Endothelial Markers and Tadalafil Response

Endothelial Dysfunction Markers as Predictors of Clinical Response to Daily Tadalafil in Men With Vasculogenic Erectile Dysfunction

This prospective cohort study will recruit eligible men attending the Urology/Andrology outpatient clinic. Baseline assessment will include demographic and clinical data, cardiovascular risk assessment, erectile-function questionnaires, routine laboratory investigations, brachial artery flow-mediated dilatation, carotid intima-media thickness, and selected circulating endothelial biomarkers including endothelin-1, nitrite/nitrate, high-sensitivity C-reactive protein, soluble vascular cell adhesion molecule-1, and soluble intercellular adhesion molecule-1. All participants will receive tadalafil 5 mg once daily for 12 weeks. Erectile function, adherence, and adverse events will be assessed during follow-up. The primary outcome will be clinical response at 12 weeks, defined as an improvement of at least 4 points in the IIEF-EF domain together with a positive response to the Global Assessment Question.

Inclusion Criteria:

• Participants must fulfill all of the following:

  • Men aged 30 to 70 years.
  • ED lasting at least 3 months.
  • IIEF-5/SHIM score of 21 or less or clinically documented ED.
  • Clinical features suggesting predominantly vasculogenic ED.
  • Sexually active or willing to attempt sexual intercourse during the study.
  • Able to complete the study questionnaires.
  • Willing to take tadalafil 5 mg once daily for 12 weeks.
  • Able to provide written informed consent.
  • Willing to avoid other ED treatments during the study unless medically necessary.

Exclusion Criteria:

• Patients will be excluded if they have:

  • ED primarily attributed to psychogenic causes.
  • Predominantly neurogenic ED.
  • Severe untreated hypogonadism likely to be the primary cause of ED.
  • Untreated hyperprolactinemia or another major endocrine disorder.
  • Significant penile anatomical abnormality interfering with intercourse, including severe Peyronie's disease.
  • Previous radical pelvic surgery or pelvic radiotherapy.
  • Active urinary or genital infection.
  • Unstable angina or unstable cardiovascular disease.
  • Recent myocardial infarction or stroke.
  • Uncontrolled hypertension or clinically significant hypotension.
  • Severe renal impairment requiring an alternative tadalafil regimen.
  • Severe hepatic impairment.
  • Active malignancy or expected survival of less than one year.
  • Major psychiatric illness, cognitive impairment or inability to comply with follow-up.
  • Current use of another PDE5 inhibitor or intracavernosal therapy that cannot be discontinued.
  • Concomitant use of organic nitrates, nitric oxide donors or nicorandil.
  • Known hypersensitivity to tadalafil.
  • Participation in another study that may affect erectile function or vascular measurements.
  • Refusal or inability to provide informed consent.