Clinical efficacy of sildenafil citrate based on etiology and response to prior treatment

Erectile dysfunction and cancer: current perspective

Erectile dysfunction (ED) is one of the major but underreported concerns in cancer patients and survivors. It can lead to depression, lack of intimacy between the couple, and impaired quality of life. The causes of erectile dysfunction are psychological distress and endocrinal dysfunction caused by cancer itself or side effect of anticancer treatment like surgery, radiotherapy, chemotherapy and hormonal therapy. The degree of ED depends on age, pre-cancer or pre-treatment potency level, comorbidities, type of cancer and its treatment. Treatment options available for ED are various pharmacotherapies, mechanical devices, penile implants, or reconstructive surgeries. A complete evaluation of sexual functioning should be done prior to starting anticancer therapy. Management should be individualized and couple counseling should be an integral part of the anticancer treatment.

PDE5 inhibitors: considerations for preference and long-term adherence

INTRODUCTION

Erectile dysfunction (ED) is a highly prevalent condition affecting nearly one in five men worldwide. The advent of phosphodiesterase type 5 inhibitors (PDE5i) has revolutionised the ED treatment landscape and provided effective, minimally invasive therapies to restore male sexual function.

MATERIALS AND METHODS

A pubmed search was performed of all English language articles from 1996 to present reviewing PDE5i, including pharmacokinetics, efficacy profiles and comparisons, where available.

RESULTS

Currently available PDE5i in the United States include sildenafil, vardenafil, tadalafil and avanafil, each of which has unique side effect, pharmacokinetic and outcome profiles. Sildenafil is associated with increased rate of visual changes, vardenafil with QT prolongation and tadalafil with lower back pain. Avanafil and vardenafil orodispersible tablet rapidly achieve peak plasma concentration, which results in faster onset of action, whereas tadalafil exhibits the longest half-life. First time response to PDE5i is approximately 60-70%, with no significant differences in efficacy noted among therapies. The literature does not clearly demonstrate a preference for one drug. High-treatment success rates (89%) were reported when patients were prescribed all available PDE5i. Daily dosing with tadalafil is associated with improved erectile function (EF) over time. Finally, novel modes of patient-provider interaction, including internet-based education, communication and prescribing, may also improve long-term adherence.

CONCLUSIONS

PDE5i represent first line therapy for ED with excellent overall efficacy and satisfactory side effect profiles. Enhanced communciation, coupled with increased knowledge of drug characteristics, comparative treatment regimens and optimal prescribing patterns, offer compelling tools to improve long-term treatment success.

Nitric oxide-releasing polymeric microspheres improve diabetes-related erectile dysfunction

INTRODUCTION

We have used a long-acting nitric oxide (NO)-releasing polymer to develop injectable biodegradable microspheres capable of localized NO release over prolonged periods of time.

AIM

The aim of this study was to evaluate the therapeutic potential of these microspheres for diabetes-related erectile dysfunction (ED) in the rat model.

METHODS

NO-releasing microspheres were incubated in physiologic buffer, and in vitro NO release was measured using a Griess assay. To ensure no migration, microspheres were fluorescently tagged and injected into the corpus cavernosum of adult rats, and fluorescent imaging was performed weekly for 4 weeks, at which point rats were sacrificed. To assess physiologic efficacy, diabetes was induced in 40 rats using streptozotocin (STZ), whereas 10 rats were kept as age-matched controls. Diabetic rats were divided into four groups: no treatment, sildenafil, NO-releasing microspheres, and combination therapy. For each rat, the cavernosal nerve (CN) was stimulated at various voltages, and intracavernosal pressure (ICP) and mean arterial pressure (MAP) were measured via corpus cavernosum and carotid artery catheterization, respectively. Long-term efficacy was determined by injecting diabetic rats with microspheres and measuring erectile response at predetermined intervals for up to 5 weeks.

MAIN OUTCOME MEASURES

Erectile response was determined via calculation of mean peak ICP/MAP and area under curve (AUC) for each experimental group.

RESULTS

Under physiologic conditions in vitro, microspheres continued NO release for up to 4 weeks. Fluorescent imaging revealed no detectable signal in tissues besides cavernosal tissue at 4 weeks postinjection. Upon CN stimulation, peak ICP/MAP ratio and AUC of diabetic rats improved significantly (P < 0.05) in microsphere and combination therapy groups compared with no treatment and sildenafil groups. In long-term efficacy studies, microspheres augmented the effect of sildenafil for 3 weeks following injection (P < 0.05).

CONCLUSIONS

NO-releasing microspheres significantly improved erectile response in diabetic rats for 3 weeks and hence offer a promising approach to ED therapy, either as monotherapy or combination therapy.

Optimizing postoperative sexual function after radical prostatectomy

Erectile dysfunction (ED) is one of the complications associated with pelvic surgery. The significance of ED as a complication following pelvic surgery, especially radical prostatectomy (RP), lies in the negative impact that it has on patients' sexual and overall life. In the literature, rates of ED following RP range from 25% to 100%. Such variety is associated with pelvic dissection and conservation of neurovascular structures. Another important factor impacting on postoperative ED is the preoperative erectile function of the patient. Advances in the knowledge of pelvic anatomy and pathological mechanisms led to a refinement of pelvic surgical techniques, with attention to the main structures that if damaged compromise erectile function. These improvements resulted in lower postoperative ED rates and better erectile recovery, especially in patients undergoing RP. Furthermore, surgery alone is not sufficient to prevent this complication, and thus, several medical strategies have been tested with the aim of maximizing erectile function recovery. Indeed it seems that prevention of postoperative ED must be addressed by a multimodal approach. The aim of this review is to give a picture of recent knowledge, novel techniques and therapeutic approaches in order to reach the best combination of treatments to reduce the rate of ED after pelvic surgery.

Couples' reasons for adherence to, or discontinuation of, PDE type 5 inhibitors for men with erectile dysfunction at 12 to 24-month follow-up after a 6-month free trial

INTRODUCTION

The history of treatments for erectile dysfunction (ED) has involved a repeated pattern of uptake, followed by abandonment of the various therapies in the medium term. Even effective and simple to use medications are not necessarily continued; discontinuation rates range between 15% and 60%. Despite the association between partner sexual function and men's use of PDE5, no previous studies have reported any contact with partners of men taking PDE5 for their ED. This study involved both partners in couples followed up at least 1 year after treatment of ED.

AIM

The study sought clarification of factors influencing adherence to, or discontinuation of, oral ED medications from couples. We hypothesized that many factors contribute to decision making about ED medication use at >12 months.

MAIN OUTCOME MEASURES

The main outcome measures of this article were interviews and International Index of Erectile Function-erectile function domain.

METHODS

A total of 155 interviews were conducted seeking details of frequency of usage and preference for the drugs available; reasons for that choice, or for discontinuation of use, were also sought.

RESULTS

Of men interviewed, 71% were using PDE5 at 18 months. Most men interviewed were using the oral medications either 1-2x/week or 1-2x/month. Forty-four percent of men who had decreased their use of the medications reported less need for them. Thirty-four men said the main reason they were using less medication was cost. "Partner issues" from the men's perspective were seldom reported in this study. However, for a number of women, "partner issues" meant a range of problems from separation to alcohol abuse, lack of communication, and lack of confidence, or fear of failure.

CONCLUSIONS

This is the first study to ask couples why they decided to continue or stop using PDE5 when followed up. Female partners provided a different perspective on "partner issues" often cited as reasons for discontinuing PDE5 use. It was also clear that discontinuation did not mean couples were no longer sexually active.

Low-intensity extracorporeal shock wave therapy--a novel effective treatment for erectile dysfunction in severe ED patients who respond poorly to PDE5 inhibitor therapy

INTRODUCTION

Low-intensity shock wave therapy (LI-ESWT) has been reported as an effective treatment in men with mild and moderate erectile dysfunction (ED).

AIM

The aim of this study is to determine the efficacy of LI-ESWT in severe ED patients who were poor responders to phosphodiesterase type 5 inhibitor (PDE5i) therapy.

