Generic DEXTROTHYROXINE SODIUM INN entry, drug patent expiration information and freedom to operate

Sponsor	Phase
Johns Hopkins University	Phase 1/Phase 2
National Heart, Lung, and Blood Institute (NHLBI)	N/A
National Heart, Lung, and Blood Institute (NHLBI)	Phase 3

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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
Abbvie	CHOLOXIN	dextrothyroxine sodium	TABLET;ORAL	012302-002	Approved Prior to Jan 1, 1982		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Abbvie	CHOLOXIN	dextrothyroxine sodium	TABLET;ORAL	012302-006	Approved Prior to Jan 1, 1982		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Abbvie	CHOLOXIN	dextrothyroxine sodium	TABLET;ORAL	012302-004	Approved Prior to Jan 1, 1982		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Abbvie	CHOLOXIN	dextrothyroxine sodium	TABLET;ORAL	012302-005	Approved Prior to Jan 1, 1982		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: September 4, 2026

Dextrothyroxine sodium, also known as D-thyroxine, is a discontinued thyroid-hormone derivative formerly marketed as Choloxin for hypercholesterolemia. Its commercial trajectory followed a short-lived pharmaceutical pattern: early interest in a novel lipid-lowering mechanism, clinical evidence of cardiovascular harm, withdrawal from the U.S. market, and collapse of the addressable market. No meaningful current branded, generic, biosimilar, or licensing market exists.

What was dextrothyroxine sodium used for?

Dextrothyroxine sodium is the sodium salt of the dextro isomer of thyroxine. It was developed as a cholesterol-lowering agent rather than as a replacement thyroid hormone.

The product was intended to reduce serum cholesterol in patients with hypercholesterolemia and related lipid disorders. Unlike levothyroxine, which is the standard replacement therapy for hypothyroidism, dextrothyroxine was positioned primarily as a metabolic and lipid-modifying medicine.

Its commercial rationale was based on the observation that thyroid hormones affect lipid metabolism. Dextrothyroxine was expected to provide lipid-lowering activity with less thyroid replacement effect than the naturally occurring levo isomer. Clinical use exposed a narrower safety margin than anticipated.

When did dextrothyroxine sodium lose market exclusivity?

Dextrothyroxine sodium no longer has a meaningful U.S. market-exclusivity position. The original product was commercialized decades ago, and any relevant composition-of-matter or product patents expired long before the product was discontinued.

Commercial factor	Status
Active ingredient	Dextrothyroxine sodium
Historical brand	Choloxin
Primary indication	Hypercholesterolemia and hyperlipidemia
U.S. commercial status	Discontinued
Current FDA exclusivity	None identified
Current Orange Book opportunity	No commercially meaningful listed-drug opportunity
Generic entry risk	Not material because the reference product is no longer an active commercial market
Biosimilar risk	Not applicable
Current revenue base	No material branded pharmaceutical revenue identified

The product’s commercial failure resulted from safety and clinical-positioning problems rather than from a conventional patent cliff. By the time lipid-lowering treatment evolved toward statins and other better-supported therapies, dextrothyroxine had lost both clinical relevance and commercial value.

What FDA regulatory action affected dextrothyroxine sodium?

The principal regulatory and market event was the discontinuation and withdrawal of the product after evidence linked dextrothyroxine treatment to adverse cardiovascular outcomes.

The Coronary Drug Project evaluated dextrothyroxine sodium in patients with established coronary disease. The dextrothyroxine arm was stopped after an excess of adverse outcomes, including mortality concerns. The findings materially weakened the benefit-risk profile of the product and undermined its use as a lipid-lowering therapy (Coronary Drug Project Research Group, 1972).

The FDA’s historical drug records identify dextrothyroxine sodium as a discontinued product. The product is not part of the current standard pharmacologic approach to hypercholesterolemia, and it has no recognized role in contemporary cholesterol-management guidelines.

What is the FDA status of Choloxin?

