CLINICAL TRIALS PROFILE FOR NALIDIXIC ACID

All Clinical Trials for nalidixic acid

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00741052 ↗	Ciprofloxacin Multiple Dose for Adult Cholera	Completed	International Centre for Diarrhoeal Disease Research, Bangladesh	Phase 3	2007-07-01	Cholera is an important diarrhoeal disease and an important cause of death, particularly during epidemic outbreaks, in Bangladesh and many other developing countries. Used as an adjunct to management of dehydration, antimicrobial therapy using an appropriate agent reduces diarrhoea duration and stool volume in severe cholera by about half. The usefulness of antimicrobials has, however, been greatly eroded by the increasing prevalence of resistant strains of V. cholerae O1. From October 2004 at the Matlab Hospital and from December 2004 at the Dhaka Hospital of ICDDR, B, V. cholerae strains became increasingly resistant to tetracycline and erythromycin- two drugs used in the treatment of severe cholera in adults and children respectively. Because of this high prevalence of resistance we resorted in early 2005 to using ciprofloxacin for treatment against multi drug resistant V. cholerae. Although all isolates were susceptible to ciprofloxacin when standard thresholds for disc-diffusion or E-test were used, but majority of the strains demonstrated a MIC value of 0.250 µg/ml, over hundred-folds greater than the V. cholerae strains tested in earlier years, which generally had a MIC of
NCT01335334 ↗	H. Pylori Eradication Using Pyklear in Adults in El Paso, Texas: a Pilot Study	Unknown status	The University of Texas Health Science Center, Houston	Phase 4	2011-03-01	The proposed open-label one arm before-after clinical trial will assess the efficacy of a 14-day quadruple therapy containing 420mg of bismuth subcitrate potassium, 375mg of metronidazole, 375mg of tetracycline hydrochloride (Pylera® packs from Axcan Pharma) and 20mg of omeprazole in eradicating H. pylori infection in 50 asymptomatic adults in El Paso, Texas. As part of the study we will obtain specimens for culture of H. pylori in a reference laboratory.
NCT01804634 ↗	Reduced Intensity Haploidentical BMT for High Risk Solid Tumors	Recruiting	Sidney Kimmel Comprehensive Cancer Center	Phase 2	2013-03-27	The purpose of this study is to see if giving reduced intensity chemotherapy, haploidentical bone marrow, post-transplant cyclophosphamide and shortened duration tacrolimus is safe and feasible for patients with very high-risk solid tumors.
NCT01804634 ↗	Reduced Intensity Haploidentical BMT for High Risk Solid Tumors	Recruiting	Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins	Phase 2	2013-03-27	The purpose of this study is to see if giving reduced intensity chemotherapy, haploidentical bone marrow, post-transplant cyclophosphamide and shortened duration tacrolimus is safe and feasible for patients with very high-risk solid tumors.
NCT02017197 ↗	Therapeutic Equivalence Between Branded and Generic WARFArin Tablets in Brazil	Completed	Fundação de Amparo à Pesquisa do Estado de São Paulo	Phase 4	2014-08-01	The purpose of this study is to assess whether the switch from branded to generic warfarin or between different generic warfarin tablets may cause fluctuation in the results of coagulation tests (International Normalized Rate, acronym INR) in patients, thus predisposing them to unnecessary risks.
NCT02017197 ↗	Therapeutic Equivalence Between Branded and Generic WARFArin Tablets in Brazil	Completed	Federal University of São Paulo	Phase 4	2014-08-01	The purpose of this study is to assess whether the switch from branded to generic warfarin or between different generic warfarin tablets may cause fluctuation in the results of coagulation tests (International Normalized Rate, acronym INR) in patients, thus predisposing them to unnecessary risks.

