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LIOTHYRONINE SODIUM Drug Patent Profile
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Which patents cover Liothyronine Sodium, and when can generic versions of Liothyronine Sodium launch?
Liothyronine Sodium is a drug marketed by Xgen Pharms, Biocon Pharma, Dr Reddys Labs Sa, Pharmobedient, Sigmapharm Labs Llc, Sun Pharm, Teva Pharms Usa, Watson Labs, and Zydus Lifesciences. and is included in ten NDAs.
The generic ingredient in LIOTHYRONINE SODIUM is liothyronine sodium. There is one drug master file entry for this compound. Nineteen suppliers are listed for this compound. Additional details are available on the liothyronine sodium profile page.
DrugPatentWatch® Litigation and Generic Entry Outlook for Liothyronine Sodium
A generic version of LIOTHYRONINE SODIUM was approved as liothyronine sodium by XGEN PHARMS on August 17th, 2005.
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Questions you can ask:
- What is the 5 year forecast for LIOTHYRONINE SODIUM?
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- What is Average Wholesale Price for LIOTHYRONINE SODIUM?
Summary for LIOTHYRONINE SODIUM
| US Patents: | 0 |
| Applicants: | 9 |
| NDAs: | 10 |
| Finished Product Suppliers / Packagers: | 17 |
| Raw Ingredient (Bulk) Api Vendors: | 1 |
| Clinical Trials: | 15 |
| Patent Applications: | 1,502 |
| What excipients (inactive ingredients) are in LIOTHYRONINE SODIUM? | LIOTHYRONINE SODIUM excipients list |
| DailyMed Link: | LIOTHYRONINE SODIUM at DailyMed |
Recent Clinical Trials for LIOTHYRONINE SODIUM
Identify potential brand extensions & 505(b)(2) entrants
| Sponsor | Phase |
|---|---|
| University of Minnesota - Clinical and Translational Science Institute | Phase 1/Phase 2 |
| University of Minnesota | Phase 1/Phase 2 |
| Aultman Health Foundation | Phase 2 |
Pharmacology for LIOTHYRONINE SODIUM
| Drug Class | l-Triiodothyronine |
Anatomical Therapeutic Chemical (ATC) Classes for LIOTHYRONINE SODIUM
US Patents and Regulatory Information for LIOTHYRONINE SODIUM
Liothyronine Sodium Market Dynamics, Patent Landscape, and Financial Trajectory
Liothyronine sodium is a mature, low-volume thyroid-hormone medicine with limited patent protection and fragmented generic competition. The U.S. market is driven by generic tablets, branded Cytomel, compounded formulations, and hospital or specialty demand rather than by exclusivity. Revenue potential is constrained by low pricing, small treatment volumes, supply disruptions, and clinical preference for levothyroxine in most hypothyroidism patients.
The commercial opportunity is strongest in reliable supply, differentiated dosage forms, combination therapy, and specialty distribution. Patent-based market protection is weak. No biosimilar pathway applies because liothyronine sodium is a synthetic small molecule.
What is liothyronine sodium and how is it used?
Liothyronine sodium is the sodium salt of synthetic triiodothyronine, or T3. It is the active thyroid hormone responsible for many of the body’s metabolic effects. The drug is approved primarily for hypothyroidism and selected thyroid-related conditions.
U.S. prescribing is limited relative to levothyroxine, or synthetic T4. Levothyroxine is generally preferred for routine replacement because of its longer half-life and more stable pharmacokinetic profile. Liothyronine has a shorter half-life, produces higher serum concentration fluctuations, and requires more frequent dosing or careful titration.
Principal indications
FDA labeling covers use in:
- Hypothyroidism
- Myxedema
- Myxedema coma, in injectable or hospital-directed settings
- Thyroid suppression testing and selected diagnostic applications
- Adjunctive treatment in certain thyroid-related clinical settings
The approved product is available in oral tablet strengths generally ranging from 5 mcg to 25 mcg and 50 mcg, depending on manufacturer and market availability. Cytomel is the best-known U.S. brand.
How large is the liothyronine sodium market?
