Endothelial Markers and Tadalafil Response

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.