TOLAZAMIDE Drug Patent Profile

Which patents cover Tolazamide, and when can generic versions of Tolazamide launch?

Tolazamide is a drug marketed by Barr, Chartwell Rx, Cosette, Duramed Pharms Barr, Interpharm, Natco, Par Pharm, Sun Pharm Industries, Superpharm, Usl Pharma, and Watson Labs. and is included in thirty NDAs.

The generic ingredient in TOLAZAMIDE is tolazamide. There is one drug master file entry for this compound. Additional details are available on the tolazamide profile page.

Summary for TOLAZAMIDE

US Patents:	0
Applicants:	11
NDAs:	30
Raw Ingredient (Bulk) Api Vendors:	1
Clinical Trials:	3
Patent Applications:	4,571
DailyMed Link:	TOLAZAMIDE at DailyMed

Recent Clinical Trials for TOLAZAMIDE

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
Canadian Institutes of Health Research (CIHR)
Canadian Network for Observational Drug Effect Studies, CNODES
Drug Safety and Effectiveness Network, Canada

See all TOLAZAMIDE clinical trials

Medical Subject Heading (MeSH) Categories for TOLAZAMIDE

Hypoglycemic Agents

Anatomical Therapeutic Chemical (ATC) Classes for TOLAZAMIDE

A10BB	Sulfonylureas
A10B	BLOOD GLUCOSE LOWERING DRUGS, EXCL. INSULINS
A10	DRUGS USED IN DIABETES
A	Alimentary tract and metabolism

US Patents and Regulatory Information for TOLAZAMIDE

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Watson Labs	TOLAZAMIDE	tolazamide	TABLET;ORAL	070244-001	Aug 1, 1986		DISCN	No	No
Watson Labs	TOLAZAMIDE	tolazamide	TABLET;ORAL	070242-001	Aug 1, 1986		DISCN	No	No
Watson Labs	TOLAZAMIDE	tolazamide	TABLET;ORAL	070515-001	Jan 9, 1986		DISCN	No	No
Watson Labs	TOLAZAMIDE	tolazamide	TABLET;ORAL	070513-001	Jan 9, 1986		DISCN	No	No
Barr	TOLAZAMIDE	tolazamide	TABLET;ORAL	070162-001	Jan 14, 1986		DISCN	No	No

Tolazamide Market Dynamics, Patent Status, FDA Regulation, and Financial Trajectory

Last updated: September 9, 2026

Tolazamide is a legacy first-generation sulfonylurea with minimal current commercial value. Its historical brand, Tolinase, has been discontinued, while generic tolazamide products have had limited or no sustained U.S. market presence. The drug has no meaningful active patent barrier, no biosimilar exposure, and no material contemporary licensing or Paragraph IV litigation profile. Commercial decline has been driven by therapeutic substitution, safety concerns, low pricing, and weak manufacturer incentives.

What is the current FDA status of tolazamide?

Tolazamide was approved for the treatment of adults with type 2 diabetes as an adjunct to diet and exercise. It is an oral sulfonylurea that stimulates pancreatic insulin secretion and is effective only when residual beta-cell function remains.

The FDA-approved product category includes 100 mg, 250 mg, and 500 mg tablets. Historical labeling identified the drug for patients with non-insulin-dependent diabetes whose hyperglycemia could not be controlled adequately with diet alone. It was not indicated for type 1 diabetes or diabetic ketoacidosis. [1]

The commercial status is materially different from the historical approval status:

Regulatory or commercial attribute	Tolazamide status
Active ingredient	Tolazamide
Drug class	First-generation sulfonylurea
Historical brand	Tolinase
Dosage form	Immediate-release oral tablets
Historical strengths	100 mg, 250 mg, 500 mg
FDA pathway	Legacy NDA and subsequent generic approvals
Current U.S. brand marketing	Discontinued
Active patent barrier	None of material commercial significance
Biosimilar exposure	None
Current market position	Niche, limited, or commercially inactive
Primary therapeutic alternatives	Metformin, glipizide, glimepiride, glyburide, insulin, GLP-1 receptor agonists, SGLT2 inhibitors

FDA drug databases and labeling repositories continue to document tolazamide as an approved drug substance and historical product, but approval documentation does not establish active commercial distribution. A product can remain listed in regulatory databases after commercial discontinuation. [2]

When does tolazamide lose exclusivity?

