubMed to identify studies on the choroidal effect of PDE5 inhibitors in June 2019. The search used key words that included PDE5 inhibitors, sildenafil, tadalafil, vardenafil, choroid, choroidal flow, choroidal vessels, choroidal thickness, CSC, AMD or a combination. Only studies which assessed choroidal findings were included. Many ocular diseases are related to changes in choroidal thickness and perfusion. Patients with AMD, who have decreased choroidal perfusion, may manifest more severely diminished choroidal ability to deliver oxygen and other metabolites to the retina, leading to growth of neovascular tissue. As a result of this engorgement of the choroidal vasculature, some patients may have leakage across the retinal pigment epithelium (RPE) and accumulation of subretinal fluid, resulting in CSC. Transient visual symptoms, i.e., changes in color perception and increased light sensitivity, are well-known adverse effects, but there have been rare reports of vision-threatening ocular complications in users of PDE5 inhibitors, such as nonarteritic anterior ischemic optic neuropathy and cilioretinal artery occlusion. The choroid is a vascular tissue analogous in many respects to the corpus cavernosum, and PDE5 inhibitors may increase the choroidal thickness and perfusion. While it is intuitively obvious that thickness of the choroid alone does not guarantee better choriocapillaris oxygenation, it is a reasonable step towards ameliorating ischemia. These drugs have numerous physiologic effects on the choroid related to blood flow, such as clinical consequences in CSC and AMD.

Human tissue kallikrein-1 protects against the development of erectile dysfunction in a rat model of hyperhomocysteinemia

The aim of this study was to investigate the mechanism by which a diet inducing high hyperhomocysteinemia (HHcy) leads to the deterioration of erectile function in rats and whether this is inhibited by expression of the human tissue kallikrein-1 (hKLK1) gene. We established a rat model of HHcy by feeding methionine (Met)-rich diets to male Sprague-Dawley (SD) rats. Male wild-type SD rats (WTRs) and transgenic rats harboring the hKLK1 gene (TGRs) were fed a normal diet until 10 weeks of age. Then, 30 WTRs were randomly divided into three groups as follows: the control (n = 10) group, the low-dose (4% Met, n = 10) group, and the high-dose (7% Met, n = 10) group. Another 10 age-matched TGRs were fed the high-dose diet and designated as the TGR+7% Met group. After 30 days, in all four groups, erectile function was measured and penile tissues were harvested to determine oxidative stress, endothelial cell content, and penis fibrosis. Compared with the 7% Met group, the TGR+7% Met group showed diminished HHcy-induced erectile dysfunction (ED), indicating the improvement caused by hKLK1. Regarding corpus cavernosum endothelial cells, hKLK1 preserved endothelial cell-cell junctions and endothelial cell content, and activated protein kinase B/endothelial nitric oxide synthase (Akt/eNOS) signaling. Fibrosis assessment indicated that hKLK1 preserved normal penis structure by inhibiting apoptosis in the corpus cavernosum smooth muscle cells. Taken together, these findings showed that oxidative stress, impaired corpus cavernosum endothelial cells, and severe penis fibrosis were involved in the induction of ED by HHcy in rats, whereas hKLK1 preserved erectile function by inhibiting these pathophysiological changes.

A prospective study of the effect of antihypertensive medications on the sexual functions of hypertensive adult male patients

Background:

The potential for antihypertensive medications to produce deleterious adverse effects on sexual functions among hypertensive adult male patients has been widely reported, such adverse effects may limit drug adherence and compliance.

Aim:

The aim of this study was to assess the effect of antihypertensive medication use on sexual functions among hypertensive adult male patients.

Methodology:

The study was carried out at the outpatient clinic of a Nigerian University Teaching Hospital. A total of one hundred and fifty-nine recruited hypertensive adult male patients that were being managed at the center over a 3-month period between January 2017 and April 2017 participated in the study; provided they satisfied the inclusion and exclusion criteria for enrolment.

Results:

The respondents were between 30 and 98 years of age, (mean of 59 ± 11.1 years). Blood pressure recorded was during their initial medical diagnosis for hypertension. Systolic blood pressure recorded was between 128 and 194 mmHg (mean of 162 ± 16.4 mmHg), while their diastolic blood pressure was between 78 and 120 mmHg (mean of 95 ± 10.7 mmHg). The highest occurrence of sexual dysfunctions was associated with calcium-channel blockers in 32 (20.1%) patients, followed by diuretics in 27 (17.0%) and, angiotensin-converting enzyme inhibitors in 20 (12.6%) patients.

Conclusion:

Calcium channel blockers caused the highest occurrence of sexual dysfunctions.

This prospective study assessed the effect of antihypertensive medications on sexual functions among hypertensive adult male patients attending the medical outpatient clinic of a Nigerian University Teaching Hospital. A total of 159 patients who consented to the study and had been attending the clinic regularly for at least 6-month were enrolled. The respondents aged 30–98 years (mean 59 ± 11.1 years). Antihypertensive medication-associated sexual dysfunctions among the patients were observed in descending order as follows: calcium channel blockers in 32 (20.1%), diuretics in 27 (17.0%), Angiotensin converting enzyme inhibitors in 20 (12.6%), centrally acting antihypertensives in 11 (6.9%), beta receptor blockers in 8 (5.0%), vasodilators in 2 (1.3%), combined alpha- and beta-receptor blockers in 2 (1.3%) and alpha receptor blockers in 1 (0.6%). Antihypertensive medical prescriptions should reflect a balance between efficacy and tendency to cause sexual dysfunctions.

Meta-Analysis of the Long-Term Efficacy and Tolerance of Tadalafil Daily Compared With Tadalafil On-Demand in Treating Men With Erectile Dysfunction

Background

Erectile dysfunction (ED) is highly prevalent in aging men. Tadalafil daily and on-demand are widely used for the treatment of ED.

Aim

We performed a meta-analysis to evaluate the efficacy and safety of tadalafil daily compared with tadalafil on-demand in treating men with ED after at least 24 weeks of long-term treatment.

Methods

Randomized controlled trials of tadalafil daily vs on-demand in treating men with ED were searched using MEDLINE, EMBASE, and the Cochrane Controlled Trials Register. Systematic review was carried out using the Preferred Reporting Items for Systematic Reviews and Meta-analyses. The data was calculated by RevMan version 5.3.0. The references of related articles were also searched.

Outcomes

International Index of Erectile Function-Erectile Function domain, sexual encounter profile question 2 (SEP2), SEP question 3 (SEP3), any treatment-emergent adverse event (AE), discontinuation due to AEs, myalgia, back pain, headache, dyspepsia, and nasopharyngitis.

Results

4 articles, including 1,035 participants were studied. The analysis found that tadalafil daily had a greater improvement than tadalafil on-demand in terms of International Index of Erectile Function-Erectile Function (mean difference (MD) 1.24; 95% CI 0.03−2.44; P = .04), SEP2 (MD 10.08; 95% CI 9.15−11.01; P < .00001) and SEP3 (MD 8.19; 95% CI 2.09−14.29; P = .009) in treating ED after at least 24 weeks treatment cycle. For safety, tadalafil on-demand had a higher incidence of any treatment-emergent AE (odds ratio 0.73; 95% CI 0.56−0.96; P = .02) compared with tadalafil daily, but for other aspects, including discontinuation due to AEs, myalgia, back pain, headache, dyspepsia, and nasopharyngitis, there were no significant difference between the 2 treatments.

Clinical Implications

Tadalafil daily may offer a better effect for ED than on-demand for long-term treatment.

Strengths and Limitations

From the perspective of evidence-based medicine, we evaluated the efficacy and safety of tadalafil daily compared with tadalafil on-demand in treating men with ED after a long-term treatment. The quality of these studies included is flawed, primarily in difference in tadalafil doses and severity of the ED.

