CLINICAL TRIALS PROFILE FOR VIAGRA

All Clinical Trials for Viagra

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00056433 ↗	Evaluation of Hydroxyurea Plus L-arginine or Sildenafil to Treat Sickle Cell Anemia	Completed	National Institutes of Health Clinical Center (CC)	Phase 1	2003-03-10	Patients with sickle cell disease have abnormal hemoglobin (the protein in red blood cells that carries oxygen to the body). This abnormality causes red blood cells to take on a sickle shape, producing disease symptoms. Fetal hemoglobin, a type of hemoglobin present in fetuses and babies, can prevent red cells from sickling. The drug hydroxyurea increases fetal hemoglobin production in patients with sickle cell disease by making a molecule called nitric oxide. The drugs L-arginine and Sildenafil (Viagra) increase the amount or the effect of nitric oxide. This study will evaluate: - The safety of giving L-arginine or Sildenafil together with hydroxyurea in patients with sickle cell disease; - The effectiveness of L-arginine plus hydroxyurea or Sildenafil plus hydroxyurea in increasing fetal hemoglobin in patients with sickle cell disease; and - The effectiveness of L-arginine plus hydroxyurea or Sildenafil and hydroxyurea in lowering blood pressure in the lungs of patients with sickle cell disease. (Pulmonary blood pressure is elevated in about one-third of patients with sickle cell disease, and this condition increases the risk of dying from the disease.) Patients with hemoglobin S-only, S-beta-thalassemia, or other sickle cell disease genotype may be eligible for this study. Before starting treatment, patients will have a complete medical history and physical examination. All patients will take hydroxyurea once a day every day by mouth for at least 2 months. They will be admitted to the NIH Clinical Center to take their first dose of hydroxyurea, and will have blood drawn through a catheter (plastic tube placed in a vein) every hour for 6 hours for tests to determine nitric oxide levels. After discharge, they will return to the clinic once every 2 weeks to check for treatment side effects and for blood tests to monitor hemoglobin and fetal hemoglobin levels. After fetal hemoglobin levels have been stable for 2 months, patients will be admitted to the Clinical Center for their first dose of L-arginine (for men) or Sildenafil (for women). Again, blood samples will be collected through a catheter once an hour for 6 hours. If there are no complications, patients will be discharged and will continue taking hydroxyurea once a day and L-arginine or Sildenafil three times a day for at least 3 months until fetal hemoglobin levels have been stable for at least 2 months. Patients will return to the clinic for blood tests every week for 2 weeks and then every 2 weeks to monitor hemoglobin and fetal hemoglobin levels and to check for treatment side effects. Patients will have eye examinations before and during treatment. Some patients with sickle cell disease develop abnormalities in the blood vessels of the eye. Also, Sildenafil can cause temporary changes in color vision. Rarely, more serious eye problems can occur, such as bleeding from the eye blood vessels or damage to the retina a layer of tissue that lines the back of the eye. Patients will also have an echocardiogram (ultrasound of the heart) before beginning treatment, after hydroxyurea treatment, and after 1 and 3 months of combined treatment with hydroxyurea and L-arginine or Sildenafil to help measure blood pressure in the lungs. Patients who develop complications from L-arginine or Sildenafil may continue in the study on hydroxyurea alone. Patients whose fetal hemoglobin levels increase with the combination therapy of hydroxyurea and L-arginine or Sildenafil may continue to take them.
NCT00080808 ↗	Nerve-Sparing Radical Prostatectomy With or Without Nerve Grafting Followed by Standard Therapy for Erectile Dysfunction in Treating Patients With Localized Prostate Cancer	Completed	National Cancer Institute (NCI)	Phase 2	2001-08-01	RATIONALE: Nerve-sparing radical prostatectomy with nerve grafting followed by standard therapies for erectile dysfunction may be effective in helping patients with prostate cancer improve sexual satisfaction and quality of life. It is not yet known whether erectile dysfunction therapy and nerve-sparing prostatectomy are more effective with or without nerve grafting. PURPOSE: This randomized phase II trial is studying nerve grafting and standard therapy to see how well they work compared to standard therapy alone in treating erectile dysfunction in patients undergoing nerve-sparing radical prostatectomy for localized prostate cancer.
NCT00080808 ↗	Nerve-Sparing Radical Prostatectomy With or Without Nerve Grafting Followed by Standard Therapy for Erectile Dysfunction in Treating Patients With Localized Prostate Cancer	Completed	M.D. Anderson Cancer Center	Phase 2	2001-08-01	RATIONALE: Nerve-sparing radical prostatectomy with nerve grafting followed by standard therapies for erectile dysfunction may be effective in helping patients with prostate cancer improve sexual satisfaction and quality of life. It is not yet known whether erectile dysfunction therapy and nerve-sparing prostatectomy are more effective with or without nerve grafting. PURPOSE: This randomized phase II trial is studying nerve grafting and standard therapy to see how well they work compared to standard therapy alone in treating erectile dysfunction in patients undergoing nerve-sparing radical prostatectomy for localized prostate cancer.
NCT00090376 ↗	Evaluate the Effects of GPI 1485 on Erectile Function Following Bilateral Nerve-Sparing Prostatectomy	Completed	Symphony Neuro Development Company	Phase 2	2003-12-01	In this phase II study, an investigative (not approved by the FDA) drug called GPI 1485 is being assessed to see if it can help preserve erectile function after prostatectomy.
NCT00090376 ↗	Evaluate the Effects of GPI 1485 on Erectile Function Following Bilateral Nerve-Sparing Prostatectomy	Completed	Eisai Inc.	Phase 2	2003-12-01	In this phase II study, an investigative (not approved by the FDA) drug called GPI 1485 is being assessed to see if it can help preserve erectile function after prostatectomy.

