Is sildenafil failure in men after radical retropubic prostatectomy (RRP) due to arterial disease? Penile duplex Doppler findings in 174 men after RRP

Prognostic value of penile colour doppler ultrasonography for recovering erectile function after radical prostatectomy

OBJECTIVE

To analyse the predictive utility of penile colour Doppler ultrasonography after the injection of vasoactive agents for recovering erectile function after radical prostatectomy.

MATERIAL AND METHODS

A retrospective study was conducted on patients with erectile dysfunction after radical prostatectomy who were treated with intracavernous injections of prostaglandins E1 between January 1, 2006 and December 31, 2012. The study included patients with no history of erectile dysfunction prior to the surgery and who did not respond to medical treatment. Colour Doppler was performed on all patients after the intracavernous injection. A peak systolic velocity ≥30cm/sec and an end diastolic velocity ≤5cm/sec were considered normal haemodynamic values. We assessed the result of the treatment during the follow-up using the International Index of Erectile Function-5.

RESULTS

We included 197 patients. The mean age was 60.8 (±6.3). The pathological diagnosis for all patients was adenocarcinoma, 74.1% of which were confined to the organ (T1-T2/Nx-N0). Treatment with injections after the surgery was started after a mean duration of 6.8 months (+3.5). The Doppler ultrasonography results were normal for 53 patients (26.9%). During the follow-up, 113 patients (57.4%) maintained functional erections; 55 of these patients (28%) did not require injections. Normal Doppler ultrasonography results were associated with a favourable response to treatment (p<.01).

CONCLUSIONS

The prostaglandin E1 test will help provide a diagnosis in erectile dysfunction for patients who have undergone prostatectomies. The test helps provide information on the vascular condition of the penis and useful prognostic information for the follow-up of these patients.

Toward a new 'EPOCH': optimising treatment outcomes with phosphodiesterase type 5 inhibitors for erectile dysfunction

Despite the marked adverse impacts of erectile dysfunction (ED) on quality of life and well-being, many patients (and/or their partners) do not seek medical attention for this problem, do not receive treatment or discontinue such treatment even when it has effectively restored erectile responses to sexual stimulation. Phosphodiesterase type 5 (PDE5) inhibitors are considered first-line therapies for men with ED. To help physicians maximise the likelihood of treatment success with these agents, we conducted an English-language PubMed search of articles involving approved PDE5 inhibitors dating from 1 January 1998 (the year in which sildenafil citrate was introduced), through 31 August 2008. In addition to sildenafil, tadalafil and vardenafil, search terms included 'adhere*', 'couple*', 'effect*', 'effic*', 'partner*', 'satisf*', 'succe*' and 'treatment outcome.' Based on our analysis, physician activities to promote favourable treatment outcomes may be captured under the mnemonic 'EPOCH': (i) Evaluating and educating patients and partners to ensure realistic expectations of therapy; (ii) Prescribing a treatment individualised to the couple's lifestyle needs and other preferences; (iii) Optimising treatment outcomes by scheduling follow-up visits with the patient to 'fine-tune' dosages and revisit key educational messages; (iv) Controlling comorbidities via lifestyle counselling, medications and/or referrals and (v) Helping patients and their partners to meet their health and psychosocial needs, potentially referring them to a specialist for other forms of therapy if they are not satisfied with PDE5 inhibitors.

Fibrosis and loss of smooth muscle in the corpora cavernosa precede corporal veno-occlusive dysfunction (CVOD) induced by experimental cavernosal nerve damage in the rat

INTRODUCTION

Corporal veno-occlusive dysfunction (CVOD), which usually is associated with a loss of smooth muscle cells (SMC) and an increase in fibrosis within the corpora cavernosa, can be induced by an injury to the cavernosal nerves. The corporal tissue expresses inducible nitric oxide synthase (iNOS), presumably as an antifibrotic and SMC-protective response.

AIMS

We studied the temporal relationship in the corpora between the expression of iNOS, other histological and biochemical changes, and the development of CVOD, after bilateral cavernosal nerve resection (BCNR) in the rat.

