Phase 2 Randomized Controlled Trial of Sildenafil Citrate

Recruiting

18 years - 70 years

All

Phase 2

200 participants needed

1 Location

Brief description of study

We are researching whether sildenafil (or a placebo) can improve cerebrovascular reactivity (CVR) in the brain for individuals with ongoing symptoms from a brain injury. CVR is the brain's ability to adjust blood vessel size to maintain proper blood flow based on its oxygen needs. Sildenafil, commonly known as Viagra, is FDA-approved for treating erectile dysfunction and pulmonary arterial hypertension (high blood pressure in the lungs). Sildenafil works by blocking the enzyme PDE5, which helps relax blood vessels and increase blood flow.

Previous research has explored sildenafil for brain injury treatment, focusing on its ability to improve CVR. Animal studies have suggested that it might enhance memory function and recovery by increasing blood flow and reducing inflammation in the brain. However, human studies are limited, and more research is needed to confirm these effects. That’s where our research study comes in. As part of our clinical trial, we are:

· Finding the best dose of sildenafil for brain injury.

· Tracking how the medication affects chronic brain injury symptoms and overall health.

Detailed description of study

Here is what to expect if you join the study:

· There will be 3 in-person visits at the University of Pennsylvania and 2 phone check-ins.

· Visit 1 will be the screening Visit (3.5 hours): A member of our research team, like a doctor or specialist, will review your medical history to see if you qualify. Afterwards, researchers will have you complete neuropsychological (memory) tests and questionnaires about your symptoms. This visit will determine if you are a candidate for the study!

· Visit 2 will be include an MRI scan and your first dose of the study drug (3 hours): You will be randomly assigned to receive either the medication (sildenafil) or a placebo (like flipping a coin). Neither you nor the researchers will initially know which you receive. This visit will involve magnetic resonance imaging or MRI scans of your brain. MRI allows us to take very detailed pictures of your brain so we can look at things like the structure or the function of how your brain is working. For a short part of these MRI scans (about 10 minutes), you will use a special breathing mouthpiece (like a snorkel) that alternates between regular air and air with 5% carbon dioxide. Inhaling this amount of carbon dioxide for one minute can produce sensations like those experienced after holding your breath for approximately 30 seconds, including shortness of breath, dizziness, and discomfort. This helps us see how your brain blood vessels react to gas changes, helping us see how the medication (or placebo) affect blood flow. You will take your first dose of the medication at this visit in the middle of the scan and be sent home with a supply to take for 4 weeks, three times daily.

· Visit 3 will be the follow-Up visit (1.5 hours): We will repeat the memory tests and ask about side effects again.

· We will complete 2 quick Phone calls (10 minutes each) between Visit 2 and Visit 3 to see experiencing any side effects.

Eligibility of study

You may be eligible for this study if you meet the following criteria:

Conditions: Traumatic Brain Injury,TBI
Age: 18 years - 70 years
Gender: All

Traumatic Brain Injury (TBI) patients aged 18-70 who had their injury over 6 months ago and continue to experience symptoms

Updated on 05 Jan 2026. Study ID: 22-1258

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