Clinical Trial Conditions for Viagra

Condition Name

Condition Name for Viagra
Intervention	Trials
Erectile Dysfunction	32
Impotence	17
Prostate Cancer	7
Pulmonary Arterial Hypertension	6

Condition MeSH

Condition MeSH for Viagra
Intervention	Trials
Erectile Dysfunction	51
Hypertension	27
Hypertension, Pulmonary	16
Prostatic Neoplasms	7

Clinical Trial Locations for Viagra

Trials by Country

Trials by Country for Viagra
Location	Trials
United States	206
Canada	17
United Kingdom	13
Australia	10
Denmark	9

Trials by US State

Trials by US State for Viagra
Location	Trials
California	17
Texas	17
New York	15
Ohio	10
Maryland	10

Clinical Trial Progress for Viagra

Clinical Trial Phase

Clinical Trial Phase for Viagra
Clinical Trial Phase	Trials
PHASE1	4
Phase 4	50
Phase 3	14

Clinical Trial Status

Clinical Trial Status for Viagra
Clinical Trial Phase	Trials
Completed	99
Unknown status	21
Terminated	18

Clinical Trial Sponsors for Viagra

Sponsor Name

Sponsor Name for Viagra
Sponsor	Trials
Pfizer	34
Pfizer's Upjohn has merged with Mylan to form Viatris Inc.	23
The University of Texas Medical Branch, Galveston	5

Sponsor Type

Sponsor Type for Viagra
Sponsor	Trials
Other	174
Industry	88
NIH	17

Viagra: Clinical Trials Update, Market Analysis, and Future Projections

Last updated: October 28, 2025

---

Introduction

Viagra (sildenafil citrate), developed by Pfizer, remains one of the most iconic pharmaceuticals for the treatment of erectile dysfunction (ED). Since its FDA approval in 1998, Viagra has revolutionized sexual health therapy and established a robust market segment. As the therapeutic landscape evolves, continuous clinical research, regulatory shifts, and changing market dynamics influence Viagra's positioning and growth trajectory. This report provides a comprehensive update on recent clinical trials, an analysis of the current market landscape, and projections for Viagra’s future.