METHODS

Rats underwent either BCNR or sham operation. Cavernosometry was performed 1, 3, 7, 15, 30, and 45 days (N = 8/groups) after surgery. Penile tissue sections were subjected to Masson trichrome staining for SMC and collagen, and immunodetection for alpha smooth muscle actin, iNOS, neuronal NOS (nNOS), endothelial NOS (eNOS), proliferating cell nuclear antigen (PCNA), and terminal transferase dUTP nick end labeling (TUNEL). Quantitative western blot analysis was done in homogenates.

MAIN OUTCOME MEASURES

Time course on the development of fibrosis and CVOD.

RESULTS

Following BCNR, CVOD was detectable 30 days later, and it became more pronounced by 45 days. In contrast, the SMC/collagen ratio in the BCNR corpora was reduced at 7 days and bottomed at 30 and 45 days, due in part to the reduction of SMC, presumably caused by an increase in apoptosis peaking at 3 days. PCNA also peaked at 3 days, but then decayed. nNOS was reduced early (3-7 days) and disappeared at 30 days, whereas eNOS was not affected. iNOS was induced at day 3, and steadily increased peaking at 30 days.

CONCLUSIONS

CVOD develops in the BCNR rat as a result of the early loss of corporal SMC by the neuropraxia-induced apoptosis, which the initial cell replication response cannot counteract, followed by fibrosis. The time course of iNOS induction supports the antifibrotic role of iNOS.

Rehabilitation of erectile function following radical prostatectomy

The concept of muscle rehabilitation after nerve injury is not a novel idea and is practiced in many branches of medicine, including urology. Bladder rehabilitation after spinal cord injury is universally practiced. The erectile dysfunction (ED) experienced after radical prostatectomy (RP) is increasingly recognized as being primarily neurogenic followed by secondary penile smooth muscle (SM) changes. There is unfortunately no standard approach to penile rehabilitation after RP because controlled prospective human studies are not available. This article reviews the epidemiology, experimental pathophysiological models, rationale for penile rehabilitation, and currently published rehabilitation strategies.

Different hemodynamic responses by color Doppler ultrasonography studies between sildenafil non-responders and responders

AIM

To determine if there are different penile hemodynamic patterns between sildenafil non-responders and responders by using color Doppler ultrasonography.

METHODS

A total of 69 erectile dysfunction (ED) patients aged 22-79 years were enrolled into the present study. Thirty-eight (55.1%) men with ED who did not respond to four attempts of treatment with 100 mg sildenafil after re-education were classified as sildenafil non-responders. A combination of three vasodilator drugs, 1.25 mg papaverine, 0.4 mg phentolamine and 5 mg prostaglandin E1, was given by intracavernous injection before penile Doppler ultrasonography was carried out. The erectile response to intracavernous injection and vascular parameters including peak systolic velocity (PSV), resistance index (RI), end diastolic velocity (EDV) and cavernosa artery diameter (CD) were measured and the results between sildenafil non-responders and responders were compared.

RESULTS

No statistical difference in vascular parameters measured by Doppler ultrasonography studies between non-responders and responders was noted. Sildenafil non-responders had a poorer penile rigidity response to intracavernous injection than responders (P < 0.05). Among patients with adequate PSV (>or=30 cm/s) and abnormal EDV (> 5 cm/s), individuals in the non-responder group had fewer positive responses to intracavernous vasodilator injection than in the responder group (35.3% vs. 72.2%, P < 0.05). Advanced age and comorbidity with diabetes mellitus were significantly associated with sildenafil non-response (P < 0.05).

CONCLUSION

Sildenafil non-responders were characterized by a poorer penile rigidity response to intracavernous injection and had an associated impaired veno-occlusive mechanism. Advanced age and comorbidity with diabetes mellitus were two common factors associated with non-response.

Central Nervous System Agents in the Treatment of Erectile Dysfunction

In the last two decades, a better understanding of the mechanisms governing erectile function and the pathophysiologies underlying erectile dysfunction (ED) have led re-searchers to investigate novel treatment concepts. Selective type-5 phosphodiesterase inhibitors are recommended as first-line therapy because of their high efficacy, but 30% to 40% of patients who have ED do not respond adequately to these agents and require alternative methods. The central nervous system plays a fundamental role in sexual behavior. Animal models have advanced our understanding of the neuroanatomic and neuropharmacologic basis of centrally induced penile erections. Clinical research with apomorphine has demonstrated efficacy in men who have a range of ED. Recent interest has focused on other centrally acting agents for ED treatment, including the melanocortin receptor agonists.