Choloxin is not an active mainstream U.S. prescription product. Historical labeling identified dextrothyroxine sodium tablets for cholesterol and lipid disorders, but the product is no longer commercially relevant in the U.S. prescription market.

The FDA regulatory record should be distinguished from a normal generic-entry scenario. A typical small-molecule drug loses exclusivity while the reference product remains available, allowing abbreviated new drug applications and Paragraph IV litigation. Dextrothyroxine sodium instead left the market after clinical and regulatory deterioration. The commercial question is therefore product abandonment, not imminent generic substitution.

What clinical evidence damaged the dextrothyroxine sodium market?

The Coronary Drug Project was the central clinical event. It tested several approaches to secondary prevention of coronary heart disease, including dextrothyroxine sodium. The dextrothyroxine group was discontinued because of unfavorable outcomes.

The clinical problems included:

Limited commercial differentiation from other lipid-lowering agents.
Potential thyroid-related cardiovascular effects.
Adverse effects in patients with pre-existing coronary disease.
Lack of a durable mortality or cardiovascular-outcomes advantage.
Increasing competition from better-established lipid-lowering therapies.

The drug’s mechanism created a strategic problem. Increasing thyroid-hormone activity could affect lipid levels but also raise the risk of tachycardia, arrhythmias, angina, and other cardiovascular complications. That tradeoff was unacceptable in the same high-risk population the product was intended to treat.

How did dextrothyroxine sodium compare with competing cholesterol drugs?

Dextrothyroxine competed in an early and rapidly changing lipid-lowering market. Its position deteriorated as safer and more effective agents emerged.

Therapy class	Historical role	Relative commercial position
Dextrothyroxine sodium	Thyroid-derived lipid-lowering therapy	Discontinued after unfavorable cardiovascular evidence
Bile-acid sequestrants	Established cholesterol reduction	Limited by gastrointestinal tolerability and administration burden
Fibrates	Triglyceride and mixed-dyslipidemia treatment	Retained selected clinical uses
Niacin	Broad lipid effects	Later reduced by tolerability and outcomes concerns
Statins	LDL-cholesterol reduction and cardiovascular-risk reduction	Became the dominant oral lipid-lowering class
PCSK9 inhibitors	Potent LDL reduction for selected high-risk patients	High-value specialty and cardiovascular market
Ezetimibe	LDL reduction, often combined with statins	Durable adjunctive market

Statins changed the economic basis of the category. They offered a clearer therapeutic target, stronger evidence for cardiovascular-risk reduction, scalable manufacturing, and broad physician adoption. Dextrothyroxine had no realistic pathway to compete against that standard.

How many patents covered dextrothyroxine sodium?

The historical product may have been associated with composition, formulation, manufacturing, or use patents, but no active commercial patent estate is relevant today.

For an obsolete small molecule such as dextrothyroxine sodium, the key patent categories would have included:

Composition-of-matter protection for the compound or stereoisomer.
Salt and crystalline-form protection.
Tablet and dosage-form formulations.
Methods for lowering serum cholesterol.
Manufacturing and purification processes.

Any such U.S. patent protection would have expired many years ago. Patent-term restoration and modern Hatch-Waxman exclusivity rules do not revive the commercial position of a discontinued product.

What formulations were historically protected?

Historical dextrothyroxine products were oral tablets containing dextrothyroxine sodium in low-milligram or sub-milligram strengths. Formulation protection, if available, would have been narrow compared with the active-ingredient claims and would have expired with the broader product opportunity.

No current formulation patent appears capable of supporting a commercially meaningful re-entry strategy. A new formulation would require a new regulatory and clinical rationale, not merely a manufacturing change.

Are there Paragraph IV challenges to dextrothyroxine sodium?

No commercially significant Paragraph IV litigation is associated with dextrothyroxine sodium in the current market.

Paragraph IV litigation requires an active reference-listed drug and a generic applicant seeking approval before listed patent expiration. Dextrothyroxine sodium does not present that pattern. Its historical patents are expired, and the reference product is not an active commercial anchor for a generic launch.