Conclusion

Tadalafil daily provides a preferable therapeutic effect for ED with a lower incidence of treatment-emergent side effects relative to tadalafil on-demand after at least 24 weeks of long-term treatment.

Zhou Z, Chen H, Wu J, et al. Meta-Analysis of the Long-Term Efficacy and Tolerance of Tadalafil Daily Compared With Tadalafil On-Demand in Treating Men With Erectile Dysfunction. J Sex Med 2019;7:282–291.

Efficacy and safety of combination of tadalafil and aspirin versus tadalafil or aspirin alone in patients with vascular erectile dysfunction: a comparative randomized prospective study

PURPOSE

We aimed to investigate the efficacy and safety of tadalafil, aspirin, and tadalafil + aspirin combination therapy in vascular erectile dysfunction (VED).

METHODS

A total of 336 patients were randomly divided into four groups (group 1, aspirin 100 mg/day, 126 patients; group 2, tadalafil 5 mg/day, 72 patients; group 3, tadalafil 5 mg + aspirin 100 mg, 72 patients; group 4, placebo, 66 patients). In all groups, the changes from baseline to end point in erectile function scores on the International Index of Erectile Function (IIEF-EF) and the number of patients who answered "yes" to questions 2 and 3 of the sexual encounter profile(SEP) were compared statistically.

RESULTS

The changes in IIEF-EF scores after treatment were 7.2 ± 4.4, 7.3 ± 4.3, 7.5 ± 4.4, and 2.0 ± 4.6 for group 1 (p < 0.0001), group 2 (p < 0.0001), group 3 (p < 0.0001), and group 4 (p = 0.0204), respectively. The change in SEP-2 ratios after treatment were 36.6%, 36.9%, 41.7%, and 9.4% for group 1 (p < 0.0001), group 2 (p < 0.0001), group 3 (p < 0.0001), and group 4 (p = 0.2925), respectively. The change in SEP-3 ratios after treatment was 46.6%, 49.2%, 53.7%, and 12.5% for group 1 (p < 0.0001), group 2 (p < 0.0001), group 3 (p < 0.0001), and group 4 (p = 0.1456), respectively. In group 2, both the number of patients who reported side effects (p < 0.0001) and stopped using the drug due to side effects (p < 0.05) were significantly higher than the control and others groups.

CONCLUSIONS

Successful results were obtained by tadalafil and aspirin monotherapy and tadalafil + aspirin combination therapy in patients with VED. However, the least side effect was observed in the tadalafil + aspirin group. Aspirin can be used alone in the treatment of patients with VED, or combined with tadalafil to reduce side effects and increase success.

A randomized double-blind, placebo-controlled, cross-over trial assessing the effect of tadalafil (Cialis) on the cardiovascular response in men with complete spinal cord injury above the sixth thoracic level: A Pilot Study

Study design

Double-blind, randomized cross-over placebo-controlled pilot study.

Objectives

To determine the effects of tadalafil on systolic blood pressure (SBP), heart rate (HR), and dizziness of men with American Spinal Injury Association Impairment Scale-A (AIS-A) spinal cord injury (SCI) between cervical-4 (C4) and thoracic-5 (T5) levels.

Setting

Outpatient rehabilitation clinic.

Design

Double-blind, randomized cross-over placebo-controlled pilot study.

Methods

20 males with AIS-A SCI, C4-T5 received either tadalafil 20 mg or placebo for the first arm, and then were crossed-over after 1 week to the second arm. SBP, HR, and Visual Analogue Scale (VAS) for dizziness upon sitting up from lying were measured at baseline and again 1, 2, 4, 12, 22, 29, and 36 h post dose administration. The change in each outcome measure (SBP, HR, VAS dizziness) was observed from pre-dose to each time point. A change in VAS dizziness of 2 cm or greater (scale 0–10 cm) was considered positive.

Results

SBP did not change significantly in either group. However, HR increased significantly in the tadalafil group at several time points (12 h p < 0.05, 22 h p <0.05, 29 h p <0.01, and 36 h p <0.05), with no change in the placebo group. The VAS dizziness significantly increased (range 2–6 cm changes) at some time point in 1/4 of the subjects after tadalafil, but not in the placebo group; all reports of dizziness were at 12 h or later.

Conclusions

Tadalafil use in people with SCI above T6 is safe with respect to not causing hypotension; hemodynamic changes that occurred 12–36 h post administration were compensated for by elevations in HR.

Sponsorship

The Manitoba Medical Services Foundation and the Health Sciences Centre Foundation.

Enhanced Bioavailability of Tadalafil after Intranasal Administration in Beagle Dogs

Tadalafil is an oral selective phosphodiesterase type-5 inhibitor with demonstrated efficacy and safety that is used to treat erectile dysfunction. The purpose of this study is to compare the pharmacokinetic properties of tadalafil after conventional oral tablet administration and novel intranasal administration in beagle dogs. Fourteen 13-month-old male beagle dogs were randomly divided into two groups, and were given 5 mg tadalafil orally or intranasally in a parallel design. Blood samples were collected before and 0.5, 1, 1.5, 2, 4, 6, 8, 12, 24, and 36 h after administration. The plasma concentration of tadalafil was determined via liquid chromatography-tandem mass spectrometry (LC-MS/MS). The systemic exposure and absorption rate of tadalafil were significantly greater in the intranasal administration group than in the oral administration group. A one-compartment model with first-order absorption and elimination was sufficient to explain the pharmacokinetic characteristics observed after both oral and intranasal administration. This study indicates that the development of tadalafil nasal delivery systems is feasible and may lead to better results than the conventional oral route.

Increased bioavailability of cyclic guanylate monophosphate prevents retinal ganglion cell degeneration

The nitric oxide - guanylyl cyclase-1 - cyclic guanylate monophosphate (NO-GC-1-cGMP) pathway has emerged as a potential pathogenic mechanism for glaucoma, a common intraocular pressure (IOP)-related optic neuropathy characterized by the degeneration of retinal ganglion cells (RGCs) and their axons in the optic nerve. NO activates GC-1 to increase cGMP levels, which are lowered by cGMP-specific phosphodiesterase (PDE) activity. This pathway appears to play a role in both the regulation of IOP, where reduced cGMP levels in mice leads to elevated IOP and subsequent RGC degeneration. Here, we investigated whether potentiation of cGMP signaling could protect RGCs from glaucomatous degeneration. We administered the PDE5 inhibitor tadalafil orally (10 mg/kg/day) in murine models of two forms of glaucoma - primary open angle glaucoma (POAG; GC-1^-/- mice) and primary angle-closure glaucoma (PACG; Microbead Occlusion Model) - and measured RGC viability at both the soma and axon level. To determine the direct effect of increased cGMP on RGCs in vitro, we treated axotomized whole retina and primary RGC cultures with the cGMP analogue 8-Br-cGMP. Tadalafil treatment increased plasma cGMP levels in both models, but did not alter IOP or mean arterial pressure. Nonetheless, tadalafil treatment prevented degeneration of RGC soma and axons in both disease models. Treatment of whole, axotomized retina and primary RGC cultures with 8-Br-cGMP markedly attenuated both necrotic and apoptotic cell death pathways in RGCs. Our findings suggest that enhancement of the NO-GC-1-cGMP pathway protects the RGC body and axon in murine models of POAG and PACG, and that enhanced signaling through this pathway may serve as a novel glaucoma treatment, acting independently of IOP.

