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 Hypertension	6

Condition MeSH

Condition MeSH for VIAGRA
Intervention	Trials
Erectile Dysfunction	51
Hypertension	27
Hypertension, Pulmonary	16
Pulmonary Arterial Hypertension	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
Rambam Health Care Campus	5

Sponsor Type

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

Viagra (sildenafil) clinical trials update, market analysis, and exclusivity-linked revenue projection (2026–2035)

Last updated: July 26, 2026

Executive summary: Sildenafil (Viagra and generics) is a mature, patent-expired erectile dysfunction (ED) therapy in most major markets, with ongoing clinical activity focused on new indications, combination regimens, and formulation/behavioral endpoints rather than primary ED efficacy. Near-term market growth is driven by volume recovery, brand-to-generic mix shifts, and regulated label expansions in select geographies. Revenue is structurally constrained by generic competition; projections assume continued share loss in branded segments, partial offset from higher penetration in underserved populations, and incremental upside from non-ED indications where sildenafil is studied.

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What clinical trials are ongoing for Viagra (sildenafil) in 2025–2026?

What trial types dominate sildenafil (Viagra) research right now?

Featured clinical activity clusters into four buckets:

1. Label-expansion studies in ED subpopulations (age, comorbidities like diabetes, cardiovascular risk stratification) and in settings where endpoints emphasize patient-reported outcomes.
2. Alternative dosing and delivery work, including optimized titration, adherence-focused designs, and formulation approaches aimed at earlier onset or improved tolerability.
3. Combination regimens (often with PDE5-use alignment plus adjunct therapies), including protocol-driven comparisons versus sildenafil monotherapy.
4. Non-ED indications in pulmonary vascular disease phenotypes, vascular dysfunction, and other cardiopulmonary-adjacent areas where sildenafil’s mechanism is under evaluation.

Which endpoints are most commonly used in recent sildenafil trials?

Across modern ED studies, endpoints tend to be:

• International Index of Erectile Function (IIEF) domain improvements
• Sexual encounter success rate
• Time-to-effect and early efficacy measures (chronobiology and onset timing)
• Safety endpoints focused on hypotension, visual effects, and interaction risk

How do trials handle cardiovascular safety and interaction risk?

Current protocols typically:

• Enforce nitrate exclusion
• Require stabilized cardiovascular status
• Track blood pressure effects and adverse event severity consistently
• Include interaction monitoring for alpha-blockers and common antihypertensives

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Where is Viagra (sildenafil) approved and what label changes matter for commercial outlook?

What are the core ED label mechanics used commercially?

For mature ED therapy, commercialization depends on:

• Standard oral dosing options
• Clear contraindication framing (notably nitrate co-administration)
• Broad prescriber familiarity and established clinical guidelines

Do label expansions change the market size significantly?

Any meaningful incremental commercial effect from label expansions usually requires:

• Clear additional patient segments (for example, specific comorbid ED subgroups)
• Reimbursement alignment and guideline adoption
• Evidence that improved outcomes translate into higher persistence and repeat purchasing

In most markets, ED remains the main driver, and label expansions tend to be incremental rather than transformative.

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What patents protect Viagra (sildenafil) and how does exclusivity timing affect revenue?

Is Viagra still protected by composition-of-matter in major markets?

No. Sildenafil’s foundational patent estate is long expired in most major jurisdictions. Current market dynamics are dominated by:

• Generic manufacturing and marketing authorizations
• Brand differentiation in non-patent factors (pricing strategy, distribution, patient support, and perceived trust)
• Any residual protection limited to later-life patents, formulations, or specific methods where they still exist in some jurisdictions

What is the practical exclusivity timeline risk for branded revenue?

Because generics have entrenched supply chains and pricing pressure, the key exclusivity question is not “when the last patent expires,” but:

• whether branded contracts or formularies preserve share
• whether payer policies cap generic uptake
• whether any remaining patent islands apply only to narrow products or specific presentations

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What is the Orange Book status of Viagra (sildenafil) and what does that imply for generics?

What does Orange Book listing typically show for sildenafil ED products?

Orange Book records usually reflect:

• Historical reference listed drug (RLD) for sildenafil ED
• Extensive abbreviated new drug applications (ANDAs) for bioequivalent generics
• A long list of ancillary patents for older products, with many either expired or not limiting generic entry anymore

How does Orange Book status affect launch timing for new generic entrants?

In a mature therapeutic with extensive ANDA coverage, new entries are less about patent-driven “entry cliffs” and more about:

• availability of manufacturing capacity
• pricing and rebate dynamics
• state-level and PBM formulary placement
• label and packaging changes that create renewed differentiation opportunities for incumbents

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Which generic companies compete with Viagra (sildenafil) most aggressively?

How competitive is the sildenafil ED generic landscape?

Sildenafil ED is heavily genericized. The most commercially relevant competitors are typically:

• large Indian generic manufacturers with export capacity into US and EU markets
• multi-product branded-generic hybrids and wholesalers that can scale distribution
• regional generic leaders in EU member states where reimbursement and procurement rules differ

What matters commercially beyond “who can make it”?

For a commodity-like API, profitability depends on:

• contracting with payers/PBMs
• formulary tier placement
• rebate structures
• supply reliability and quality systems

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What formulations are protected for Viagra (sildenafil) and do they block generics?

Are formulation-specific patents still blocking competition?

In most cases, formulation-specific patents for sildenafil have limited remaining commercial impact. Where present, they typically:

• cover narrow presentation changes
• apply to certain dosing strengths or packaging
• expire on staggered timelines by jurisdiction

For revenue modeling, formulation patents generally act as “minor share shields,” not as major exclusivity.

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How strong is the patent estate for Viagra (sildenafil) versus generic entry risk?

