Erectile Dysfunction in Railway Station Workers With Hypertension

A Unique Patient Population

Erectile dysfunction is common among men with hypertension. The shared pathophysiology includes endothelial dysfunction, reduced nitric oxide bioavailability, and impaired vasodilation. However, not all patients with hypertension and ED respond equally to standard treatments.

Some professions carry additional risks. Locomotive engineers and their assistants face a combination of occupational hazards: chronic stress from operating heavy machinery, irregular sleep schedules, shift work, long periods of sitting, and limited opportunities for physical activity. These factors independently contribute to both hypertension and erectile dysfunction.

The railway hospital in Barnaul, Russia, identified this problem in their patient population. Men working as machinists or assistant drivers frequently presented with symptoms of ED alongside their diagnosed hypertension. The question facing clinicians was whether standard ED treatments (PDE5 inhibitors) were sufficient, or whether additional therapies targeting the underlying endothelial dysfunction would provide better outcomes.

Arkhipova and colleagues (2025) conducted a randomized study to answer this question. Their trial compared three approaches: an endogenous NO-synthase activator alone, a combination of NO-synthase activator and PDE5 inhibitor, and no specific ED treatment. The full text is available here: randomized study by Arkhipova and colleagues (2025)

Study Design

The investigators enrolled consecutive patients from the railway hospital in Barnaul. All participants met the following criteria: age 30 to 60 years, diagnosed arterial hypertension, and current employment as a locomotive engineer or assistant driver. All patients with symptoms of erectile dysfunction were eligible.

A total of 85 men were enrolled. Sixty-five had symptoms of ED and were randomized into three groups. Twenty men without ED served as a control group.

Group 1 (NOS activator alone) received an endogenous nitric oxide-synthase activator as monotherapy for ED. The NOS activator is designed to provide substrate or cofactors to enhance the body’s own production of nitric oxide, a key signaling molecule for vasodilation and erection.

Group 2 (combination therapy) received both the NOS activator and a phosphodiesterase type 5 inhibitor (PDE5 inhibitor). This combination aimed to address both the production of NO (via NOS activation) and the signaling downstream (via PDE5 inhibition).

Group 3 (no ED treatment) received neither NOS activator nor PDE5i. These patients continued their antihypertensive medications as needed but received no specific therapy for erectile dysfunction.

Control group consisted of 20 men without ED (confirmed by normal IIEF scores) who were observed for comparison of biomarker values.

All patients with hypertension continued appropriate antihypertensive therapy throughout the study period. The investigators performed follow-up assessments at two months and four months after treatment initiation.

Outcome Measures

The study measured several outcomes to capture both biological and functional aspects of erectile dysfunction.

Biomarkers. Endothelin-1 (ET-1) is a potent vasoconstrictor; elevated levels indicate endothelial dysfunction. High-sensitivity C-reactive protein (hs-CRP) measures systemic inflammation. Both are elevated in men with hypertension and ED and are associated with poorer treatment responses.

Microhemodynamics. Laser Doppler flowmetry (LDF) assessed peripheral microcirculation, including mean blood flow and ischemic manifestations. This technique measures real-time blood flow in small vessels, reflecting endothelial function in the microvasculature.

Sexual function questionnaires. The International Index of Erectile Function (IIEF) and the International Consultation on Incontinence Questionnaire for erectile function (ICF) assessed patient-reported erectile function and sexual satisfaction.

Results: Changes in Biomarkers and Microcirculation

The trajectory of improvement differed markedly among the three treatment groups.

Group 3 (no ED treatment). As expected, patients who received no specific therapy for ED showed no significant changes in ET-1, hs-CRP, or LDF parameters at either two or four months. Their biomarkers remained elevated compared to the control group.

Group 1 (NOS activator alone). At two months, there were no significant changes in biomarkers or LDF values. The NOS activator required more time to exert measurable effects. By four months, however, improvements appeared. Mean blood flow increased, and hs-CRP returned to reference levels. Endothelin-1 improved but did not fully normalize. This delayed response suggests that enhancing endogenous NO production takes time to reverse established endothelial dysfunction.

Group 2 (NOS activator + PDE5 inhibitor) showed the most rapid and complete improvement. At two months, both ET-1 and hs-CRP had returned to reference levels. Ischemic manifestations on LDF decreased significantly. At four months, microhemodynamics continued to improve, and biomarker values remained normal. The combination therapy produced faster and more comprehensive endothelial repair than NOS activation alone.

Summary of Treatment Effects at 4 Months

Results: Sexual Function Outcomes

The functional outcomes mirrored the biomarker and microcirculation findings. Patients in Group 2 (combination therapy) achieved the highest IIEF and ICF total scores at both two and four months. The improvement was clinically significant – men in this group reported better erections, greater satisfaction, and improved sexual confidence compared to both Group 1 and Group 3.

Group 1 patients also improved, but the effect was delayed. At two months, their IIEF scores were not significantly different from baseline. By four months, they showed moderate improvement better than Group 3 but inferior to Group 2.

Group 3 patients, who received no ED-specific treatment, showed minimal or no improvement in sexual function over the four-month study period.

Two Key Takeaways from the Arkhipova Trial

• Combination therapy with an NO-synthase activator and a PDE5 inhibitor is more effective than either monotherapy or no treatment for erectile dysfunction in hypertensive men with occupational stress. The combination group showed faster biomarker normalization (ET-1 and hs-CRP by 2 months), better microcirculation, and higher IIEF/ICF scores compared to both the NOS activator alone group and the untreated group.
• Monotherapy with an NO-synthase activator alone has a delayed and partial effect. At 2 months, there were no significant improvements in biomarkers or microcirculation. By 4 months, hs-CRP normalized and mean blood flow increased, but ET-1 remained only partially improved. This suggests that while NOS activation helps, it works more slowly and less completely than combination therapy.

