CLINICAL TRIALS PROFILE FOR ISONIAZID

505(b)(2) Clinical Trials for isoniazid

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	NCT01589497 ↗	Essentiality of INH in TB Therapy	Completed	National Institute of Allergy and Infectious Diseases (NIAID)	Phase 2	2015-06-30	Tuberculosis (TB) disease is caused by bacteria that have infected the lung. TB bacteria are very small living agents that are spread by coughing and can be killed by taking TB drugs. To kill these TB bacteria TB patients have to take a combination of four drugs for 2 months and then two drugs for a further 4 months. During the first 2 months patients take rifampicin, isoniazid, ethambutol, and pyrazinamide. After that patients take only isoniazid and rifampicin for a further 4 months, making a total of 6 months therapy. In A5307 the investigators wanted to test a new combination of drugs to see if the investigators could treat TB faster in the future. Studies in animals have suggested that one of the four drugs, isoniazid, only works for a few days and may not be needed after the first two doses of TB treatment to kill the TB bacteria. After that its effects wear off to the point that it may even interfere with the other drugs. The investigators wanted to see if stopping isoniazid early, or using moxifloxacin, a different drug, instead could treat TB faster. This study was the first time that this type of regimen without isoniazid had been tested in humans. If the investigators could show that isoniazid stops working after a few days, the investigators could then try to see if they could possibly make a better tuberculosis treatment in the future.
New Combination	NCT01589497 ↗	Essentiality of INH in TB Therapy	Completed	AIDS Clinical Trials Group	Phase 2	2015-06-30	Tuberculosis (TB) disease is caused by bacteria that have infected the lung. TB bacteria are very small living agents that are spread by coughing and can be killed by taking TB drugs. To kill these TB bacteria TB patients have to take a combination of four drugs for 2 months and then two drugs for a further 4 months. During the first 2 months patients take rifampicin, isoniazid, ethambutol, and pyrazinamide. After that patients take only isoniazid and rifampicin for a further 4 months, making a total of 6 months therapy. In A5307 the investigators wanted to test a new combination of drugs to see if the investigators could treat TB faster in the future. Studies in animals have suggested that one of the four drugs, isoniazid, only works for a few days and may not be needed after the first two doses of TB treatment to kill the TB bacteria. After that its effects wear off to the point that it may even interfere with the other drugs. The investigators wanted to see if stopping isoniazid early, or using moxifloxacin, a different drug, instead could treat TB faster. This study was the first time that this type of regimen without isoniazid had been tested in humans. If the investigators could show that isoniazid stops working after a few days, the investigators could then try to see if they could possibly make a better tuberculosis treatment in the future.
New Formulation	NCT02043314 ↗	A Bioequivalence Study of Two Different Dosages of Isoniazid Tablet Formulations in Human Healthy Volunteers	Completed	Oswaldo Cruz Foundation	Phase 1	2008-10-01	The recommended treatment for latent tuberculosis infection for adults is a daily dose of isoniazid 300mg during 6 months. In Brazil, isoniazid was formulated as 100 mg tables. The treatment duration and the high pill burden compromised patient adherence to the treatment. The Brazilian National Programme for Tuberculosis requested the development of a new 300mg isoniazid formulation. The aim of the study is to compare the bioavailability of the isoniazid 300mg new formulation and three 100mg tablets of the reference formulation. The study is a randomized, single dose, open label, fasting, two-phase crossover bioequivalence study with a wash out period of 7 days (>7 half-life) in 28 healthy human volunteers. For the determination of isoniazid in human plasma, the investigators developed and validated a sensitive, simple and rapid HPLC-MS/MS method. This will support the strategy adopted by the Brazilian National Program for Tuberculosis for the treatment of latent tuberculosis. The new formulation will increase patients' adherence to the treatment and quality of life. Medical doctors in Brazil should become aware of the new formulation and the new treatment strategy in order to prescribe the right medication and avoid errors that could result in a high frequency of adverse events. Future research studies should evaluate pharmacovigilance, acceptability of the new tablet formulation and its impact on the cure rate.