Tolazamide lost practical market exclusivity decades ago. The drug predates the modern Hatch-Waxman patent and generic-competition framework, and its historical market was subsequently supplied by generic manufacturers.

No active tolazamide patent estate appears to restrict generic entry in the United States. The relevant commercial question is therefore not patent expiry but whether a manufacturer has sufficient demand to support production, regulatory maintenance, distribution, and pharmacovigilance costs.

What patents protect tolazamide?

No commercially relevant composition-of-matter patent remains in force for tolazamide. The molecule is an old small-molecule sulfonylurea, and any original compound patent protection expired long ago.

The likely patent profile is:

Patent category	Current commercial relevance
Composition of matter	Expired
Basic formulation	Expired or irrelevant
Immediate-release tablet	No meaningful barrier
Method of treating type 2 diabetes	Expired or unenforceable as a market barrier
Manufacturing process	No known blocking estate
Combination therapy	No material tolazamide-specific estate
Patent-term extension	Not commercially relevant
Orange Book-listed patents	No meaningful active barrier identified

Tolazamide also lacks the formulation complexity found in extended-release products, injectable delivery systems, transdermal systems, or biologic therapies. Its tablet formulation does not create a durable intellectual-property moat.

What is the Orange Book status of tolazamide?

The Orange Book is unlikely to provide a current patent-based barrier to tolazamide generic entry. Historical tolazamide products may appear in FDA product records even when their manufacturers no longer market them.

The principal Orange Book implications are:

1. No active listed patent is expected to delay an abbreviated new drug application.
2. A new generic applicant would generally face product development and regulatory execution issues rather than patent litigation.
3. A Paragraph IV certification would have limited practical value if no blocking patent were listed.
4. The lack of active commercial reference-product competition can still create regulatory and sourcing complications, depending on the status of the reference product and available FDA comparators.

FDA Orange Book listings must be distinguished from actual marketplace availability. The Orange Book reports approved drug products and patent or exclusivity information; it does not guarantee active wholesale distribution or pharmacy stocking. [3]

How many patents cover tolazamide?

No material active patent estate is identifiable for tolazamide as a marketed product. The relevant number for commercial planning is effectively zero blocking U.S. patents.

This is a very different profile from newer diabetes products:

Drug	Patent position	Commercial protection
Tolazamide	No meaningful active barrier	None
Metformin immediate-release	Legacy generic	None
Glipizide	Legacy generic	None
Glimepiride	Legacy generic	None
Semaglutide	Active composition, formulation, and use claims in major jurisdictions	Substantial
Empagliflozin	Multiple active or recently active patent positions depending on jurisdiction	Substantial
Tirzepatide	Active composition and use patent estate	Substantial

For tolazamide, freedom to operate is comparatively straightforward. The principal diligence issues are formulation equivalence, API quality, regulatory status, and manufacturing economics.

What caused tolazamide’s market decline?

Tolazamide’s decline reflects therapeutic substitution rather than a patent cliff tied to a single event.

Clinical substitution

Tolazamide was displaced first by later-generation sulfonylureas and then by non-sulfonylurea therapies. Glipizide and glimepiride offered more convenient dosing and became more familiar to prescribers. Metformin became the standard initial pharmacologic therapy for most adults with type 2 diabetes because of its efficacy, low cost, weight neutrality, and established clinical evidence. [4]

Sulfonylureas also became less attractive as treatment guidelines placed greater emphasis on cardiovascular, renal, weight, and hypoglycemia outcomes. Current diabetes standards prioritize agents such as GLP-1 receptor agonists and SGLT2 inhibitors for selected patients with cardiovascular disease, heart failure, chronic kidney disease, or obesity. [5]

Safety and tolerability

Tolazamide carries class-related hypoglycemia risk. Historical FDA labeling also discussed concerns regarding cardiovascular mortality associated with oral hypoglycemic agents based on the University Group Diabetes Program findings. [1]

The drug has other commercial disadvantages:

• Weight gain risk.
• Dependence on residual pancreatic beta-cell function.
• Reduced usefulness as type 2 diabetes progresses.
• Hypoglycemia risk in older adults and patients with impaired renal or hepatic function.
• Limited differentiation from cheaper and more widely used alternatives.