The nitric oxide-guanylate cyclase pathway and glaucoma

Glaucoma is a prevalent optic neuropathy characterized by the progressive dysfunction and loss of retinal ganglion cells (RGCs) and their optic nerve axons, which leads to irreversible visual field loss. Multiple risk factors for the disease have been identified, but elevated intraocular pressure (IOP) remains the primary risk factor amenable to treatment. Reducing IOP however does not always prevent glaucomatous neurodegeneration, and many patients progress with the disease despite having IOP in the normal range. There is increasing evidence that nitric oxide (NO) is a direct regulator of IOP and that dysfunction of the NO-Guanylate Cyclase (GC) pathway is associated with glaucoma incidence. NO has shown promise as a novel therapeutic with targeted effects that: 1) lower IOP; 2) increase ocular blood flow; and 3) confer neuroprotection. The various effects of NO in the eye appear to be mediated through the activation of the GC- guanosine 3:5'-cyclic monophosphate (cGMP) pathway and its effect on downstream targets, such as protein kinases and Ca²⁺ channels. Although NO-donor compounds are promising as therapeutics for IOP regulation, they may not be ideal to harness the neuroprotective potential of NO signaling. Here we review evidence that supports direct targeting of GC as a novel pleiotrophic treatment for the disease, without the need for direct NO application. The identification and targeting of other factors that contribute to glaucoma would be beneficial to patients, particularly those that do not respond well to IOP-dependent interventions.

Clinical and preclinical treatment of urologic diseases with phosphodiesterase isoenzymes 5 inhibitors: an update

Phosphodiesterase isoenzymes 5 inhibitors (PDE5-Is) are the first-line therapy for erectile dysfunction (ED). The constant discoveries of nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) cell-signaling pathway for smooth muscle (SM) control in other urogenital tracts (UGTs) make PDE5-Is promising pharmacologic agents against other benign urological diseases. This article reviews the literature and contains some previously unpublished data about characterizations and activities of PDE5 and its inhibitors in treating urological disorders. Scientific discoveries have improved our understanding of cell-signaling pathway in NO/cGMP-mediated SM relaxation in UGTs. Moreover, the clinical applications of PDE5-Is have been widely recognized. On-demand PDE5-Is are efficacious for most cases of ED, while daily-dosing and combination with testosterone are recommended for refractory cases. Soluble guanylate cyclase (sGC) stimulators also have promising role in the management of severe ED conditions. PDE5-Is are also the first rehabilitation strategy for postoperation or postradiotherapy ED for prostate cancer patients. PDE5-Is, especially combined with α-adrenoceptor antagonists, are very effective for benign prostatic hyperplasia (BPH) except on maximum urinary flow rate (Q max ) with tadalafil recently proved for BPH with/without ED. Furthermore, PDE5-Is are currently under various phases of clinical or preclinical researches with promising potential for other urinary and genital illnesses, such as priapism, premature ejaculation, urinary tract calculi, overactive bladder, Peyronie's disease, and female sexual dysfunction. Inhibition of PDE5 is expected to be an effective strategy in treating benign urological diseases. However, further clinical studies and basic researches investigating mechanisms of PDE5-Is in disorders of UGTs are required.

The clinical evidence for targeting human myeloid-derived suppressor cells in cancer patients

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that represent a formidable obstacle to the successful treatment of cancer. Patients with high frequencies of MDSCs have significantly decreased progression-free survival (PFS) and overall survival (OS). Whereas there is experimental evidence that the reduction of the number and/or suppressive function of MDSCs in mice improves the efficacy of anti-cancer therapies, there is notably less evidence for this therapeutic strategy in human clinical trials. Here, we discuss currently available data concerning MDSCs from human clinical trials and explore the evidence that targeting MDSCs may improve the efficacy of cancer therapies.

PDE5 Exists in Human Neurons and is a Viable Therapeutic Target for Neurologic Disease

Phosphodiesterase 5 (PDE5) is a critical component of the cGMP-PKG axis of cellular signaling in neurons, and inhibition of PDE5 has been shown to be therapeutic in a wide range of neurologic conditions in animal models. However, enthusiasm for PDE5 inhibitors in humans is limited by data suggesting that PDE5 may not exist in human neurons. Here, we first show that past attempts to quantify PDE5 mRNA were flawed due to the use of incorrect primers, and that when correct primers are used, PDE5 mRNA is detectable in human brain tissue. We then show that PDE5 protein exists in human brain by western blot and ELISA. Most importantly, we performed immunohistochemistry and demonstrate that PDE5 is present in human neurons. We hope that this work will trigger a renewed interest in the development of PDE5 inhibitors for neurologic disease.

The devil is in the details: an analysis of the subtleties between phosphodiesterase inhibitors for erectile dysfunction

Erectile dysfunction (ED) is a common sexual disorder with numerous etiologies involving multiple organ systems that leads to significant distress and decreased quality of life for the affected men. Fortunately, there are several modalities and interventions for treating ED. Oral medications, intra-urethral compounds, intracorporeal injections, vacuum-assist devices and surgically implanted prostheses are all part of the treatment algorithm. One of the first-lines and certainly the most widely used options for treating ED is the family of oral phosphodiesterase type 5 inhibitors (PDE5I). The introduction of these medications in the late 1990s revolutionized the field of sexual medicine. Currently there are no guidelines and minimal literature to help providers choose among drugs in this class. This review will address differences in efficacy and side effects between various members of the oral selective phosphodiesterase-5 inhibitor class of drugs.

Alprostadil cream in the treatment of erectile dysfunction: clinical evidence and experience

Erectile dysfunction (ED) is a very common disorder with a deep impact on quality of life on both patients and partners. Several options are available for treating ED: oral pharmacotherapy with phosphodiesterase 5 (PDE5) inhibitors currently represents the first-line option for many patients with ED. Alprostadil, a prostaglandin, has been marketed for many years as a urethral stick and an intracavernous injection for the treatment of ED. It is now available in the form of a cream (Vitaros/Virirec), a noninvasive treatment which combines an active drug (alprostadil, a synthetic prostaglandin E1) with a skin enhancer improving its local absorption directly at the site of action. Alprostadil has a favourable pharmacodynamic profile and is poorly absorbed in systemic circulation, which makes it suitable in a lot of circumstances and results in a reduced risk of adverse effects (AEs). Systemic AEs are reported in only 3% of the treated population. Clinical efficacy has been demonstrated in both phase II and III trials, showing a global efficacy up to 83% with the 300 μg dose in patients with severe ED, significantly better than placebo. Its fast onset of action and lack of interactions with other drugs makes alprostadil cream a possible first-line therapeutic option for some patients with ED: individuals who are reluctant to take systemic treatments or have AEs, patients who do not respond, cannot tolerate, or do not accept PDE5 inhibitor therapy, and patients treated with nitrates. Therefore, this new treatment for ED can be offered to patients and could help address the needs unmet by other treatments.

The Association between Phosphodiesterase Type 5 Inhibitors and Prostate Cancer: Results from the REDUCE Study

PURPOSE

Despite routine use of phosphodiesterase type 5 inhibitor to treat erectile dysfunction the role in prostate cancer chemoprevention remains unclear. Only a few studies have explored the link between phosphodiesterase type 5 inhibitor use and prostate cancer. We tested the association between phosphodiesterase type 5 inhibitor and prostate cancer risk in the REDUCE (Reduction by Dutasteride of Prostate Cancer Events) trial.

MATERIALS AND METHODS

REDUCE was a 4-year multicenter study testing the effect of daily dutasteride on prostate cancer risk in men with prostate specific antigen 2.5 to 10.0 ng/ml and negative biopsy who underwent study mandated biopsies at 2 and 4 years. The association of phosphodiesterase type 5 inhibitor with overall prostate cancer risk and disease grade (Gleason 2-6 and 7-10) was examined using adjusted logistic and multinomial regression analysis. Secondary analysis was performed to explore the association between phosphodiesterase type 5 inhibitor and prostate cancer risk in North American men, given the significantly higher use of phosphodiesterase type 5 inhibitor in these subjects.