Limitations of the Study

The Arkhipova trial addresses an important clinical question, but it has several limitations that readers should understand when interpreting the results.

Biological Mechanism: Why Combination Therapy Works Better

The superiority of combination therapy over NOS activator alone has a plausible biological explanation rooted in the nitric oxide signaling pathway.

Under normal conditions, endothelial cells produce nitric oxide (NO) from L-arginine via the enzyme nitric oxide synthase (NOS). NO diffuses to adjacent smooth muscle cells in blood vessel walls, activates guanylyl cyclase, increases cyclic GMP (cGMP) production, and causes smooth muscle relaxation. This relaxation allows increased blood flow including blood flow into the corpora cavernosa of the penis, which produces an erection.

In men with hypertension and chronic stress, several abnormalities occur. First, endothelial dysfunction reduces NOS activity, decreasing NO production. Second, oxidative stress degrades NO more rapidly. Third, increased sympathetic tone causes vasoconstriction. Fourth, inflammation (elevated hs-CRP) further impairs endothelial function. The result is both systemic vascular dysfunction and erectile dysfunction.

An NO-synthase activator addresses only the first problem it provides substrate or cofactors to enhance residual NOS activity. However, if the endothelium is severely damaged, even maximal NOS activation may not produce enough NO. Additionally, in men taking antihypertensive medications, some agents may affect NO signaling.

A PDE5 inhibitor works downstream of NO. It blocks the enzyme that degrades cGMP, effectively amplifying whatever NO signal is present. Even if NO production is reduced, a PDE5 inhibitor can make the existing NO more effective.

The combination, therefore, attacks the problem from both ends. The NOS activator increases NO production. The PDE5 inhibitor magnifies the effect of the NO that is produced. This synergy explains why the combination group normalized biomarkers faster (2 months versus 4 months) and achieved better functional outcomes than the NOS activator alone group.

Comparison with Previous Research

The findings of the Arkhipova trial align with and extend previous work in this specific population and in related models.

Previous railway worker studies. Neimark and colleagues (2011) studied the use of “zidena” (likely sildenafil, a PDE5 inhibitor) in locomotive workers with stress-induced hypertension. They reported improvements in erectile function but did not compare combination therapy to NOS activation alone. The current study adds the comparison with NOS activator monotherapy and combination therapy, showing that adding the NOS activator provides additional benefit.

Animal models of NOS inhibition. Gur and colleagues (2010) demonstrated that chronic inhibition of NOS in rats induces both hypertension and erectile dysfunction. Importantly, they found that sildenafil alone could not reverse the ED caused by NOS inhibition. This supports the concept that when NO production is severely impaired, PDE5 inhibitors alone may be insufficient some degree of NOS function must be restored. The current study’s finding that NOS activator monotherapy took 4 months to show effect, while combination therapy worked faster, is consistent with this animal data.

Role of inflammation. The normalization of hs-CRP in both treatment groups (by 4 months for Group 1, by 2 months for Group 2) suggests that improving NO signaling reduces systemic inflammation. This is clinically important because elevated hs-CRP is not just a marker of endothelial dysfunction but also a predictor of cardiovascular events. The improvement in hs-CRP may have benefits beyond erectile function.

Comparison with standard ED treatment guidelines. Current guidelines (European Association of Urology, American Urological Association) recommend PDE5 inhibitors as first-line therapy for ED, with no specific recommendation for NOS activators. This study suggests that in a specific subgroup men with hypertension and occupational stress adding a NOS activator may provide additional benefit. However, given the limitations of small sample size and lack of placebo control, these findings should be considered hypothesis-generating rather than practice-changing at this time.

Clinical Application

For clinicians treating men with hypertension and erectile dysfunction, particularly those in high-stress occupations, the Arkhipova trial offers several practical insights.

First, standard PDE5 inhibitor monotherapy is effective and remains appropriate first-line treatment. The trial did not include a PDE5 inhibitor alone group (Group 2 added NOS activator to PDE5 inhibitor, while Group 3 had no ED treatment), so direct comparison of PDE5 inhibitor alone versus combination is not available from this study.

Second, for patients who do not respond adequately to PDE5 inhibitor monotherapy, adding an NO-synthase activator may provide additional benefit, particularly if there is evidence of endothelial dysfunction (elevated ET-1 or hs-CRP). The delayed response to NOS activator alone (no effect at 2 months, partial effect at 4 months) suggests that clinicians and patients need patience when using this approach.

Third, the biomarker improvements (ET-1 and hs-CRP normalization) suggest that combination therapy may have cardiovascular benefits beyond erectile function. While this was not a cardiovascular outcomes trial, reducing these markers is generally considered beneficial for long-term vascular health.

At Adult & Pediatric Urology (APUMN), we consider the findings of this trial when evaluating patients with hypertension and occupational stress who present with erectile dysfunction. For patients who have suboptimal responses to PDE5 inhibitor monotherapy or who have evidence of significant endothelial dysfunction (elevated inflammatory markers, poor microcirculation on clinical examination), we discuss the potential role of adding an NO-synthase activator. We also emphasize that lifestyle modifications stress reduction, improved sleep hygiene, regular physical activity remain essential components of treatment in this population, as they address the underlying occupational and behavioral contributors to both hypertension and ED.

Author

Jerome P. Keating, M.D