All Clinical Trials for isoniazid

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00000588 ↗	Chelation Therapy of Iron Overload With Pyridoxal Isonicotinoyl Hydrazone	Completed	National Heart, Lung, and Blood Institute (NHLBI)	Phase 2	1989-06-01	To demonstrate the safety and effectiveness of orally-administered pyridoxal isonicotinoyl hydrazone (PIH) for the chronic treatment of iron overload.
NCT00000588 ↗	Chelation Therapy of Iron Overload With Pyridoxal Isonicotinoyl Hydrazone	Completed	Case Western Reserve University	Phase 2	1989-06-01	To demonstrate the safety and effectiveness of orally-administered pyridoxal isonicotinoyl hydrazone (PIH) for the chronic treatment of iron overload.
NCT00000636 ↗	Prophylaxis Against Tuberculosis (TB) in Patients With Human Immunodeficiency Virus (HIV) Infection and Confirmed Latent Tuberculous Infection	Completed	National Institute of Allergy and Infectious Diseases (NIAID)	N/A	1969-12-31	To evaluate and compare the effectiveness of a 2-month regimen of rifampin and pyrazinamide versus a 1-year course of isoniazid (INH) to prevent the development of tuberculosis in patients who are coinfected with HIV and latent Mycobacterium tuberculosis (MTb). Current guidelines recommend 6 to 12 months of treatment with INH for purified protein derivative (PPD)-positive individuals. Problems with this treatment include compliance, adverse reaction, and the possibility of not preventing disease due to INH-resistant organisms. Studies suggest that two or three months of rifampin and pyrazinamide may be more effective than longer courses of INH. A two-month prevention course should help to increase compliance. In addition, the use of two drugs (rifampin and pyrazinamide) may help overcome problems with drug resistance.

Clinical Trial Conditions for isoniazid

Condition Name

Condition Name for isoniazid
Intervention	Trials
Tuberculosis	118
HIV Infections	29
Tuberculosis, Pulmonary	25

Condition MeSH

Condition MeSH for isoniazid
Intervention	Trials
Tuberculosis	213
Tuberculosis, Pulmonary	62
HIV Infections	41

Clinical Trial Locations for isoniazid

Trials by Country

Trials by Country for isoniazid
Location	Trials
United States	314
South Africa	79
China	78
Canada	50
Brazil	40

Trials by US State

Trials by US State for isoniazid
Location	Trials
California	28
New York	26
Texas	24
Illinois	20
Colorado	20

Clinical Trial Progress for isoniazid

Clinical Trial Phase

Clinical Trial Phase for isoniazid
Clinical Trial Phase	Trials
PHASE4	3
PHASE3	5
PHASE2	6

Clinical Trial Status

Clinical Trial Status for isoniazid
Clinical Trial Phase	Trials
Completed	108
Recruiting	42
Not yet recruiting	30

Clinical Trial Sponsors for isoniazid

Sponsor Name

Sponsor Name for isoniazid
Sponsor	Trials
National Institute of Allergy and Infectious Diseases (NIAID)	43
Centers for Disease Control and Prevention	22
Johns Hopkins University	15

Sponsor Type

Sponsor Type for isoniazid
Sponsor	Trials
Other	560
NIH	59
U.S. Fed	47

Last updated: May 20, 2026

Isoniazid Clinical Trials Update and Market Forecast (2026–2036): Patent, Exclusivity, and Competitive Landscape

Isoniazid is an established, off-patent anti-tuberculosis (TB) active ingredient used in first-line combination therapy. No current patent- or regulatory-led scarcity drivers are apparent for new entrants; market outcomes are driven by TB program demand, drug procurement cycles, quality supply, and manufacturing scale rather than near-term exclusivity cliffs.

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What is the current clinical trials landscape for isoniazid?

Direct clinical-trial activity for isoniazid as a standalone drug is limited because isoniazid’s role is standard-of-care and most contemporary research focuses on regimens and special populations.

Current trial themes

• Short-course TB regimens that use isoniazid-containing combinations as part of fixed-dose or regimen-level strategies.
• Drug-susceptible vs drug-resistant TB regimen optimization where isoniazid may be included or omitted depending on resistance patterns (notably INH resistance).
• Pharmacokinetics and dosing in pediatrics, pregnancy, and comorbidity populations.
• Safety and adherence work tied to regimen tolerability, including hepatotoxicity risk management (isoniazid-associated liver toxicity remains the main clinical constraint).

Featured snippet answer

• Clinical development for isoniazid centers on regimen optimization and special-population PK/safety rather than brand-new isoniazid molecules.

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Which isoniazid trials are active by indication (TB, MDR-TB, pediatric, pregnancy)?

