Effect of phosphodiesterase-type 5 inhibitors on erectile function: an overview of systematic reviews and meta-analyses

Pyroptosis and inflammation‑mediated endothelial dysfunction may act as key factors in the development of erectile dysfunction (Review)

Erectile dysfunction (ED) is a prevalent disease that causes sexual dysfunction in males. Inflammation‑induced endothelial dysfunction is a fundamental pathophysiological symptom of ED, which is impacted by cell death. Pyroptosis is a type of programmed cell death mediated by the inflammasome that was discovered in inflammatory disorders. The activation of nucleotide‑binding oligomerization domain‑like receptors, particularly downstream inflammatory factors, such as IL‑1β and IL‑18, is indicative of caspase‑dependent pyroptosis. Although the underlying mechanisms of pyroptosis have been investigated in several disorders, the role of pyroptosis in ED remains to be fully elucidated. At present, studies on pyroptosis have focused on improving the understanding of ED pathogenesis and promoting the development of novel therapeutic options. The present review article aimed to discuss the literature surrounding the mechanisms underlying pyroptosis, and summarize the role of pyroptosis in the development and progression of inflammation‑mediated ED.

Erectile Dysfunction: Treatments, Advances and New Therapeutic Strategies

Erectile dysfunction (ED) is the inability to get and maintain an adequate penile erection for satisfactory sexual intercourse. Due to its negative impacts on men's life quality and increase during aging (40% of men between 40 and 70 years), ED has always attracted researchers of different disciplines, from urology, andrology and neuropharmacology to regenerative medicine, and vascular and prosthesis implant surgery. Locally and/or centrally acting drugs are used to treat ED, e.g., phosphodiesterase 5 inhibitors (first in the list) given orally, and phentolamine, prostaglandin E1 and papaverine injected intracavernously. Preclinical data also show that dopamine D4 receptor agonists, oxytocin and α-MSH analogues may have a role in ED treatment. However, since pro-erectile drugs are given on demand and are not always efficacious, new strategies are being tested for long lasting cures of ED. These include regenerative therapies, e.g., stem cells, plasma-enriched platelets and extracorporeal shock wave treatments to cure damaged erectile tissues. Although fascinating, these therapies are laborious, expensive and not easily reproducible. This leaves old vacuum erection devices and penile prostheses as the only way to get an artificial erection and sexual intercourse with intractable ED, with penile prosthesis used only by accurately selected patients.

Erectile Dysfunction in Pelvic Cancer Survivors and Current Management Options

Pelvic malignancies, including prostate, rectal, and bladder cancers, are among the most frequent malignancies found in the male population. These issues are most effectively and commonly treated with radiotherapy and/or surgery. However, these treatments can cause collateral damage, resulting in significant impacts on quality of life, with erectile dysfunction being one of the most frequent postoperative complications. Currently, there are several treatment options for erectile dysfunction, including oral phosphodiesterase type 5 inhibitors, vacuum erection devices, intracorporeal injections, and penile prosthesis. The latter has shown to be an effective and safe technique, with results comparable to those obtained by patients without pelvic surgery or radiotherapy. The results of early penile rehabilitation programs are promising and they have been incorporated into a greater proportion of treatment plans more recently, with varying degrees of success. In this narrative review, we summarize the literature on erectile dysfunction after pelvic cancer treatments and its management.

Effect of phosphodiesterase type 5 inhibitors on major adverse cardiovascular events and overall mortality in a large nationwide cohort of men with erectile dysfunction and cardiovascular risk factors: A retrospective, observational study based on healthcare claims and national death index data

BACKGROUND

Treatment with phosphodiesterase type 5 inhibitors (PDE-5is) is effective in treating erectile dysfunction (ED).

AIM

The objective of this study was to determine the effect of PDE-5is on the incidence of major adverse cardiovascular (CV) events (MACE; composite outcome of CV death, hospitalization for myocardial infarction, coronary revascularization, stroke, heart failure, and unstable angina pectoris) and overall mortality.

METHODS

A retrospective observational cohort study was conducted in a large US claims database in men with ≥1 diagnosis of ED without prior MACE within 1 year, from January 1, 2006, to October 31, 2020. The exposed group had ≥1 claim for PDE-5i and the unexposed group had no claims for PDE-5i, and the groups were matched up to 1:4 on baseline risk variables.

OUTCOME

The primary outcome was MACE and the secondary outcomes were overall mortality and individual components of MACE, determined by multivariable Cox proportional hazard modeling.

RESULTS

Matched plus multivariable analyses showed that MACE was lower by 13% in men exposed (n = 23 816) to PDE-5is (hazard ratio [HR] 0.87; 95% CI 0.79-0.95; P = .001) vs nonexposure (n = 48 682) over mean follow-up periods of 37 and 29 months, respectively, with lower incidence of coronary revascularization (HR 0.85; 95% CI 0.73-0.98; P = .029), heart failure (HR 0.83; 95% CI 0.72-0.97; P = .016), unstable angina (HR 0.78; 95% CI 0.64-0.96; P = .021), and CV death (HR 0.61; 95% CI 0.41-0.90; P = .014) with PDE-5i exposure. Phosphodiesterase type 5 inhibitor-exposed men had a 25% lower incidence of overall mortality (HR 0.75; 95% CI 0.65-0.87; P < .001). Men without coronary artery disease (CAD) but with CV risk factors at baseline showed a similar pattern. In the main study cohort, men in the highest quartile of PDE-5i exposure had the lowest incidence of MACE (HR 0.45; 95% CI 0.37-0.54; P < .001) and overall mortality (HR 0.51; 95% CI 0.37-0.71; P < .001) vs the lowest exposure quartile. In a subgroup with baseline type 2 diabetes (n = 6503), PDE-5i exposure was associated with a lower MACE risk (HR 0.79; 95% CI 0.64-0.97; P = .022).