---

Clinical Trials Update

Ongoing and Recent Clinical Studies

Over the past two years, Viagra's pipeline has expanded beyond its initial indication. Pfizer and other research entities are investigating sildenafil's potential in various off-label and novel therapeutic areas:

• Pulmonary Arterial Hypertension (PAH): While sildenafil’s role in PAH is established (e.g., Revatio), recent trials focus on optimizing dosing and combination therapies. The ongoing SPHIRE-2 trial assessed sildenafil’s efficacy alongside endothelin receptor antagonists, aiming to refine treatment protocols for PAH patients.

• Female Sexual Dysfunction (FSD): A significant subset of clinical research explores sildenafil’s impact on female sexual arousal disorder, though results have been mixed. The SILFRA study (2021) investigated sildenafil's ability to improve sexual function in women, but regulatory approval remains unachieved due to inconsistent outcomes.

• Cardiovascular and Neurodegenerative Conditions: Sildenafil’s vasodilatory effects are under review for potential benefits in cerebrovascular ischemia and Alzheimer’s disease. Preliminary phase II trials suggest hemodynamic improvements, but larger studies are necessary.

• COVID-19 and Pulmonary Complications: Recent exploratory trials examined sildenafil in mitigating pulmonary hypertension linked to COVID-19, with other studies investigating anti-inflammatory properties. These are largely early-stage and investigational.

Regulatory Developments and Approval Changes

Although Viagra remains approved for ED, regulators in some markets are re-evaluating sildenafil’s broader indications. Notably:

• The European Medicines Agency (EMA) approved sildenafil for pediatric pulmonary hypertension in 2020, based on childhood PAH trials.
• Regulatory agencies are scrutinizing off-label uses, with some jurisdictions contemplating expanded indications for cardiovascular conditions linked to endothelial dysfunction.

Adverse Events and Safety Profile

Recent pharmacovigilance reviews reaffirm sildenafil’s safety, with common adverse effects including headache, flushing, nasal congestion, and transient visual disturbances. Serious adverse events remain rare, supporting its continued safety for approved indications. Nonetheless, ongoing studies monitor long-term safety, especially when used in combination with other therapies.

---

Market Analysis

Global Market Size and Growth Trends

The global ED drug market has experienced remarkable growth, driven by aging populations, increasing prevalence of ED, and rising awareness:

• Market Valuation: Estimated at USD 4.6 billion in 2022, with projections to reach USD 7.4 billion by 2030 at a compound annual growth rate (CAGR) of approximately 5.4%[1].
• Regional Dynamics: North America dominates the market, accounting for over 45% of revenues, driven by high ED awareness and healthcare expenditure. Europe follows, with emerging markets like Asia-Pacific showing accelerated growth due to increased healthcare access and shifting attitudes towards sexual health.

Competitive Landscape and Key Players

While Viagra retains substantial market share, generic formulations and alternative ED therapies have increased competition:

• Generics: Since patent expiry in 2013, generic sildenafil dominates price-sensitive segments, leading to decreased prices but steady volume sales.
• Alternative Therapies: Pharmaceutical innovations like Cialis (tadalafil), Levitra (vardenafil), and emerging PDE5 inhibitors challenge Viagra's market share, offering advantages like longer duration (e.g., tadalafil’s 36-hour window).
• Emerging Non-Pharmacological Solutions: Technologies such as stem cell therapy and penile implants are gaining traction, potentially impacting future demand.

Market Challenges and Opportunities

• Challenges:

  • Patent Expirations: Leading to price erosion and increased generics market penetration.
  • Regulatory Restrictions: Increased scrutiny over off-label uses and safety concerns could influence marketing strategies.
  • Cultural Factors: Taboos surrounding sexual health in certain regions hinder market expansion.

• Opportunities:

  • Novel Indications: Expanding sildenafil’s use in pulmonary hypertension, cardiovascular, and neurodegenerative conditions could diversify revenue streams.
  • Combination Therapies: Partnering sildenafil with other agents enhances efficacy and patient adherence.
  • Digital Health Integration: Telemedicine and digital therapeutics may broaden access and compliance.