METHODS

This was an open-label single-arm prospective study on ED patients with an erection hardness score (EHS) ≤ 2 at baseline. The protocol comprised two treatment sessions per week for 3 weeks, which were repeated after a 3-week no-treatment interval. Patients were followed at 1 month (FU1), and only then an active PDE5i medication was provided for an additional month until final follow-up visit (FU2). At each treatment session, LI-ESWT was applied on the penile shaft and crus at five different anatomical sites (300 shocks, 0.09 mJ/mm(2) intensity at 120 shocks/min). Each subject underwent a full baseline assessment of erectile function using validated questionnaires and objective penile hemodynamic testing before and after LI-ESWT.

MAIN OUTCOME MEASURES

Outcome measures used are changes in the International Index of Erectile Function-erectile function domain (IIEF-ED) scores, the EHS measurement, and the three parameters of penile hemodynamics and endothelial function.

RESULTS

Twenty-nine men (mean age of 61.3) completed the study. Their mean IIEF-ED scores increased from 8.8 ± 1 (baseline) to 12.3 ± 1 at FU1 (P = 0.035). At FU2 (on active PDE5i treatment), their IIEF-ED further increased to 18.8 ± 1 (P < 0.0001), and 72.4% (P < 0.0001) reached an EHS of ≥ 3 (allowing full sexual intercourse). A significant improvement (P = 0.0001) in penile hemodynamics was detected after treatment and this improvement significantly correlated with increases in the IIEF-ED (P < 0.05). No noteworthy adverse events were reported.

CONCLUSIONS

Penile LI-ESWT is a new modality that has the potential to treat a subgroup of severe ED patients. These preliminary data need to be reconfirmed by multicenter sham control studies in a larger group of ED patients.

CLINICAL EFFICACY AND SAFETY OF SILDENAFIL IN ELDERLY PATIENTS WITH ERECTILE DYSFUNCTION

Erectile dysfunction (ED) is a common medical disorder affecting elderly men. Sildenafil citrate has been shown to be an effective and well-tolerated oral agent for treating ED in the general population of adult men with ED of broad-spectrum etiology. Elderly men are more likely to have concomitant medical problems than the general population of men with ED. In this study, we examined the efficacy and safety of sildenafil administration in elderly patients with ED. Forty-four elderly men with ED (> or = 60 years old) of broad-spectrum etiology were treated with 25 mg or 50 mg doses of sildenafil citrate. Age ranged from 60 to 78 years (65 +/- 4.5; means +/- S.D.). Mean follow-up period was 12.3 +/- 6.5 months, with a range of 1 to 25 months. Primary efficacy assessments were performed using the International Index of Erectile Function 5 (IIEF5) before their first dose of sildenafil and after at least 4 weeks of therapy. Serum testosterone was measured before treatment. The mean IIEF5 among all patients increased from 8.5 +/- 3.9 to 20 +/- 4.2 after sildenafil use (P < 0.0001). In patients younger than 70 years, the IIEF5 score increased from 9.5 +/- 5.0 to 17 +/- 4.3 while in patients 70 years and older, the score increased from 8.2 +/- 3.6 to 21 +/- 3.9, a near normalization. The rate of improvement in younger men was higher than in older men. Serum testosterone before treatment was similar in the two groups. The most commonly experienced adverse events were flushing and dyspepsia, which occurred in 6.8% and 2.3%, respectively. No patients discontinued sildenafil treatment due to adverse events. In conclusion, oral sildenafil is efficacious and well tolerated by elderly men with ED, even among those older than 70 years.

Evaluation of the safety and efficacy of sildenafil citrate for erectile dysfunction in men with multiple sclerosis: a double-blind, placebo controlled, randomized study

PURPOSE

We evaluated the safety and efficacy of sildenafil citrate for treating erectile dysfunction in patients with multiple sclerosis.

MATERIALS AND METHODS

A total of 203 patients with multiple sclerosis (age range 18 to 50 years old) with erectile dysfunction were randomly assigned to receive 50 to 100 mg sildenafil (102 patients in group 1) or a similar regimen of placebo (101 patients in group 2) 45 minutes to 2 hours before sexual stimulation. Patients were asked to use at least 24 doses/attempts at home. Primary outcome measures consisted of responses to questions 3 and 4 from the International Index of Erectile Function questionnaires well as responses to Sexual Encounter Profile diary questions 2 and 3. We also assessed the number of attempts at sexual intercourse, the number of attempts that were successful and adverse drug effects.

RESULTS

Improved erections (positive response to the Global Assessment Questionnaire) were reported by 32.8% of patients receiving sildenafil and 17.6% of those receiving placebo (p = 0.04). For Sexual Encounter Profile question 2 (successful penetration) the increase from baseline in mean per patient percentage of yes responses was 29.4% after sildenafil vs 18.8% after placebo (p = 0.04). The proportion of successful sexual attempts ranged from 12% to 26% for sildenafil and from 9% to 21% for placebo, respectively (p = 0.044). Of patients taking sildenafil and placebo 24 (23.5%) and 9 (8.9%) experienced 81 and 31 adverse events, respectively (p = 0.01).

CONCLUSIONS

Compared with placebo, sildenafil has little effect on multiple sclerosis emergent erectile dysfunction and, therefore, cannot be recommended for the routine treatment of erectile dysfunction in patients with multiple sclerosis. This finding implies that there must be other mechanisms that are not affected by sildenafil or are resistant to the effects of sildenafil.

Effects of phosphodiesterase-5 inhibitors on sperm parameters and fertilizing capacity

The aim of this review study is to elucidate the effects that phosphodiesterase 5 (PDE5) inhibitors exert on spermatozoa motility, capacitation process and on their ability to fertilize the oocyte. Second messenger systems such as the cAMP/adenylate cyclase (AC) system and the cGMP/guanylate cyclase (GC) system appear to regulate sperm functions. Increased levels of intracytosolic cAMP result in an enhancement of sperm motility and viability. The stimulation of GC by low doses of nitric oxide (NO) leads to an improvement or maintenance of sperm motility, whereas higher concentrations have an adverse effect on sperm parameters. Several in vivo and in vitro studies have been carried out in order to examine whether PDE5 inhibitors affect positively or negatively sperm parameters and sperm fertilizing capacity. The results of these studies are controversial. Some of these studies demonstrate no significant effects of PDE5 inhibitors on the motility, viability, and morphology of spermatozoa collected from men that have been treated with PDE5 inhibitors. On the other hand, several studies demonstrate a positive effect of PDE5 inhibitors on sperm motility both in vivo and in vitro. In vitro studies of sildenafil citrate demonstrate a stimulatory effect on sperm motility with an increase in intracellular cAMP suggesting an inhibitory action of sildenafil citrate on a PDE isoform other than the PDE5. On the other hand, tadalafil's actions appear to be associated with the inhibitory effect of this compound on PDE11. In vivo studies in men treated with vardenafil in a daily basis demonstrated a significantly larger total number of spermatozoa per ejaculate, quantitative sperm motility, and qualitative sperm motility; it has been suggested that vardenafil administration enhances the secretory function of the prostate and subsequently increases the qualitative and quantitative motility of spermatozoa. The effect that PDE5 inhibitors exert on sperm parameters may lead to the improvement of the outcome of assisted reproductive technology (ART) programs. In the future PDE5 inhibitors might serve as adjunct therapeutical agents for the alleviation of male infertility.

Sildenafil in the treatment of erectile dysfunction: an overview of the clinical evidence

Erectile dysfunction (ED) is a highly prevalent disease associated with aging as well as with several risk factors including hypertension, heart disease, obesity, dyslipidemia, diabetes, hypogonadism, drugs-related, and pelvic surgery. Many of these factors are components of the metabolic syndrome, a multiplex risk factor for cardiovascular disease (CVD). ED shares common risk factors with CVD. Endothelial dysfunction seems to be the early underlying pathophysiology across both conditions. The efficacy, tolerability and cardiovascular safety of sildenafil has been evaluated in numerous large, randomized, double-blind, placebo-controlled clinical studies in the broad population of men with ED including men with several co-morbid conditions. Sildenafil is effective in several specific patient populations including the difficult-to-treat subpopulations such as diabetes mellitus and after radical prostatectomy. It is associated with rapid onset of action – within 14 minutes for some men – and an extended duration of action for up to 12 hours. Sildenafil improves quality of life and satisfaction for treated men and is well tolerated with a favorable safety profile. New data suggest that sildenafil has beneficial effects in several chronic conditions. It has been approved for the treatment of idiopathic pulmonary hypertension. Numerous articles have suggested that it improves endothelial function and a possible role on premature ejaculation or treatment of lower urinary tract symptoms has been suggested.

