CLINICAL TRIALS PROFILE FOR DIDANOSINE

505(b)(2) Clinical Trials for DIDANOSINE

This table shows clinical trials for potential 505(b)(2) applications. See the next table for all clinical trials

Trial Type	Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
New Combination	NCT00002234 ↗	Safety and Effectiveness of Giving an Anti-HIV Drug Combination of Adefovir Dipivoxil Plus Didanosine Plus Efavirenz Plus Lamivudine Once Daily to HIV-Infected Patients	Completed	Bristol-Myers Squibb	Phase 2	1969-12-31	The purpose of this study is to see if it is safe and effective to give HIV-infected patients a new combination of anti-HIV drugs taken once daily.
New Combination	NCT00002234 ↗	Safety and Effectiveness of Giving an Anti-HIV Drug Combination of Adefovir Dipivoxil Plus Didanosine Plus Efavirenz Plus Lamivudine Once Daily to HIV-Infected Patients	Completed	Dupont Applied Biosciences	Phase 2	1969-12-31	The purpose of this study is to see if it is safe and effective to give HIV-infected patients a new combination of anti-HIV drugs taken once daily.
New Combination	NCT00002234 ↗	Safety and Effectiveness of Giving an Anti-HIV Drug Combination of Adefovir Dipivoxil Plus Didanosine Plus Efavirenz Plus Lamivudine Once Daily to HIV-Infected Patients	Completed	Glaxo Wellcome	Phase 2	1969-12-31	The purpose of this study is to see if it is safe and effective to give HIV-infected patients a new combination of anti-HIV drugs taken once daily.
New Combination	NCT00002234 ↗	Safety and Effectiveness of Giving an Anti-HIV Drug Combination of Adefovir Dipivoxil Plus Didanosine Plus Efavirenz Plus Lamivudine Once Daily to HIV-Infected Patients	Completed	Gilead Sciences	Phase 2	1969-12-31	The purpose of this study is to see if it is safe and effective to give HIV-infected patients a new combination of anti-HIV drugs taken once daily.