---

Future Projections

Market Growth Outlook

Despite increasing competition, Viagra’s brand recognition, combined with the expanding acceptance of sexual health issues, supports sustained demand:

• Volume and Value Growth: Volume sales are expected to plateau due to generics but will be offset by higher prices in premium markets and expanded indications.
• Innovative Therapeutic Applications: Targeted clinical trials may unlock new patent protections and exclusive marketing rights, rejuvenating revenue streams.
• Emerging Markets: Growth driven by urbanization, healthcare infrastructure improvements, and cultural shifts.

Impact of Developing Technologies

The integration of sildenafil into broader therapeutic categories and personalized medicine approaches will shape future growth trajectories. Pharmacogenomics, for example, could enable tailored dosing strategies, improving efficacy and safety profiles.

Regulatory and Market Risks

Potential regulatory constraints, off-label use restrictions, and public health concerns about overprescription may impact growth. Conversely, continued scientific validation and expanding indications could mitigate these risks.

---

Key Takeaways

• Clinical Trial Landscape: Sildenafil continues to be investigated for new indications, including pulmonary hypertension, cardiovascular, and neurodegenerative disorders. Most new research remains in early phases, awaiting validation.
• Market Dynamics: While generic sildenafil flooded the market post-patent expiry, Viagra retains strong brand recognition that can be leveraged in specialized markets and emerging indications. The high prevalence of ED and aging demographics sustainably fuel market growth.
• Competitive Pressures: The rise of alternative PDE5 inhibitors and non-pharmacological solutions offers challenges but also opportunities for innovation and differentiation.
• Future Outlook: Viability depends on successful expansion into new therapeutic areas, regulatory approvals for off-label uses, and adapting marketing strategies to regional and cultural nuances.

---

FAQs

1. Will Viagra maintain its market dominance amid increasing generics and competition?
While generics have eroded some sales margins, Viagra’s brand strength and potential to expand into new indications sustain its competitive edge. Strategic brand positioning and innovative therapeutic research are crucial to maintaining its prominence.

2. Are there ongoing studies that could lead to new approved uses for sildenafil?
Yes. Research into sildenafil’s role in pulmonary arterial hypertension, neurodegenerative diseases, and COVID-19-related pulmonary issues is ongoing, with some promising late-stage clinical results, potentially broadening its therapeutic profile.

3. How does the safety profile of Viagra compare to its competitors?
Viagra’s safety profile is well-characterized and comparable to other PDE5 inhibitors. Serious adverse effects are rare, but caution is essential for patients with cardiovascular risks or those taking nitrates.

4. What emerging markets offer the highest growth potential for sildenafil?
Asia-Pacific, Latin America, and Africa show significant growth potential due to improving healthcare infrastructure, rising awareness, and shifting cultural perceptions around sexual health.

5. Could future patent protections for sildenafil impact the market?
Potential patent extensions or new formulations could temporarily bolster exclusivity, but the patent landscape for sildenafil is saturated. Generic competition is likely to dominate, emphasizing the importance of innovation and indication expansion.

---

References

1. Grand View Research. Erectile Dysfunction Drugs Market Size, Share & Trends Analysis Report. 2022.
2. European Medicines Agency. Schering-Plough Pharmaceuticals: Sildenafil for Pediatric Pulmonary Hypertension. 2020.
3. Pfizer Inc. Scientific publications on sildenafil clinical trials. 2021–2022.
4. MarketWatch. Global Erectile Dysfunction Drugs Market Forecast. 2023.
5. ClinicalTrials.gov. Ongoing sildenafil studies. 2023.

---

In summary, Viagra remains a cornerstone in sexual health therapy with evolving clinical applications and a resilient market position. Strategic investments in research, diversified indications, and regional expansion are essential to sustain growth amid rising competition and regulatory landscapes.