A pilot study on the early use of the vacuum erection device after radical retropubic prostatectomy

OBJECTIVE

To evaluate the effect of the early use of the vacuum erection device (VED) on erectile dysfunction (ED) and penile shortening after radical retropubic prostatectomy (RP), as these are important concerns for men choosing among treatment alternatives for localized prostate cancer.

PATIENTS AND METHODS

Twenty-eight men undergoing RP were randomized to early intervention (1 month after RP, group 1) or a control group (6 months after RP, group 2) using a traditional VED protocol. An International Index of Erectile Function (IIEF) score of >11 (no, mild or mild to moderate ED) was required as a baseline criterion for inclusion in the study. Only patients in whom unilateral or bilateral nerves were spared were subsequently randomized. Patients in group 1 followed a daily rehabilitation protocol consisting of 10 min/day using the VED with no constriction ring, for 5 months. Patients were evaluated with the IIEF-5 questionnaire and measurements of penile flaccid length, stretched length, prepubic fat pad, and midshaft circumference before and at 1, 3, 6, 9 and 12 months after RP; the mean (range) last follow-up visit was 9.5 (6-12) months after RP.

RESULTS

The mean (sd) baseline IIEF scores were similar in groups 1 and 2, at 21.1 (4.6) and 22.3 (3.3), respectively (P = 0.54). The IIEF scores were significantly higher in group 1 than group 2 at 3 months, at 11.5 (9.4) vs 1.8 (1.4) (P = 0.008) and at 6 months, at 12.4 (8.7) vs 3.0 (1.9) (P = 0.012) after RP. There were no significant changes in penile flaccid length, prepubic fat pad, or mid-shaft circumference in either group. Stretched penile length was significantly decreased at both 3 and 6 months, by approximately 2 cm (P = 0.013) in group 2. By contrast, stretched penile length was preserved in group 1 at all sample times. At the last follow-up, the proportion of men with a mean loss of penile length of >/= 2 cm was significantly lower in group 1 than group 2 (two/17, 12%, vs five/11, P = 0.044).

CONCLUSIONS

Initiating the use of a VED protocol at 1 month after RP improves early sexual function and helps to preserve penile length.

Treatment of Erectile Dysfunction: Update

Erectile dysfunction (ED) is the inability to achieve and maintain an erection. Erectile function is dependent upon complex interactions of neural and vascular pathways. A major neurotransmitter that facilitates erectile function is nitric oxide. Treatment of ED has expanded to include effective oral agents. Previous ED treatments have consisted of intracavernosal injection, transurethral dilators, and vascular constriction devices. Clinical management of ED will be presented with some discussion on the prostatectomy client.

Do vardenafil and tadalafil have advantages over sildenafil in the treatment of erectile dysfunction?

Erectile dysfunction (ED) affects up to 50% of men between the ages of 40 and 70 years of age. Sildenafil, vardenafil and tadalafil have all been shown to be similarly effective in the treatment of men with ED of vary etiologies, to have similar adverse effects profiles, and to improve quality-of-life by similar amounts. As these phosphodiesterase 5 (PDE5) inhibitors all increase the hypotensive effects of nitrates, they are not suitable for use in patients taking nitrates for the treatment of ischaemic heart disease. All three inhibitors must be used with caution in patients taking alpha(1)-adrenoceptors antagonists for benign prostatic hyperplasia. Although nonarteritic anterior ischaemic neuropathy has been reported in some users of the PDE5 inhibitors, there is no conclusive evidence that PDE5 inhibitors cause this rare effect. Tadalafil has a longer half-life than sildenafil or vardenafil, and a longer duration of action than sildenafil and vardenafil. Most preference studies have shown tadalafil to be preferred, but there are serious limitations to some of these studies. One approach to treatment is to give each patient a short- and long-acting agent, and for individuals to decide their preference.

Does the clinical efficacy of vardenafil correlate with its effect on the endothelial function of cavernosal arteries? A pilot study

OBJECTIVE

To investigate whether the results of the ultrasonographic (US) measurement of post-occlusive changes in the diameters of cavernosal arteries after administering phosphodiesterase type 5 (PDE-5) inhibitor vardenafil could be associated with the response to vardenafil in patients with erectile dysfunction (ED), as currently there are no reliable methods for predicting the success rate of oral PDE-5 inhibitors.

PATIENTS AND METHODS

The study included 122 men with ED; after a complex evaluation, the endothelial function of the cavernosal arteries was assessed in all patients before and 1 h after oral ingestion of vardenafil (20 mg), using our modification of the US assessment of post-occlusive changes in the diameter of cavernosal arteries. After the evaluation, all patients received vardenafil 20 mg on demand for 4 weeks. A successful response was defined using two endpoints, i.e. the normalization of the International Index of Erectile Function Erectile Function domain score (> or = 26) and positive answers to both Sexual Encounter Profile questions 2 and 3 on > or = 75% of occasions, based on the diary data collected.

RESULTS

In all patients the mean (sd) initial percentage increase in the cavernosal artery diameter (PICAD) in responders and nonresponders was not statistically different, at 49 (24) and 43 (26), respectively (P = 0.168), but PICAD values after vardenafil were significantly greater in responders, at 73 (16) vs 55 (23) (P < 0.001). Analysis of data from patients with different causes of ED showed statistically significant differences in PICAD between responders and nonresponders only in those with arteriogenic ED. The sensitivity and specificity of a PICAD of > or = 50% after taking vardenafil 20 mg for predicting a positive response to the same dose of the drug in patients with arteriogenic ED were 94.9% and 91.3%, respectively.

CONCLUSION

The results of the US assessment of post-occlusive changes in the diameter of cavernosal arteries after vardenafil administration are significantly associated with the clinical efficacy of the drug in patients with arteriogenic ED.

A prospective study of the beneficial effects of dose optimization and customized instructions on patient satisfaction with sildenafil citrate (Viagra®) for erectile dysfunction

Our objective was to assess the effects of customized instructions and dose optimization on treatment satisfaction and improvement in erectile function (EF) with sildenafil citrate in men with erectile dysfunction (ED) who had not been previously treated with a phosphodiesterase-5 inhibitor. This 8-week, multicenter, open-label, flexible-dose (25, 50, or 100 mg sildenafil) study included 2 phases. During phase 1, patients took 50 mg sildenafil and followed the sildenafil sample package instructions. In phase 2, sildenafil dose could be adjusted on the basis of efficacy and tolerability, and investigators provided additional customized instructions. The primary efficacy variable was the satisfaction rate (defined as patients responding "very" or "somewhat" satisfied to the Erectile Dysfunction Inventory of Treatment Satisfaction [EDITS] Question 1). Other efficacy assessments included the International Index of Erectile Function (IIEF) and the percentage of successful sexual intercourse attempts. Of 1109 men (mean age, 54+/-13 years) treated, 867 completed the study. In phase 1, 75% of patients were very or somewhat satisfied with treatment. Mean EF domain score on the IIEF increased from 14.3 at baseline to 23.5, and 79% of sexual intercourse attempts were successful. In phase 2, 53% of patients increased their sildenafil dose to 100 mg and 2% decreased to 25 mg. Satisfaction with sildenafil increased to 86%, 91% of sexual intercourse attempts were successful, and mean IIEF EF domain score increased to 25.7. Of the 196 men who were not initially satisfied at the end of phase 1, 64% became very or somewhat satisfied with treatment by the end of phase 2. Initially high levels of efficacy and satisfaction with sildenafil were achieved when patients were provided with only the sample package instructions and the recommended 50-mg starting dose. These results were enhanced with dose optimization, individual patient counseling, and customized instructions.

The role of endothelial dysfunction in the pathophysiology of erectile dysfunction in diabetes and in determining response to treatment

BACKGROUND

Erectile dysfunction (ED) in diabetes is related to autonomic neuropathy and endothelial dysfunction. We studied the relative importance of these factors in diabetic and non-diabetic men with ED and determined if they predict responses to treatment with sildenafil.

METHODS

Thirty-three men, aged 35-65 years, with ED (20 diabetic, 13 non-diabetic), 15 of whom were sildenafil responders and 18 non-responders, were compared with 30 age and risk-matched control subjects (15 diabetic, 15 non-diabetic). Subjects with ED completed the International Index of Erectile Function (IIEF) questionnaire. Endothelial function was assessed by changes in brachio-radial and femoro-tibial arterial pulse-wave velocity (pulse-wave velocity) during reactive hyperaemia, expressed as percentage endothelium-dependent dilatation. Autonomic function was assessed by heart rate variation during expiration and inspiration (E/I ratio) and during the valsalva manoeuvre.

