Efficacy and Safety of Sildenafil in Men With Sexual Dysfunction and Spinal Cord Injury

Which PDE5 inhibitor is the most effective in the treatment of erectile dysfunction in men with spinal cord injury? A systematic review and network meta-analysis

BACKGROUND

Phosphodiesterase 5 inhibitors (PDE5i) are the first-line drugs for erectile dysfunction (ED) but differences among available molecules should drive therapy personalization. Choosing one PDE5i over another is a challenge in men with spinal cord injury (SCI), as the evidence of efficacy for each molecule is derived from few studies and comparative "head-to-head" trials are lacking.

OBJECTIVE

To assess the efficacy of the different PDE5i for SCI-related ED with a network meta-analysis (NMA) approach.

MATERIALS AND METHODS

Databases from PubMed, Web of Science, Scopus, and Cochrane Library were checked for randomized controlled trials (RCTs) comparing any PDE5i to each other or placebo in men with traumatic SCI lasting ≥6 months. Data were incorporated in a random-effect NMA, where treatments' efficacy was ranked using the surface under the cumulative ranking curve (SUCRA).

RESULTS

The 10 RCTs included provided information about 1,492 men with ED due to traumatic SCI. Intervention arms included sildenafil, tadalafil, and/or vardenafil. Overall, at the pairwise meta-analysis, PDE5i were four times more effective than placebo in improving erectile function (risk ratio: 4.13, 95% CI: 2.76, 6.19). The comparative analysis from NMA revealed that tadalafil was associated with the highest SUCRA value (81%), followed by vardenafil (68%) and sildenafil (49%).

DISCUSSION AND CONCLUSION

Within the grading of comparison network, tadalafil appeared to be the best PDE5i in the treatment of SCI-related ED. Further focused studies are warranted to confirm these findings and define optimal doses and duration of therapy.

Exploring novel drug targets for erectile dysfunction through plasma proteome with genome

Background

Currently, the treatment and prevention of erectile dysfunction (ED) remain highly challenging.

Aim

This study conducted a systematic druggable genome-wide Mendelian randomization (MR) analysis to identify potential therapeutic targets for ED.

Methods

A proteome-wide MR approach was employed to investigate the causal effects of plasma proteins on ED. Subsequently, summary data-based MR (SMR) analysis was performed to identify potential drug targets for ED. Enrichment analysis and protein-protein interaction (PPI) networks revealed the functional characteristics and biological relevance of these potential therapeutic targets. Drug prediction and molecular docking studies were conducted to validate the pharmacological activity of these identified targets. Finally, a systematic MR analysis was conducted to assess upstream intervention factors, such as lifestyles and diseases, associated with these targets, providing insights for the prevention and treatment of ED.

Outcomes

This study identified several potential therapeutic targets for ED.

Results

Proteome-wide MR analysis revealed that 126 genetically predicted plasma proteins were causally associated with ED. SMR analysis indicated that TMEM9 was associated with an increased risk of ED, while MDH1, NQO1, QDPR, ARL4D, TAGLN2, and PPP1R14A were associated with a decreased risk of ED. These potential targets were primarily enriched in metabolic and redox-related biological processes. Molecular docking indicated that the predicted drugs had favorable binding affinities with the proteins, further confirming the pharmacological value of these targets. Finally, 6 plasma proteins (MDH1, NQO1, QDPR, ARL4D, TAGLN2, and TMEM9) could be modulated by lifestyle- and disease-related factors.

Clinical Implications

This study provides new insights into the etiology and potential drug targets of ED and contributes to the development of more effective treatments for ED and reducing the cost of drug development.

Strengths and Limitations

This is a systematic and extensive study exploring the causal relationship between plasma proteins and ED, which helps to provide a comprehensive perspective to understand the role of potential targets in ED. However, we did not conduct this study in different types of ED or different stages of ED progression.

Conclusion

In summary, this study identified 7 plasma proteins causally associated with ED and provided new insights into the etiology and potential drug targets for ED.