Distribution economics

A low-volume generic tablet can become commercially unavailable even without patent protection. Manufacturers must maintain validated processes, source active pharmaceutical ingredient, comply with current good manufacturing practice requirements, maintain pharmacovigilance systems, and manage inventory for a small patient population.

Tolazamide has limited pricing power because:

• The active ingredient is old.
• Multiple therapeutic substitutes exist.
• Payers have little reason to prefer it.
• Prescriber familiarity is low.
• Hospitals and pharmacies can substitute other sulfonylureas or metformin.
• Small volumes reduce manufacturing scale efficiency.

What is tolazamide’s financial trajectory?

Public companies do not generally report tolazamide revenue separately. The product has no identifiable current branded revenue stream, and any generic sales are likely immaterial at the consolidated-company level.

Period	Financial trajectory	Main driver
1960s-1970s	Branded prescription revenue	Adoption of oral sulfonylureas
1980s-1990s	Declining brand economics	Generic competition and newer sulfonylureas
2000s	Structural contraction	Metformin-centered treatment and broader generic substitution
2010s	Niche or intermittent generic activity	Low demand and limited manufacturer participation
2020s	Minimal or non-material reported revenue	Therapeutic displacement and possible product discontinuation

The product’s revenue trajectory is therefore best characterized as a long-term erosion curve rather than a recoverable patent-cliff opportunity.

A re-entry product could generate some revenue if a manufacturer became one of few suppliers. That opportunity would depend on sustained pharmacy demand, reimbursement, reliable API supply, and the absence of manufacturing competitors. It would not depend on premium pricing or exclusivity. A manufacturer would face the risk that demand is too low to cover fixed regulatory and supply-chain costs.

Are there Paragraph IV challenges or tolazamide patent lawsuits?

No material recent Paragraph IV challenge, patent lawsuit, or settlement agreement is associated with tolazamide’s current commercial position.

That outcome is predictable because:

• The relevant patents are old or expired.
• The drug has no meaningful brand franchise.
• Generic entry does not threaten a significant active revenue stream.
• A new applicant would not obtain a commercially valuable patent settlement if no blocking patent remained.

The absence of litigation does not indicate strong market demand. It reflects the absence of a valuable patent dispute.

What formulations are protected by tolazamide patents?

Tolazamide is primarily associated with conventional immediate-release tablets. No commercially meaningful extended-release, depot, injectable, inhaled, transdermal, or device-based formulation has established a separate market.

The formulation profile creates little opportunity for lifecycle management. A manufacturer could pursue a modified-release or combination product, but such a program would face:

• Limited clinical differentiation.
• A small addressable population.
• Competition from established diabetes products.
• The need for new clinical and bioequivalence evidence.
• Weak payer incentives.
• Low probability of recovering development costs.

The existing tablet is relatively simple to manufacture. That reduces technical barriers but also reduces defensibility.

Which companies are challenging tolazamide?

No major branded company is currently challenging tolazamide because there is no meaningful branded franchise to attack. The competitive landscape consists primarily of therapeutic substitutes and potential generic suppliers.

Direct drug competition

Competitor	Competitive advantage over tolazamide
Metformin	Guideline preference, low cost, broad use
Glipizide	Greater prescribing familiarity and generic availability
Glimepiride	Once-daily dosing and later-generation positioning
Glyburide	Historical sulfonylurea familiarity
DPP-4 inhibitors	Lower hypoglycemia risk, although higher cost
GLP-1 receptor agonists	Weight loss and cardiometabolic benefits
SGLT2 inhibitors	Cardiovascular and renal outcome advantages
Insulin	Use in advanced disease and severe hyperglycemia

Tolazamide is therefore exposed to substitution from both low-cost generic drugs and higher-value branded therapies.

What generic launch risks exist for tolazamide?

A new generic launch would face low patent risk but meaningful commercial risk.

Regulatory risk

The applicant would need to establish pharmaceutical equivalence and bioequivalence against the applicable reference product. If an actively marketed reference product is unavailable, regulatory planning may become more complicated.