Indication mapping used in trial registries

• Pulmonary TB, drug-susceptible
  • Regimen comparisons and implementation studies where isoniazid is a backbone component.
• Extrapulmonary TB
  • Regimen equivalence and outcome studies.
• Latent TB infection (LTBI)
  • Prevention strategies using isoniazid-based schedules, often compared with rifamycin-based regimens.
• Drug-resistant TB
  • INH resistance dynamics drive inclusion versus discontinuation of isoniazid in effective regimens.
• Pediatrics
  • PK-guided dosing and weight-band regimens, adherence tools, and palatability/safety.
• Pregnancy
  • Maternal-fetal safety and dosing consistency.

Commercial implication

• Even where isoniazid is “standard,” trial activity concentrates on how it is delivered within multi-drug regimens, which keeps the IP and manufacturing perimeter mostly at the formulation and combination-product level.

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How are isoniazid formulations and fixed-dose combinations being studied?

Most formulation work targets

• Bioavailability consistency and tablet/capsule stability under procurement and storage conditions.
• Pediatric usability (dose dispersibility, crushability, or granulation uniformity).
• Fixed-dose combinations (FDCs) for treatment programs seeking reduced pill burden.

Featured snippet answer

• Trials and development focus on regimen-grade reliability: stable, scalable, and program-suitable formulations for TB control.

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What patents protect isoniazid, and how much of the market is IP-controlled?

Core molecule

• Isoniazid is a legacy, small-molecule anti-TB drug with broad generic availability. The primary active ingredient is widely off-patent in major markets.

Where patenting still matters

• Formulations (specific excipient systems, release characteristics, pediatric-dose forms).
• Manufacturing methods (granulation, compression, impurity control strategies).
• Combination products (fixed-dose multi-drug tablets/capsules that include isoniazid).

Featured snippet answer

• IP protection, where present today, is mostly on downstream product attributes, not on the isoniazid molecule itself.

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What is the Orange Book status of isoniazid in the US?

Isoniazid is an established active ingredient with many ANDA-filed products historically. Orange Book entries for active ingredient products typically show:

• Older patents expired or close to expired.
• Remaining listings, if any, are usually related to formulation/manufacturing claims in specific product lines rather than broad composition-of-matter.

Market impact

• Orange Book patent barriers have minimal effect on entry economics for conventional isoniazid tablets/capsules.

(No Orange Book listing identifiers are provided here because a complete, product-by-product status requires a drug-name-to-ANDA/NDA mapping that is not included in the available input.)

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When does isoniazid lose exclusivity, and what are the generic entry risks?

Featured snippet answer

• Isoniazid exclusivity has long since passed; current generic entry risk is dominated by regulatory approval and supply chain execution rather than patent expiration events.

Practical generic risks

• Quality systems and impurities: isoniazid impurity profiles and acceptable limits drive batch release.
• Bioequivalence: regimen program buyers often demand tight BE evidence for switching.
• FDC alignment: if demand shifts to isoniazid-containing FDCs, BE requirements and formulation equivalence become the gating items.

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What Paragraph IV challenges exist for isoniazid?

As an off-patent active ingredient, Paragraph IV litigation is not a meaningful near-term driver for isoniazid compared with newer branded antibiotics or disease-specific specialty drugs.

Market impact

• Buyer switching is typically procurement-driven rather than litigation-constrained.

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How strong is the patent estate for isoniazid-based products?

Estate strength assessment (high level)

• Molecule: weak to none for driving enforceable barriers.
• Formulations and combinations: moderate but narrow, often product-line specific.

Bottom line

• Patent-driven defensibility is limited; competitive advantage usually comes from cost, reliability of supply, and program relationships.

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How does isoniazid compare with rifamycin-based regimens in market dynamics?

Commercial substitution

• Many TB programs have shifted portions of LTBI and regimen preferences toward rifamycin-based schedules because of shorter duration, better adherence, or program logistics.

Competitive implication

• Even if isoniazid volumes remain stable as part of standard TB regimens, growth can be constrained by substitution toward regimens where isoniazid is reduced.

Featured snippet answer

• Isoniazid demand remains anchored in TB programs but can face volume pressure from regimen evolution.

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What is the regulatory and FDA pathway exposure for isoniazid generics?

US pathway

• Generic isoniazid products typically use the ANDA route with bioequivalence to reference listed drug(s).

Regulatory gating

• BE documentation, chemistry manufacturing controls (CMC), and impurity acceptance.
• For combination products: tighter alignment to fixed-dose specifications.

Commercial implication

• Regulatory time is less about exclusivity and more about manufacturing scale-up and dossier acceptance.

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What is the competitive landscape for isoniazid manufacturing and supply?

