TAPAZOLE Drug Patent Profile

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Which patents cover Tapazole, and what generic alternatives are available?

Tapazole is a drug marketed by King Pharms and King Pharms Llc and is included in two NDAs.

The generic ingredient in TAPAZOLE is methimazole. There is one drug master file entry for this compound. Twenty-one suppliers are listed for this compound. Additional details are available on the methimazole profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Tapazole

A generic version of TAPAZOLE was approved as methimazole by MYLAN on March 29^th, 2000.

Summary for TAPAZOLE

US Patents:	0
Applicants:	2
NDAs:	2
Raw Ingredient (Bulk) Api Vendors:	1
Clinical Trials:	3
Patent Applications:	4,525
Drug Prices:	Drug price information for TAPAZOLE
DailyMed Link:	TAPAZOLE at DailyMed

See drug prices for TAPAZOLE

See drug sales revenues for TAPAZOLE

Recent Clinical Trials for TAPAZOLE

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

Sponsor	Phase
Case Comprehensive Cancer Center	Phase 2
Emory University	Early Phase 1
University of Pisa	N/A

See all TAPAZOLE clinical trials

US Patents and Regulatory Information for TAPAZOLE

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
King Pharms	TAPAZOLE	methimazole	TABLET;ORAL	007517-002	Approved Prior to Jan 1, 1982		DISCN	Yes	No
King Pharms Llc	TAPAZOLE	methimazole	TABLET;ORAL	040320-002	Mar 31, 2000		DISCN	No	No
King Pharms	TAPAZOLE	methimazole	TABLET;ORAL	007517-004	Approved Prior to Jan 1, 1982		DISCN	Yes	No

Tapazole (Methimazole) Market Dynamics, Patent Status, and Financial Trajectory

Last updated: October 6, 2026

Tapazole is the branded U.S. formulation of methimazole, an antithyroid medicine used mainly for Graves' disease and hyperthyroidism. Its commercial position is mature and largely genericized. The active ingredient has no meaningful remaining composition-of-matter exclusivity, Tapazole has limited standalone revenue disclosure, and market value is concentrated in low-cost generic methimazole rather than the historical brand.

What is Tapazole and how is it used?

Tapazole contains methimazole, a thionamide that inhibits thyroid hormone synthesis. FDA labeling covers treatment of hyperthyroidism, including Graves' disease and toxic multinodular goiter, and preparation of patients for thyroidectomy or radioactive iodine therapy.[1]

Tapazole is supplied as oral tablets, historically in 5 mg and 10 mg strengths. Generic methimazole is widely available in the same strengths. Clinical demand is recurring because Graves' disease and other hyperthyroid conditions require months to years of treatment in some patients.

Product characteristic	Tapazole
Active ingredient	Methimazole
Therapeutic class	Thionamide antithyroid drug
Primary use	Hyperthyroidism and Graves' disease
Dosage form	Oral tablet
Common strengths	5 mg and 10 mg
FDA regulatory pathway	Original new drug application
Generic competition	Extensive
Biosimilar exposure	None
Prescription status	Prescription drug

Methimazole is generally preferred over propylthiouracil for many nonpregnant adults because of dosing convenience and a more favorable hepatic safety profile. Propylthiouracil remains an alternative in selected circumstances, including some first-trimester pregnancy cases and thyroid storm management.[2]

What is the FDA and Orange Book status of Tapazole?

Tapazole is an older approved drug with no current exclusivity profile comparable to recently approved products. The FDA Orange Book identifies approved methimazole products across multiple manufacturers, while the brand product has limited commercial relevance relative to generic tablets.[3]

The original Tapazole approval dates to the early era of FDA drug regulation. Its regulatory value comes from continued approval and labeling history, not from current market exclusivity. The product is not a biologic and is not subject to the biosimilar framework under the Public Health Service Act.

Does Tapazole have FDA exclusivity?

No commercially significant FDA exclusivity period remains for Tapazole. Any original approval exclusivity expired decades ago. The product also has no practical new chemical entity exclusivity because methimazole has been marketed for many decades.

FDA approval of generic methimazole products allows multiple manufacturers to compete through abbreviated new drug applications. Generic applicants generally rely on the reference product's established safety and efficacy record while demonstrating pharmaceutical equivalence and bioequivalence.

Is Tapazole listed in the Orange Book?