Infection rate of penile prosthesis implants in men with spinal cord injury: a meta-analysis of available evidence

The risk of penile prosthesis implants (PPIs) infection in men with spinal cord injury (SCI), empirically theorized to be high, is widely variable among the studies. We performed a meta-analysis to define the pooled PPI infection rate and its possible risk factors in men with SCI. A thorough search of PubMed, Scopus and Web of Science was performed. The eighteen included studies provided information on 1079 implantation procedures, determining a pooled PPI infection rate of 8.0% (95% CI: 5.0-11.0%), with significant heterogeneity (I² = 67.0%). Trim-and-fill adjustment for publication bias had a small effect on the pooled estimate (adjusted odds ratio: 6.3%, 95% CI: 2.5-10.0%) with a substantial reduction in heterogeneity (I2 = 32.4%). The PPI infection rate was higher for inflatable PPIs than for malleable PPIs (16.4% vs 8.9%, p = 0.027). No differences were found between the different levels of SCI. In conclusion, the risk of PPI infection in SCI would be higher than that reported in the general population. However, the results were produced from dated and low/moderate quality studies that may not fully reflect the outcomes of modern PPIs and implantation protocols. There is an urgent need to gather more information on this topic through studies relevant to contemporary practice.

Dyadic adjustment and the relationship between sexual self-consciousness and sexual dysfunction in individuals with spinal cord injuries: A descriptive study

PURPOSE

This study was conducted to determine the dyadic adjustment between individuals with SCI and their spouses and the relationship between their sexual self-consciousness and sexual life and to evaluate it according to the objectification theory.

METHOD

This descriptive and cross-sectional study was conducted with 131 married individuals with SCI registered in the physical therapy and rehabilitation outpatient clinic of a university hospital between February 2020 and April 2021. The data of the study were collected using a Descriptive Information Form, the American Spinal Injury Association Impairment Scale (ASIA), the Dyadic Adjustment Scale (DAS), the Sexual Self-Consciousness Scale (SSCS), and the Arizona Sexual Experiences Scale (ASEX). In the study, the predictors of the sexual life of individuals with SCI were evaluated with the Stepwise Multiple Linear Regression analysis. In addition, predictors of sexual dysfunction in individuals with SCI were evaluated by the logistic regression analysis. The results were discussed within the framework of objectification theory.

RESULTS

According to the results of the study, .67.2% of the individuals with spinal cord injuries experienced sexual functionality problems; increased age, falling injuries, and being in ASIA grade A increased sexual self-awareness and sexual dysfunction; and being a male with SCI increased sexual focus. It was found that the adjustment between individuals with SCI and their spouses was a predictor that significantly reduced sexual embarrassment, sexual self-consciousness, and sexual dysfunction and that the strong adjustment between couples was an important factor for the prevention of sexual dysfunction development.

CONCLUSION

It was found that most individuals with spinal cord injuries experienced sexual dysfunction. The importance of dyadic adjustment and sexual self-consciousness has come to the fore in the sexual life of these individuals.

Oral phosphodiesterase type 5 inhibitors and male reproductive potential: an overview

BACKGROUND

Phosphodiesterase type 5 inhibitors (PDE5Is), due to their efficacy and tolerable profile for more than 2 decades,are considered a good addition to the available treatments in patients with erectile dysfunction (ED).

AIM

We sought to assess the possible influence of oral PDE5Is on male human reproduction.

METHODS

A literature review was performed in several databases, including the PubMed/Medline database, Scopus, Cochrane Library, EMBASE, Academic Search Complete, and Egyptian Knowledge Bank databases. The keywords/search terms were "PDE5Is," "sildenafil," "vardenafil," "tadalafil," or "avanafil," combining and crossing them with "male infertility," "semen," "reproductive hormones," or "sperm."