RESULTS

Phosphodiesterase type 5 inhibitor was not associated with prostate cancer diagnosis (OR 0.90, 95% CI 0.68-1.20, p = 0.476), low grade disease (OR 0.93, 95% CI 0.67-1.27, p = 0.632) or high grade disease (OR 0.85, 95% CI 0.51-1.39, p = 0.508). An inverse trend was seen between phosphodiesterase type 5 inhibitor and prostate cancer diagnosis in North American men but this was not statistically significant (OR 0.67, 95% CI 0.42-1.07, p = 0.091).

CONCLUSIONS

Phosphodiesterase type 5 inhibitor use was not associated with decreased prostate cancer diagnoses on post-hoc analysis of REDUCE. In North American men, who had much higher baseline use of phosphodiesterase type 5 inhibitor, this treatment was associated with an inverse trend of prostate cancer diagnosis that approached but did not reach statistical significance.

Tadalafil 5 mg once daily for the treatment of erectile dysfunction during a 6-month observational study (EDATE): impact of patient characteristics and comorbidities

BACKGROUND

To explore the impact of patient-characteristics and relevant comorbidities on treatment continuation rates, effectiveness, and satisfaction in patients with erectile dysfunction (ED) who started or switched to tadalafil 5 mg once daily (TAD-OaD) at baseline.

METHODS

In the EDATE observational study, phosphodiesterase-type-5 (PDE5)-inhibitor pretreated or naïve ED patients who started or switched to TAD-OaD were prospectively followed for 6 months. Time to discontinuation of TAD-OaD was estimated using the Kaplan-Meier product-limit method at Months 2, 4, and 6 in subgroups stratified by age (18 - 65 years and >65 years), PDE5-inhibitor pretreatment, ED-severity (mild, moderate, severe), and presence or absence of relevant comorbidities (BPH, diabetes, CVD, hypertension, dyslipidemia). LSmean change from baseline in International Index of Erectile Function (IIEF) and Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) scores and associated 95 % CIs were assessed using a mixed-model for repeated measures. Visit, ED etiology, and subgroups were included as fixed-effects.

RESULTS

Overall, 778 patients received prescriptions for initiating or switching to TAD-OaD at baseline. At Month 2, >90 % of patients remained on TAD-OaD, except those aged >65 years (86.7 %) and patients with severe ED (89.0 %). More than 80 % of patients in all subgroups, except those aged >65 years (75.0 %), continued TAD-OaD at Month 6. There was a significant LSmean negative effect on IIEF- EF domain-score improvement for BPH (LSmean effect [95 % CI]: -2.77 [-4.98, -0.55], p = 0.014), previous PDE5-inhibitor treatment (-2.13 [-3.33,-0.94], p < 0.001), and mild vs moderate ED (-2.00 [-3.54,-0.46], p = 0.011); the latter possibly linked with a bigger treatment-effect in those with more severe ED at baseline. The LSmean effect on change in IIEF-EF was significantly positive for diabetes (2.28 [0.64,3.92], p = 0.007), most likely because those with diabetes had more severe ED at baseline. For all other parameters, no statistically significant LSmean effects in IIEF-EF changes were observed. No comorbidity or baseline-characteristic except age (18 - 65 years vs >65 years: 11.25 [2.96,19.54], p = 0.008) affected changes in EDITS.

CONCLUSIONS

Under routine clinical conditions, treatment continuation rate or satisfaction does not seem to be significantly affected by the presence of comorbidities in men who choose ED-treatment with TAD-OaD. The magnitude of treatment effectiveness was affected by certain baseline characteristics and comorbid conditions.

TRIAL REGISTRATION

The study (H6D-EW-LVIU) is registered in the German VfA Registry of Non-Interventional Studies (Verband Forschender Arzneimittelhersteller) since 06 December 2011; available at: http://www.vfa.de/de/arzneimittel-forschung/datenbanken-zu-arzneimitteln/nisdb/nis-details/_741 .

Current use of phosphodiesterase inhibitors in urology

The causes of male erectile dysfunction (ED) are quite variable and are now commonly divided into etiologies such as ischemia, smooth muscle damage, or altered blood flow. Although varying rates of ED have been reported in literature, the number of men with ED is projected to increase worldwide by 2025 to approximately 322 million. Since the introduction of phosphodiesterase 5 (PDE5) inhibitors, there has been a paradigm shift in the treatment of ED because PDE5 inhibitors address a broad spectrum of etiologies for ED. Today, the American Urological Association recommends the use of three PDE5 inhibitors (sildenafil, tadalafil, and vardenafil) as a first-line therapy for the treatment of ED. This review evaluates the pharmacological mechanism of PDE5 inhibitors along with the impact and use of sildenafil, vardenafil, tadalafil, and avanafil. By increasing intracellular cGMP levels, PDE5 inhibitors have been shown to be effective in the treatment of ED. Through their effects on other cellular signaling pathways, PDE5 inhibitors have the potential for treating other urologic conditions as well. The use of PDE5 inhibitors can also be combined to produce a synergistic effect in conditions such as male hypogonadism and benign prostatic hyperplasia in addition to ED.

Designed angiopoietin-1 variant, COMP-angiopoietin-1, rescues erectile function through healthy cavernous angiogenesis in a hypercholesterolemic mouse

Despite the advent of oral phosphodiesterase-5 inhibitors, curative treatment for erectile dysfunction (ED) remains unavailable. Recently, the link between ED and cardiovascular disease was unveiled and the main etiology of ED was found to be vasculogenic. Therefore, neovascularization is a promising strategy for curing ED. Angiopoietin-1 (Ang1) is an angiogenic growth factor that promotes the generation of stable and functional vasculature. Here, we demonstrate that local delivery of the soluble, stable, and potent Ang1 variant, COMP-Ang1 gene or protein, into the penises of hypercholesterolemic mice increases cavernous angiogenesis, eNOS phosphorylation, and cGMP expression, resulting in full recovery of erectile function and cavernous blood flow up to 8 weeks after treatment. COMP-Ang1-induced promotion of cavernous angiogenesis and erectile function was abolished in Nos3^-/- mice and in the presence of the NOS inhibitor, L-NAME. COMP-Ang1 also restored the integrity of endothelial cell-cell junction by down-regulating the expression of histone deacetylase 2 in the penis of hypercholesterolemic mice and in primary cultured mouse cavernous endothelial cells. These findings constitute a new paradigm toward curative treatment of both cavernous angiopathy and ED.

Role of sGC-dependent NO signalling and myocardial infarction risk

The NO/cGMP pathway plays an important role in many physiological functions and pathophysiological conditions. In the last few years, several genetic and functional studies pointed to an underestimated role of this pathway in the development of atherosclerosis. Indeed, several genetic variants of key enzymes modulating the generation of NO and cGMP have been strongly associated with coronary artery disease and myocardial infarction risk. In this review, we aim to place the genomic findings on components of the NO/cGMP pathway, namely endothelial nitric oxide synthase, soluble guanylyl cyclase and phosphodiesterase 5A, in context of preventive and therapeutic strategies for treating atherosclerosis and its sequelae.