Co-administration of low doses of intranasal PT-141, a melanocortin receptor agonist, and sildenafil to men with erectile dysfunction results in an enhanced erectile response

OBJECTIVES

To evaluate the safety and pharmacodynamic effect of co-administration of subtherapeutic doses of PT-141, a cyclic heptapeptide melanocortin analogue, and sildenafil to patients with erectile dysfunction.

METHODS

Nineteen patients with erectile dysfunction who were responders to either Viagra or Levitra by self-report were given 25 mg sildenafil and 7.5 mg intranasal PT-141, 25 mg sildenafil and an intranasal placebo spray, and a placebo tablet and an intranasal placebo spray in a randomized cross-over design. Erectile activity in response to two 30-minute episodes of visual sexual stimulation was assessed by RigiScan during a 6-hour postdose period.

RESULTS

The erectile response induced by co-administration of PT-141 and sildenafil was significantly greater than the response elicited by administration of sildenafil alone. Co-administration of PT-141 and sildenafil was safe and well-tolerated and did not result in new adverse events or adverse events that were increased in frequency or severity compared with monotherapy.

CONCLUSIONS

Co-administration of intranasal PT-141 and a phosphodiesterase type 5 inhibitor may constitute a treatment alternative for patients in whom higher doses of a single therapy are not effective or well tolerated.

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.

Evaluation of the safety, pharmacokinetics and pharmacodynamic effects of subcutaneously administered PT-141, a melanocortin receptor agonist, in healthy male subjects and in patients with an inadequate response to Viagra®

PT-141, a cyclic heptapeptide melanocortin analog, was evaluated following subcutaneous administration to healthy male subjects and to patients with erectile dysfunction (ED) who report an inadequate response to Viagra. An inadequate response was defined for this study by patient report indicating that achievement of an erection suitable for vaginal penetration occurred < or =50% of the time while taking 100 mg Viagra. Erectile responses were assessed by RigiScan in healthy subjects in the absence of visual sexual stimulation (VSS) and in ED patients in the presence of VSS. Doses ranging from 0.3 to 10 mg were administered to healthy male subjects, resulting in a statistically significant erectile response at doses greater than 1.0 mg. ED patients were treated with placebo, 4 or 6 mg PT-141 in a crossover design in the presence of VSS. The erectile response induced by PT-141 was statistically significant at both doses. PT-141 was safe and well tolerated in both studies. The erectogenic potential of PT-141, its tolerability profile and its ability to cause significant erections in patients who do not have an adequate response to a PDE5 inhibitor suggest that PT-141 may provide an alternative treatment for ED with a potentially broad patient base.

Sildenafil in erectile dysfunction: a critical review

Sildenafil citrate (Viagra) is a potent orally active cGMP-specific phosphodiesterase type 5 (PDE5) inhibitor that is effective as a peripheral conditioner in the treatment of male erectile dysfunction (ED) of organic, psychogenic or mixed aetiology. Sildenafil is the first effective oral agent in the management of ED that has had a revolutionary impact on management of ED. The present review has been subdivided into five major sections. Based on the most recent peer-reviewed publications, the first section is aimed at critically evaluating PDE5 selectivity as well as the pharmacokinetics and pharmacodynamics of the drug, mainly to assess the best doses for each group of patients (i.e. adult and elderly men). Effectiveness in a broad spectrum ED population is the subject of the second section of the review, principally reporting post-marketing company-independent results. Safety and tolerability are the key concerns of the third section, with a broad consideration of the most commonly reported adverse events. Special attention has been paid to the cardiovascular safety of the drug, chiefly outlining the positive and potentially protective cardiac effects of sildenafil. Moreover, the impact of sildenafil in special patient populations is considered, namely in men complaining of diabetes mellitus, depression, neurological disorders, renal failure and those who have undergone a radical prostatectomy. Sildenafil and the ageing male has been especially underlined. Finally, the review covers a few new potential applications of sildenafil in ED patients with regard to high-dose treatment and combination therapy. The review ends with several considerations regarding the direct and/or indirect impact of sildenafil over quality of life and quality of partnership.