Clinical Trial Conditions for nalidixic acid

Condition Name

Condition Name for nalidixic acid
Intervention	Trials
Cholera	1
H. Pylori Associated Phlegmonous Gastritis	1
H. Pylori Infection	1
H. Pylori Infection, Gastritis, Resistance and Treatment	1

Condition MeSH

Condition MeSH for nalidixic acid
Intervention	Trials
Cholera	1
Gastrointestinal Diseases	1
Gastritis	1
Digestive System Diseases	1

Clinical Trial Locations for nalidixic acid

Trials by Country

Trials by Country for nalidixic acid
Location	Trials
United States	6
Bangladesh	1
Greece	1
Brazil	1

Trials by US State

Trials by US State for nalidixic acid
Location	Trials
New York	2
Florida	1
Texas	1
North Carolina	1
Maryland	1

Clinical Trial Progress for nalidixic acid

Clinical Trial Phase

Clinical Trial Phase for nalidixic acid
Clinical Trial Phase	Trials
Phase 4	3
Phase 3	1
Phase 2	1

Clinical Trial Status

Clinical Trial Status for nalidixic acid
Clinical Trial Phase	Trials
Completed	3
Recruiting	2
Unknown status	1

Clinical Trial Sponsors for nalidixic acid

Sponsor Name

Sponsor Name for nalidixic acid
Sponsor	Trials
International Centre for Diarrhoeal Disease Research, Bangladesh	1
The University of Texas Health Science Center, Houston	1
Sidney Kimmel Comprehensive Cancer Center	1

Sponsor Type

Sponsor Type for nalidixic acid
Sponsor	Trials
Other	9

Last updated: May 23, 2026

Nalidixic Acid Clinical Trials, Market Analysis, and Projection (2026)

Nalidixic acid is an older oral fluoroquinolone antibacterial with limited late-stage development activity and no meaningful contemporary late-phase registration pipeline. Commercial value is largely tied to local/regional generic sales rather than branded, innovation-led growth. Near-term market trajectory is driven by (1) mature off-patent status, (2) antibiotic stewardship constraints, and (3) stable demand in lower-acuity urinary tract infection use where products remain available.

Are there active clinical trials for nalidixic acid?

No clinically active, late-stage, or registrational trials were identified as current for nalidixic acid in the modern development era. Demand today is met through existing approved generics in multiple geographies, with clinical research largely historical and pharmacovigilance focused.

What trial phases exist historically for nalidixic acid?

Published and registry data for nalidixic acid predominantly reflects earlier eras when fluoroquinolones were being established. Those studies typically include:

• Phase 2–3 evaluations for uncomplicated urinary infections
• Comparisons against older urinary antiseptics/antibiotics
• Dose-ranging and pharmacokinetics in the 1960s–1990s

What endpoints dominated older nalidixic acid trials?

Common historical endpoints included:

• Clinical cure in urinary tract infection (UTI)
• Microbiological eradication (baseline pathogen clearance)
• Time to symptom improvement
• Adverse event rates (GI intolerance, CNS effects)

What is nalidixic acid’s market size and who sells it?

Nalidixic acid’s market is best characterized as mature, generic, and fragmented, with local or regional manufacturers supplying licensed products.

How is the market segmented in practice?

Market demand is typically segmented by:

• Prescription-only antibiotic channels (varies by country)
• UTI indications, often in lower-resource settings
• Generic product formulations (immediate-release tablets/capsules in many jurisdictions)

Which product types matter commercially?

• Oral immediate-release dosage forms are the primary commercial format.
• Fixed-dose strengths vary by market; availability is the key differentiator rather than novel formulation.

What drives pricing and availability?

• Competitive generic tendering (public health procurement)
• National antibiotic policy changes that shift preferred UTI regimens
• Regulatory actions tied to safety concerns and stewardship guidance

Why does nalidixic acid have limited growth potential versus newer fluoroquinolones?

Clinical practice and policy have moved away from nalidixic acid for uncomplicated infections due to:

• Lower perceived efficacy for broader UTI pathogen resistance profiles compared with newer agents
• Safety and tolerability constraints documented over decades (notably CNS effects and seizure risk in susceptible patients)
• Stewardship guidelines favoring more targeted or narrower alternatives when appropriate

When does nalidixic acid lose exclusivity? Is it still under patent?

Nalidixic acid is long off primary patent protection in major markets. Today’s market is governed by:

• Generic regulatory approvals
• Product-specific patents, if any, on formulation/process in certain jurisdictions
• Brand-specific label exclusivities, if present historically, which do not extend the concept of new chemical entity exclusivity

What patent estate and IP barriers exist for nalidixic acid generics?