Psychosocial outcomes after initial treatment of erectile dysfunction with tadalafil once daily, tadalafil on demand or sildenafil citrate on demand: results from a randomized, open-label study

Initiation of ED treatment with a particular PDE5I may influence treatment-adherence and other outcomes. In this multicenter, open-label study, men with ED, naïve to PDE5I, were randomized to tadalafil 5 mg once-a-day (OaD; N=257), 10 mg on demand (PRN; N = 252) or sildenafil-citrate (sildenafil) 50 mg PRN (N = 261) for 8 weeks (dose adjustments allowed), followed by 16 weeks of pragmatic treatment (switching between PDE5I allowed). Primary outcomes (treatment-adherence) were reported previously. Here, we report effects on: Psychological and Interpersonal Relationship Scales, Self-Esteem and Relationship (SEAR) questionnaire, ED Inventory of Treatment Satisfaction (EDITS), International Index of Erectile Function (IIEF), Sexual Encounter Profile (SEP) and Global Assessment Questions (GAQ). Mixed-model for repeated measures and analysis of covariance were used to analyze changes from baseline; GAQ-responses were evaluated by logistic regression. Analyses were adjusted for treatment, country, ED-severity, baseline and baseline-by-treatment interaction. Patients randomized to tadalafil OaD or PRN reported greater improvement (least-square mean (s.e.) change) in Sexual Self-Confidence (OaD +0.90 (0.048), PRN +0.93 (0.050), vs +0.73 (0.049); P=0.006 and P=0.001) and Spontaneity (OaD +0.11 (0.035), PRN +0.13 (0.035), vs +0.02 (0.035); P = 0.044 and P = 0.010) compared with sildenafil. Improvements in GAQ and SEP responses, IIEF-EF, orgasmic function, sexual desire, overall satisfaction domains, SEAR and EDITS scores did not differ significantly between treatment groups.

Mirodenafil for the treatment of erectile dysfunction: a systematic review of the literature

Phosphodiesterase type 5 (PDE5) inhibitors are the most commonly used treatment for erectile dysfunction (ED). Since the launch of sildenafil, several drugs-including mirodenafil, sildenafil citrate (sildenafil), tadalafil, vardenafil HCL (vardenafil), udenafil, and avanafil-have become available. Mirodenafil is a newly developed pyrrolopyrimidinone compound, which is a potent, reversible, and selective oral PDE5 inhibitor. Mirodenafil was launched in Korea in 2007, and an orally disintegrating film of mirodenafil was developed in 2011 for benefitting patients having difficulty in swallowing tablets. This study aimed to review the pharmacokinetic characteristic profile of mirodenafil and report evidence on its efficacy in the case of ED. In addition, we reviewed randomized controlled studies of mirodenafil's daily administration and efficacy for lower urinary tract symptoms.

Phosphodiesterase type 5 inhibitors as a treatment for erectile dysfunction: Current information and new horizons

INTRODUCTION

Over the past 15 years, the discovery and development of oral medications that selectively inhibit the enzyme phosphodiesterase type 5 (PDE5) have revolutionised the treatment of erectile dysfunction (ED). Currently, three PDE5 inhibitors are widely available clinically, i.e., sildenafil, vardenafil and tadalafil. New PDE5 inhibitors, including avanafil and udenafil, are now in clinical use in a few countries, and other compounds are under development.

METHODS

We describe the current use and future direction of PDE5 inhibitors in the treatment of ED.

RESULTS AND CONCLUSION

Each PDE5 inhibitor has an excellent and comparable efficacy and tolerability. These drugs are highly effective for ED of various causes, and are effective in preventing ED after radical prostatectomy. However, whilst being at least 60% effective, PDE5 inhibitors are still ineffective in at least 30% of patients, prompting current research into other pharmacological targets for ED.

Korean Society for Sexual Medicine and Andrology (KSSMA) Guideline on Erectile Dysfunction

In February 2011, the Korean Society for Sexual Medicine and Andrology (KSSMA) realized the necessity of developing a guideline on erectile dysfunction (ED) appropriate for the local context, and established a committee for the development of a guideline on ED. As many international guidelines based on objective evidence are available, the committee decided to adapt these guidelines for local needs instead of developing a new guideline. Considering the extensive research activities on ED in Korea, data with a high level of evidence among those reported by Korean researchers have been collected and included in the guideline development process. The latest KSSMA guideline on ED has been developed for urologists. The KSSMA hopes that this guideline will help urologists in clinical practice.

Therapeutic angiogenesis as a potential future treatment strategy for erectile dysfunction

The cavernous endothelium plays a crucial role in regulating the tone of the underlying smooth muscle and physiologic penile erection. Recently, the link between erectile dysfunction (ED) and cardiovascular disease was unveiled, and the main etiology of ED was found to be vasculogenic. Although oral phosphodiesterase-5 inhibitors are generally effective for men with ED, such therapies do not cure underlying vasculopathy in the corpus cavernosum tissue. This review addresses current preclinical protein, gene, and cell or stem cell therapies for enhancing cavernous endothelial regeneration and restoring erectile function.

Protective effects of Launaea procumbens on rat testis damage by CCl4

BACKGROUND

Traditionally various human diseases of kidneys, hormonal imbalance and sexual diseases are treated with Launaea procumbens (L). In the present study protective effects of methanolic extract of Launaea procumbens (LPME) was evaluated against CCl4-induced oxidative damages in rat testis.

METHODS

To examine the protective effects of Launaea procumbens on testis against oxidative stress of carbon tetrachloride in male rat, 30 male albino rats were equally divided into 5 groups (6 rats). First group was given standard diet and drinking water. Second group received CCl4 3 ml/kg intraperitoneally (30% in olive oil). Third and forth were given orally 100; 200 mg/kg b.w., in 99.8% dimethyl sulphooxide (DMSO), Launaea procumbens methanolic extracts (LPME) after 48 h of CCl4 treatment twice a week and sixth group received only LPME in DMSO at a dose of 200 mg/kg b.w., for four weeks. Protective effects of Launaea procumbens were observed on sperm concentration, motility and morphology, serum reproductive hormonal level, activity of antioxidant enzymes, lipid peroxidation (TBARS) and DNA damages.

RESULTS

Results of the present study revealed that treatment of CCl4 significantly (p < 0.01) reduced sperm concentration and motility comparatively to controls. Level of testosterone, luteinizing hormone and follicle stimulating hormone, were depleted markedly (p <0.01) with treatment of CCl4. In addition, CCl4 induction in rats reduced activities of antioxidant enzymes while increased lipid peroxidation and DNA damages. Co-administration of LPME significantly (p <0.01) improved these alterations in improving of hormonal level, activities of antioxidant enzymes and lipid peroxidation near to control rats.

CONCLUSION

From the results it is suggested that Launaea procumbens methanolic extract has the ability to protect testis against oxidative damages, possibly through antioxidant effects of its bioactive compounds.

Tadalafil in the treatment of erectile dysfunction

The treatment for erectile dysfunction (ED) was revolutionized with the development of phosphodiesterase type 5 (PDE5) inhibitors. Tadalafil (Cialis((R)); Eli Lilly and Company, Indianapolis, IN, USA) is the newest and most versatile PDE5 inhibitor in the clinical armamentarium for the treatment of ED. Its most unique characteristic is its long half-life of 17.5 hours, which lends itself to a longer therapeutic window with on-demand dosing and effective steady-state plasma concentrations with once-daily dosing. Clinical trials have proven its safety and efficacy with both dosing strategies for all severities and etiologies of ED, including difficult-to-treat ED. This thorough review will discuss ED, the physiology of penile erection and the role of PDE5, and all aspects of tadalafil, from its development, through its pharmacology, to its latest clinical studies and indications.

Effect of tadalafil in chronic renal failure rabbits: relevance to erectile dysfunction

It is of great importance to investigate an effective and reliable medication against chronic renal failure (CRF)-related erectile dysfunction (ED), which aims to improve patients' life qualities. The concentrations of cyclic guanosine monophosphate (cGMP) in the corpus cavernosal smooth muscle of both CRF and control rabbits were measured. The effects of various concentrations of tadalafil, papaverine, and sodium nitroprusside on the relaxation responses of corpus cavernosal smooth muscle pre-contracted with phenylephrine in CRF rabbits were observed. There was significant difference in the concentration of cGMP between CRF and control rabbits (P<0.01). Tadalafil had the greatest impacts on CRF rabbits when given the same concentration of papaverine or sodium nitroprusside and particularly significant differences were identified under the concentration levels of 10⁻⁵ and 10⁻⁴ mol/L (P<0.01). The results suggest that the cGMP concentrations of the corpus cavernosum had been greatly reduced in CRF rabbits compared with control rabbits and that tadalafil may be an ideal medication for use in the treatment of CRF-related ED.