Market structure

• Large number of manufacturers across India, China, and other generic hubs.
• Procurement systems driven by tenders and panel lists (including global health procurement mechanisms).

Key differentiators that matter now

• Batch consistency and impurity control.
• Ability to supply large contract volumes on schedule.
• Regulatory history and audit performance.

Featured snippet answer

• The competitive bottleneck is manufacturing execution, not patent barriers.

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Market analysis: isoniazid demand drivers and revenue outlook

Key demand drivers

• Ongoing global TB incidence and treatment program scale.
• LTBI prevention strategies that still use isoniazid-based schedules in certain guidelines and settings.
• Multi-drug regimen standardization for drug-susceptible TB.
• Stock replenishment cycles and procurement-driven purchasing patterns.

Key headwinds

• Regimen evolution toward rifamycin-based strategies for LTBI and some TB prevention schedules.
• INH resistance reduces the effective role of isoniazid in drug-resistant TB regimens.
• Quality-driven consolidation: fewer suppliers may win top-tier panel contracts over time.

Pricing and margin reality

• Isoniazid is a low-cost commodity active ingredient; price compression is typical.
• Margin upside is most likely for:
  • reliable contract incumbents,
  • suppliers with strong audit outcomes,
  • and those with formulation specialization (e.g., pediatric-friendly or FDC offerings).

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How to project isoniazid market growth (2026–2036) using scenario ranges

Projection framework used (qualitative-to-quantitative structure)

• Baseline demand tracks TB program spending and treatment coverage.
• Adjust growth for substitution effects (rifamycin-based regimens) and INH resistance prevalence.
• Adjust supply-side constraints for compliance and capacity additions.

Scenarios

• Base case: low single-digit CAGR driven by procurement replacement cycles and stable TB program demand.
• Downside: mid single-digit decline/flat volumes in markets shifting away from INH schedules for LTBI and where INH resistance reduces effective use.
• Upside: modest growth if program emphasis maintains isoniazid-based regimens plus increased pediatric and adherence-focused formulation penetration.

Featured snippet answer

• Expect flat-to-low-growth global volumes in the next decade, with the strongest growth pockets tied to regimen inclusion stability and FDC/pediatric formulation adoption.

(No numeric market size is provided because the input does not include any source datasets or figures, and producing a precise revenue forecast without cited market baselines would not meet a hard-data standard.)

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What market exposure does isoniazid face by geography and procurement structure?

US and EU

• Primarily generic; market depends on supply reliability and formulary coverage.
• Substitution trends in LTBI regimens can dampen incremental growth.

India and China

• Large internal demand and export manufacturing base.
• Competitive intensity is high; outcomes depend on cost and quality audit performance.

Global health procurement markets

• Tenders and panel lists drive volume swings.
• Supplier qualification and post-market quality performance dominate.

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What commercial opportunities exist for isoniazid outside “plain tablets”?

• Pediatric-optimized dosing forms (improved usability).
• FDC products designed for program logistics.
• Stable, low-impurity specifications aligned to stringent procurement requirements.
• Anti-tuberculosis pack-based adherence solutions (where allowed and commercially feasible).

Featured snippet answer

• The most bankable “growth lever” is product usability and program fit, not new clinical efficacy.

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Key Takeaways

• Isoniazid clinical development is mostly regimen-level optimization and special-population PK/safety rather than new molecular entities.
• The isoniazid molecule is off-patent; exclusivity is not a near-term barrier to generic entry.
• Competitive pressure remains structurally high; supplier advantage comes from manufacturing reliability, regulatory acceptance, and procurement performance.
• Market growth is expected to be flat-to-low single digit under base-case assumptions, with substitution toward rifamycin-based LTBI regimens and INH resistance shaping upside/downside.

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FAQs

1. Which TB regimens still rely on isoniazid as a backbone therapy?
2. Do isoniazid fixed-dose combinations have different regulatory and CMC requirements than single-ingredient tablets?
3. How does INH resistance change the role of isoniazid in drug-resistant TB regimens?
4. What formulation attributes (impurity control, dissolution, pediatric usability) most affect isoniazid procurement approvals?
5. What are the main quality-system risks that cause isoniazid generic batch rejection during tender cycles?

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References

1. WHO. Global tuberculosis report. World Health Organization. (Latest edition at time of publication).
2. FDA. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. U.S. Food and Drug Administration.
3. ClinicalTrials.gov. Isoniazid (Search results). U.S. National Library of Medicine.