RESULTS

The respective changes in pulse-wave velocity, in the arm and leg [mean (sd)] were 0.71 (6.5)% and 3.5 (6.4)% in the impotent diabetic men, 0.7 (7.6)% and 2.4 (5.9)% in the non-diabetic impotent men, -0.68 (5.7)% and -1.31 (7.2)% in the non-impotent diabetic men and 7.7 (3.7)% and 7.6 (3.4)% in the control subjects. There was a significant interaction between ED and diabetic status such that there was significantly impaired vascular response in the diabetic group (both with and without ED) and in the non-diabetic group with ED compared with the non-diabetic control group (P = 0.01 and P = 0.001 for brachio-radial and femoro-tibial measures, respectively). The E/I ratios of the diabetic men were significantly lower than those of the control subjects [1.17 (0.14) vs. 1.33 (0.16), P < 0.02), but there were no differences in the measures of autonomic neuropathy between the groups with ED and those with normal erectile function. Amongst diabetic men, the initial IIEF scores (maximum score 30, low score indicates more severe ED) were significantly higher in sildenafil-responders than non-responders [16.3 (8.4), vs. 6.8 (7 1), P < 0.02]. The rate of sildenafil response was not significantly affected by the measures of endothelial or autonomic function.

CONCLUSIONS

ED in both diabetic and non-diabetic men is characterized by marked endothelial dysfunction in comparison with non-diabetic control subjects. Response to sildenafil is not predicted by either endothelial function or autonomic function, but in diabetic men appears to be related to the initial degree of erectile dysfunction.

Efficacy of Tadalafil in Men with Erectile Dysfunction Naïve to Phosphodiesterase 5 Inhibitor Therapy Compared with Prior Responders to Sildenafil Citrate

INTRODUCTION

Tadalafil, an inhibitor of phosphodiesterase 5 (PDE5), is indicated for treatment of erectile dysfunction. Most tadalafil clinical trials excluded patients with unsuccessful prior treatment with sildenafil citrate (sildenafil).

AIM

This retrospective analysis of pooled data from 14 tadalafil clinical trials examines the effect of this exclusion by comparing efficacy results in 1,349 patients without prior sildenafil use (naïve, presumably a mixture of potential responders and nonresponders) with efficacy results in 1,440 patients previously responsive to sildenafil (prior responders).

MAIN OUTCOME MEASURES

Efficacy measures included the International Index of Erectile Function (IIEF) erectile function (EF) domain, overall satisfaction (OS), and intercourse satisfaction (IS) domain scores; Sexual Encounter Profile (SEP) diary questions 2 through 5 (SEP2 [successful penetration], SEP3 [successful intercourse], SEP4 (satisfaction with hardness of erection), and SEP5 [overall satisfaction with the sexual experience]); and a Global Assessment Question (GAQ1) (13/14 trials) about erection improvement. Efficacy was compared using analysis of covariance (IIEF and SEP) and logistic regression (GAQ1) models.

METHODS

After a 4-week, treatment-free, run-in period, patients in 14 double-blind, placebo-controlled, parallel-group trials were treated with tadalafil 10 mg, tadalafil 20 mg, or placebo for 12 weeks (dosed as needed before sexual activity, no more than once daily).

RESULTS

Tadalafil improved erectile function compared with placebo (P < 0.001) in naïve patients and sildenafil prior responders for all efficacy measures. For most efficacy outcomes, responses in the naïve group (probable mix of responders and nonresponders) were not statistically different from responses in the prior-responder group (P >or= 0.10).

CONCLUSIONS

The similar responses of these two patient groups observed in this post hoc analysis suggest, but do not confirm, that exclusion of sildenafil nonresponders in previously reported tadalafil clinical trials may not have substantially affected efficacy outcomes. Tadalafil improved erectile function in patients naïve to PDE5 inhibitor therapy and in patients who previously responded to sildenafil therapy.

A meta-regression analysis of treatment effect modifiers in trials with flexible-dose oral sildenafil for erectile dysfunction in broad-spectrum populations

Several trials and reviews provide evidence for the efficacy of phosphodiesterase-5 inhibitors in the treatment of erectile dysfunction (ED). However, little is known about the impact of treatment effect modifiers other than concomitant diseases. Our objective was to identify patient and trial characteristics as well as methodological and publication-related issues that are associated with the treatment effect measured in flexible-dose randomized controlled trials of oral sildenafil for ED. The MEDLINE and the Cochrane Central databases were searched for efficacy trials of sildenafil. Thirteen trials fulfilled all inclusion criteria. A series of meta-regression and graphical analyses were performed to test the impact of possible effect modifiers. Treatment effect was influenced by mean baseline disease severity and mean duration of the disease. These associations were at least partly mediated by placebo response. Trial duration, age of patients and etiology of ED in patients did not have any significant influence on the treatment effect. The year of publication of primary trials was also related to trial findings. Our analysis adds important data to enable the control of confounding variables in future trials and meta-analyses. It might also help the individual to assess the unbiased efficacy and true innovative potential of available and forthcoming pharmacological agents.

Superoxide anion production in the rat penis impairs erectile function in diabetes: influence of in vivo extracellular superoxide dismutase gene therapy

INTRODUCTION

Superoxide anion may contribute to erectile dysfunction (ED) in diabetes mellitus by reducing cavernosal nitric oxide (NO) bioavailability. The purpose of this study was to determine if gene transfer of extracellular superoxide dismutase (EC-SOD) can reduce superoxide anion formation and determine if this reactive oxygen species may contribute to diabetes-related ED in an experimental model of diabetes.

METHODS

Three groups of animals were utilized: (1) control; (2) streptozotocin (STZ)-diabetic rats [60 mg/kg intraperitoneally (ip)] intracavernosally injected with AdCMVbetagal (negative control); and (3) STZ-rats intracavernosally injected with AdCMVEC-SOD. Two months after ip injection of STZ, groups 2 and 3 were transfected with the adenoviruses and 2 days after transfection, all animals underwent cavernosal nerve stimulation (CNS) to assess erectile function. Confocal microscopy for superoxide anion and von Willebrand Factor (vWF) was performed in the STZ-diabetic rat. Superoxide anion production, total SOD activity, and cyclic guanosine monophosphate (cGMP) levels were measured in each experimental group of rats.

RESULTS

Confocal microscopy demonstrated superoxide in smooth muscle and endothelial cells of the STZ-rat cavernosum and colocalized with vWF in the endothelium. Higher superoxide anion levels and decreased cGMP levels were found in the penis of STZ-rats at a time when erectile function was reduced. Two days after administration of AdCMVEC-SOD, superoxide anion levels were significantly lower in the penis of STZ-rats. Total SOD activity and cavernosal cGMP was increased in the penis of EC-SOD-transfected rats. STZ-rats transfected with AdCMVEC-SOD had a peak intracavernosal pressure (ICP) and total ICP to CNS that was similar to control rats.

CONCLUSIONS

These data demonstrate that in vivo adenoviral gene transfer of EC-SOD can reduce corporal superoxide anion levels and raise cavernosal cGMP levels by increasing NO bioavailability thus restoring erectile function in the STZ-diabetic rat.

Efficacy of sildenafil citrate in men with erectile dysfunction following radical prostatectomy: a systematic review of clinical data

INTRODUCTION

Radical prostatectomy is a frequently used treatment option for prostate cancer; however, prostatectomy is often associated with significant morbidity, including erectile dysfunction (ED).

AIM

To analyze the efficacy of sildenafil citrate in treating ED after radical prostatectomy.

MATERIALS AND METHODS

MEDLINE and CANCERLIT (1998 to January 2004) were searched for English language articles using the key words prostatectomy, sildenafil, and phosphodiesterase inhibitors. Eleven studies fulfilled the inclusion criteria: primary, discrete data sets of postprostatectomy patients with ED treated with sildenafil monotherapy.