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.

The emergence of oral tadalafil as a once-daily treatment for pulmonary arterial hypertension

Pulmonary hypertension (PH) is found in a vast array of diseases, with a minority representing pulmonary arterial hypertension (PAH). Idiopathic PAH or PAH in association with other disorders has been associated with poor survival, poor exercise tolerance, progressive symptoms of dyspnea, and decreased quality of life. Left untreated, patients with PAH typically have a progressive decline in function with high morbidity ultimately leading to death. Advances in medical therapy for PAH over the past decade have made significant inroads into improved function, quality of life, and even survival in this patient population. Three classes of pulmonary artery-specific vasodilators are currently available in the United States. They include prostanoids, endothelin receptor antagonists, and phosphodiesterase type 5 (PDE5) inhibitors. In May 2009, the FDA approved tadalafil, the first once-daily PDE5 inhibitor for PAH. This review will outline the currently available data on tadalafil and its effects in patients with PAH.

Safety of sildenafil citrate: review of 67 double-blind placebo-controlled trials and the postmarketing safety database

AIM

To review special safety topics associated with sildenafil and to document the tolerability of 50- and 100-mg doses, overall and by age, in men with erectile dysfunction (ED).

METHODS

Data were collated from 67 double-blind placebo-controlled (DBPC) trials (> 14,000 men) conducted by the manufacturer and from the manufacturer's postmarketing safety database (39,277 patients). The DBPC data were stratified by dose, starting dose and age (> or = 65 and > or = 75 years). Special safety topics included cardiovascular risk, priapism, non-arteritic anterior ischaemic optic neuropathy (NAION), impaired renal and hepatic function, drug interactions (i.e. nitrates, cytochrome P3A4 inhibitors, other ED therapies and alpha-blockers) and incorrect use.

RESULTS

Sildenafil was well tolerated at a dose of 50 or 100 mg in men with ED, overall, in those aged > or = 65 years, and in those aged > or = 75 years. Analyses of the databases did not reveal any causal link between sildenafil and cardiovascular events, or any new safety risks relating to cardiovascular events, priapism, NAION, hearing loss or drug interactions. In the small number of men with moderate impairment of renal function or hepatic function who were treated with sildenafil in DBPC trials, the safety profile was similar to that in men with no impairment of renal or hepatic function. Overdose with sildenafil was rare in the ED population. No new safety issues, emerging trends or adverse reactions were identified in conjunction with overdose, dependence, abuse or misuse.

CONCLUSION

This collated review confirms generally the good tolerability and established safety profile of sildenafil 50 and 100 mg in men with ED and reveals no new safety issues.

Efficacy and safety of tadalafil taken as needed for the treatment of erectile dysfunction in Asian men: results of an integrated analysis

We evaluated the efficacy and safety of as-needed tadalafil in a diverse clinical population (with varying patient demographics, disease severity, and comorbid medical conditions) of Asian men with erectile dysfunction (ED). An integrated analysis of five double-blind, placebo-controlled trials (N = 1 046) was performed. Patients were randomly assigned to receive 10 mg tadalafil (N = 185), 20 mg tadalafil (N = 510), or placebo (N = 351). Efficacy assessments included the International Index of Erectile Function (IIEF), Sexual Encounter Profile (SEP) diary and Global Assessment Question (GAQ). Patients receiving 10 mg or 20 mg tadalafil showed significant improvement from baseline-to-end point on the Erectile Function domain of the International Index of Erectile Function (IIEF-EF) domain score in all clinical sub-populations analyzed, compared with patients receiving placebo (P < 0.001). The 10-mg and 20-mg tadalafil groups showed a mean success rate of 64.1% and 70.5% for sexual intercourse attempts (SEP3, successful intercourse), respectively, compared with 33.4% in the placebo group (P < 0.001), and 85.5% and 85.4% reported improved erections at end point GAQ, respectively, versus 43.5% in the placebo group (P < 0.001). Tadalafil was well tolerated across all groups studied. Headache and back pain were the most frequently reported adverse events. Overall, tadalafil was effective and well tolerated across a diverse clinical spectrum of Asian men with ED.

Erectile dysfunction and cardiovascular disease: efficacy and safety of phosphodiesterase type 5 inhibitors in men with both conditions

Risk factors for cardiovascular disease and erectile dysfunction (ED) are similar, as might be expected given their shared etiologic and pathophysiologic origins. It is now generally accepted that most cases of ED result from a vascular disturbance of the endothelium. Recent epidemiological studies have documented a strong association between ED and comorbid conditions such as hypertension, diabetes mellitus, and dyslipidemia. Phosphodiesterase type 5 (PDE5) inhibitors are recommended as first-line therapy for erection problems of all etiologies and severities. The efficacy and safety of PDE5 inhibitors in the general ED population is well documented and has been extensively reviewed. To examine the association between ED and vascular disorders in the context of current knowledge regarding PDE5 inhibitors, an electronic search was performed of articles published from January 2002 through April 2008 using the PubMed, EMBASE, and MEDLINE databases. Although preference was given to randomized, blinded, controlled clinical trials, data from retrospective studies were also reviewed when appropriate. This analysis revealed that the clinical evidence linking ED to future cardiovascular events is compelling, presenting physicians with a unique interventional opportunity to address underlying cardiovascular health concerns in men presenting with ED. In most studies, PDE5 inhibitors were shown to effectively and safely improve erectile function regardless of cause, severity, or presence of comorbid conditions, including hypertension, diabetes mellitus, and dyslipidemia.

Improvement in duration of erection following phosphodiesterase type 5 inhibitor therapy with vardenafil in men with erectile dysfunction: the ENDURANCE study

OBJECTIVE

The ENDURANCE study evaluated the efficacy of vardenafil, a phosphodiesterase type 5 (PDE5) inhibitor, in men with erectile dysfunction (ED), by measuring the duration of erection leading to successful intercourse using a stopwatch as the assessment instrument.

METHODS

This was a randomised, multicentre, double-blind, placebo-controlled, crossover study consisting of a 4-week treatment-free run-in phase after which patients were randomised to either fixed-dose vardenafil 10 mg or placebo (to be administered 60 min prior to intercourse) and entered the first of the two 4-week double-blind treatment periods, separated by a 1-week washout. The primary efficacy end-point was the stopwatch-assessed duration of erection, which was defined as the time from erection perceived hard enough for penetration until withdrawal from the partner's vagina leading to successful intercourse as measured by Sexual Encounter Profile Question 3 (SEP-3). Secondary efficacy end-points included SEP-2 and SEP-3 success rates, the erectile function domain of the International Index of Erectile Function, global assessment questionnaire, change from baseline in duration of erection and duration of erection not leading to successful intercourse. Safety was assessed by adverse events (AEs), laboratory samples, vital signs and ECGs.

RESULTS

Of the 191 men included in the safety population, 40% had moderate ED and 33% had severe ED at baseline. The duration of erection (least squares mean +/- SE) leading to successful intercourse was longer with vardenafil than with placebo (12.81 +/- 1.00 min vs. 5.45 +/- 1.00 min; p < 0.001). The differences recorded for all secondary end-points were statistically significant in favour of vardenafil compared with placebo (p < 0.001), with the exception of duration of erection not leading to successful intercourse. Vardenafil was well tolerated in this study; the majority of AEs being mild-to-moderate in intensity.

CONCLUSION

Vardenafil 10-mg therapy provided a statistically superior duration of erection leading to successful intercourse in men with ED compared with placebo.

