A Phase 4 interventional study of Tadalafil; Current on-demand PDE5 inhibitor and Tadalafil 5 mg in Erectile Dysfunction and Tadalafil, sponsored by Al-Azhar University. Recruiting at 1 site in Egypt. Open to male participants aged 18 Years to 70 Years. Per ClinicalTrials.gov, last updated 2026-09-01.
Sponsored by Al-Azhar University · Phase 4, Interventional, and Treatment
This randomized trial will compare daily tadalafil 5 mg as adjunct therapy versus monotherapy in men with on-demand PDE5 inhibitor-resistant erectile dysfunction. The study will evaluate changes in erectile function, treatment satisfaction, partner satisfaction, and safety over 12 weeks.
Erectile dysfunction (ED) is a common male sexual disorder, and oral phosphodiesterase type 5 (PDE5) inhibitors are commonly used as first-line treatment. However, some men continue to report inadequate erectile function despite appropriate on-demand PDE5 inhibitor use, adequate sexual stimulation, and dose optimization.
This prospective, randomized, parallel-group trial will evaluate whether adding an on-demand PDE5 inhibitor to daily tadalafil 5 mg provides greater improvement in erectile function than daily tadalafil 5 mg alone in men with on-demand PDE5 inhibitor-resistant ED.
Eligible participants will be men aged 21 to 70 years with ED for at least 6 months who have used an on-demand PDE5 inhibitor for at least 3 months without satisfactory improvement. Inadequate response will be confirmed by an International Index of Erectile Function-Erectile Function domain (IIEF-EF) score below 26, self-reported inability to achieve or maintain an erection sufficient for satisfactory intercourse in at least 50% of attempts, and documented appropriate medication use with adequate sexual stimulation.
Participants will be randomly assigned in a 1:1 ratio to one of two treatment groups for 12 weeks. The adjunct-therapy group will receive tadalafil 5 mg once daily together with the participant's established on-demand PDE5 inhibitor at the effective dose, taken before sexual activity according to the approved prescribing instructions and study restrictions. The monotherapy group will receive tadalafil 5 mg once daily without an additional on-demand PDE5 inhibitor.
The primary outcome will be the change in IIEF-EF score from baseline to Week 12. Secondary outcomes will include the proportion of treatment responders, Sexual Encounter Profile Question 2 success rate, Sexual Encounter Profile Question 3 success rate, Erection Hardness Score, erectile dysfunction treatment satisfaction, partner satisfaction where applicable, psychological well-being, treatment adherence, and safety.
Sexual Encounter Profile Question 2 will assess the percentage of evaluable sexual attempts during which vaginal penetration was achieved. Sexual Encounter Profile Question 3 will assess the percentage of evaluable sexual attempts during which the erection lasted long enough for successful intercourse. Participants will record these outcomes during the treatment period.
Safety assessments will include treatment-emergent adverse events, serious adverse events, treatment discontinuations because of adverse events, vital signs, and clinically relevant laboratory abnormalities. Participants will be assessed at baseline and at Weeks 4, 8, and 12.
Participants receiving nitrates, men with unstable cardiovascular disease, severe renal or hepatic impairment, uncontrolled blood pressure abnormalities, untreated hypogonadism, severe penile anatomical deformity, previous penile prosthesis, history of priapism, or other protocol-defined exclusion criteria will not be enrolled.
The study will be conducted at the Departments of Urology of Al-Hussein University Hospital and Al-Sayed Galal University Hospital, Al-Azhar University, Cairo, Egypt. The study will be conducted in accordance with the Declaration of Helsinki, Good Clinical Practice principles, and applicable regulatory requirements. Written informed consent will be obtained from every participant before any study-specific procedure.
701 studies on the registry are indexed under Erectile Dysfunction; 125 are open to participants now.
This study's planned enrollment of 260 is above the median of 70 across 551 interventional studies indexed under Erectile Dysfunction.
Browse Erectile Dysfunction studies →Al-Azhar University is the lead sponsor of 531 studies on the registry; 172 are open to participants now.
Of its 5 completed or terminated interventional studies of FDA-regulated products, 0 (0%) have results posted.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Child-Pugh class
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive tadalafil 5 mg orally once daily for 12 weeks plus their current effective on-demand PDE5 inhibitor, taken 1-2 hours before sexual activity, with a maximum of once daily.
Drug: Tadalafil; Current on-demand PDE5 inhibitor · Drug: Tadalafil 5 mg
Participants will receive tadalafil 5 mg orally once daily for 12 weeks.
Drug: Tadalafil 5 mg
Tadalafil 5 mg orally once daily for 12 weeks plus the participant's current effective on-demand PDE5 inhibitor, taken 1-2 hours before sexual activity, with a maximum of once daily.
Tadalafil 5 mg orally once daily for 12 weeks.
change in International Index of Erectile Function-Erectile Function score from baseline to week 12.
The International Index of Erectile Function-Erectile Function domain score ranges from 1 to 30, with higher scores indicating better erectile function.
Time frame: 12 weeks
Adverse effect / side effect
a harmful effect that is attributable to the intervention.
Time frame: 12 weeks
Responder rate
proportion of participants achieving International Index of Erectile Function-Erectile Function score of at least 26 or an increase of at least 5 points from baseline. A score of 26 or higher is commonly used to indicate normal erectile function, and a 5-point increase is a clinically meaningful response threshold in erectile dysfunction studies
Time frame: 12 weeks
Percentage of Sexual Attempts With Successful Intercourse - Sexual Encounter Profile Question 3
Participants will complete Sexual Encounter Profile Question 3 for each evaluable sexual attempt during the treatment period: "Did your erection last long enough for you to have successful intercourse?" The outcome will be calculated for each participant as: SEP Q3 success rate = number of sexual attempts with a "yes" response total number of evaluable sexual attempts × 100 SEP Q3 success rate= total number of evaluable sexual attempts number of sexual attempts with a "yes" response * 100 The treatment groups will be compared using the participant-level percentage of successful sexual attempts.
Time frame: 12 weeks
Percentage of Sexual Attempts With Successful Vaginal Penetration - Sexual Encounter Profile Question 2
Participants will complete Sexual Encounter Profile Question 2 (SEP Q2) for each evaluable sexual attempt during the 12-week treatment period: "Were you able to insert your penis into your partner's vagina?" For each participant, the SEP Q2 success rate will be calculated as: SEP Q2 success rate = number of sexual attempts with a "yes" response total number of evaluable sexual attempts × 100 SEP Q2 success rate= total number of evaluable sexual attempts number of sexual attempts with a "yes" response * 100 The treatment groups will be compared according to the percentage of sexual attempts resulting in successful vaginal penetration.
Time frame: 12 weeks
Erection Hardness Score
It is a patient-reported 4-point scale used to assess erection firmness, ranging from 0 to 4, with higher scores indicating firmer erections.
Time frame: 12 weeks
Erectile Dysfunction Inventory of Treatment Satisfaction.
is an 11-item patient questionnaire scored from 0 to 100, where higher scores mean greater treatment satisfaction. Each item is rated from 0 to 4, the mean item score is calculated, and then multiplied by 25 to produce the final index score.
Time frame: 12 weeks
the 7-item Generalized Anxiety Disorder scale
scored from 0 to 21, with cutoffs of 5, 10, and 15 often used for mild, moderate, and severe anxiety
Time frame: 12 weeks
partner-reported satisfaction
7 items scored 0 to 6, with a total score from 0 to 42; higher scores mean greater satisfaction
Time frame: 12 weeks
Treatment adherence
Proportion of participants adherent to treatment
Time frame: 12 weeks
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Studies of the drug tested here: Tadalafil