Methimazole products are represented in FDA approval and therapeutic-equivalence records. The brand's current listing and marketing status can change as sponsors discontinue, transfer, or update products. Orange Book records should be read together with FDA discontinued-drug records and current labeling databases because a discontinued brand presentation can remain relevant as a reference product for generic approval history.[3][4]

No active, high-value patent position is generally associated with the mature Tapazole tablet market.

What patents protect Tapazole and methimazole?

The core methimazole molecule is long off-patent. The original chemical and product protection periods expired before the current generic market developed. No active composition-of-matter patent is expected to block generic methimazole tablets in the United States.

Protection category	Current commercial impact
Methimazole composition patent	Expired
Original Tapazole product protection	Expired
New chemical entity exclusivity	Expired
Tablet formulation patents	No material blocking estate identified for standard tablets
Method-of-use patents	No material blocking estate identified for standard hyperthyroidism treatment
Manufacturing patents	Potentially relevant to individual suppliers, not a broad market barrier
Orange Book-listed patent barrier	No meaningful barrier identified
Biosimilar exclusivity	Not applicable

Are there Tapazole formulation patents?

Standard immediate-release methimazole tablets are mature products. Their formulation technology is conventional and does not create a meaningful barrier to entry comparable to extended-release, injectable, depot, or complex delivery products.

A supplier could hold process, excipient, packaging, or manufacturing know-how that is not publicly important to the broader market. Such rights would affect a particular manufacturer rather than protect the Tapazole franchise as a whole.

Are there methimazole method-of-use patents?

The principal uses of methimazole, including treatment of hyperthyroidism and Graves' disease, are established clinical applications. They are not commercially protected by a broad, enforceable method-of-use estate that would prevent generic prescribing.

When does Tapazole lose exclusivity?

Tapazole lost practical market exclusivity decades ago. Generic methimazole is now the dominant competitive structure, and the brand cannot rely on patent protection to preserve price or share.

The relevant exclusivity timeline is:

Period	Event and market implication
Original approval era	Tapazole entered the market as a branded methimazole product
Subsequent decades	Original regulatory and patent protections expired
Generic entry period	Multiple manufacturers began supplying methimazole tablets
Current market	Generic competition determines price, availability, and share

The economic distinction is important. A product can remain FDA-approved and clinically recognized after it loses commercial exclusivity. Tapazole has retained therapeutic relevance while losing the pricing power associated with a protected brand.

How many patents cover Tapazole?

No material active U.S. patent estate is generally associated with the standard Tapazole tablet. The commercially relevant protection count is effectively zero for composition, basic tablet formulation, and established hyperthyroidism indications.

That assessment does not eliminate the possibility of supplier-specific process patents, trademarks, or nonpublic manufacturing know-how. Those rights do not create a broad barrier against generic methimazole.

Which companies are challenging Tapazole?

Generic manufacturers have already challenged the historical exclusivity of Tapazole through the ordinary U.S. generic approval pathway. The market is therefore in the post-challenge phase rather than an early Paragraph IV litigation phase.

Publicly important competitive pressure comes from approved generic methimazole suppliers, including manufacturers that sell 5 mg and 10 mg tablets through wholesalers, pharmacies, hospitals, and government channels. The number of suppliers can change because generic manufacturers enter, exit, transfer approvals, or experience manufacturing constraints.

Are there current Paragraph IV challenges to Tapazole?

A current high-value Paragraph IV campaign is not a defining feature of the Tapazole market. Paragraph IV litigation is most economically important before generic entry, when a patent holder can delay approval or negotiate a launch date. Tapazole's core protections expired too long ago for that model to drive current market economics.

Any historical ANDA litigation would have limited present value unless it affected an active product presentation or a remaining formulation right.

What is the financial trajectory for Tapazole?

Tapazole's standalone financial trajectory is not publicly transparent because sponsors do not generally report brand-level revenue for this mature product. The available commercial conclusion is that branded Tapazole revenue is structurally constrained by generic substitution, low unit prices, and limited differentiation.

Revenue drivers

Methimazole demand is supported by:

• Continued diagnosis of Graves' disease and other hyperthyroid disorders.
• Long-term medical management for patients who do not undergo definitive therapy.
• Preoperative treatment before thyroidectomy.
• Preparation before radioactive iodine treatment.
• Recurring prescriptions in endocrinology and primary care.