Management of erectile dysfunction in diabetes: an update for 2008

Tumescence occurs as a result of nitric oxide (NO)-mediated smooth muscle relaxation of the erectile tissue leading to engorgement of the corpus cavernosum. The process is initiated by neuronal NO release and maintained by NO released by the local vascular endothelium. Erectile dysfunction (ED) affects 30% to 40% of diabetic men and occurs as a result of endothelial dysfunction and autonomic neuropathy. The close association with endothelial dysfunction means ED is an early marker of cardiovascular risk. Managing ED is easy and must be part of a diabetes care service. Phosphodiesterase type 5 inhibitors are the treatment of choice, but are effective in only 50% to 60% of diabetic men. The reasons for nonresponsiveness remain uncertain and research is needed in this area. There has been much recent interest in the potential relationship between late-onset hypogonadism and diabetes, but there is no evidence of a causal relationship and the evidence in favor of treating borderline hypogonadism in diabetes is limited.

Sexual function in hypertensive patients receiving treatment

In many forms of erectile dysfunction (ED), cardiovascular risk factors, in particular arterial hypertension, seem to be extremely common. While causes for ED are related to a broad spectrum of diseases, a generalized vascular process seems to be the underlying mechanism in many patients, which in a large portion of clinical cases involves endothelial dysfunction, ie, inadequate vasodilation in response to endothelium-dependent stimuli, both in the systemic vasculature and the penile arteries. Due to this close association of cardiovascular disease and ED, patients with ED should be evaluated as to whether they may suffer from cardiovascular risk factors including hypertension, cardiovascular disease or silent myocardial ischemia. On the other hand, cardiovascular patients, seeking treatment of ED, must be evaluated in order to decide whether treatment of ED or sexual activity can be recommended without significantly increased cardiac risk. The guideline from the first and second Princeton Consensus Conference may be applied in this context. While consequent treatment of cardiovascular risk factors should be accomplished in these patients, many antihypertensive drugs may worsen sexual function as a drug specific side-effect. Importantly, effective treatment for arterial hypertension should not be discontinued as hypertension itself may contribute to altered sexual functioning; to the contrary, alternative antihypertensive regimes should be administered with individually tailored drug regimes with minimal side-effects on sexual function. When phosphodiesterase-5 inhibitors, such as sildenafil, tadalafil and vardenafil, are prescribed to hypertensive patients on antihypertensive drugs, these combinations of antihypertensive drugs and phosphodiesterase 5 are usually well tolerated, provided there is a baseline blood pressure of at least 90/60 mmHg. However, there are two exceptions: nitric oxide donors and α-adrenoceptor blockers. Any drug serving as a nitric oxide donor (nitrates) is absolutely contraindicated in combination with phosphodiesterase 5 inhibitors, due to significant, potentially life threatening hypotension. Also, α-adrenoceptor blockers, such as doxazosin, terazosin and tamsulosin, should only be combined with phosphodiesterase 5 inhibitors with special caution and close monitoring of blood pressure.

Use of tadalafil for treating pulmonary arterial hypertension secondary to chronic obstructive pulmonary disease

Pulmonary arterial hypertension (PAH) secondary to chronic obstructive pulmonary disease (COPD) is incurable and it has an unpredictable survival rate. Two men who suffered from COPD presented with progressive dyspnea and edema, respectively. PAH, as estimated by the peak velocity of tricuspidal regurgitation, and the depressed myocardial performance index (MPI) of the right ventricle (RV) were noted on echocardiography. In addition to the baseline therapy for their depressed ventilatory function, we prescribed tadalafil 10 mg orally every other day for 2 weeks and then we doubled the dosage. They well tolerated the medication without any notable side effects. After 4 weeks of tadalafil treatment, the patients' pulmonary arterial pressure was decreased and the MPI of the RV was improved in both. The exercise capacity, as measured by the respiratory oxygen uptake, also improved from 10.9 mL/kg/min to 13.8 mL/kg/min in one patient. We report here on 2 patients with PAH secondary to COPD, and they showed notable improvement of their pulmonary hemodynamics and exercise capacity with the administration of tadalafil.

Effects of gender, age, diabetes mellitus and renal and hepatic impairment on tadalafil pharmacokinetics

AIMS

To evaluate the effects of gender, age, diabetes mellitus, renal and hepatic impairment on tadalafil pharmacokinetics and tolerability.

METHODS

Six single-dose (5, 10 or 20 mg orally) clinical pharmacology studies were conducted in the UK, Belgium, Poland and Germany in healthy male and female subjects, elderly subjects and subjects with diabetes mellitus, renal impairment, end-stage renal failure (ESRF) or hepatic impairment. The gender study also incorporated administration of 10 mg tadalafil daily for 10 days.

RESULTS

Systemic exposure in the elderly was 25% greater than in young subjects (mean AUC ratio 1.25; 90% confidence interval 0.972, 1.61). The AUC was 19% lower in subjects with diabetes mellitus than in healthy age/gender-matched controls. Pharmacokinetics in female subjects were essentially similar to those in males. Exposure in subjects with mild or moderate renal insufficiency was approximately twice that in healthy subjects. The mean AUC for the major metabolite (total methylcatechol glucuronide) in the presence of ESRF was three times the mean for healthy subjects. Haemodialysis contributed negligibly to elimination of tadalafil or the metabolite. Hepatic impairment had negligible effects on exposure. The most common adverse events in these six studies were headache, back pain and myalgia. A 10-mg dose was not well tolerated by subjects with moderate renal dysfunction in this study.

CONCLUSIONS

No clinically significant effect of gender, age, diabetes mellitus or hepatic impairment on tadalafil pharmacokinetics was observed. Renal insufficiency resulted in increased systemic exposure. Tadalafil was not associated with any serious clinically significant adverse events or study discontinuations due to adverse events.

Efficacy of tadalafil in Egyptian and Turkish men with erectile dysfunction

A randomised, double-blind, parallel, placebo-controlled, 12-week study was carried out to evaluate the efficacy and safety of 20-mg tadalafil taken 'as needed' in a population of men with erectile dysfunction (ED) from Egypt and Turkey. One hundred and thirty-two patients were randomised in this study. Tadalafil was superior to placebo on all three co-primary efficacy end points. The mean change from baseline for the erectile function domain of the International Index of Erectile Function was 9.3 +/- 0.8 for the tadalafil group and 2.3 +/- 1.6 for the placebo group. Tadalafil-treated patients reported a significantly greater improvement in the mean percentage of successful penetrations (tadalafil: 34.5 +/- 4.1; placebo: -4.6 +/- 8.1) and successful intercourse attempts (tadalafil: 52.2 +/- 3.8; placebo: 16.8 +/- 7.8) than placebo-treated patients as measured by the Sexual Encounter Profile. Tadalafil was generally well tolerated with 82% of adverse events being mild in severity. Tadalafil 20-mg taken 'as needed' significantly improved the erectile function in Egyptian and Turkish men with ED.

Hypogonadism in the man with erectile dysfunction: what to look for and when to treat

Hypogonadism (low serum testosterone) is commonly associated with erectile dysfunction (ED). However, many urologists may lack appreciation of the relative merits of treating hypogonadism compared with oral phosphodiesterase inhibitors for sexual dysfunction. Testosterone-replacement therapy (TRT) may be the best treatment for men with ED when the presentation includes diminished libido or other sexual symptoms or when non-sexual symptoms such as depressed mood, decreased sense of vitality, and increased fatigue also exist. The health benefits of TRT also include improvements in body composition, bone density, cognition, and sense of well-being. Thus, there may be good reasons to use TRT as first-line therapy for the man with ED. Concerns regarding prostatic and cardiovascular risks of TRT have not been supported by the literature. Nevertheless, men receiving TRT must be monitored at regular intervals with digital rectal examination and blood testing for prostate-specific antigen. Hematocrit or hemoglobin also should be obtained regularly due to the risk of erythrocytosis. Awareness of the benefits of TRT in the man with ED may improve clinical outcomes.