Manufacturing risk

The drug is technically simpler than a biologic or complex formulation, but low production volume can make dedicated manufacturing uneconomic. API suppliers may also prioritize higher-volume sulfonylureas.

Commercial risk

Pharmacy benefit managers and wholesalers may not actively promote the product. A new entrant could encounter limited demand, low reimbursement, and rapid price compression if another supplier re-enters.

Clinical risk

Prescribing has shifted toward therapies with lower hypoglycemia risk or demonstrated cardiovascular and renal benefits. A new tolazamide product would have limited ability to change treatment patterns.

How does tolazamide compare with other legacy diabetes drugs?

Tolazamide has a weaker current commercial position than metformin and glipizide because those products retain broader guideline use and stronger supply-chain participation.

Attribute	Tolazamide	Metformin	Glipizide
Drug class	First-generation sulfonylurea	Biguanide	Second-generation sulfonylurea
Current guideline role	Limited	Foundational therapy	Add-on or alternative therapy
Hypoglycemia risk	Material	Low as monotherapy	Material
Weight effect	Gain possible	Neutral or modest loss	Gain possible
Patent barrier	None	None	None
Generic supply depth	Limited	Deep	Deep
Commercial attractiveness	Low	Moderate due to volume	Moderate due to volume
Strategic value	Low	High-volume generic	Established generic alternative

What is the geographic coverage of tolazamide?

Tolazamide’s commercial availability is likely uneven across jurisdictions. Legacy drugs can remain available in selected markets through local manufacturers while disappearing from the United States or other highly consolidated markets.

Geographic factors include:

• National registration status.
• Local treatment guidelines.
• Availability of alternative sulfonylureas.
• API sourcing.
• Government procurement practices.
• Pharmacy substitution rules.
• Manufacturer portfolio strategy.

No broad multinational growth platform is associated with tolazamide. Any remaining sales are more likely to arise from localized generic distribution than from coordinated global commercialization.

Key Takeaways

• Tolazamide is a legacy oral sulfonylurea with minimal current commercial value.
• The historical Tolinase brand has been discontinued.
• No meaningful active patent estate appears to block generic entry.
• Paragraph IV litigation and patent settlements are not material current issues.
• Financial decline resulted from therapeutic substitution, safety concerns, generic pricing, and low manufacturer incentives.
• Metformin, glipizide, glimepiride, GLP-1 receptor agonists, SGLT2 inhibitors, and insulin are the principal competitive alternatives.
• A generic relaunch would face low patent risk but substantial demand, reimbursement, supply, and regulatory execution risk.
• Tolazamide has no meaningful biosimilar risk because it is a conventional small-molecule drug.
• The asset has little licensing value unless bundled with a broader legacy-generic portfolio.

FAQs About Tolazamide Market and Patent Status

Is tolazamide still available by prescription?

Availability is limited and may vary by manufacturer, wholesaler, pharmacy, and country. Historical FDA approval does not establish continuous commercial distribution.

Is tolazamide more effective than metformin?

No broad modern treatment strategy gives tolazamide a preferred position over metformin. Metformin generally has stronger guideline support and a more favorable hypoglycemia and weight profile.

Can a company launch a generic version of tolazamide without patent litigation?

A launch would likely face little patent risk because the relevant intellectual-property protection is old. Regulatory, sourcing, and commercial viability are more significant barriers.

Does tolazamide have a 180-day generic exclusivity period?

A generic applicant could receive exclusivity only if it met the statutory requirements for first-filer status and other conditions. No current commercial opportunity should be assumed from historical generic exclusivity.

Is tolazamide included in modern diabetes treatment guidelines?

Tolazamide is not a leading modern treatment option. Current guidelines emphasize metformin and agents selected according to cardiovascular, renal, weight, hypoglycemia, and cost considerations. [5]

References

1. U.S. Food and Drug Administration. (n.d.). Tolazamide tablets prescribing information. FDA labeling archive.

2. U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs database. https://www.accessdata.fda.gov/scripts/cder/daf/

3. U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

4. UK Prospective Diabetes Study Group. (1998). Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes. The Lancet, 352(9131), 854-865.

5. American Diabetes Association Professional Practice Committee. (2025). Standards of care in diabetes - 2025. Diabetes Care, 48(Supplement 1).