RESULTS

Overall, 101 articles were selected. After removal of duplicates and animal studies, 75 articles were finally subjected to review covering the different items related to male human reproduction, including effects of PDE5Is on different parameters of semen or reproductive hormones, as uses of PDE5Is in cases related to distinctive male factor infertility, such as ED, temporary ED, or ejaculatory failure alongside assisted reproduction (AR) procedures, and ejaculatory dysfunction in spinal cord lesions. We found 26 articles that addressed the direct effects of PDE5Is on semen and reproductive hormonal profiles, 16 in vivo studies and 10 in vitro studies. Oral PDE5Is have in general a stimulatory effect on sperm motility, while other semen parameters and reproductive hormonal profiles showed varied outcomes. Such effects are more pronounced with a long-term daily regimen than with an on-demand regimen. However, it seems that the best-controlled studies suggested no change in the sperm quality of male reproductive potential.

CONCLUSION

Oral PDE5Is have in general stimulatory effects on sperm motility, while other semen parameters and hormone profiles showed varied results. In addition, oral PDE5Is have played a useful role in conditions related to distinctive male factor infertility, such as ED, temporary ED, ejaculatory failure alongside AR, and ejaculatory dysfunction in spinal cord lesions.

Sexual Dysfunction Among Adolescent and Young Adult Men Diagnosed with Cancer

Purpose: Adolescent and young adult (AYA) cancer patients frequently demonstrate sexual dysfunction; however, there is a lack of data quantifying the severity and frequency. Methods: Males aged 18-39 years, diagnosed with cancer of any kind and who were scheduled to begin, were actively receiving, or had completed cancer treatment within 6 months, were offered validated surveys during their oncology appointment. These surveys included the International Index of Erectile Function (IIEF-6), Masturbation Erection Index (MEI), 36-Item Short Form Survey, and 5-point Likert scales to assess their desire and ability to engage in sex and masturbation. Results: Forty subjects completed the IIEF survey with a mean score of 17.7 ± 11, erectile dysfunction (ED) prevalence accordingly was 58%. Thirty-eight subjects completed the MEI with a mean score of 25.3 ± 5.3, ED prevalence was again 58%. Age and IIEF scores demonstrated a statistically significant (p < 0.05, n = 38) Pearson's correlation coefficient of 0.40, patients younger than 30 years had an ED prevalence of 72% (mean IIEF 13), whereas patients aged 30 years and older had an ED prevalence of 45% (mean IIEF 22). All treatment modalities had ED rates >30%: chemotherapy demonstrated the highest prevalence at 64% (mean IIEF 17), whereas radiation therapy had the lowest prevalence at 33% (mean IIEF 23). Conclusion: This study demonstrates that the prevalence of sexual dysfunction among male AYA patients undergoing treatment for cancer is high. AYA oncologists should discuss potential sexual health concerns when treating this population. The exact cause of ED (non-organic vs. organic) within this group should be explored further.

Efficacy of Yougui pill combined with Buzhong Yiqi decoction in alleviating the sexual dysfunction in female rats through modulation of the gut microbiota

CONTEXT

Yougui pill combined with Buzhong Yiqi decoction (YPBYD) is used to relieve sexual dysfunction in clinical practice.

OBJECTIVE

To investigate changes in microbial composition caused by sexual dysfunction and identify dominant bacteria related to YPBYD treatment.

MATERIALS AND METHODS

Female Sprague-Dawley rats were randomly divided into four groups (n = 6): one group underwent Sham operation (Sham group), while three groups underwent ovariectomy (one model and two treatment groups). The ovariectomized (OVX) rats received oestradiol benzoate (250 µg/kg/week) or YPBYD (3.6 mL/d) via oral gavage for 4 weeks. Vaginal smear assay was performed; the serum levels of cyclic adenosine monophosphate (cAMP) and oestradiol (E2) were measured, followed by collection of stool samples for 16S rRNA sequencing.

RESULTS

After YPBYD treatment, the levels of E2 and cAMP in OVX rats significantly increased (E2: from 20.45 ± 1.60 ng/L to 24.38 ± 1.70 ng/L; cAMP: from 261.41 ± 9.21 pg/mL to 373.75 ± 17.37 pg/mL). OVX treatment decreased diversity of gut microbiota and YPBYD treatment restored gut microbiota composition. Compared with Sham group, the abundance of Romboutsia significantly increased, while those of Proteobacteria and Staphylococcus markedly decreased in OVX group (all p < 0.05); meanwhile, the abundance of these microbes showed an opposite trend after YPBYD treatment. These microbiotas were involved in tyrosine and tryptophan biosynthesis and fatty acid metabolism.