Liothyronine sodium is a niche pharmaceutical market inside the much larger thyroid-replacement category. The market includes finished-dose tablets, injectable liothyronine products, compounded capsules or liquids, and combination products containing levothyroxine and liothyronine.
Public companies generally do not report liothyronine revenue as a separate line item. Pfizer reports broader product categories rather than standalone Cytomel sales, while generic manufacturers typically include liothyronine in portfolios of established products. As a result, market size must be assessed through prescription volume, product availability, reimbursement, and supplier economics rather than company-reported segment revenue.
Market structure
| Market segment | Commercial position | Primary demand driver |
|---|---|---|
| Generic liothyronine tablets | Mainstream U.S. supply | Price, formulary access, availability |
| Cytomel | Branded reference product | Brand loyalty, physician familiarity, supply confidence |
| Injectable liothyronine | Specialized and hospital-oriented | Severe hypothyroidism and acute care |
| Compounded liothyronine | Fragmented alternative | Custom dosing and patient-specific formulations |
| T4/T3 combination products | Limited niche | Patients inadequately controlled on T4 alone |
| International products | Country-specific | Local regulatory approval and supply |
Demand is relatively inelastic for patients who require T3, but the addressable population is limited. Clinical guidelines continue to favor levothyroxine monotherapy for most patients, restricting broad substitution into liothyronine-based treatment.
What is the financial trajectory for liothyronine sodium?
The financial trajectory is mature and stable at the category level, with limited volume growth and periodic price volatility. Revenue is more likely to increase through price changes, shortages, formulation differentiation, or improved distribution than through expanding treatment prevalence.
Revenue drivers
The principal commercial drivers are:
- Generic price increases during supply shortages.
- Continued demand from patients who use T3 despite guideline preference for levothyroxine.
- Higher-value branded or specialty formulations.
- Hospital demand for injectable products.
- Compounded preparations where commercial dosage strengths do not meet patient needs.
- Reimbursement changes and pharmacy substitution.
Generic competition places a ceiling on sustainable pricing when multiple suppliers are active. That ceiling can temporarily disappear when manufacturers exit, experience manufacturing problems, or face active pharmaceutical ingredient constraints.
Margin profile
Liothyronine tablets use an established active ingredient and conventional oral manufacturing process. Technical manufacturing complexity is lower than for biologics, modified-release systems, or complex sterile products. However, the product has several economic disadvantages:
- Small market size limits manufacturing scale.
- Multiple strengths increase inventory requirements.
- Dose uniformity is commercially important because the product is administered in microgram quantities.
- Low annual treatment volume can reduce supplier willingness to maintain broad inventories.
- Regulatory and quality costs are high relative to product revenue.
- Shortages can create reputational and commercial pressure without producing durable category growth.
The result is a market with potentially attractive short-term gross margins during supply constraints but modest long-term growth.
When does liothyronine sodium lose exclusivity?
Liothyronine sodium lost meaningful molecule-level exclusivity decades ago. The active ingredient is an established synthetic thyroid hormone, and generic versions have been approved for many years.
Cytomel does not have a modern composition-of-matter patent barrier comparable with newer small-molecule medicines. Its commercial protection depends primarily on brand recognition, regulatory status, supply reliability, physician familiarity, and any product-specific labeling or formulation rights.
Exclusivity status
| Exclusivity type | Current position |
|---|---|
| New chemical entity exclusivity | Expired |
| Composition-of-matter patent | No meaningful active barrier expected for the old molecule |
| Basic oral tablet protection | Expired |
| Generic entry | Established |
| Pediatric exclusivity | Not a current commercial barrier |
| Orphan exclusivity | Not a general protection for standard liothyronine tablets |
| Biosimilar exclusivity | Not applicable |
FDA Orange Book listings must be reviewed by product and application because listed patents can change. The commercial issue, however, is not molecule-level exclusivity. Generic competition is already established.
What patents protect liothyronine sodium products?
The core liothyronine sodium molecule and conventional immediate-release tablets are not protected by an effective modern patent estate. Any relevant patent value would arise from a specific formulation, dosage form, delivery system, manufacturing method, or combination product.
