When will the patents on TAPAZOLE expire, and when will TAPAZOLE go generic?

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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	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
King Pharms Llc	TAPAZOLE	methimazole	TABLET;ORAL	040320-002	Mar 31, 2000		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
King Pharms	TAPAZOLE	methimazole	TABLET;ORAL	007517-004	Approved Prior to Jan 1, 1982		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
King Pharms Llc	TAPAZOLE	methimazole	TABLET;ORAL	040320-001	Mar 31, 2000		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Exclusivity Expiration

Last updated: July 6, 2026

Tapazole (Methimazole) Investment Scenario and Patent/Exclusivity Fundamentals Analysis

Tapazole (methimazole) is an off-patent, legacy oral small molecule used for hyperthyroidism. The investment case is driven almost entirely by (1) ongoing demand stability for antithyroid drugs, (2) generic price dynamics and formulary positioning, and (3) the residual legal risk from any remaining brand-specific Orange Book listings (if present) rather than new exclusivity. Patent upside is typically limited for methimazole tablets; commercial differentiation tends to come from supply reliability, dosage strength coverage, and product-claims value rather than novel IP.

If the current U.S. market is served by fully generic products with no active brand-protecting patents or exclusivity tethered to a specific brand label, the “brand” investment is usually a value-protection or cash-flow profile, not an R&D growth profile.

What patents protect Tapazole (methimazole) in the US?

No actionable Tapazole-specific patent estate can be stated here without a reliable Orange Book and litigation mapping for the exact marketed product (strengths, dosage form, and label). For methimazole specifically, the active ingredient is historically old and commonly associated with early 20th-century chemistry and later formulation/packaging improvements, many of which expired long ago.

Investment implication: in most methimazole markets, the patent question resolves to “no meaningful active protection,” shifting valuation to competitive economics, manufacturing capacity, and distribution contracts.

Which patent types usually matter for antithyroid brands like Tapazole?

Active ingredient composition-of-matter: typically long expired for historical small molecules.
Formulation patents: may cover specific tablet compositions, release behavior, or excipient systems.
Method-of-use patents: may cover dosing regimens or therapeutic uses (but antithyroid dosing is usually generic practice).
Device or packaging patents: bottle child-resistant features are often not a durable brand moat.

When does Tapazole lose exclusivity in the US?

For a legacy molecule like methimazole, “exclusivity” is typically exhausted via:

expiration of the last relevant Orange Book-listed patent, and/or
expiration of any granted exclusivity periods tied to brand approvals (typically not relevant for older ANDAs).

Investment implication: exclusivity-driven revenue extension is usually not the driver. The practical timing risk is whether any still-listed brand patents create a barrier to generic entry.

What does “loss of exclusivity” translate to commercially?

Entry tends to accelerate after:
- the last listed patent expires, or
- a patent is found invalid/non-infringed, or
- a settlement allows sooner entry.
Subsequent pricing usually follows:
- rapid erosion for the first entrants,
- then consolidation around lowest cost suppliers and reliable manufacturers.

What is the Orange Book status of Tapazole (methimazole) by strength and dosage form?

A strength-by-strength Orange Book status table is not possible to produce accurately in this response without the actual Orange Book record list for Tapazole (including NDA holder/labeler, product numbers, and listed patents).

Investment implication: the Orange Book is the single source-of-truth for brand patent barriers in litigation and licensing strategy. Without it, any claim of “remaining protection” would not be decision-grade.

How strong is the patent estate for Tapazole (methimazole) and what barriers remain?

For methimazole, the likely structure of the estate (where any later patents exist) would be dominated by:

formulation or process improvements that protect a particular branded manufacturing route or excipient blend, or
narrow method-of-use claims.

Investment implication: for investors, the key is not whether patents exist in general, but whether they:

are still active today, and
map cleanly to a specific ANDA product with a current Paragraph IV or a controlled launch.

Absent that mapped data, the default investment view is that the product behaves like an off-patent generic commodity.

How does the strength profile usually score for legacy antithyroid small molecules?

Validity risk: high for old chemistry and broad claims.
Infringement risk: high due to generic formulation differences and multiple salt/grade sourcing.
Remedy timing: delayed unless there is active, specific ANDA litigation.

What generic entry risks exist for Tapazole (methimazole)?

If Tapazole’s U.S. supply is already primarily served by generics, the remaining entry risk is usually:

not “whether generics can enter,” but
“whether a specific supplier can remain competitive on cost and compliance,” and
“whether any remaining brand-listed patents still block certain strengths or labeling.”

Investment implication: the dominant downside is pricing and margin compression, not brand-specific legal blocking.

What drives pricing and margin compression in methimazole markets?

multiple generic suppliers with similar bioequivalence,
procurement-driven formulary selection,
tendering and contracting at large group purchasing organizations,
periodic manufacturing quality events.

Which companies sell methimazole and how does Tapazole compete commercially?

A decision-grade competitor map requires current labeling, distributor relationships, and NDC-level share data. That mapping is not provided here.

Investment implication: Tapazole’s competitiveness depends on:

whether it retains any managed-care or pharmacy channel preference versus generics,
whether it has reliable supply compared with the lowest-cost generics,
whether it maintains favorable rebate positions.

What formulation patents protect methimazole tablets, and do they create a moat?

For legacy oral tablets, formulation patents are often narrow:

excipient ratios,
particle size distribution,
tablet hardness/fracturability specs,
manufacturing process parameters.

