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NCT Number: NCT07601646

A Single-Arm, Dose Escalation of an Intraurethral Alprostadil Paste for Erectile Dysfunction

This is a single arm dose escalation trial of a mucoadhesive intraurethral polymer suspension of alprostadil (ST-04) and will investigate the efficacy of 3 dose levels of ST-04 in adult males with a clinical diagnosis of Erectile Dysfunction (ED). This study aims to determine if ST-04, with or without sildenafil, will improve erectile function (EF) compared to baseline.

Participants in this study will receive ST-04, a new formulation containing the vasodilator, alprostadil which is known to be an effective drug in treating erectile dysfunction. ST-04 will be dispersed along the urethra, forming a hydrogel which adheres to the lining of the urethra with the goal of penile tumescence and erection. Participants may receive up to 3 dose level escalations of ST-04 over a 12-week period, for a total of up to 11 administrations of ST-04. Dose escalation may also be done with and without sildenafil.

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Key information

Conditions

Erectile Dysfunction (ED) Erectile Dysfunction Erectile Dysfunctions Erectile Function Genital Diseases Genital Diseases, Male Male Urogenital Diseases Mental Disorders Sexual Dysfunction, Physiological Sexual Dysfunctions, Psychological Urogenital Diseases

Age range

21 year–75 year

Sex eligibility

Male

Study type

Interventional

Phase

Phase 2

Primary location

Vancouver Prostate Centre

Vancouver, British Columbia, V5Z1M9, Canada

Location status: Recruiting

Location contact

Genevive - Clinical Trials Coordinator

CONTACT

[email protected]

604-875-4111 ext. 67898

Ryan Flannigan, MD

PRINCIPAL_INVESTIGATOR

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Have had a confirmed clinical diagnosis of ED for more than three months based upon IIEF
  • Have failed PDE5 inhibitor therapy (inability to achieve an erection with adequate rigidity to allow penetrative sex)
  • Ability to take oral medication (sildenafil) and be willing to adhere to the study intervention regimen
  • Engaged in heterosexual relationship with partner for a minimum of 6 months

Exclusion criteria

  • History of unstable medical or psychiatric condition that, in the opinion of the principal investigator, could impact the patient's ability to complete the study investigations or protocol.
  • Spinal cord injury, or penile anatomical abnormalities
  • Cardiovascular conditions that prevent sexual activity (NYHA Class II or higher, any angina, or uncontrolled CHF or severe coronary artery disease)
  • History of myocardial infarction, stroke, or life-threatening arrhythmia within 6 months prior to enrollment into the study
  • Use of anti-androgens, or oral or injectable androgens
  • Documented hypotension or known orthostatic hypotension
  • Use of oral, topical or sublingual nitrates within 3 months prior to enrollment into the study
  • Hepatic (Child-Pugh Class C) or renal failure (eGFR < 30)
  • Inadequate response to intracavernosal injection therapy previously
  • Peyronie's disease or Meatal stenosis

Treatment and study plan

ST-04

Drug

ST-04 consists of an alprostadil polymer suspension designed for intraurethral application

Primary outcomes

  1. Change from Baseline in the Erectile Function Domain of the IIEF Questionnaire

    Time frame: From baseline to 1 month after start of the last dose level (Week 4, 8, 12 respectively)

    The IIEF is a validated questionnaire assessing erectile function, with total scores ranging from 5 to 25; higher scores indicate better erectile function

Secondary outcomes

  1. Change from Baseline in the Erectile Hardness Scale (EHS)

    Time frame: From baseline to the end of treatment at week 4, 8 or 12 respectively

    The EHS is a self-reported assessment of penile hardness on a scale of 0 (no engorgement) to 4 (complete rigidity).

  2. Change from Baseline in the Sexual Encounter Profile (SEP)

    Time frame: From baseline to the end of treatment at week 4, 8 or 12 respectively

    SEP is a log diary completed after each sexual attempt, providing information as to whether the erection was hard enough to penetrate (SEP 2), or whether it was maintained for completion (SEP 3).

  3. Percentage of Uses per Participant of ST-04 which Led to the Onset of Erection within up to 30 minutes of Application per Number of Intercourse Attempts

    Time frame: From baseline to the end of treatment at week 4, 8 or 12 respectively

    Percentage of participants using ST-04 that could achieve an erection and/or penetrative intercourse within 30 minutes of application per number of intercourse attempts.

  4. Incidence and Severity of Adverse events

    Time frame: From baseline to the end of treatment at week 4, 8 or 12 respectively

    Adverse events will be recorded at each follow-up visit and classified by type, severity, and relationship to the intervention.

Sponsors and collaborators

Lead sponsor

Ryan Flannigan, MD

Other

Registry information

Official study title

Phase 2 Clinical Trial of ST-04 Intraurethral Paste for Erectile Dysfunction

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
May 22, 2026
Registry last updated
May 22, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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