Potential patent categories
Formulation patents
A company could pursue patents covering:
- Modified-release liothyronine
- Sustained or delayed T3 delivery
- Stabilized tablets
- Improved dissolution profiles
- Liquid or oral-mucosal dosage forms
- Fixed-dose T4/T3 combinations
- Abuse-resistant or tamper-resistant dosage forms, although this is not a central commercial use
- Specific excipient systems that improve content uniformity or stability
A formulation patent would need to provide a clinically meaningful or technically non-obvious advantage. A simple change in excipient or tablet shape would face substantial validity and obviousness risk if the claimed result is predictable.
Method-of-use patents
Potential method claims could target:
- Treatment of persistent hypothyroid symptoms despite levothyroxine
- Patient populations with impaired T4-to-T3 conversion
- Genotype-defined thyroid-hormone treatment
- Specific titration protocols
- Use in severe hypothyroidism or myxedema
- Combination therapy with levothyroxine
Method-of-use claims would depend on clinical evidence and enforceable labeling. Broad claims covering all hypothyroidism treatment would be vulnerable because liothyronine’s therapeutic use is old and well documented.
Manufacturing patents
Manufacturing claims could cover:
- Improved microgram-dose content uniformity
- Stable active pharmaceutical ingredient handling
- Reduced degradation during tablet compression
- High-throughput low-dose blending
- Injectable sterile manufacturing
- Packaging systems that protect potency
Manufacturing patents can create operational barriers, but they rarely prevent generic entry where alternative processes are available.
What is the Orange Book status of Cytomel and generic liothyronine?
Cytomel is an FDA-approved prescription product, and generic liothyronine sodium tablets are approved through abbreviated new drug applications. The Orange Book is the relevant U.S. source for application status, therapeutic equivalence, and listed patents or exclusivity.
The practical Orange Book position is:
- Cytomel is the reference branded product.
- Generic liothyronine products compete through ANDA approvals.
- Any remaining listed patent must be assessed at the individual product-application level.
- Generic applicants generally do not face a live basic-molecule patent barrier.
- Therapeutic-equivalence status and product availability may vary by strength and manufacturer.
The principal commercial risk is product discontinuation or temporary unavailability, not loss of patent protection.
Which companies compete in liothyronine sodium?
Competition is fragmented across branded, generic, specialty, and compounding channels.
Key competitive groups
| Competitor group | Examples | Competitive advantage |
|---|---|---|
| Branded originator | Pfizer’s Cytomel | Brand recognition and reference-product status |
| Large generic manufacturers | Companies such as Hikma, Viatris/Mylan, Amneal, and others depending on current approvals | Scale, pharmacy distribution, broad portfolios |
| Specialty manufacturers | Established-drug suppliers focused on selected dosage forms | Niche availability and customer service |
| Compounding pharmacies | 503A and 503B facilities | Custom strengths and dosage forms |
| Combination-product developers | Specialty thyroid companies and compounders | Differentiated T4/T3 dosing |
Manufacturer participation can change because of discontinuations, shortages, acquisition activity, or portfolio rationalization. The number of approved products is therefore less important than the number of suppliers actively shipping each strength.
Which companies are challenging Cytomel through generic entry?
Generic companies have challenged the branded market through approved ANDA products rather than through a high-profile modern Paragraph IV campaign. Liothyronine’s age means that generic entry does not depend on defeating a current composition-of-matter patent.
Potential Paragraph IV exposure would arise only if Cytomel or a newer formulation had a listed patent covering a specific product. For conventional immediate-release liothyronine tablets, the commercial record is consistent with established generic availability and no meaningful active patent dispute blocking routine entry.
Paragraph IV risk
| Issue | Assessment |
|---|---|
| Core molecule challenge | Commercially irrelevant because molecule protection expired |
| Conventional tablet challenge | Generic entry already established |
| Modified-release product challenge | Potentially material if patents are listed |
| T4/T3 combination challenge | Product-specific and potentially significant |
| Manufacturing-process challenge | Usually avoidable through alternative processes |
| Brand litigation leverage | Limited for old immediate-release products |
A company launching a new formulation would face the greater litigation risk. The relevant disputes would concern formulation scope, obviousness, written description, enablement, and infringement by equivalent release profiles.
What formulation patents could create commercial value?