Nalidixic acid IP is not a practical barrier for entry in most markets because the active ingredient is mature and off-patent globally. Where barriers exist, they are typically:

• Weak or narrow formulation/process patents tied to specific manufacturing improvements
• Local, expired or near-expired secondary patents

Do formulation or method-of-use patents still matter?

In a mature drug like nalidixic acid, formulation patents can matter only when:

• A specific excipient system or particle engineering method is claimed
• A manufacturer relies on a distinct process that could be implicated in an infringement theory

For commercial planning, the dominant reality is that market access is more affected by regulatory clearance and supply continuity than enforceable chemical IP.

What is nalidixic acid’s regulatory status (FDA/EMA) and what does it imply for commercialization?

Nalidixic acid is not a major, actively supported UTI antibiotic in the US market under current standard therapy patterns. In the EU, historical authorization status and local availability vary. Commercial implications are:

• Limited investment appetite for new registration dossiers
• No meaningful pathway advantage for new entrants unless a local regulator supports renewed indications, formulations, or label expansions

How strong is nalidixic acid’s clinical evidence base today?

The evidence base is substantial historically but is not aligned with current guideline-centric development standards. That reduces the incentive for:

• Re-running late-phase trials
• Building contemporary comparative dossiers against modern stewardship-preferred options

What are the practical clinical use patterns in 2026?

• Use persists where older antibiotics remain on formularies and where local stewardship frameworks allow.
• In many markets, clinician preference has shifted toward other agents based on resistance patterns and safety profiles.

Market projection for nalidixic acid (2026–2031): base, downside, and upside

Base case: Flat to low-single-digit decline driven by:

• Competitive generic erosion
• Antibacterial stewardship shifts
• Gradual substitution to newer guideline-preferred antibiotics

Downside case: Mid-single-digit declines if:

• Additional policy restrictions tighten older fluoroquinolone use
• Availability reduces due to manufacturer rationalization

Upside case: Marginal stabilization or slight growth if:

• Local procurement continues for older regimens in certain UTI niches
• Resistance landscapes increase reliance on older agents in constrained settings

Key projection drivers by category

• Regulatory: label restrictions and availability
• Clinical: guideline alignment and stewardship protocols
• Competitive: generic price compression and supply chain stability
• Safety perception: substitution away from older fluoroquinolones where stewardship is strict

What are the generic entry risks for nalidixic acid?

Low IP risk, moderate regulatory risk, and material commercial execution risk. Risks include:

• Submission and approval timelines in specific countries
• Supplier qualification and batch release costs
• Rapid price erosion post-approval
• Potential label tightening that reduces treatable populations

Manufacturing/IP barriers

• Manufacturing barriers are typically not chemical synthesis bottlenecks for nalidixic acid because the molecule is mature.
• The binding constraint is quality system execution and regulatory compliance, plus ability to compete at low tender prices.

How does nalidixic acid compare with other UTI antibiotics in commercial attractiveness?

Nalidixic acid underperforms newer agents in innovation-led commercial attractiveness because:

• No modern development pipeline supports new indications
• Lower differentiation versus current standard-of-care alternatives
• Safety and stewardship limits reduce growth levers

Key Takeaways

• Nalidixic acid is a mature antibiotic with limited contemporary clinical trial activity and generic-driven market dynamics.
• Near-term market outlook is flat to declining as stewardship and standard-of-care preferences move toward other UTI regimens.
• IP is not a major barrier for generic competition; commercial outcomes hinge on regulatory approvals, supply continuity, and procurement pricing.
• Growth is unlikely without major regulatory label expansion or renewed evidence-led repositioning, which has not emerged as an active development theme in the current landscape.

FAQs

1. Is nalidixic acid still prescribed for UTIs in 2026?
2. Which countries still market nalidixic acid generics for urinary tract infections?
3. Does nalidixic acid have any active formulation patents that block generic entry?
4. What safety monitoring is most relevant to nalidixic acid in clinical practice?
5. How do antibiotic stewardship guidelines affect nalidixic acid availability and use?

References

1. FDA. Drug Approval Reports and related databases. U.S. Food and Drug Administration.
2. EMA. European Medicines Agency. EPAR and national authorization information.
3. ClinicalTrials.gov. Nalidixic acid search results. U.S. National Library of Medicine.
4. WHO. Antimicrobial stewardship and global guidance documents. World Health Organization.