Revenue constraints

The principal constraints are:

• Generic methimazole substitution.
• Low tablet prices.
• Lack of patent protection.
• Limited formulation differentiation.
• Availability of definitive alternatives, including radioactive iodine and surgery.
• Absence of a premium delivery system or specialty distribution model.

The market can grow in prescription volume while remaining flat or declining in dollar value. That pattern is common in mature genericized medicines: patient demand rises, but unit prices and brand share fall.

Financial variable	Expected direction for Tapazole brand	Rationale
Prescription demand for methimazole	Stable to modestly increasing	Chronic disease prevalence and diagnosis
Brand share	Declining or minimal	Generic substitution
Average selling price	Downward pressure	Multiple generic suppliers
Gross margin	Lower than protected-brand historical levels	Commodity pricing
Standalone revenue visibility	Low	No consistent public product-level reporting
Generic market value	Stable to modest growth	Volume offsets price erosion
Licensing value	Low	No clear exclusivity asset

What is the revenue exposure for the manufacturer?

Revenue exposure is likely immaterial at the level of a diversified pharmaceutical company unless the sponsor has a concentrated generic portfolio or temporary supply advantage. Tapazole is not comparable to a protected specialty product with billions of dollars in annual sales.

The more relevant economic asset is an approved methimazole supply position. A manufacturer can earn revenue through reliable availability, wholesaler relationships, hospital contracts, and temporary competitor shortages. Those advantages are operational rather than patent-driven.

How strong is the Tapazole patent estate?

The Tapazole patent estate is weak from an exclusivity and litigation perspective. Its commercial strength depends on supply execution, manufacturing cost, regulatory compliance, and distribution.

Estate dimension	Assessment
Composition-of-matter protection	None of current commercial significance
Patent term remaining	None of commercial significance
Formulation protection	Weak or absent for standard tablets
Method-of-use protection	Weak or absent
Manufacturing barriers	Moderate only where supplier-specific
Regulatory barrier	Low for established generic products
Brand recognition	Historically established but commercially limited
Litigation leverage	Low
Pricing power	Low

A generic supplier with an approved application can compete without overcoming a meaningful patent wall. The principal risks are FDA compliance, manufacturing interruptions, active pharmaceutical ingredient sourcing, and commercial contracting.

What generic entry risks exist for Tapazole?

Generic entry risk is already realized rather than prospective. The more relevant risk is continued price erosion and substitution among generic suppliers.

Generic launch scenarios

Scenario	Market effect
Additional generic entrant	Lower prices and reduced share for existing suppliers
Supplier exit	Temporary price firming and possible availability pressure
Manufacturing warning or recall	Short-term shortage risk and channel disruption
Stable multi-supplier market	Persistent low prices and limited margins
Brand relaunch	Limited adoption unless supported by clear supply or clinical differentiation
New formulation	Potential niche value, but would require meaningful clinical or economic advantage

A new Tapazole launch would face a difficult reimbursement environment. Payers and pharmacies generally favor lower-cost generic methimazole unless the branded product offers a distinct dosage, supply reliability, or patient-service benefit.

What manufacturing and intellectual-property barriers affect methimazole?

Manufacturing barriers are more important than patent barriers. Methimazole tablets require compliant active pharmaceutical ingredient sourcing, validated formulation processes, content uniformity, stability testing, packaging controls, and FDA-compliant quality systems.

Potential supply risks include:

• Dependence on a limited number of active pharmaceutical ingredient suppliers.
• FDA manufacturing observations or warning letters.
• Batch failures and recalls.
• Contract manufacturing capacity constraints.
• Inventory reductions caused by low-margin economics.
• Wholesaler concentration.
• Demand spikes linked to competitor shortages.

These issues can create short-term pricing opportunities for a supplier with available inventory. They do not create durable market exclusivity.

How does Tapazole compare with competing hyperthyroidism treatments?

Tapazole competes with both pharmacologic and definitive treatments. Methimazole is usually the principal chronic oral therapy, but the treatment decision depends on age, pregnancy status, disease severity, patient preference, and the likelihood of remission.

Treatment	Competitive position
Generic methimazole	First-line oral option for many adults; low cost
Branded Tapazole	Same active ingredient as generic methimazole; limited differentiation
Propylthiouracil	Alternative in selected patients; greater liver-safety concerns
Radioactive iodine	Definitive treatment; eliminates the need for chronic antithyroid therapy in many patients
Thyroidectomy	Definitive treatment; used when anatomy, severity, pregnancy planning, or patient preference supports surgery
Beta blockers	Symptom control, not a substitute for antithyroid treatment

Methimazole's main competitive advantage is clinical familiarity and low cost. Its main commercial disadvantage is the absence of product differentiation.