All Clinical Trials for DIDANOSINE

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00000625 ↗	A Randomized, Double-Blind Phase II/III Trial of Monotherapy vs. Combination Therapy With Nucleoside Analogs in HIV-Infected Persons With CD4 Cells of 200-500/mm3	Completed	Bristol-Myers Squibb	Phase 2	1969-12-31	To determine the efficacy and safety of zidovudine ( AZT ) versus didanosine ( ddI ), AZT plus ddI, and AZT plus zalcitabine ( ddC ) in preventing disease progression in HIV-infected patients with CD4 counts of 200-500 cells/mm3.
NCT00000625 ↗	A Randomized, Double-Blind Phase II/III Trial of Monotherapy vs. Combination Therapy With Nucleoside Analogs in HIV-Infected Persons With CD4 Cells of 200-500/mm3	Completed	Glaxo Wellcome	Phase 2	1969-12-31	To determine the efficacy and safety of zidovudine ( AZT ) versus didanosine ( ddI ), AZT plus ddI, and AZT plus zalcitabine ( ddC ) in preventing disease progression in HIV-infected patients with CD4 counts of 200-500 cells/mm3.
NCT00000625 ↗	A Randomized, Double-Blind Phase II/III Trial of Monotherapy vs. Combination Therapy With Nucleoside Analogs in HIV-Infected Persons With CD4 Cells of 200-500/mm3	Completed	National Institute of Allergy and Infectious Diseases (NIAID)	Phase 2	1969-12-31	To determine the efficacy and safety of zidovudine ( AZT ) versus didanosine ( ddI ), AZT plus ddI, and AZT plus zalcitabine ( ddC ) in preventing disease progression in HIV-infected patients with CD4 counts of 200-500 cells/mm3.
NCT00000637 ↗	A Randomized Comparative Trial of Zidovudine (AZT) Versus 2',3'-Dideoxyinosine (ddI) Versus AZT Plus ddI in Symptomatic HIV-Infected Children	Completed	Bristol-Myers Squibb	Phase 3	1969-12-31	To compare the effectiveness of treatment with zidovudine (AZT) compared to didanosine (ddI) and compared to the combination of AZT and ddI as determined by survival and disease progression. To compare the relative safety and tolerance of AZT versus ddI versus AZT plus ddI in symptomatic HIV infected children; to compare the virological and immunological parameters in the three treatment groups. AZT has been shown to delay the progression of AIDS in HIV infected individuals. However, bone marrow toxicity is a frequent adverse effect. Also, HIV resistance to AZT sometimes occurs in patients who initially respond to treatment, but later have progression of the disease. Thus, new drug treatments are needed. Studies of ddI in adults and children indicate some effectiveness of the drug. A direct comparison of AZT and ddI treatment in children has not been made. Combination antiviral treatment (AZT plus ddI) may give added therapeutic benefit to children.
NCT00000637 ↗	A Randomized Comparative Trial of Zidovudine (AZT) Versus 2',3'-Dideoxyinosine (ddI) Versus AZT Plus ddI in Symptomatic HIV-Infected Children	Completed	Glaxo Wellcome	Phase 3	1969-12-31	To compare the effectiveness of treatment with zidovudine (AZT) compared to didanosine (ddI) and compared to the combination of AZT and ddI as determined by survival and disease progression. To compare the relative safety and tolerance of AZT versus ddI versus AZT plus ddI in symptomatic HIV infected children; to compare the virological and immunological parameters in the three treatment groups. AZT has been shown to delay the progression of AIDS in HIV infected individuals. However, bone marrow toxicity is a frequent adverse effect. Also, HIV resistance to AZT sometimes occurs in patients who initially respond to treatment, but later have progression of the disease. Thus, new drug treatments are needed. Studies of ddI in adults and children indicate some effectiveness of the drug. A direct comparison of AZT and ddI treatment in children has not been made. Combination antiviral treatment (AZT plus ddI) may give added therapeutic benefit to children.
NCT00000637 ↗	A Randomized Comparative Trial of Zidovudine (AZT) Versus 2',3'-Dideoxyinosine (ddI) Versus AZT Plus ddI in Symptomatic HIV-Infected Children	Completed	National Institute of Allergy and Infectious Diseases (NIAID)	Phase 3	1969-12-31	To compare the effectiveness of treatment with zidovudine (AZT) compared to didanosine (ddI) and compared to the combination of AZT and ddI as determined by survival and disease progression. To compare the relative safety and tolerance of AZT versus ddI versus AZT plus ddI in symptomatic HIV infected children; to compare the virological and immunological parameters in the three treatment groups. AZT has been shown to delay the progression of AIDS in HIV infected individuals. However, bone marrow toxicity is a frequent adverse effect. Also, HIV resistance to AZT sometimes occurs in patients who initially respond to treatment, but later have progression of the disease. Thus, new drug treatments are needed. Studies of ddI in adults and children indicate some effectiveness of the drug. A direct comparison of AZT and ddI treatment in children has not been made. Combination antiviral treatment (AZT plus ddI) may give added therapeutic benefit to children.
NCT00000652 ↗	A Phase I Study to Evaluate the Safety and Toxicity of the Combination of Zidovudine and 2',3'-Dideoxyinosine (Didanosine) in Children With HIV Infection	Completed	National Cancer Institute (NCI)	Phase 1	1969-12-31	To assess the safety and tolerance of the combination of zidovudine (AZT) and didanosine (ddI) in children with HIV infection. New approaches to using available agents may provide increased or improved treatment options for AIDS. Combination therapy is expected to play a major role in improving survival and quality of life for HIV-infected individuals. AZT and ddI are two agents that have been most extensively evaluated and for which the evidence for antiretroviral effectiveness is strongest.

Clinical Trial Conditions for DIDANOSINE

Condition Name

Condition Name for DIDANOSINE
Intervention	Trials
HIV Infections	144
HIV Infection	4
HIV	3
AIDS	3

Condition MeSH

Condition MeSH for DIDANOSINE
Intervention	Trials
HIV Infections	150
Acquired Immunodeficiency Syndrome	40
Infections	37
Infection	35

Clinical Trial Locations for DIDANOSINE

Trials by Country

Trials by Country for DIDANOSINE
Location	Trials
Puerto Rico	39
Thailand	28
Spain	23
Canada	14
South Africa	10

Trials by US State

Trials by US State for DIDANOSINE
Location	Trials
California	92
New York	75
Illinois	61
Florida	57
Massachusetts	54

Clinical Trial Progress for DIDANOSINE

Clinical Trial Phase

Clinical Trial Phase for DIDANOSINE
Clinical Trial Phase	Trials
Phase 4	13
Phase 3	19
Phase 2/Phase 3	1

Clinical Trial Status

Clinical Trial Status for DIDANOSINE
Clinical Trial Phase	Trials
Completed	136
Unknown status	8
Terminated	6

Clinical Trial Sponsors for DIDANOSINE

Sponsor Name

Sponsor Name for DIDANOSINE
Sponsor	Trials
National Institute of Allergy and Infectious Diseases (NIAID)	81
Bristol-Myers Squibb	45
Glaxo Wellcome	18

Sponsor Type

Sponsor Type for DIDANOSINE
Sponsor	Trials
Industry	112
NIH	98
Other	42

Didanosine: Clinical Trials, Market Analysis, and Projection

Last updated: February 19, 2026

This report analyzes the current clinical trial landscape, market dynamics, and future projections for didanosine, a nucleoside analog reverse transcriptase inhibitor.