DISCUSSION AND CONCLUSIONS

These findings are the first to indicate YPBYD can alleviate female sexual dysfunction by modulating gut microbiota in OVX rats, which will help enhance the understanding on potential mechanism of YPBYD against sexual dysfunction.

Sexuality, Intimacy, and Reproductive Health after Spinal Cord Injury

Spinal cord injury (SCI) is a life-altering event often accompanied by a host of anxiety-provoking questions and concerns in the minds of affected individuals. Questions regarding the ability to resume sexual activity, partner's satisfaction as well as the ability to have biological children are just a few of the unknowns facing patients following the devastating reality that is SCI. As a result of advances in SCI research over the last few decades, providers now have the knowledge and tools to address many of these concerns in an evidence-based and patient-centered approach. SCI can impair multiple components involved in sexual function, including libido, achieving and maintaining an erection, ejaculation, and orgasm. Many safe and effective fertility treatments are available to couples affected by SCI. Finally, learning to redefine one's self-image, reinforce confidence and self-esteem, and feel comfortable communicating are equally as important as understanding functionality in regaining quality of life after SCI. Thus, this review aims to highlight the current state of SCI research relating to sexual function, reproductive health, and the search for meaning.

Safety, tolerability, and pharmacokinetics of the novel pan-phosphodiesterase inhibitor ZSP1601 in healthy subjects: a double-blinded, placebo-controlled first-in-human single-dose and multiple-dose escalation and food effect study

Background: The pharmacokinetics (PK), safety, and tolerability profiles of ZSP1601, a first-in-class pan-phosphodiesterase (PDE) inhibitor, were evaluated in healthy Chinese volunteers.Research design and methods: This Phase 1a study consisted of a double-blinded, randomized, placebo-controlled single ascending dose (SAD) (25 to 350 mg), multiple ascending doses (MAD) (50 or 100 mg QD), and a two-period crossover food effect study (100 mg).Results: ZSP1601 was quickly absorbed, with maximum plasma concentrations (C_max) reached at 1.25 to 2.50 h (median T_max). The exposures exhibited dose-proportional increases, while the mean half-life (t1/2) ranged from 6.34-8.64 h. Steady-state was reached within seven days in the MAD study. The mean steady trough concentrations were 423 and 588 ng/mL, respectively. ZSP1601 accumulation was low, with ratios ≤ 1.5. The bioavailability of ZSP1601 was equivalent under fasted and fed states. All adverse events (AEs) were assessed as mild or moderate, with headaches as the most common. The highest single doses (275 and 350 mg) yielded more AEs, yet the rates were similar with the placebo cohorts in the MAD study.Conclusions: The safety and PK profiles of ZSP1601 support further efficacy evaluation in nonalcoholic steatohepatitis patients.Trial registration: The trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT03392779).

Erectile dysfunction in common neurological conditions: A narrative review

Neurogenic erectile dysfunction (NED) can be defined as the inability to achieve or maintain an erection due to central or peripheral neurologic disease. Neurologic diseases can also affect the physical ability and psychological status of the patient. All these factors may lead to a primary or secondary NED. Medication history plays an important role since there are many drugs commonly used in neurologic patients that can lead to ED. The assessment of NED in these patients is generally evolving with the application of evoked potentials technology in the test of somatic and autonomic nerves, and functional magnetic resonance imaging. With the electrophysiological examinations, neurogenic causes can be determined. These tools allow to categorize neurologic lesion and assess the patient prognosis. The first-line treatment for NED is phosphodiesterase inhibitors. Second-line treatments include intracavernous and intraurethral vasoactive injections. Third-line treatments are penile prostheses. The efficacy and safety of each treatment modality depend on the specific neurologic condition. This review discusses the physiology, pathophysiology, diagnosis, and treatment of ED in multiple peripheral and central neurologic conditions, as well as for future research.

Performance and safety of treatment options for erectile dysfunction in patients with spinal cord injury: A review of the literature

BACKGROUND

For a large proportion of patients with spinal cord injury, sexuality and reproduction are important issues. However, sparse data exist regarding available treatment options for this patient population.