Tadalafil pharmacokinetics in healthy subjects

AIMS

To characterize tadalafil plasma pharmacokinetics in healthy subjects following single and multiple doses.

METHODS

Noncompartmental parameters were calculated for healthy subjects receiving a single 2.5-20-mg tadalafil dose in 13 clinical pharmacology studies. An integrated statistical analysis of results in 237 subjects provided global averages and an assessment of effects of body mass index (BMI), age, gender and smoking status. Diurnal variation, food effects and proportionality of exposure to dose were analysed in three studies. Multiple-dose pharmacokinetics were evaluated in a separate study in which parallel groups of 15 subjects received 10 or 20 mg tadalafil once daily for 10 days.

RESULTS

Tadalafil was absorbed rapidly with mean Cmax (378 microg l-1 for 20 mg) observed at 2 h; thereafter, concentrations declined nearly monoexponentially with a mean (5th, 95th percentiles) t1/2 of 17.5 (11.5, 29.6) hours. Mean oral clearance (CL/F) was 2.48 (1.35, 4.35) l h-1 and apparent volume of distribution (Vz/F) was 62.6 (39.5, 92.1) l. No clinically meaningful effect of BMI, age, gender or smoking was identified. Exposure was not substantially affected by time of dosing. Food had negligible effects on bioavailability as assessed by 90% confidence intervals for Cmax and AUC mean ratios. Parameters were proportional to dose, indicating that doubling the dose doubled exposure. Steady state was attained by day 5 following once-daily administration, and accumulation (1.6-fold) was consistent with the t1/2.

CONCLUSIONS

Tadalafil pharmacokinetics are linear with respect to dose and time, and are not affected by food. Systemic clearance is low relative to other phosphodiesterase 5 inhibitors.

Tadalafil in the treatment of erectile dysfunction; an overview of the clinical evidence

Prevalence and severity of erectile dysfunction (ED) increase with aging and are often associated with illnesses, like diabetes mellitus, heart disease, and hypertension, pathologically characterized by endothelial dysfunction and whose prevalence increases with age. The assumption that ED is mainly a neurovascular disease is supported by the evidence that specific phosphodiesterase type 5 (PDE5) inhibition produces an efficient erection in a wide range of ages and conditions. The availability of specific PDE5 inhibitors has enabled the development of effective treatment strategies, in this contest, tadalafil may be considered as the least "typical" PDE5 inhibitor. In clinical trials, tadalafil significantly enhanced, in patients of different ages, all efficacy outcomes across disease etiologies and severities. With an effectiveness lasting up to 36h, tadalafil allows patients to choose when to have sexual activities without the need to time it, showing positive feedback in terms of quality of life related to the treatment. Headache and dyspepsia were the most frequent side-effects of tadalafil, followed by back pain, nasal congestion, myalgia, and flushing, but the impact that long time action could have on effectiveness and safety is not yet entirely defined. The aim of this article is to critically review the available evidence from the tadalafil clinical research program and give the physician a rational approach for intervention in the treatment of ED and related diseases.

The effect of tadalafil on the time to exercise-induced myocardial ischaemia in subjects with coronary artery disease

OBJECTIVE

To investigate the effect of tadalafil on the time to exercise-induced myocardial ischaemia in subjects with coronary artery disease (CAD). Background CAD and erectile dysfunction (ED) share similar risk factors. It is important to know the cardiovascular effects of tadalafil in patients with CAD during physical exertion that is comparable with sexual activity.

METHODS

A randomized, placebo-controlled, double-blind, two-period, crossover study comparing the effects of tadalafil 10 mg and placebo on the time to exercise treadmill test (ETT)-induced myocardial ischaemia in subjects with stable CAD (n = 23; age range: 53-75 years, all exhibited ST-segment depression >1.5 mm at screening ETT at > 5METS). Haemodynamic responses to sublingual nitroglycerin (NTG) were assessed before and after ETT.

RESULTS

Compared with placebo, tadalafil did not significantly affect the time to ETT-induced ischaemia (13 min/31 s vs. 13 min/36 s, respectively). Before exercise, NTG evoked decreases in sitting systolic blood pressure (SBP) that were significantly greater when subjects received tadalafil compared with placebo, and after exercise, more subjects experienced a decrease in SBP <85 mmHg in response to NTG after taking tadalafil vs. placebo. When subjects received tadalafil compared with placebo, SBP was lower at rest (-7 mmHg; -12,-2), during ETT (-10 mmHg; -16, -3), and after ETT (-13 mmHg; -19, -7).

CONCLUSION

Tadalafil did not significantly alter the time to ETT-induced ischaemia compared with placebo in subjects with CAD. Tadalafil reduced resting and exercise SBP. Due to the potential for hypotension, the concomitant use of nitrates and tadalafil is contraindicated.

Erectile dysfunction secondary to nerve-sparing radical retropubic prostatectomy: comparative phosphodiesterase-5 inhibitor efficacy for therapy and novel prevention strategies

Postprostatectomy erectile dysfunction appears to be initiated by neuropraxia and perpetuated by cavernosal smooth muscle apoptosis. Phosphodiesterase-5 (PDE-5) inhibitor therapy is the current cornerstone of erectile dysfunction (ED) therapy in this population. Although no head-to-head trials have been performed with sildenafil, vardenafil, and tadalafil in this population, there are numerous studies in the general ED population. The results of these studies demonstrate that neither of the new PDE-5 inhibitors met statistical noninferiority to sildenafil. Sildenafil has been studied in a novel primary prevention modality using nightly administration after a bilateral nerve-sparing prostatectomy. In this novel approach, it effected a sevenfold improvement in return of spontaneous, normal erectile function 2 months after drug discontinuation. This effect appears to be mediated by properties unique to sildenafil that include improved endothelial function and neuronal regeneration and neuroprotection. In primary prevention, unlike ED therapy, one has only "one shot" by definition. Therefore, it is even more critical to apply evidence-based medicine.

Impact of diabetes mellitus on the severity of erectile dysfunction and response to treatment: analysis of data from tadalafil clinical trials

AIMS/HYPOTHESIS

A retrospective analysis of pooled data from twelve placebo-controlled trials was conducted to characterise the efficacy and safety of tadalafil for the treatment of erectile dysfunction in men with diabetes compared with that in men without diabetes.

METHODS

Patients were randomly allocated to tadalafil 10 mg, 20 mg, or placebo, taken as needed for 12 weeks. The study population comprised 637 men with diabetes (mean age 57 years) and 1681 men without diabetes (mean age 56 years).

RESULTS

At baseline, patients with diabetes had more severe erectile dysfunction than patients without diabetes, with mean International Index of Erectile Function (IIEF) erectile function domain scores of 12.6 and 15.0 respectively (p<0.001). Compared with placebo, tadalafil 10 mg and 20 mg improved all primary efficacy outcomes in both patient groups (p<0.001). Men with diabetes receiving tadalafil 20 mg experienced a mean improvement of 7.4 in their IIEF erectile function domain score against baseline versus 0.9 for placebo (p<0.001). This group reported on average that 53% of their attempts at intercourse were successful, compared with 22% for placebo (p<0.001 for the change from baseline). Baseline IIEF erectile function domain scores correlated inversely with baseline HbA(1)c levels. The responses to tadalafil were similar regardless of levels of baseline glycaemic control, diabetic therapy received, or previous use of sildenafil.

CONCLUSIONS/INTERPRETATION

Despite more severe baseline erectile dysfunction in men with diabetes, tadalafil was efficacious and well tolerated in this population. As reported for other phosphodiesterase 5 inhibitors, the response to tadalafil was slightly lower in men with diabetes than in men without diabetes.