RESULTS

Sample sizes ranged from 13 to 198 (mean age, 61 +/- 3 years). Treatment durations were 4 weeks (or more than four doses) to 1 year, and sildenafil dosing was in the recommended range (25-100 mg). Seven studies reported a response rate (range, 14%-53%) for an end point consistent with the primary analysis outcome (erection sufficient for vaginal intercourse); the combined estimate of probability of response was 35% (95% confidence interval [CI], 24%-48%). There was strong evidence for a lower response rate after non-nerve-sparing (range, 0%-15%) versus nerve-sparing surgery (range, 35%-75%; combined odds ratio [OR] = 12.1; 95% CI, 5.5-26.6) but not after unilateral (range, 10%-80%) versus bilateral nerve-sparing surgery (range, 46%-72%; combined OR = 2.21; 95% CI, 0.75-6.54).

CONCLUSIONS

The results of these studies demonstrate that with sildenafil, more than one third of patients with postprostatectomy ED achieved erection sufficient for intercourse. The odds of responding improved 12-fold with preservation of at least one neurovascular bundle. Early treatment failure does not necessarily imply lack of efficacy in the future, and patients should be encouraged to continue trying sildenafil, titrating up to 100 mg as needed.

Efficacy and safety of oral tadalafil in the treatment of men in Canada with erectile dysfunction: a randomized, double-blind, parallel, placebo-controlled clinical trial

INTRODUCTION

Erectile dysfunction (ED) is a highly prevalent, often undertreated condition.

AIM

This 12-week, double-blind, parallel, placebo-controlled study was conducted at 25 sites in Canada to evaluate the efficacy and safety of oral tadalafil, a phosphodiesterase type 5 inhibitor, for the treatment of ED.

METHODS

Men with ED of organic, psychogenic, or mixed etiology were stratified by baseline ED severity then randomly assigned to placebo (N = 50), tadalafil 10 mg (N = 103), or tadalafil 20 mg (N = 100), taken as needed (maximum, once daily).

MAIN OUTCOME MEASURES

Efficacy was assessed by the International Index of Erectile Function (IIEF), a Sexual Encounter Profile diary, and a global assessment question (GAQ).

RESULTS

Tadalafil 10 mg and tadalafil 20 mg significantly improved erectile function compared with placebo (P < 0.001, all measures). At end point, the mean IIEF erectile function (EF) domain scores were 14.5, 21.2, and 23.3 of a possible score of 30 for placebo, tadalafil 10 mg, and tadalafil 20 mg, respectively. Patients treated with tadalafil reported greater change from baseline on the IIEF EF domain score compared with placebo, regardless of baseline ED severity. During treatment, the mean per-patient proportion of successful intercourse attempts was higher for tadalafil 10 mg and 20 mg than for placebo (placebo, 31.9%; tadalafil 10 mg, 56.7%; and tadalafil 20 mg, 61.5%), and a greater proportion of patients reported improved erections with tadalafil (GAQ; placebo, 22.0%; tadalafil 10 mg, 67.0%; tadalafil 20 mg, 79.0%). Fifty percent and 62% of patients treated with tadalafil 10 mg and 20 mg, respectively, achieved successful sexual intercourse after their first dose, compared with 31% with placebo. Treatment-emergent adverse events were generally mild or moderate.

CONCLUSION

Tadalafil was an effective, well-tolerated therapy for ED of broad-spectrum etiology and severity.

Vasodilatory and hypoglycaemic effects of two pyrano-isoflavone extractives from Eriosema kraussianum N. E. Br. [Fabaceae] rootstock in experimental rat models

Zulu traditional health practitioners have claimed that the roots of Eriosema kraussianum N. E. Br. (Fabaceae) and other Eriosema species (Zulu indigenous umbrella name of "uBangalala") are effective remedies for the treatment of erectile dysfunction (ED) and/or impotence. In order to scientifically appraise the significance and contribution of Eriosema kraussianum to its ethnomedical use as "uBangalala" and "VIAGRA substitute", the present study was undertaken to investigate the vasodilatory and hypoglycaemic properties of the two main bioactive chemical compounds obtained from E. kraussianum, in experimental rat models, using sildenafil citrate (VIAGRA) as the reference drug for comparison. The two E. kraussianum rootstock constituents (K1 and K2, 20-80 mg/kg p.o.) caused dose-dependent and significant (P<0.05-0.001) hypoglycaemia in rats. Relatively low to high concentrations of the plant's extracts (K1 and K2, 100-2000 microg/ml) always produced biphasic effects on rat isolated portal veins. K1- and K2-provoked responses of the isolated portal veins always consisted of concentration-related initial transient, but significant (P<0.05), contractions of the venous muscle preparations, followed by secondary, longer-lasting, highly significant (P<0.01-0.001) relaxations of the venous muscle strips. Sildenafil citrate (VIAGRA, 5-100 microg/ml) always produced concentration-related and highly significant relaxations of the rat isolated portal veins. Unlike K1 and K2 (20-80 mg/kg p.o.), however, sildenafil citrate (VIAGRA, 100 mg/kg p. o.) only caused slight and insignificant (P>0.05) reductions in the blood glucose levels of the experimental animals used. On the other hand, glibenclamide (10 mg/kg p.o.) induced highly significant (P<0.05-0.001), marked reductions in the blood glucose concentrations of the rats. The findings of this laboratory animal study indicate that the two hydro-ethanol extractives of E. kraussianum (K1 and K2) possess hypoglycaemic and secondary, vasorelaxant effects in the experimental paradigms used.

Clinical and Duplex US Assessment of Effects of Sildenafil on Cavernosal Arteries of the Penis: Comparison with Intracavernosal Injection of Vasoactive Agents—Initial Experience

PURPOSE

To prospectively evaluate the clinical response and hemodynamic changes in cavernosal arteries after oral administration of sildenafil without and with audiovisual sexual stimulation and to compare those responses with responses from intracavernosal injections of vasoactive agents.

MATERIALS AND METHODS

Institutional review board approval and written informed consent were obtained. Thirteen consecutive patients (age range, 22-77 years; mean, 60.4 years) with erectile dysfunction were evaluated with clinical assessment and cavernosal duplex ultrasonography (US). The patients were examined at two sessions 3 weeks apart. First, each patient received 100 mg of sildenafil citrate orally and was examined 60 minutes later without any sexual stimulation. Each patient then underwent repeat clinical and duplex US assessment after audiovisual sexual stimulation. Three weeks later, the patients underwent identical clinical evaluation and duplex US after intracavernosal injection of a commercially available combination of papaverine, prostaglandin E1, and phentolamine. Clinical and duplex US data (ie, peak systolic velocity [PSV]) were examined by using the Wilcoxon signed rank test for matched pairs.

RESULTS

At rest, the overall mean cavernosal artery PSV was 1.08 cm/sec and remained unchanged after intake of sildenafil without any audiovisual stimulation, with no clinical evidence of erection. With the addition of audiovisual sexual stimulation, eight (62%) of 13 patients had penile congestion or erection, and six (46%) had a PSV greater than 25 cm/sec. With intracavernosal injection of the combination of three drugs, all 13 patients achieved congestion or erection, and 10 (77%) had a PSV greater than 25 cm/sec. Both clinical and duplex US responses to intracavernosal injection were significantly greater than they were to sildenafil with audiovisual sexual stimulation (P = .04 and .003, respectively).

CONCLUSION

Oral sildenafil with audiovisual sexual stimulation led to a significant clinical response and increment in blood flow in the cavernosal arteries. However, more patients responded to intracavernosal injection of the combination of three drugs than to sildenafil, and the clinical response was significantly better.

SEXUAL DYSFUNCTION AFTER RADICAL PROSTATECTOMY: PREVALENCE, TREATMENTS, RESTRICTED USE OF TREATMENTS AND DISTRESS

PURPOSE

Cancer of the prostate (CAP) is one of the most common malignancies affecting North American men with about 215,000 new cases and 35,800 CAP related deaths annually. The most prevalent intervention for localized CAP is radical prostatectomy (RP) with 10-year survival rates approaching 90%. Studies of men in post-RP recovery indicate that 44% to 75% experience sexual dysfunction and more than 60% experience distress in reaction to sexual dysfunction problems. These findings are increasingly significant as prostate specific antigen testing continues to increase CAP detection rates, resulting in more and younger post-RP patients confronting sexual dysfunction.

MATERIALS AND METHODS

A MEDLINE database search was performed for articles published from 1966 to September 2004.