Investment implication: unless formulation patents are still active and specifically listed for a brand’s product, they rarely create durable pricing power.

What would count as a durable formulation moat in this segment?

active Orange Book-listed formulation patents that are being asserted in litigation, and
ANDA products that must mirror the branded manufacturing approach to avoid infringement.

Without active listings and litigation linkage, formulation IP generally does not support a strong investment thesis.

What method-of-use patents exist for methimazole and hyperthyroidism dosing?

Method-of-use barriers are usually weak for historical dosing practices because:

clinical dosing ranges are standard,
labeling claims for antithyroid drugs are mature,
generic products can often claim under carved label instructions.

Investment implication: method-of-use IP rarely drives monetization for old small molecules unless a company can prove novel regimens tied to specific claims.

What Tapazole patent litigation affects generic launches in the US?

A litigation and settlement timeline requires docket-level data and Orange Book-to-ANDA linkage. That dataset is not included here.

Investment implication: if no active brand patents remain, generic launch “risk” turns into competitive and regulatory execution risk rather than legal block risk.

How should investors read litigation outcomes for legacy antithyroid brands?

Paragraph IV filings can indicate remaining brand protection even for commodity drugs.
Settlements with “carve-out” dates can delay some strengths or packaging configurations.
Consent decrees can lock in “at-risk” non-assert positioning that affects investor views on future generic pricing.

How does Tapazole compare with other antithyroid drugs (carbimazole, propylthiouracil) for investment drivers?

Tapazole competes within the therapeutic class:

Methimazole (Tapazole): standard for many adults with hyperthyroidism.
Propylthiouracil (PTU): often used in specific patient subsets (commonly referenced in pregnancy-related contexts in clinical practice).
Carbimazole: used outside the U.S. or in regions where available; in the U.S. the comparative landscape differs.

Investment implication: class-level demand stability helps mitigate unit volatility, but it does not protect margins once generics dominate methimazole tablets.

What is the FDA regulatory status of Tapazole (NDA, ANDA, bioequivalence, labeling)?

A current regulatory status summary is not possible without:

the NDA holder and approval history,
Orange Book product listing,
ANDA references and recent approvals.

Investment implication: for valuation, the relevant point is whether Tapazole has active brand exclusivity or enforceable Orange Book listings. For methimazole, the expectation in developed markets is off-patent behavior with generic dominance.

What FDA milestones or upcoming approvals could shift Tapazole’s outlook?

Milestones that can shift outlook include:

new NDA filings with brand differentiation,
approvals of new generic manufacturers that alter supply reliability,
label updates that affect payer coverage or therapeutic substitution.

Investment implication: without identifiable upcoming branded events or active generic entry schedules tied to litigation, the practical drivers remain supply and pricing cycles.

Commercial fundamentals: What revenue and margin exposure does Tapazole face?

For off-patent legacy products:

revenues depend on contracted channel volume and rebate structures,
margins face steady erosion as additional generics enter or supply improves.

Investment implication: the more important fundamental question becomes:

who controls supply reliability,
who holds the best contracted position,
whether manufacturing compliance disruptions create short-term price spikes.

A numeric revenue model cannot be provided here without actual financial disclosures, segment sales, or current market share datasets for Tapazole in the relevant geography.

Investment scenario: Base case, downside, and upside

Base case (most likely): “generic commodity” dynamics

continued generic penetration,
pricing pressure consistent with other legacy off-patent oral tablets,
demand stability from ongoing hyperthyroidism treatment needs.

Downside: “margin compression plus supply shocks”

lower net pricing due to stronger generic tendering,
compliance or manufacturing disruptions at a key supplier leading to temporary price volatility then normalization.

Upside: “brand resilience via formulary/rebate + supply reliability”

Tapazole retains channel preference due to contracting advantages or fewer supply interruptions,
sustained volume offsets margin pressure.

What to watch for (decision-grade):

Orange Book listings that remain active for Tapazole-specific strengths.
Any Paragraph IV litigation filings tied to the Tapazole label.
Any settlement-triggered “delayed generic” dates.
NDC-level supply and pricing moves in major wholesalers.

Key Takeaways

Tapazole (methimazole) is a legacy antithyroid oral therapy; the investment model is driven by generic competition and supply economics more than by patent-led exclusivity.
A precise patent/exclusivity view must be grounded in Tapazole’s Orange Book listings and any associated ANDA Paragraph IV records, including strength-level product mapping.
The core financial exposure is margin compression risk under commodity-like pricing, moderated by supply reliability and channel contracting.
Litigation can matter only if active Orange Book-listed patents remain and are tied to specific ANDA entries; absent that linkage, expect generic behavior.

FAQs

Do methimazole tablets have any remaining U.S. brand protection that blocks generics?
How do Paragraph IV filings for methimazole affect future pricing and launch timing?
What drives net pricing for legacy antithyroid generics versus brands in managed care?
Which manufacturing compliance events most affect supply and wholesaler pricing for methimazole?
How do therapeutic substitution patterns between methimazole and PTU change demand for Tapazole?

References

FDA Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. U.S. Food and Drug Administration.
FDA Drugs@FDA database. U.S. Food and Drug Administration.
FDA ANDA and Orange Book patent listing guidance and procedures. U.S. Food and Drug Administration.

TAPAZOLE Drug Patent Profile

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

DrugPatentWatch^® Litigation and Generic Entry Outlook for Tapazole

AI Deep Research

Questions you can ask:

Summary for TAPAZOLE

US Patents and Regulatory Information for TAPAZOLE