What is Didanosine's Current Clinical Trial Status?

Didanosine (ddI) is primarily known for its historical role in HIV/AIDS treatment. Its current clinical trial activity is minimal, focusing on exploring repurposing for other indications and understanding its long-term effects.

Key Clinical Trial Areas:

• Repurposing for Ocular Diseases: Limited preclinical and early-stage clinical investigations explore didanosine's potential in treating viral or inflammatory conditions affecting the eye. This research is often academic or in very early stages, with few large-scale trials.
• Long-term Safety and Efficacy Monitoring: As a drug with established toxicities (e.g., pancreatitis, neuropathy), ongoing research may involve observational studies or registries tracking long-term patient outcomes in specific populations, though these are not typically "active" interventional trials.
• Combination Therapy Research (Historical Context): While not current active trials, understanding didanosine's historical use in combination therapies for HIV is crucial for assessing residual market relevance and potential future research avenues if resistance patterns shift.

Current Trial Registrations:

A review of major clinical trial registries (e.g., ClinicalTrials.gov) reveals a low number of active interventional studies for didanosine. The majority of listed trials are either completed, terminated, or administrative in nature, often relating to retrospective analyses or the study of adverse events.

• Example Search Results (as of Q2 2024): Typically, fewer than 5 active, interventional trials are identified. These often involve small patient cohorts and focus on specific, niche applications.

Challenges in Current Trials:

• Toxicity Profile: The well-documented side effects of didanosine, including pancreatitis, peripheral neuropathy, and hyperuricemia, limit its broader application and make it challenging to recruit for new trials, especially in naive patient populations.
• Availability of Superior Alternatives: The development of highly effective and safer antiretroviral therapies (ART) has largely superseded didanosine for HIV treatment.
• Limited Commercial Interest: Pharmaceutical companies typically focus R&D investment on novel compounds or significant improvements on existing therapies, reducing commercial sponsorship for didanosine trials.

How Has Didanosine's Market Evolved?

Didanosine's market trajectory has been defined by its initial success as a groundbreaking HIV medication, followed by a significant decline due to the advent of more effective and safer treatments.

Historical Market Dominance (1990s - Early 2000s):

• FDA Approval: Approved by the U.S. Food and Drug Administration (FDA) in 1991 as Videx.
• First-Line Therapy: Was among the first nucleoside analog reverse transcriptase inhibitors (NRTIs) available, making it a cornerstone of early HIV combination therapy regimens.
• Peak Sales: Achieved peak annual sales in the hundreds of millions of U.S. dollars during the late 1990s.

Market Decline Factors:

• Emergence of Protease Inhibitors and Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs): Development of these drug classes offered greater efficacy and improved side-effect profiles.
• Introduction of Highly Active Antiretroviral Therapy (HAART): The combination of multiple drug classes dramatically improved patient outcomes and reduced viral load, rendering monotherapy or less effective combinations like those including didanosine obsolete for initial treatment.
• Increased Toxicity Concerns: Long-term use of didanosine was associated with significant adverse events, including dose-limiting toxicities like pancreatitis and peripheral neuropathy, leading to dosage reductions and eventual discontinuation in many treatment guidelines.
• Dosing Regimen Simplification: Newer ART regimens offered simpler dosing (e.g., once-daily formulations), which improved patient adherence compared to the multiple daily doses required for didanosine in its early formulations.
• Generic Competition: As patents expired, generic versions entered the market, further driving down prices and reducing revenue for the originator.

Current Market Position:

• Niche Use: Didanosine is no longer recommended as a first-line or second-line agent for HIV treatment by major international guidelines (e.g., U.S. Department of Health and Human Services, WHO). Its use is limited to salvage therapy or in specific regions where access to newer ART is restricted, often as part of off-patent, multi-drug regimens.
• Orphan Drug Status: In some specific therapeutic areas, didanosine might retain a niche market or be explored under orphan drug designations for rare conditions, though this is not its primary market.
• Manufacturing and Supply: Production is primarily by generic manufacturers. The market size is significantly smaller than its historical peak, serving a residual demand.
• Pricing: Prices for generic didanosine are considerably lower than its original branded pricing, reflecting the competitive landscape and reduced demand.

Market Size Estimation (Current):

Estimating the precise current global market size for didanosine is challenging due to its status as a generic with limited widespread use. However, based on its reduced role in HIV treatment and minimal new indications, the global market is estimated to be in the low tens of millions of U.S. dollars annually, a fraction of its historical peak. This market is primarily driven by sales in low- and middle-income countries where access to newer ART remains a challenge, and by limited use in specific salvage therapy situations.

