Daily Tadalafil 5 mg Combined With On-Demand Sildenafil 100 mg for Treatment of Erectile Dysfunction in PDE-5I Non Responder Patients

February 2, 2026 updated by: Mansoura University

Daily Tadalafil 5 mg Combined With On-Demand Sildenafil 100 mg for Treatment of Erectile Dysfunction in PDE-5I Non Responder Patients: A Multicenter Randomized, Double-Blind, Placebo-Controlled Trial

The goal of this clinical trial is to evaluate whether daily dosing with tadalafil 5 mg combined with on-demand sildenafil 100 mg can improve erectile function in men with erectile dysfunction (ED) who do not respond to PDE5 inhibitor alone.

The main questions it aims to answer are:

  • Does the combination of daily tadalafil and on-demand sildenafil lead to a greater improvement in erectile function (measured by the IIEF-EF domain) compared with on-demand sildenafil alone?
  • Is the combination therapy safe and well tolerated in this patient population?

Researchers will compare:

  • Group A: Daily tadalafil 5 mg plus on-demand sildenafil 100 mg
  • Group B: Daily placebo plus on-demand sildenafil 100 mg

to determine whether the combination regimen provides superior improvement in erectile function and patient satisfaction.

Participants will:

  • Undergo baseline assessment including medical history, physical examination, and laboratory tests.
  • Be randomly assigned to one of the two treatment groups.
  • Take the assigned medications for 12 weeks.
  • Complete follow-up evaluations at 4, 8, and 12 weeks, including:

International Index of Erectile Function (IIEF-15) questionnaire Erection Hardness Score (EHS) assessment Reporting of any adverse effects

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

500

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Egypt
      • Alexandria, Egypt
        • Recruiting
        • Faculty of medicine, Alexandria University
        • Contact:
      • Aswān, Egypt
        • Recruiting
        • Faculty of medicine, Aswan university
        • Contact:
      • Asyut, Egypt
        • Recruiting
        • Faculty of Medicine - Assiut University
        • Contact:
      • Cairo, Egypt
        • Recruiting
        • Cairo University, faculty of medicine
        • Contact:
      • Cairo, Egypt
        • Recruiting
        • Faculty of Medicine, Ain Shams University
        • Contact:
      • Cairo, Egypt
        • Recruiting
        • Faculty of medicine, Azhar University
        • Contact:
      • Cairo, Egypt
        • Recruiting
        • Faculty of medicine, october 6 Univeristy
        • Contact:
      • Luxor, Egypt
        • Recruiting
        • Faculty of medicine, Luxor university
        • Contact:
      • Minya, Egypt
        • Recruiting
        • faculty of medicine, Minya University
        • Contact:
      • Tanta, Egypt
        • Recruiting
        • Faculty of medicine, Tanta University
        • Contact:
          • Maged Ragab, Professor of Urology
          • Phone Number: +201006632607
          • Email: Mmregy@gmail.com
    • Dakahlia Governorate
      • Al Mansurah, Dakahlia Governorate, Egypt
        • Recruiting
        • Urology and Nephrology center, Mansoura University
        • Contact:
          • Ahmed El-Assmy, Professor of Urology
          • Phone Number: +201227112513
          • Email: a_assmy@yahoo.com
        • Contact:
        • Principal Investigator:
          • Yahya H El-morsy, MSc of Urology

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Sexually active male.
  • History of ED for ≥6 months.
  • Erectile function domain of IIEF-15 score <17.
  • Documented failure to respond to PDE-5I [definition of non-responder patients are patients with ED who don't respond to maximum dose of PDE-5I on ≥4 occasions in spite of accurate timing and good sexual stimulation].
  • Stable sexual relationship ≥ 6 months.

Exclusion Criteria:

  • Penile anatomical deformities or Peyronie's disease.
  • Pelvic surgery or radiation.
  • Active malignancy or severe systemic illness.
  • Previous penile surgery of any kind, such as penile prosthesis, penile lengthening, penile cancer surgery, penile plication or grafting.
  • Contraindication to PDE5i (High risk cardiac patients, patients on nitrates, hypotension).
  • Using other treatments for ED e.g., Intra-cavernoasl prostaglandin injection therapy.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Group A
Daily tadalafil 5 mg and on-demand sildenafil 100 mg
Drug: Tadalafil 5 mg & Sildenafil 100mg
daily dosing of Tadalafil 5 mg combined with on demand Sildenafil 100mg
Placebo Comparator: Group B
daily Placebo and on demand sildenafil 100 mg
Drug: Sildenafil 100mg & placebo
Daily Placebo combined with on demand Sildenafil 100mg

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in International Index of Erectile Function-5 (IIEF-5) total score
Time Frame: from baseline to 12 weeks after starting treatment
The IIEF-5 is a validated 5-item questionnaire assessing erectile function, with total scores ranging from 5 to 25; higher scores indicate better erectile function.
from baseline to 12 weeks after starting treatment

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Erection Hardness Score (EHS), assessed using the validated 4-point Erection Hardness Scale
Time Frame: from baseline to 12 weeks after starting treatment
The Erection Hardness Score (EHS) is a validated 4-point scale assessing penile rigidity, with higher scores indicating better erectile hardness.
from baseline to 12 weeks after starting treatment
Change in International Index of Erectile Function (IIEF-15) total score
Time Frame: from baseline to 12 weeks after treatment
The International Index of Erectile Function (IIEF-15) is a validated 15-item questionnaire assessing erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction, with total scores ranging from 5 to 75; higher scores indicate better sexual function.
from baseline to 12 weeks after treatment
Incidence and severity of adverse events graded according to CTCAE version 5.0
Time Frame: from baseline up to 12 weeks after treatment
Adverse events will be recorded at each follow-up visit and classified by type, severity, and relationship to the intervention. Severity will be graded according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.
from baseline up to 12 weeks after treatment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Mansoura University

Collaborators

Alexandria University
Cairo University
Assiut University
Ain Shams University
Al-Azhar University
Tanta University
Minia University
October 6 University
Aswan University
Luxor university

Investigators

  • Study Chair: Ahmed A Shokeir, professor of urology, Urology & Nephrology Center, Masnoura university, Egypt

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 1, 2025

Primary Completion (Estimated)

December 1, 2026

Study Completion (Estimated)

June 1, 2027

Study Registration Dates

First Submitted

November 18, 2025

First Submitted That Met QC Criteria

February 2, 2026

First Posted (Actual)

February 6, 2026

Study Record Updates

Last Update Posted (Actual)

February 6, 2026

Last Update Submitted That Met QC Criteria

February 2, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • RP.25.09.1039

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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