L-Citrulline and Tadalafil for Mild to Moderate Erectile Dysfunction

NCT07642505 | Recruiting Phase 4

• 1 other identifier: FMBSUREC-07062026g-Badawy
• Study Type: interventional
• Target: 133
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Erectile Dysfunction

Keywords

L-citrulline; Tadalafil; International Index of Erectile Function

Outcome Measures

Primary Outcomes (1)

• 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

  Baseline to 12 weeks

Secondary Outcomes (3)

• Change in International Index of Erectile Function-5 Score

  Baseline to 12 weeks

• Treatment Adherence

  From treatment initiation to 12 weeks

• Proportion of Participants Achieving Erection Hardness Score Grade 4

  12 weeks

Study Arms (3)

L-Citrulline

EXPERIMENTAL

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

Tadalafil

ACTIVE COMPARATOR

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

L-Citrulline Plus Tadalafil

EXPERIMENTAL

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

Interventions

L-Citrulline DRUG

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.

L-Citrulline; L-Citrulline Plus Tadalafil

Tadalafil DRUG

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.

L-Citrulline Plus Tadalafil; Tadalafil

L-Citrulline Placebo DRUG

Oral placebo preparation matching L-citrulline, administered for 12 weeks as part of the double-dummy design

Tadalafil

Tadalafil Placebo DRUG

Oral placebo preparation matching tadalafil, administered for 12 weeks as part of the double-dummy study design.

L-Citrulline

Eligibility Criteria

• Age: 30 Years - 70 Years
• Sex: male
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Male patients aged 30 to 70 years.
• Erectile dysfunction for at least 3 months.
• Mild to moderate erectile dysfunction, defined by International Index of Erectile Function-Erectile Function domain score from 11 to 25.
• Stable sexual relationship during the study period.
• Willingness to attempt sexual activity during the study period.
• Ability to complete study questionnaires and attend follow-up visits.
• Written informed consent.

You may not qualify if:

• Severe erectile dysfunction, defined by International Index of Erectile Function-Erectile Function domain score of 10 or less.
• Current nitrate or nicorandil use.
• Contraindication or hypersensitivity to tadalafil or L-citrulline.
• Unstable cardiovascular disease, unstable angina, recent myocardial infarction or stroke, uncontrolled hypertension, or high-risk arrhythmia.
• Severe hepatic impairment.
• Severe renal impairment.
• Untreated hypogonadism requiring hormonal treatment.
• Hyperprolactinemia or uncontrolled endocrine disorder.
• Major neurogenic erectile dysfunction, spinal cord injury, or previous radical pelvic surgery causing severe erectile dysfunction.
• Significant Peyronie's disease preventing intercourse.
• Active major psychiatric illness impairing reliable assessment.
• Use of phosphodiesterase type 5 inhibitors, intracavernosal injection therapy, vacuum device therapy, testosterone therapy, L-arginine, L-citrulline, or erectile dysfunction nutraceuticals during the washout period before randomization.
• Participation in another clinical trial during the previous 3 months.

Sponsors & Collaborators

• Beni-Suef University: lead

Study Sites (1)

Department of Urology- Beni-Suef University Hospitals

Banī Suwayf, Beni Suweif Governorate, 02456, Egypt

RECRUITING

MeSH Terms

Conditions

Erectile Dysfunction

Interventions

Citrulline; Tadalafil

Condition Hierarchy (Ancestors)

Genital Diseases, Male; Genital Diseases; Urogenital Diseases; Sexual Dysfunction, Physiological; Male Urogenital Diseases; Sexual Dysfunctions, Psychological; Mental Disorders

Intervention Hierarchy (Ancestors)

Amino Acids, Diamino; Amino Acids; Amino Acids, Peptides, and Proteins; Carbolines; Pyridines; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Indole Alkaloids; Indoles; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Heterocyclic Compounds, 3-Ring

Study Officials

• Hany F Badawy

  Faculty of medicine Beni-Suef University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Hany F Badawy, MD

CONTACT

+201149525028; HANYFATHY86@GMAIL.COM

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: The study will use a double-blind, double-dummy design when matching placebo preparations are available. Participants, care providers, investigators, and outcome assessors will be masked to treatment allocation. Active and placebo preparations of L-citrulline and tadalafil will be dispensed in coded treatment packs according to the randomization sequence.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Lecturer of Urology, Faculty of Medicine, Beni-Suef University

Model Details: Participants will be randomized in a 1:1:1 ratio to one of three parallel treatment arms: L-citrulline 1500 mg/day, tadalafil 5 mg/day, or combination therapy with L-citrulline 1500 mg/day plus tadalafil 5 mg/day. Each participant will receive the allocated oral treatment for 12 weeks, with follow-up visits at baseline, week 4, week 8, and week 12.

Study Record Dates

• First Submitted: June 8, 2026
• First Posted: June 11, 2026
• Study Start: June 8, 2026
• Primary Completion (Estimated): November 1, 2026
• Study Completion (Estimated): December 1, 2026
• Last Updated: June 12, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share

Locations

EG (1)