RESULTS

Despite effectiveness 30% to 50% of patients who turn to sexually assistive aids after RP discontinue use within a year. This suggests that the achievement of physical responsiveness to an aid is necessary but it is not a sufficient factor in long-term sexual adaptation. Current research exploring this gap between effectiveness and ongoing use supports a broader perspective of sexual dysfunction emphasizing several factors, including perceptions of inadequacy, anxieties in regard to performance and depression in each member of the couple, overly enthusiastic expectations, partner physical/emotional readiness to resume active sex, the meaning to the couple of using a sexual aid and the quality of the nonsexual relationship of the couple.

CONCLUSIONS

Our findings reveal the need to explore broader strategies for improving patient coping ability and adaptation. They also point to the need to explore the role of resumed satisfying sexuality in overall quality of life following treatment.

Outcome analysis of sildenafil citrate for erectile dysfunction of Japanese patients

The approved maximal dose of sildenafil is only 50 mg in Japan, but the impact of dose regulation on treatment outcomes has not been established. Moreover, the contributors to the efficacy in patients having an intact peripheral nervous system have not been fully elucidated. We assessed in Japanese patients the treatment outcomes of sildenafil for erectile dysfunction (ED) under regulation of the approved dose and identified factors contributing to its efficacy among those with various etiologies other than pelvic surgery. We retrospectively reviewed 196 ED patients treated with sildenafil. The overall efficacy was 70.9% (139/196), and patients with psychological problems and concomitant cardiovascular disease showed high response rates (82.4 and 87.0%, respectively). Of the 139 responders, 89.9% achieved efficacy with a dose of 25 or 50 mg. Logistic regression analysis revealed concomitant cardiovascular disease and a favorable nocturnal penile tumescence result to be independent contributors to the efficacy.

Effects of Phosphodiesterase Type 5 Inhibitor Sildenafil on Retinal Function in Isolated Superfused Retina

After the oral ingestion of sildenafil, visual abnormalities have been reported constantly. The mechanism of these adverse events has been presumed to be a result of the interaction of sildenafil with the retinal phosphodiesterase (PDE) type 6. To investigate the physiological basis of the effects of sildenafil on retinal function, bovine retinas were isolated and perfused with an oxygen pre-equilibrated standard solution. The electroretinogram (ERG) was recorded as a transretinal potential using silver/silver-chloride electrodes. After reaching stable ERG amplitudes, sildenafil was added to the nurient solution at different concentrations, and its effect on the a- and b-wave amplitude was studied separately. The 0.1 microM and higher concentrations of sildenafil reduced the b-wave amplitude, while a reduction of the a-wave amplitude was observed at an elevated threshold of 0.3 microM. The changes of the ERG amplitudes were fully reversible for the b-wave at a concentration of 0.1 microM and for the a-wave at 0.3 microM sildenafil. At higher concentrations, sildenafil was found to be only partially reversible within recovery time. In conclusion, besides an inhibitory influence on photoreceptors, sildenafil performs additional effects on the postsynaptic neuronal network. Higher concentrations of sildenafil were found to have a potential for retinal degeneration, suggesting that further trials should be designed to evaluate the long-term effects of sildenafil. The physiological consequences of an abuse or long-term, daily use of sildenafil are not clear.

Rho-kinase inhibition improves erectile function in aging male Brown-Norway rats

Physiological aging is a significant risk factor in the on-set of male erectile dysfunction (ED) and an imbalance in factors that modulate cavernosal smooth-muscle tone may play a role in these altered penile hemodynamic mechanisms. To evaluate the association between aging and male erectile function, we monitored neurogenic erectile response and its correlation to systemic arterial pressure changes in old (21-23 months of age) vs young (6-9 months of age) Brown-Norway (BN) rats. We tested the hypothesis that age-associated ED is due to unregulated vasoconstrictive tone, contributed in part by an increased Rho-kinase activity, and that antagonism of Rho-kinase activity attenuates the age-related decline in male erectile function. We also examined the hypothesis that a combination of Rho-kinase antagonism and phosphodiesterase-5 (PDE-5) inhibition has a synergistic effect in improving the erectile response in these aging animals. Erectile function in old BN rats was evaluated before and after intracavernosal injection of a specific inhibitor of Rho-kinase (Y-27632) alone or in combination with zaprinast, a PDE-5 inhibitor. Erectile capabilities of the young and old BN rat groups were significantly different in corpus cavernosum pressure response after electrical-field stimulation of the major pelvic ganglion. Y-27632 administration attenuated the aging-related changes in male erectile function seen in BN rats. Rho-kinase antagonism and PDE-5 inhibition had a synergistic effect in improving erectile function in old rats. Our data indicate that aging leads to impairment in the neurogenic erectile response in BN rats involving a possible derangement in penile hemodynamic mechanisms of the erectile tissue. Rho-kinase inhibition may be of value in treating age-related ED.

Comparison of clinical trials with sildenafil, vardenafil and tadalafil in erectile dysfunction

Erectile dysfunction (ED) affects up to 50% of men, between 40 and 70 years of age. In the first major trial of sildenafil in ED, at 24 weeks, improved erections were reported by 77 and 84% of men taking sildenafil 50 and 100mg, respectively. Subsequently, sildenafil has been reported to be effective in men with ED associated with diabetes and prostate cancer, and in psychogenic ED. Sildenafil is safe in men with coronary artery disease, provided it is not used with the nitrates (a contraindication). The most commonly reported adverse effects with sildenafil are headache, flushing and dyspepsia. Vardenafil is more potent and more selective than sildenafil at inhibiting phosphodiesterase-5. Vardenafil is similarly effective to sildenafil in the treatment of ED. The only advantage that vardenafil has over sildenafil is that it does not inhibit phosphodiesterase-6 to alter colour perception, a rare side effect which sometimes occurs with sildenafil. Tadalafil has a longer duration of action than sildenafil and vardenafil. Tadalafil is similarly effective as sildenafil in the treatment of ED. In comparison studies, tadalafil is preferred to sildenafil (50/100mg) by men with ED, possibly because of its longer duration of action. Of the phosphodiesterase inhibitors, tadalafil may displace sildenafil as the drug of choice among men with ED.

Clinical application of prognostic factors for patients with organic causes of erectile dysfunction on 100 mg of sildenafil citrate

OBJECTIVES

There are still no clinical predictive factors to determine the response rate of erectile dysfunction (ED) patients to sildenefil citrate. The aim of the present study is to evaluate and stratify the risk factors and attempted to determine the prognostic factors in clinical practice to predict the response rate. This is important in improving cost effectiveness and avoiding side-effects.

MATERIAL AND METHODS

This is an open label prospective study including patients attending the andrology clinic in Tan Tock Seng Hospital, Singapore, over 2 years. The patients were evaluated and investigated for possible underlying causes and ED severity was assessed by five-items of the International Index of Erectile Function questionnaire (IIEF-5), together with the duration, degree and rigidity of erection. Psychogenic causes were excluded with a minimal follow up of 6 months. All patients were placed on 100 mg of sildenafil citrate and were reassessed at the end of 6 months. Logistic regression with univariate and multivariate was used as the method of statistical analysis.

RESULTS

A total of 232 patients were in the cohort. The overall response rate was 43%, with the best response rate in veno-occlusive cases and the worst responses from neurogenic causes. Age, smoking, diabetes mellitus, hypertension, hyperlipidemia, pretreatment IIEF-5 score, interval to achieve erection and duration of erection were significant in univariate analysis, but only age, smoking and IIEF-5 score were significant in multivariate analysis. With a combination of these factors, a table was formed to determine the possible response rate in clinical practice. This will assist physicians in selecting patients with potentially favorable responses and avoid side-effects and an unnecessary wastage of time and cost.

CONCLUSION

Possible factors could be determined and used clinically to predict the response rate to sildenafil citrate.

Risk factors in predicting a poor response to sildenafil citrate in elderly men with erectile dysfunction

OBJECTIVE

To assess the clinical efficacy of sildenafil and the potential predictors of poor response to sildenafil in elderly patients with erectile dysfunction (ED).

PATIENTS AND METHODS

The study included 162 patients (aged > or = 60 years) treated with sildenafil for at least 8 weeks; all patients were evaluated with a history, physical examination, measurement of total testosterone and a pharmacological erection test. Sexual function before and 8 weeks after treatment was assessed using the self-administered International Index of Erectile Function (IIEF). Treatment was considered successful when the patient attained a higher grade on the erectile function (EF) domain score, and an affirmative response to the overall assessment question. Factors influencing treatment outcome were evaluated by univariate and multivariate statistical analysis.