What Are the Future Market Projections for Didanosine?

The future market for didanosine is projected to remain constrained, with limited potential for significant growth. Its historical role is cemented, and its current utility is diminishing.

Key Projection Factors:

• Continued Dominance of Modern ART: Advances in HIV treatment continue to yield highly effective, well-tolerated, and simple-to-administer regimens. These will further marginalize didanosine's utility in HIV management.
• Limited Pipeline for New Indications: While academic interest in repurposing may persist, the significant toxicity profile of didanosine presents a substantial barrier to its development for new, mainstream indications. The cost and risk associated with navigating regulatory hurdles for a drug with known safety concerns are high.
• Geographic Dependency: The residual market will likely remain dependent on specific geographic regions with limited access to newer ART or where off-patent drugs are more cost-effective for public health programs.
• Focus on Long-Term Toxicity Management: Any future research or market presence will likely be intertwined with managing its known toxicities rather than expanding its therapeutic scope.
• Potential for Minimal Use in Research: Didanosine might continue to be used as a comparator drug in research studies investigating novel antiviral mechanisms or drug delivery systems, but this does not translate into significant market volume.

Projected Market Trend:

The market for didanosine is expected to continue a slow decline over the next 5-10 years. This decline will be driven by:

• Increasing global access to next-generation ART.
• Heightened awareness and management of didanosine's toxicity.
• Lack of significant new therapeutic applications progressing through clinical development.

Quantitative Projection:

• Next 5 Years: Expect a slight decrease in market value, potentially falling to under $5 million USD annually.
• Beyond 5 Years: The market may stabilize at a very low volume, serving only the most niche applications or research needs, with its commercial significance becoming negligible.

Competitive Landscape:

The competitive landscape is dominated by generic manufacturers. The absence of proprietary development means pricing is largely driven by production costs and demand. There are no significant new entrants or innovative developments expected to alter this dynamic.

Investment Considerations:

For investors, the didanosine market presents minimal opportunity for growth or significant returns. Its established toxicity, lack of novel applications, and decreasing relevance in its primary indication make it a low-priority asset. Any investment would need to be solely focused on generic manufacturing with extremely low overheads, serving a highly specialized, diminishing demand.

Key Takeaways

• Didanosine clinical trial activity is minimal, primarily focused on academic explorations of repurposing and long-term safety monitoring.
• The drug's market has contracted dramatically from its peak in the 1990s due to the development of superior HIV treatments and concerns over its toxicity profile.
• Didanosine's current market is niche, largely confined to salvage therapy or regions with limited access to modern antiretroviral therapy, with an estimated annual global market value in the low tens of millions of U.S. dollars.
• Future market projections indicate a continued slow decline, with its commercial significance expected to become negligible within the next decade, driven by advancements in ART and a lack of new therapeutic applications.

Frequently Asked Questions

1. Is didanosine still recommended for HIV treatment? Didanosine is no longer recommended as a first-line or second-line treatment for HIV by major international health organizations due to the availability of more effective and safer alternatives. Its use is generally limited to specific salvage therapy situations or in regions with restricted access to newer antiretroviral therapies.

2. What are the main side effects associated with didanosine? Significant side effects of didanosine include pancreatitis, peripheral neuropathy (nerve damage leading to numbness, tingling, or pain), hyperuricemia (high uric acid levels), and liver toxicity. These toxicities were a major factor in its decline in clinical use.

3. Are there any ongoing clinical trials for didanosine for new indications? While academic research may explore repurposing didanosine for other conditions, large-scale, commercially sponsored clinical trials for new indications are rare. The drug's established toxicity profile presents a considerable challenge for developing new therapeutic uses.

4. Who are the primary manufacturers of didanosine today? Production of didanosine today is primarily by generic pharmaceutical manufacturers. There are no major innovator companies actively developing or marketing new formulations or indications for the drug.

5. What is the projected market size of didanosine in the next five years? The global market for didanosine is projected to continue its decline and may fall to under $5 million USD annually within the next five years, due to increasing access to advanced HIV treatments and a lack of significant new applications.

Citations

[1] U.S. Food and Drug Administration. (1991). Prescribing Information: Videx. [2] U.S. Department of Health and Human Services. (Ongoing). Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents. [3] World Health Organization. (Ongoing). Consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection. [4] ClinicalTrials.gov. (Data accessed Q2 2024). Search results for "Didanosine". [5] Market research reports on antiretroviral drug markets (proprietary, generalized data from multiple sources).