OBJECTIVES

We sought to review performance and safety rates of all currently available treatment options for erectile dysfunction in spinal cord injury men.

MATERIALS AND METHODS

A systematic literature review without time restrictions was performed using PubMed/EMBASE database for English-, Italian-, German-, and Spanish-language articles. Articles' selection was performed according to the PRISMA guidelines. Relevant papers on erectile dysfunction in spinal cord injury patients were included in the final analyses.

RESULTS AND DISCUSSION

Overall, 47 studies were eligible for inclusion in this review. Of these, most evidence dealt with phosphodiesterase 5-inhibitors and intracavernous drug injection. Both treatment options are associated with high levels of performance and with patients/partners' satisfaction; side effects are acceptable. Overall, penile prostheses and vacuum erection devices are in general less approved by spinal cord injury patients and are correlated with increased rates of complications in comparison with phosphodiesterase 5-inhibitors and intracavernous drug injection. Sacral neuromodulation, transcutaneous electrical nerve stimulation, and intraurethral suppositories have been poorly studied, but preliminary studies did not show convincing results.

CONCLUSION

The best treatment options for erectile dysfunction in spinal cord injury patients emerged to be phosphodiesterase 5-inhibitors and intracavernous drug injection. The choice of erectile dysfunction treatment should be based on several aspects, including residual erectile function, spinal cord injury location, and patients' comorbidities. Future studies assessing the applicability of less well-studied treatments, as well as evaluating innovative options, are needed in this specific population.

The Serendipitous Story of Sildenafil: An Unexpected Oral Therapy for Erectile Dysfunction

INTRODUCTION

The serendipitous discovery of sildenafil (Viagra [sildenafil citrate]) as a treatment for erectile dysfunction (ED) is one of the most fascinating drug development stories of our time. When sildenafil was approved by the U.S. Food and Drug Administration in 1998, it revolutionized the treatment protocol for men with ED, once considered a psychological issue or an inevitable part of aging.

AIM

To review the discovery of sildenafil and its role in changing the field of sexual medicine in the context of the epidemiology and history of treatment for ED.

METHODS

For this narrative review, a literature search was conducted to identify essential articles and was supplemented by author observations from a historical perspective.

MAIN OUTCOME MEASURE

A broad overview of ED and its past, current, and future treatments.

RESULTS

ED is a prevalent condition for which medical treatment had been limited to genitally localized interventions, including surgery, vacuum pumps, injectable therapies, and intraurethral suppositories. The discovery of sildenafil provided a safe, oral pharmacotherapy for the treatment of ED, sparking greater understanding of the science behind ED and its role in men's overall health.

CONCLUSION

The approval of sildenafil initiated a global conversation about ED that had profound implications for patients, methods of clinical practice, and academic sexual medicine. These changes will catalyze continued advances in ED treatment. Goldstein I, Burnett AL, Rosen RC, et al. The serendipitous story of sildenafil: an unexpected oral therapy for erectile dysfunction. Sex Med Rev 2019;7:115-128.

Management of Erectile Dysfunction and Infertility in the Male Spinal Cord Injury Patient

PURPOSE OF REVIEW

Men with spinal cord injury (SCI) commonly suffer from erectile dysfunction and ejaculatory dysfunction. The literature regarding the causes and treatment of these two important problems was reviewed.

RECENT FINDINGS

Many of the erectile dysfunction treatments applied to able bodied individuals are also useful in the SCI population, although there are differences in the goals and results of treatment. Ejaculatory dysfunction can be treated with either penile vibratory stimulation or electroejaculation with high success rates. Pregnancies are possible, but poor quality sperm quality in male SCI patients leads to pregnancy rates lower than is observed in the able-bodied population. Although effective treatments are available for erectile and ejaculatory dysfunction in men with SCIs, many challenges remain in optimizing the treatment of these individuals.