What litigation and settlement agreements affect Tapazole?

No major current patent litigation or settlement agreement appears to control the commercial timing of generic methimazole. The market is mature, and generic entry has already occurred.

Historical disputes involving old drug products may remain in court records, but they have limited effect on current investment or licensing decisions unless they concern an active formulation, an enforceable process patent, or a live regulatory application.

For diligence purposes, the relevant legal review should focus on:

1. Current Orange Book entries.
2. FDA approval and discontinuation records.
3. Product liability and manufacturing litigation.
4. Supply agreements and contract manufacturing terms.
5. Any active trademark or unauthorized-branding disputes.

What is the competitive landscape for Tapazole?

The market is fragmented among generic manufacturers and distributors. Competition is based on price, supply continuity, wholesaler access, quality history, and purchasing contracts.

Brand equity has limited value because prescribers can select generic methimazole by active ingredient. A sponsor seeking growth would need to compete through one of four routes:

• Lower-cost manufacturing.
• Superior supply reliability.
• A differentiated dosage form.
• A specialty-market strategy tied to adherence or patient support.

A conventional brand relaunch without differentiation would face limited commercial upside.

What is the outlook for Tapazole and methimazole?

Methimazole should remain clinically relevant because hyperthyroidism is a recurring and chronic treatment market. The product's financial outlook is different from its clinical outlook. Patient use can remain stable while brand revenue remains low.

The base case is a mature generic market with modest volume growth, continuing price pressure, and periodic supply disruptions. Upside would come from a shortage, a differentiated formulation, or a concentrated supplier position. Downside would come from further generic entry, reimbursement reductions, or a shift toward definitive treatment.

Key Takeaways

• Tapazole is the branded methimazole tablet product used for hyperthyroidism and Graves' disease.
• Generic methimazole dominates the U.S. commercial market.
• The core methimazole composition and original Tapazole protections expired decades ago.
• No material active patent estate is expected to block standard generic tablets.
• Current Paragraph IV litigation is not a central market driver.
• Tapazole has no biosimilar exposure because it is a small-molecule drug.
• Standalone brand revenue is not generally disclosed and is likely limited by generic substitution.
• Market value depends more on manufacturing reliability and distribution than on intellectual property.
• Methimazole demand should remain stable to modestly growing, while branded pricing power remains weak.
• Radioactive iodine, thyroidectomy, propylthiouracil, and generic methimazole define the competitive environment.

FAQs

Is Tapazole still commercially available in the United States?

Methimazole remains available in the United States through generic products. The availability of a specific Tapazole-branded presentation depends on the sponsor's current marketing status and distribution activity.

Is methimazole the same as Tapazole?

Yes. Tapazole is a brand name for methimazole. Generic methimazole tablets contain the same active ingredient and are used for the same principal indications.

Can a company obtain a new patent for a methimazole formulation?

A new patent could potentially cover a genuinely novel formulation, delivery system, manufacturing process, or clinical use if it meets patentability requirements. A conventional immediate-release methimazole tablet would face substantial novelty and obviousness challenges.

Does Tapazole have orphan-drug protection?

Tapazole is not commercially dependent on orphan-drug protection. Its principal use in hyperthyroidism is an established indication, and no current orphan exclusivity is central to the product's market position.

What would increase the value of a methimazole asset?

The strongest value drivers would be a differentiated dosage form, a clinically meaningful adherence advantage, reliable supply during shortages, or a low-cost manufacturing platform. A conventional branded tablet without exclusivity would have limited licensing value.

References

1. U.S. Food and Drug Administration. (n.d.). Tapazole (methimazole) tablets prescribing information. FDA. https://www.accessdata.fda.gov/drugsatfda_docs/label/

2. Ross, D. S., Burch, H. B., Cooper, D. S., Greenlee, M. C., Laurberg, P., Maia, A. L., Rivkees, S. A., Samuels, M., Sosa, J. A., Stan, M. N., & Walter, M. A. (2016). 2016 American Thyroid Association guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid, 26(10), 1343-1421. https://doi.org/10.1089/thy.2016.0229

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

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