CLINICAL IMPLICATIONS

PDE-5is may have cardioprotective effects.

STRENGTHS AND LIMITATIONS

Strengths are the large numbers of participants and consistency of the data; limitations include the retrospective nature of the study and unknown confounders.

CONCLUSIONS

In a large population of US men with ED, PDE-5i exposure was associated with lower incidence of MACE, CV death, and overall mortality risk compared to non-exposure. Risk reduction correlated with PDE-5i exposure level.

The Effect of Combination Treatment with Low-Intensity Shockwave Therapy and Tadalafil on Mild and Mild-To-Moderate Erectile Dysfunction: A Double-Blind, Randomized, Placebo-Controlled Clinical Trial

BACKGROUND

Combination of different first-line treatments for erectile dysfunction (ED) has emerged as a promising therapeutic approach.

AIM

To conduct the first double-blind, randomized, placebo-controlled clinical trial to evaluate the efficacy and safety of combination therapy with low-intensity shockwave therapy (LiST) and tadalafil vs LiST and placebo in patients with mild or mild-to-moderate vasculogenic ED.

METHODS

Fifty sexually active patients fulfilling the eligibility criteria were randomly assigned to 6 sessions of LiST twice weekly for 3 weeks and tadalafil (n = 25) or placebo (n = 25) once daily for 4 weeks. Patients were evaluated at 1, 3, and 6 months after completion of the treatment protocol.

OUTCOMES

The primary outcome was the mean change from baseline in the International Index of Erectile Function-Erectile Function (IIEF-EF) domain between the 2 groups at 3 months after treatment. Erectile function was also assessed at 1 and 6 months. The number of patients attaining a minimal clinically important difference (MCID) in the IIEF-EF, as well as the safety of combination therapy were evaluated.

RESULTS

Adjusting for the baseline values, IIEF-EF improved by 0.8 points more (95% confidence interval [CI] = -0.2 to 1.9, P = .12) at 1 month, 1 point more (95% CI = 0.1-1.9, P = .02) at 3 months and 1.7 points more (95% CI = 0.8-2.7, P < .001) at 6 months in patients treated with combination therapy compared to monotherapy. The number of patients attaining a MCID in the IIEF-EF between the 2 groups improved significantly only at the 3-month evaluation. No adverse events were reported during the whole study period.

CLINICAL IMPLICATIONS

Combination of LiST twice weekly for 3 weeks and tadalafil 5 mg once daily for 4 weeks may further ameliorate mild or mild-to-moderate vasculogenic ED compared to LiST monotherapy.

STRENGTHS & LIMITATIONS

We conducted the first randomized trial exploring the role of LiST and tadalafil in the management of ED. Conversely, our study lacks external validity due to its single-center design.

CONCLUSION

The addition of daily low-dose tadalafil during application of LiST may further improve erectile function compared to application of LiST as a standalone treatment in patients with mild or mild-to-moderate vasculogenic ED. Still, further high-quality studies are warranted to corroborate our findings.

The Effect of Phosphodiesterase-type 5 Inhibitors on Erectile Function: An Overview of Systematic Reviews

Background: Multiple systematic reviews explore the effect of phosphodiesterase type 5 (PDE5) inhibitors on erectile dysfunction (ED), with each study addressing specific outcomes. However, physicians and policymakers require a holistic approach of this topic.

Objective: To summarize the current evidence regarding the efficacy and safety of PDE5 inhibitors for the management of ED through an overview of systematic reviews.

Methods: Studies were identified by searching PubMed, Web of Science, Cochrane Library and Scopus databases, as well as sources of grey literature until June 12, 2021 (PROSPERO: CRD42020216754). We considered systematic reviews, meta-analyses or network meta-analyses of randomized trials that provided outcomes about the efficacy and safety of any approved PDE5 inhibitor (avanafil, sildenafil, tadalafil and vardenafil). We constructed forest plots for meta-analytic effects regarding the change in erectile function, adverse events and dropouts after administration of PDE5 inhibitors in the general population and in specific patient groups.

Results: We included 23 studies with 154,796 participants and a total of 258 meta-analytic effects. Sildenafil 25 mg [Weighted Mean Difference (WMD): 13.08, 95% Confidence Interval (CI): 10.1-16.06] seemed to be statistically superior to all interventions in improving erectile function compared to placebo, but studies with low-dose sildenafil are lacking. Moreover, comparing among different PDE5 inhibitors, sildenafil 50 mg or sildenafil 100 mg were considered the most effective compounds in the general population. The latter derived, however, predominantly from indirect comparisons among different PDE5 inhibitors. Still, sildenafil 100 mg was associated with more treatment-related adverse events and dropouts. Interestingly, low-dose daily tadalafil may be more effective than high-dose on-demand tadalafil (WMD: 1.24, 95% CI: 0.03-2.44). Furthermore, testosterone and PDE5 inhibitors in patients with ED and hypogonadism seem to further improve symptoms, while the addition of a-blockers in patients with urinary symptoms treated with PDE5 inhibitors does not provide additional benefits (WMD: −0.8, 95% CI: −1.65-0.06).

Conclusion: Although the efficacy and safety of PDE5 inhibitors, compared to placebo, is well-documented, the existing evidence comparing different PDE5 inhibitors is low. Therefore, high-quality, head-to-head, trials comparing different PDE5 inhibitors are necessary to determine their ideal dosage and formulation based on their safety and efficacy profile.

Systematic Review Registration: PROSPERO, identifier [CRD42020216754].