The relevant legal risks for a company attempting to revive the molecule would instead involve:

FDA approval requirements.
Clinical safety and cardiovascular-outcomes evidence.
Product liability exposure.
Physician and payer acceptance.
Manufacturing controls for an older active pharmaceutical ingredient.
Potential competition from established lipid-lowering therapies.

Does dextrothyroxine sodium have biosimilar risk?

No. Dextrothyroxine sodium is a chemically synthesized small molecule, not a biologic. The Biologics Price Competition and Innovation Act biosimilar pathway does not apply.

Any future competitor would use the generic-drug pathway under Section 505(j) of the Federal Food, Drug, and Cosmetic Act if an eligible reference product and regulatory framework were available. In practice, the larger barrier is the absence of a viable market and the unfavorable historical benefit-risk profile.

What is the financial trajectory of dextrothyroxine sodium?

Publicly reported revenue data for Choloxin and dextrothyroxine sodium are not available in the form of a continuous, reliable product-level series. The financial trajectory can be reconstructed qualitatively from regulatory and clinical events.

Period	Market condition	Financial implication
Initial commercialization	Novel thyroid-derived lipid-lowering product	Early revenue opportunity in a developing cholesterol market
Pre-withdrawal period	Safety concerns and competitive pressure	Prescribing contraction and declining commercial value
Post-Coronary Drug Project	Unfavorable cardiovascular evidence	Sharp erosion of physician demand
Discontinuation	Product removed from routine U.S. use	Branded revenue effectively ended
Current period	No active mainstream market	No material recurring pharmaceutical revenue

The product likely generated value during the period before the widespread adoption of statins, but it did not develop into a durable franchise. Its economic life ended through a combination of clinical failure, safety risk, and therapeutic substitution.

For a pharmaceutical company, the asset’s present value is close to zero as a conventional commercial product. A revival would require a new indication, a redesigned benefit-risk profile, and modern clinical evidence. Those investments would face a high opportunity cost compared with developing or licensing established lipid-lowering technologies.

Which companies challenged or commercialized dextrothyroxine sodium?

Choloxin was the principal historical brand associated with dextrothyroxine sodium. Historical drug references and labeling identify legacy pharmaceutical commercialization, but no current major pharmaceutical company markets the product in the United States.

The molecule does not have an active competitive landscape comparable with levothyroxine, atorvastatin, rosuvastatin, ezetimibe, or PCSK9 inhibitors. There is no material current manufacturer competition, licensing market, or branded-versus-generic share contest.

Are there licensing deals for dextrothyroxine sodium?

No significant current licensing transactions involving dextrothyroxine sodium are identified. The molecule lacks the characteristics that typically drive licensing activity:

No active patent estate.
No current FDA commercial franchise.
No differentiated clinical claim.
No established reimbursement position.
No active physician demand.
No clear development pathway against contemporary lipid-lowering standards.

A transaction involving the compound would more likely concern archival rights, analytical standards, or research use than a commercial prescription product.

What manufacturing and intellectual-property barriers remain?

The physical manufacture of dextrothyroxine sodium is not likely to present an insurmountable technical barrier for a qualified pharmaceutical manufacturer. The commercial barrier is stronger than the synthetic barrier.

A potential manufacturer would need to address:

Validated synthesis and stereochemical control.
Impurity profiling and assay methods.
Stability of the sodium salt and tablet formulation.
Current good manufacturing practice compliance.
Clinical pharmacology and dose justification.
Cardiovascular safety monitoring.
Adequate clinical evidence for any proposed indication.
Product liability and pharmacovigilance systems.

Because the active ingredient is old, manufacturing know-how may be obtainable through literature and historical technical records. That does not create a viable business case. The absence of enforceable patent barriers would permit competition, but it would also reduce the incentive to fund costly clinical redevelopment.

What generic launch scenarios exist for dextrothyroxine sodium?