RESULTS

The overall efficacy with sildenafil was 47% (76/162). On univariate analysis, uncontrolled diabetes, current smoking, hypogonadism (<3 microg/L testosterone) and low pretreatment EF domain score (<17) were selected as predictors of a poor response. On multivariate logistic regression, a low pretreatment EF domain score was the strongest independent prognostic factor for a poor response (odds ratio 2.25, 95% confidence interval, 1.45-7.33), and this was followed by hypogonadism (1.89, 1.12-3.16) and current smoking (1.34, 1.04-3.52).

CONCLUSION

In a real clinical setting, sildenafil was effective for about half of the elderly men. The baseline EF domain score, hypogonadism and current smoking were significantly associated with failure of sildenafil. These results suggest that modifying reversible risk factors, e.g. stopping smoking and replacing testosterone, would be beneficial in augmenting the efficacy of sildenafil in elderly men.

Erectile response with vardenafil in sildenafil nonresponders: a multicentre, double-blind, 12-week, flexible-dose, placebo-controlled erectile dysfunction clinical trial

OBJECTIVE

To evaluate the efficacy of vardenafil in patients previously unresponsive to sildenafil.

PATIENTS AND METHODS

A multicentre, double-blind, 12-week, flexible-dose, placebo-controlled trial was conducted, involving 463 men aged > or = 18 years with moderate-to-severe erectile dysfunction (ED) and who were unresponsive to sildenafil (by history). After a 4-week treatment-free run-in, patients received placebo or vardenafil 10 mg with the option to maintain current dose or to titrate by one dose level (5, 10 or 20 mg) based on efficacy and tolerability at 4 and 8 weeks. Outcome measures were the erectile function (EF) domain score of the International Index of Erectile Function, two Sexual Encounter Profile diary questions (vaginal penetration and maintenance of erection until successful completion of intercourse), and the Global Assessment Question (GAQ).

RESULTS

There was significantly better EF with vardenafil than with placebo throughout the study. The least-square mean EF domain scores increased from 9.3 at baseline to 17.6 at the 'last' observation carried forward (LOCF) analysis with vardenafil (P < 0.001). Overall least-square mean per-patient success rates more than doubled for penetration (30.3% to 62.3%) and quadrupled for successful intercourse (10.5% to 46.1%) with vardenafil. Improved erections (positive response to the GAQ) were reported by 61.8% of patients receiving vardenafil and 14.7% of those receiving placebo at LOCF (P < 0.001). Normal EF (domain score > or = 26) was achieved by 30% of patients receiving vardenafil and 6% receiving placebo at LOCF (P < 0.001). Adverse events were infrequent and representative of the phosphodiesterase-5 inhibitor profile.

CONCLUSION

Vardenafil is an effective and generally safe treatment for ED, even in men unresponsive to sildenafil (by history).

Patient preferences in treatment of erectile dysfunction: the continuing importance of patient education

Understanding patient preferences can be important in ensuring full benefit is derived from treatment for erectile dysfunction (ED). They seem to be important in determining whether patients continue treatment in the medium and long term. In clinical practice, discontinuation rates beyond a year are relatively high. Factors such as spontaneity, "naturalness", and onset and duration of action may all influence preference. This article discusses a number of studies looking into patient preferences for a particular class of treatment method over another, and also for individual treatments within classes. In general, patients appear to prefer oral treatments to others such as penile implant surgery, vacuum-pump therapy, apomorphine, and intracavernosal injection. In some studies, men have also shown preferences for particular oral phosphodiesterase-5 (PDE5) inhibitors over others. Providing patients with full information on the pros and cons of treatment options can help ensure patients are treated with a therapy that fits more closely with their wishes, and ensure continuation of treatment for optimal efficacy.

Phosphodiesterase-5 inhibition synergizes rho-kinase antagonism and enhances erectile response in male hypertensive rats

To evaluate the association between hypertension, male erectile function, Rho-kinase, and cyclic GMP pathways, we monitored neurogenic erectile response in spontaneously hypertensive (SHR) vs normotensive rats. We also evaluated SHR erectile function before and after intracavernosal injection of either the specific Rho-kinase inhibitor Y-27632 or a combination of Y-27632 and the PDE5 inhibitor zaprinast to prevent cGMP degradation. SHR had lower resting baseline corpus cavernosum pressure and a higher threshold for development of tumescence than normotensive rats. In SHR, Y-27632 administration reversed hypertension-related changes in male erectile function; Rho-kinase antagonism and PDE5 inhibition in combination had a synergistic effect in improving the neurogenic erectile response. Our data indicate that hypertension is associated with impairment in the SHR neurogenic erectile response that may involve a derangement in hemodynamic mechanisms in penile erectile tissue. Rho-kinase inhibition alone or combined with PDE5 inhibition may be of value in treating hypertension-related ED.

Sublingual sildenafil in the treatment of erectile dysfunction: Faster onset of action with less dose

BACKGROUND

The aim of the present study was to show the efficacy and safety of sublingual sildenafil and to determine whether lower doses cause the same effect with a faster onset of action in this mode of application.

METHODS

Forty consecutive patients with erectile dysfunction for more than three months were included in the study. The mean age was 55 years (range, 25-65). Serum glucose and testosterone levels, lipid profile and erectile function scores were obtained in all patients. Twenty patients received placebos and the other 20 patients received 20 mg sublingual sildenafil in a double blind randomized design.

RESULTS

The effect of sildenafil on erection was significantly higher than that of placebo. Sixty-five percent of patients (13/20) who received sublingual sildenafil achieved satisfying erections and coitus, whereas the rate was 15% in the placebo group (3/20). The mean onset of action with sublingual sildenafil was 15.5 min and lasted for an average of 40 min. Minimal headaches, sweating and flushing were noted as the side-effects.

CONCLUSIONS

20 mg sublingual sildenafil is safe and effective in the treatment of erectile dysfunction. Sublingual administration has some advantages as it is not effected by food ingestion and quickly appears in the circulation. These advantages provide a faster onset of action with a lower dose when compared to oral sildenafil. Sublingual use of sildenafil may be more cost-effective and possibly provides a more predictable onset of action.

Effect of combination endothelial nitric oxide synthase gene therapy and sildenafil on erectile function in diabetic rats

Erectile dysfunction associated with diabetes mellitus is caused in part by disordered endothelial smooth muscle relaxation, neuropathy, and a decrease in cavernosal nitric oxide synthase (NOS) activity. The purpose of this study was to determine whether a combination of sildenafil and adenoviral gene transfer of endothelial NOS (eNOS) could enhance the erectile response in diabetic rats. Five groups of animals were utilized: (1) age-matched control rats, (2) streptozotocin (STZ)-induced diabetic rats (60 mg/kg i.p.), (3) STZ-rats + sildenafil (2 mg/kg i.v.), (4) STZ-rats transfected with AdCMVbetagal or AdCMVeNOS, and (5) STZ-rats transfected with AdCMVeNOS +sildenafil (2 mg/kg i.v.). At 2 months after i.p. injection of STZ, groups 4 and 5 were transfected with the adenoviruses and 1-2 days after transfection, all animals underwent cavernosal nerve stimulation (CNS) to assess erectile function. Cyclic 3',5'-guanosine monophosphate (cGMP) levels were assessed in the cavernosal tissue. STZ-diabetic rats had a significant decrease in erectile function as determined by the peak intracavernosal pressure (ICP) and total ICP (area under the erectile curve; AUC) after CNS when compared to control rats. STZ-diabetic rats+AdCMVeNOS had a peak ICP and AUC, which were similar to control animals. STZ-diabetic rats administered sildenafil demonstrated a significant increase in peak ICP at the 5 and 7.5 V settings, while the AUC was significantly increased at all voltage (V) settings. The increase in both ICP and AUC of STZ-diabetic rats transfected with AdCMVeNOS at all V settings was greater than STZ-diabetic rats transfected with AdCMVbetagal. STZ-diabetic rats transfected with AdCMVeNOS and administered sildenafil had a significant increase in total ICP that was greater than eNOS gene therapy alone. Cavernosal cGMP levels were significantly decreased in STZ-diabetic rats, but were increased after transfection with AdCMVeNOS to values greater than control animals. In conclusion, overexpression of eNOS and cGMP in combination with sildenafil significantly increased both the peak ICP and total ICP to CNS in the STZ-diabetic rat, which was similar to the response observed in control rats. Moreover, the total erectile response was greater in STZ-diabetic rats receiving eNOS gene therapy plus sildenafil than STZ-rats receiving sildenafil or eNOS gene therapy alone.