Patent strength assessment in a mature PDE5 inhibitor asset

For Viagra specifically, the patent estate is historically strong but is now:

• largely non-blocking for standard sildenafil ED tablets in major markets
• more relevant for defense against “skinny labeling” or secondary product variants in select filings
• less relevant for true entry barriers compared with manufacturing, pricing, and distribution

Net effect: litigation and licensing activity is lower than it would be for an actively protected brand. Market risk is driven primarily by price competition and contracting cycles, not by patent cliffs.

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What patent litigation affects sildenafil (Viagra) and generics?

How litigation risk manifests for mature sildenafil

In a generic-heavy space, litigation tends to relate to:

• last-mile patent assertions for secondary patents (if still in force)
• generic labeling differences and product-specific claims
• procedural disputes in Hatch-Waxman cases

Does litigation change the revenue trajectory?

For Viagra, the market impact of litigation is usually:

• short-lived at the brand level
• limited to specific jurisdictions where injunctions or settlements temporarily delay entry

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What settlement agreements or Paragraph IV outcomes matter most for Viagra?

Why Paragraph IV outcomes rarely reset the market for Viagra

Paragraph IV events can influence timing for specific ANDA entrants, but given the number of approved generics and the long lapse of primary exclusivity, the commercial effect tends to be:

• incremental market share shifts
• local price stabilization followed by renewed competition

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What market size and revenue projection should investors model for Viagra (2026–2035)?

How to model revenue in a commodity-generic market

For Viagra, branded revenue projection should be built from:

• assumed ED patient pool growth (population, aging, diagnosis rates)
• penetration into sildenafil therapy
• persistence and switching behavior between brand and generics
• payer contracting and reimbursement dynamics
• price erosion tied to generic share

Projection framework (mechanics)

Use a scenario approach with three drivers:

1. Volume growth: steady ED demand growth in emerging markets and continued diagnosis/treated prevalence.
2. Branded share: declining structural share under generic competition.
3. Net price: driven by contracting and rebate pressure; branded premium narrows.

Base-case projection (directional)

• Branded Viagra revenue: declines in most mature markets after accounting for continued generic penetration.
• Global blended sildenafil revenue: grows modestly in volume terms, with price pressure offset by more treatment adoption.
• Upside lever: any meaningful label expansion or non-ED indication adoption that changes the treated population.

Downside scenario

• accelerated generic pricing resets in key markets
• stronger PBM formularies favoring cheapest generics
• slower diagnosis growth due to access or reimbursement constraints

Upside scenario

• payer contracts preserve brand share longer than typical
• product differentiation through patient support, adherence programs, or localized marketing strategy
• non-ED indication evidence expands prescriber use outside classic ED therapy

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How does Viagra (sildenafil) compare with Cialis (tadalafil) and Levitra (vardenafil) on clinical and market outlook?

Clinical positioning differences that affect prescribing

• Sildenafil: shorter onset profile perception and common titration use
• Tadalafil: longer duration perception and once-daily use patterns in ED
• Vardenafil: secondary profile competition with similar ED indications

Commercial implication

Market share between PDE5 inhibitors depends on:

• duration preference, tolerance, and comorbidity coverage
• guideline endorsement
• payer preference and formulary tiering
• generic pricing execution

In most markets, sildenafil faces direct competition from multiple generic PDE5 inhibitors, not just from branded Viagra.

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What manufacturing and IP barriers shape sildenafil supply and pricing?

What constrains supply in a mature generic category?

Key risks include:

• API sourcing reliability and compliance readiness
• sterile vs non-sterile quality systems (tablets are lower complexity than injectables, but GMP consistency remains critical)
• batch-to-batch stability and dissolution specifications
• regulatory inspection outcomes and import compliance in specific geographies

How do these barriers affect price?

Supply disruptions typically cause short-term price spikes, but the category’s multiple suppliers usually restore competition quickly.

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Key Takeaways

• Sildenafil (Viagra) clinical research in 2025–2026 skews toward optimization, subgroup endpoints, and combination or alternate use patterns; no broad evidence indicates a shift away from the ED core market.
• Patent-driven exclusivity is largely not the main commercial driver; branded revenue is constrained by established generic availability.
• Market outlook is primarily volume growth versus branded share erosion under pricing pressure; the main upside is incremental label expansion or non-ED indication adoption.
• Competitive risk is driven by formulary and contracting dynamics across PDE5 inhibitor generics, especially against tadalafil and vardenafil.

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FAQs

1. What is the most important driver of branded Viagra revenue versus generic sildenafil?
   Payer formulary placement and rebate-driven pricing that determine whether patients remain on the brand or switch to the cheapest equivalent.

2. Do new sildenafil clinical trials usually support a new indication or a dosing optimization?
   Most studies in recent years focus on dosing/titration, adherence and patient-reported outcomes in ED subgroups, with a smaller set examining non-ED mechanisms.

3. What are the main safety and interaction concerns that shape sildenafil prescribing?
   Nitrate contraindication, blood pressure effects, and interaction monitoring with alpha-blockers and common cardiovascular regimens.

4. How should investors model revenue in a mature PDE5 inhibitor like Viagra?
   Use volume growth assumptions tied to treated ED prevalence and separate branded share and net price erosion under generic competition.

5. What competitive factors matter more than clinical efficacy for sildenafil ED in late-life markets?
   Contracting, supply reliability, packaging and distribution execution, and PBM tier placement.

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References

1. FDA. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. US Food and Drug Administration.
2. ClinicalTrials.gov. Sildenafil (Viagra) clinical trials database. U.S. National Library of Medicine.
3. EMA. European public assessment reports and EPARs for sildenafil-containing products. European Medicines Agency.
4. WHO. ATC classification and drug utilization context for PDE5 inhibitors. World Health Organization.