A conventional generic launch is unlikely to create material market value. Three scenarios are theoretically possible:

Scenario	Probability from a commercial perspective	Outcome
Legacy generic re-entry	Low	Limited demand and regulatory complications
Reformulated product for dyslipidemia	Low	Requires new clinical evidence and payer adoption
New indication or specialty use	Very low	Requires differentiated efficacy and safety data
Research or compounding supply	Narrow niche	Small-volume, non-franchise opportunity

The most plausible commercial use would be a limited research or specialty supply channel rather than a mass-market cardiovascular product. Any effort to relaunch the drug as a general cholesterol treatment would face entrenched competition from inexpensive generics and highly effective branded therapies.

How strong is the patent estate for dextrothyroxine sodium?

The current patent estate is commercially weak to nonexistent.

Patent-estate factor	Assessment
Composition-of-matter protection	Expired
Formulation protection	Expired or commercially irrelevant
Method-of-use protection	Expired or commercially irrelevant
Manufacturing protection	No current blocking position identified
Patent litigation leverage	Minimal
Freedom to operate	Generally favorable from an expired-patent perspective
Investment attractiveness	Low without a new clinical thesis

Patent freedom to operate does not equal commercial attractiveness. The molecule may be technically unblocked while remaining clinically obsolete and economically unattractive.

What is the outlook for dextrothyroxine sodium?

The outlook is inactive. Dextrothyroxine sodium has no meaningful current FDA-market opportunity, no relevant exclusivity period, no biosimilar issue, and no visible commercial pipeline.

Its historical market demonstrates the risk of developing a mechanism that improves a surrogate biomarker without establishing a favorable cardiovascular-outcomes profile. The product’s decline was driven by evidence and therapeutic substitution, not merely by patent expiration.

Key Takeaways

Dextrothyroxine sodium was historically marketed as Choloxin for hypercholesterolemia.
The Coronary Drug Project found unfavorable outcomes that damaged the drug’s benefit-risk profile.
The product is discontinued and has no meaningful current U.S. commercial market.
Active patent, exclusivity, Orange Book, and Paragraph IV opportunities are not commercially significant.
Biosimilar competition is irrelevant because dextrothyroxine sodium is a small molecule.
No significant current licensing activity or product-level revenue stream is identified.
Statins and newer lipid-lowering therapies eliminated the molecule’s competitive position.
A commercial relaunch would require new clinical evidence and would face a high probability of economic failure.

FAQs

Is dextrothyroxine sodium the same as levothyroxine?

No. Dextrothyroxine sodium is the dextro isomer of thyroxine and was used historically for lipid lowering. Levothyroxine is the levo isomer used primarily for thyroid-hormone replacement.

Is Choloxin still available by prescription?

Choloxin is not a current mainstream U.S. prescription product. Its historical commercial use ended after unfavorable clinical and regulatory developments.

Can a generic manufacturer still launch dextrothyroxine sodium?

A manufacturer could theoretically pursue regulatory approval if an appropriate pathway and reference product existed, but the commercial opportunity is limited by discontinuation, weak demand, and safety concerns.

Did dextrothyroxine sodium reduce LDL cholesterol?

It could affect serum cholesterol, but its clinical utility was undermined by cardiovascular safety concerns and the lack of a favorable outcomes profile compared with later lipid-lowering therapies.

Is dextrothyroxine sodium a viable pharmaceutical investment?

On the available commercial record, it is not a viable conventional pharmaceutical investment. Its patent estate is obsolete, its FDA market position is inactive, and its historical safety profile creates substantial redevelopment risk.

References

Coronary Drug Project Research Group. (1972). The Coronary Drug Project: Findings leading to discontinuation of the dextrothyroxine sodium group. Journal of the American Medical Association.
U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs database. https://www.accessdata.fda.gov/scripts/cder/daf/
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (n.d.). Dextrothyroxine sodium product labeling and historical drug records. Drugs@FDA database. https://www.accessdata.fda.gov/scripts/cder/daf/

US Patents:	0
Tradenames:	1
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	104
Clinical Trials:	3
DailyMed Link:	dextrothyroxine sodium at DailyMed

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