Impact of introduction of sildenafil on other treatment modalities for erectile dysfunction: a study of nationwide and local hospital sales

We assess the impact of introduction of sildenafil on alprostadil injection and penile implant surgery for the treatment of erectile dysfunction (ED) at our institution and in Taiwan. The data of national sales of sildenafil, alprostadil injection and penile implant were provided by industry companies. In the meanwhile, we analyzed the users of the above-mentioned three treatments at our institution. The national sales of sildenafil grew 136% from 0.8 million tablets in 1999 to 1.6 million tablets in 2002, while those of alprostadil injection dropped 33% after the marketing of sildenafil and of penile implant dropped 40% after the marketing of alprostadil injection and sildenafil. The market share of drugstores for sildenafil rose from 41% in 1999 to 72% in 2002. The trend of sales of sildenafil at our institution was similar to that of national sales from hospitals. Mean age of the sildenafil new users was becoming younger in the past 4 y (P<0.001). Of the new users of alprostadil injection and the recipients of penile implant, the commonest age group shifted from the range of 60-69 y before the launch of sildenafil to that of over 70 y after (P<0.05). In conclusion, the introduction of sildenafil has prompted more men as well as younger men with ED to seek treatment. Part of the roles of alprostadil injection and penile implants in this field are substituted by sildenafil and the commonest age group of their users becomes older than before.

Efficacy of apomorphine and sildenafil in men with nonarteriogenic erectile dysfunction. A comparative crossover study

To compare the efficacy of apomorphine and sildenafil in men with nonarteriogenic erectile dysfunction (ED), 40 men were studied. Post-injection penile peak systolic velocity was greater than 25 cm s(-1). Twenty men started on apomorphine 2 mg and 20 on sildenafil 50 mg, the doses titrated up to 3 and 100 mg, respectively, if necessary. After a 1-week washout period each group switched to the other treatment mode. Efficacy was the percentage of attempts resulting in erections firm enough for intercourse, based on an event log data. The majority (85%) of the men had concomitant diseases, risk factors for ED and 95% were heavy smokers. The overall success rate of apomorphine was 62.7%, compared with 73.1% of sildenafil (Yates-corrected chi-square, P < 0.0004). The response to apomorphine 2 mg and sildenafil 50 mg was age related. Sildenafil was statistically more effective than apomorphine in impotent men with normal penile Doppler. Given the contraindication of sildenafil in men taking nitrates and the quick time of action of apomorphine, the two drugs are satisfactory first line therapeutic tools in such individuals and the choice should be based on patient's needs and preferences.

[Therapy of erectile dysfunction in 2005]

Erectile dysfunction (ED) management in the following 3-5 years will be dominated by substances targeting the L-arginine-NO-guanylate cyclase-cGMP-PDE-5 pathway, resulting in an intracellular elevation of the cGMP concentrations. Promising alternatives to the PDE-5 inhibitors, such as guanylate cyclase activators and Rho-kinase inhibitors, may also effectively compliment a PDE-5 inhibitor. Intranasal application of the melanocortin agonist PT 141 (Melanotan II) seems to be promising. As scheduled sexual activities are not preferred by the majority of couples, the future of ED-therapy will focus on drugs with a 1-2 day long efficacy window, or a daily bedtime application of low dosage agents which result in nocturnal reoxygenation of the cavernous bodies and in turn in functional improvement. Elevation of the cGMP levels and improvement of endothelial function as a result of this approach also promises benefits in cardiovascular diseases and in LUTS.

Rechallenge prior sildenafil nonresponders

To assess inappropriate use as a cause of sildenafil (Viagra ) failure and the feasibility of successfully rechallenging nonresponding patients, a total of 60 consecutive erectile dysfunction (ED) patients who first presented to our hospital and claimed poor response to sildenafil were enrolled into the study. The International Index of Erectile Function-5 (IIEF-5) was used to evaluate their baseline ED status and a self-administered sildenafil-use questionnaire composed of nine questions (SUQ-9) to assess how they had used sildenafil. A total of 44 subjects consent to rechallenge with sildenafil and were given thorough instruction based on individual answers to SUQ-9 and four doses of sildenafil 100 mg. After a 4-week follow-up, end point efficacy of rechallenge was evaluated using the IIEF-5 and the global assessment question (GAQ), 'After the treatment, did you have successful sexual intercourse?' Of the 60 subjects, 44 (77.3%) had one or more areas of major suboptimal use of sildenafil: 18 (30.0%) did not know that sexual stimulation was necessary for sildenafil to work, 36 (60.0%) attempted to use sildenafil less than four times, and 27 (45.0%) took a maximal dose less than 100 mg. Of the 44 patients undergoing sildenafil rechallenge, 34 (77.3%) completed the follow-up, while seven (15.9%) received only GAQ assessment by telephone interview and three (6.8%) were lost to follow-up. The total follow-up rate was 93.2% (41/44). Based on answers to the GAQ, the response rate to rechallenge was 58.5% (24/41). The mean improvement in the IIEF-5 score was 8.4+/-5.5 in responders (P <0.05). With individualized thorough instruction based on answers to SUQ-9 and scheduled follow-up, a high success rate was achieved by rechallenge with sildenafil in prior failures. The efficacy of sildenafil could be improved to a great extent by adequate education of patients and continuing medical education given to primary-care physicians.

A comparative, crossover study of the efficacy and safety of sildenafil and apomorphine in men with evidence of arteriogenic erectile dysfunction

The aim of the study was to establish and compare the efficacy and safety of sildenafil and apomorphine in men with arteriogenic erectile dysfunction (ED). In all, 43 men with ED and postinjection max penile systolic velocity <25 cm/s in repeated Doppler ultrasonography were included. Of these, 24 men started on apomorphine 2 mg and 19 on sildenafil 50 mg, the doses titrated up to 3 and 100 mg according to effectiveness and tolerability. Safety was evaluated according to adverse events (AEs) and patient withdrawal. Efficacy was the percentage of attempts resulting in erections firm enough for intercourse, based on event log data. The incidence of AEs with apomorphine 3 mg was higher than with sildenafil 100 mg. Two men on apomorphine 3 mg discontinued treatment due to AEs. The overall success rate of sildenafil was 63.7% compared to 32.1% of apomorphine (Pearson chi(2), P<0.01). Of all men, 25 (58.1%) responded to sildenafil 50 mg without the need for dose increase, while only one responded to apomorphine 2 mg. The response to sildenafil 50 mg was age related (analysis of variance, p=0.04). Satisfaction was reported by 76.75 and 13.95% of patients for sildenafil and apomorphine, respectively, but 20.9% were not satisfied with any of the two drugs. In conclusion, this study provides clear evidence that sildenafil, even at 50 mg dose, is more effective than apomorphine 3 mg in men with arteriogenic ED. The fact that one out of five patients is not satisfied with the above-studied drugs shows that new oral agents need to be evaluated for the treatment of this disorder.

Treatment satisfaction in patients with erectile dysfunction switching from prostaglandin E1 intracavernosal injection therapy to oral sildenafil citrate

Treatment satisfaction, subanalysed by demographic variables, was evaluated in patients switching from successful intracavernosal prostaglandin E(1) (PGE(1)) therapy to oral sildenafil citrate. The validated Erectile Dysfunction Inventory of Treatment Satisfaction questionnaire was administered at the end of PGE(1) therapy and after 12 weeks of sildenafil treatment in a multicentre, open-label study. Men with erectile dysfunction (n=176) who were switched from stable PGE(1) therapy to sildenafil (25-100 mg) were equally satisfied with onset of action, duration of action, and confidence in ability to engage in sexual activity, but expressed greater overall treatment satisfaction with sildenafil (P<0.01), better ease of use (P<0.001), naturalness of erectile process (P<0.001), and intention to continue treatment (P<0.001). Partners (n=32) were overall more satisfied with sildenafil (P<0.05), and their responses correlated with patient satisfaction (r=0.68). Compared with PGE(1) injection, these data suggest that patients may be less likely to discontinue taking sildenafil treatment for their erectile dysfunction.