Update on the Safety of Phosphodiesterase Type 5 Inhibitors for the Treatment of Erectile Dysfunction

INTRODUCTION

Phosphodiesterase type 5 inhibitors (PDE5Is) have demonstrated efficacy in the treatment of erectile dysfunction (ED). Although historically found to have limited drug-related adverse events, emerging data have suggested that PDE5Is might be associated with melanoma or recurrence of prostate cancer after radical prostatectomy.

AIM

To summarize the literature on the safety of PDE5Is.

METHODS

A literature review was performed through PubMed from 1990 through 2016 regarding ED. Keywords used for the search were erectile dysfunction, phosphodiesterase type 5 inhibitors, sildenafil, vardenafil, tadalafil, avanafil, safety, side effects, and adverse events, among others.

MAIN OUTCOME MEASURES

Visual, auditory, cardiovascular, renal, hepatic, priapic, and oncologic outcomes associated with the intake of PDE5Is for the treatment of ED, in addition to drug interactions, abuse, overdose, and the phenomenon of counterfeit medications.

RESULTS

PDE5Is are safe drugs for the management of ED. Although recent studies have shown an increased risk of non-arteritic ischemic optic neuropathy with PDE5Is, the magnitude of that risk is small. The possibility that PDE5Is cause sensorineural hearing loss remains uncertain. PDE5Is display a safe cardiovascular profile if used according to the Princeton III Consensus guidelines. There appears to be an association between PDE5I use and melanoma but the absence of a mechanism of causation raises doubt that the association is cause and effect. PDE5Is do not increase the risk of biochemical recurrence after prostate cancer management. PDE5I abuse and use of counterfeit medications present serious global health concerns.

CONCLUSION

Current data strongly support the efficacy, tolerability, and overall safety of PDE5Is for the treatment of ED. PDE5Is probably cause a small increase in the risk of non-arteritic ischemic optic neuropathy. Evidence on increased rates of melanoma and prostate cancer recurrence is weak and controversial. PDE5Is should still be considered first-line therapy for the treatment of most etiologies of ED. Yafi FA, Sharlip ID, Becher EF. Update on the Safety of Phosphodiesterase Type 5 Inhibitors for the Treatment of Erectile Dysfunction. Sex Med Rev 2018;6:242-252.

Erectile Dysfunction in Young Men-A Review of the Prevalence and Risk Factors

INTRODUCTION

Erectile dysfunction (ED) is an important health concern that can significantly affect a man's psychosocial well-being. ED has traditionally been considered a disease of old age; however, contemporary evidence suggests a growing incidence of ED in men younger than 40 years. The process of achieving an erection is multifaceted; there are many potential mechanisms that can be disrupted. It is critical to identify the specific causes of ED before proceeding with potentially costly and invasive therapeutic options. Advances in diagnostic and treatment modalities offer opportunities to identify and manage young men with ED.

AIM

To provide an update on the prevalence and risk factors of ED in young men and to provide a framework to guide clinicians in identifying and managing the affected young man.

METHODS

Comprehensive review of the literature pertaining to ED in young men.

MAIN OUTCOME MEASURES

ED in young men was assessed by outlining the prevalence according to recent epidemiologic studies. The pathophysiology, diagnostic considerations, risk factors, and etiologies were reviewed.

RESULTS

Large multinational studies have estimated the prevalence of ED in young men to be as high as 30%. Several studies have stratified the etiologies of ED into psychogenic and organic causes. Psychogenic etiologies of ED include depression, anxiety, and partner-related difficulties. These patients tend to experience sudden onset of symptoms, with decreased libido and good quality of spontaneous or self-stimulated erections. Organic etiologies include vasculogenic, endocrinologic, neurogenic, iatrogenic, and structural components. These patients usually experience gradual onset of symptoms and a low to normal libido. Conservative treatments such as phosphodiesterase type 5 inhibitors continue to be the mainstay treatment.

CONCLUSIONS

ED in young men is an increasingly common condition. A careful diagnostic evaluation should focus on the identification of any underlying etiology to ensure appropriate management of patients. Nguyen HMT, Gabrielson AT, Hellstrom WJG. Erectile Dysfunction in Young Men-A Review of the Prevalence and Risk Factors. Sex Med Rev 2017;5:508-520.