A Phase 4 interventional study of L-Citrulline and Tadalafil in Erectile Dysfunction, sponsored by Beni-Suef University. Recruiting at 1 site in Egypt. Open to male participants aged 30 Years to 70 Years. Per ClinicalTrials.gov, last updated 2026-06-12.
Sponsored by Beni-Suef University · Phase 4, Interventional, and Treatment
Erectile dysfunction is a common male sexual health problem that may affect quality of life and sexual relationships. Tadalafil 5 mg once daily is an established oral treatment for erectile dysfunction. L-citrulline is an oral nitric oxide pathway supplement that may improve erectile function by increasing L-arginine availability.
This randomized trial will compare three oral treatment regimens in men with mild to moderate erectile dysfunction: L-citrulline 1500 mg/day, tadalafil 5 mg/day, and the combination of L-citrulline 1500 mg/day plus tadalafil 5 mg/day. Participants will receive treatment for 12 weeks and will be followed at baseline, week 4, week 8, and week 12.
The primary outcome will be the change in the International Index of Erectile Function-Erectile Function domain score from baseline to 12 weeks. Secondary outcomes will include changes in IIEF-5/SHIM score, Erection Hardness Score, SEP diary outcomes, treatment adherence, adverse events, and treatment discontinuation.
This is a prospective, randomized, three-arm, parallel-group, active-controlled clinical trial conducted at the Urology outpatient clinics of the Department of Urology, Faculty of Medicine, Beni-Suef University, Egypt.
Adult men with mild to moderate erectile dysfunction will be enrolled after written informed consent. Eligible participants will be randomized in a 1:1:1 ratio to receive one of three oral treatment regimens for 12 weeks: L-citrulline 1500 mg/day, tadalafil 5 mg/day, or combination therapy with L-citrulline 1500 mg/day plus tadalafil 5 mg/day.
The preferred design is double-blind and double-dummy, using active and matching placebo preparations when available. Participants will be assessed at baseline, week 4, week 8, and week 12. Baseline assessment will include medical and sexual history, review of comorbidities and medications, physical examination, relevant laboratory tests, and validated erectile function questionnaires.
The primary endpoint is change in the International Index of Erectile Function-Erectile Function domain score from baseline to 12 weeks. Secondary endpoints include change in IIEF-5/SHIM score, change in Erection Hardness Score, proportion of patients achieving Erection Hardness Score grade 4, change in affirmative SEP-3 responses, adherence, treatment-emergent adverse events, and discontinuation due to adverse events.
701 studies on the registry are indexed under Erectile Dysfunction; 125 are open to participants now.
This study's planned enrollment of 133 is above the median of 70 across 551 interventional studies indexed under Erectile Dysfunction.
Browse Erectile Dysfunction studies →Beni-Suef University is the lead sponsor of 349 studies on the registry; 125 are open to participants now.
Counted across the registry records on this site, refreshed daily.
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 reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
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.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Washout period
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants assigned to this arm will receive oral L-citrulline 1500 mg/day for 12 weeks. In the double-dummy design, participants will receive active L-citrulline plus tadalafil placebo.
Drug: L-Citrulline · Drug: Tadalafil Placebo
Participants assigned to this arm will receive oral tadalafil 5 mg once daily for 12 weeks. In the double-dummy design, participants will receive active tadalafil plus L-citrulline placebo.
Drug: Tadalafil · Drug: L-Citrulline Placebo
Participants assigned to this arm will receive combination oral therapy with L-citrulline 1500 mg/day plus tadalafil 5 mg once daily for 12 weeks.
Drug: L-Citrulline · Drug: Tadalafil
Oral L-citrulline 1500 mg/day administered for 12 weeks as an active oral nitric oxide pathway supplement for men with mild to moderate erectile dysfunction.
Oral tadalafil 5 mg once daily administered for 12 weeks as active phosphodiesterase type 5 inhibitor therapy for men with mild to moderate erectile dysfunction.
Oral placebo preparation matching L-citrulline, administered for 12 weeks as part of the double-dummy design
Oral placebo preparation matching tadalafil, administered for 12 weeks as part of the double-dummy study design.
Change in International Index of Erectile Function-Erectile Function Domain Score
Change in the International Index of Erectile Function-Erectile Function domain score from baseline to week 12. The Erectile Function domain score ranges from 1 to 30, with higher scores indicating better erectile function. A greater positive change indicates greater improvement in erectile function
Time frame: Baseline to 12 weeks
Change in International Index of Erectile Function-5 Score
Change in the International Index of Erectile Function-5 score, also known as the Sexual Health Inventory for Men score, from baseline to week 12. The score ranges from 5 to 25, with higher scores indicating better erectile function. A greater positive change indicates greater improvement.
Time frame: Baseline to 12 weeks
Treatment Adherence
Percentage of prescribed study medication doses taken during the 12-week treatment period, assessed by patient report and treatment accountability at follow-up visits. Higher percentages indicate better adherence
Time frame: From treatment initiation to 12 weeks
Proportion of Participants Achieving Erection Hardness Score Grade 4
Percentage of participants achieving Erection Hardness Score grade 4 at week 12. Grade 4 indicates that the penis is completely hard and fully rigid.
Time frame: 12 weeks
Plan to share: No — Individual participant data will not be shared because the study includes sensitive individual-level sexual health data and treatment-related clinical information. Only aggregated, de-identified results will be reported in publications or presentations. Any future sharing of de-identified participant-level data would require additional approval from the Research Ethics Committee, Faculty of Medicine, Beni-Suef University.
No publications or documents are linked to this record.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drugs tested here: Citrulline · Tadalafil