Erectile dysfunction (ED) is the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual activity, affecting tens of millions of men worldwide and often reflecting underlying vascular, neurological, or hormonal conditions. Beyond its impact on quality of life and relationships, ED can be an early warning sign of cardiovascular disease.
What's actually going on in research
Phosphodiesterase type 5 (PDE5) inhibitors such as sildenafil and tadalafil remain first-line treatment for most men and are highly effective. Trials are exploring regenerative approaches — low-intensity shockwave therapy, platelet-rich plasma, and stem cell injections — that aim to restore natural erectile function rather than provide on-demand symptom relief. Melanocortin receptor agonists and intraurethral and topical drug delivery systems are also in active development.
Shockwave therapy
Low-intensity extracorporeal shockwave therapy applies acoustic energy to penile tissue to stimulate new blood vessel growth; trials are determining optimal dosing and which patient subgroups respond best.
Regenerative cell therapy
Platelet-rich plasma and mesenchymal stem cell injections are in trials testing whether they can repair damaged cavernous tissue and restore natural erectile capacity, potentially offering longer-lasting results than PDE5 inhibitors.
Melanocortin agonists
Bremelanotide and related melanocortin receptor agonists stimulate erections through a central nervous system pathway distinct from PDE5 inhibitors, potentially helping men who do not respond to standard oral drugs.
What to know before you search
Eligibility depends on ED severity, underlying causes such as diabetes or prior prostate surgery, and prior response to PDE5 inhibitors.
What types of trials are currently open
- Drug therapy trials — Testing new oral, topical, and intraurethral formulations beyond PDE5 inhibitors.
- Shockwave therapy trials — Evaluating low-intensity shockwave devices for vascular ED, comparing dosing schedules and patient selection.
- Regenerative therapy trials — Studying platelet-rich plasma and stem cell injections to restore natural erectile tissue function.
- Psychological and combination trials — Testing combined physical and psychological interventions, particularly for mixed-cause ED.
- Cardiovascular risk trials — Studying whether treating ED also reduces cardiovascular event risk in men with overlapping vascular risk factors.
Recently added Erectile Dysfunction trials
L-Citrulline and Tadalafil for Mild to Moderate Erectile Dysfunction
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.
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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