The strongest opportunity is a product that addresses liothyronine’s pharmacokinetic limitations. Immediate-release T3 produces a rapid concentration increase and relatively short duration. A formulation that smooths exposure could support improved adherence, lower peak-related adverse effects, or more convenient dosing.
Higher-value formulation concepts
Sustained-release liothyronine
A sustained-release tablet or capsule could seek protection around release kinetics, dose uniformity, and clinical exposure. The commercial value would depend on demonstrated superiority or meaningful patient preference over generic immediate-release products.
Fixed-dose T4/T3 combination
A combination tablet could reduce pill burden and target patients receiving both hormones. Patent claims could cover ratio, dissolution, stability, and administration timing. Regulatory approval would require evidence supporting the combination and dose ratio.
Liquid or microdose products
Liquid liothyronine could address pediatric, geriatric, swallowing, and fine-titration needs. Its patent value would depend on stability, preservative selection, dosing accuracy, and container-closure performance.
Injectable formulations
Injectable liothyronine has hospital value but a smaller outpatient market. Sterility, stability, manufacturing controls, and supply reliability may create stronger operational barriers than patent protection.
What FDA regulatory issues affect liothyronine sodium?
Liothyronine sodium is an FDA-approved prescription drug. Regulatory risk is concentrated in manufacturing quality, potency, stability, labeling, and supply continuity.
The drug has a narrow dosing range expressed in micrograms. Small absolute variations can be clinically important. FDA scrutiny therefore focuses on:
- Content uniformity
- Assay and degradation products
- Dissolution
- Bioequivalence
- Batch-to-batch consistency
- Stability across shelf life
- Accurate strength labeling
- Manufacturing change controls
- Sterility for injectable products
Generic applicants must demonstrate bioequivalence to the relevant reference product under the ANDA pathway. A modified-release or combination product may require a different regulatory strategy, including clinical pharmacology studies and potentially clinical efficacy data.
Is there biosimilar risk for liothyronine sodium?
No. Liothyronine sodium is a synthetic small-molecule drug, not a biologic. Biosimilar competition under the Public Health Service Act does not apply.
Competitive entry occurs through:
- ANDAs for conventional generic products
- 505(b)(2) applications for modified or differentiated formulations
- New drug applications for novel combinations or delivery systems
- State-regulated compounding channels
This distinction matters commercially. A new liothyronine formulation would not obtain an automatic biologic-style reference-product protection period. Its protection would depend on FDA exclusivity, formulation patents, method-of-use patents, and commercial differentiation.
What patent litigation affects liothyronine sodium?
There is no widely recognized, category-defining patent litigation campaign comparable with disputes involving newer high-revenue medicines. The conventional liothyronine market is largely post-exclusivity.
Litigation exposure is more likely in three areas:
- A new sustained-release T3 product with Orange Book-listed formulation patents.
- A fixed-dose T4/T3 combination with claims covering dose ratio or release characteristics.
- A specialty formulation where the sponsor uses a 505(b)(2) pathway and seeks three-year regulatory exclusivity.
For established immediate-release tablets, competition is more likely to be affected by supply, quality, and contracting than by patent injunctions.
What licensing deals involve liothyronine sodium?
Liothyronine has limited licensing value compared with newer thyroid-directed therapies. The active ingredient is old and broadly available. Licensing value would therefore depend on a differentiated asset, such as:
- Sustained-release delivery technology
- Combination therapy
- Pediatric liquid formulation
- Hospital injectable product
- Regional commercialization rights
- Manufacturing or supply rights
- A clinical dataset supporting a defined patient subgroup
Cytomel’s commercial rights have historically been associated with large pharmaceutical ownership, including King Pharmaceuticals and Pfizer. The brand’s value is tied to an established label and distribution network rather than exclusivity over liothyronine itself.
How does liothyronine compare with levothyroxine?
| Attribute | Liothyronine sodium | Levothyroxine sodium |
|---|---|---|
| Hormone | Synthetic T3 | Synthetic T4 |
| Half-life | Shorter | Longer |
| Dosing stability | More variable | More stable |
| Standard first-line use | No | Yes |
| Generic competition | Established | Extensive |
| Market size | Niche | Large |
| Formulation opportunity | High because of pharmacokinetics | High because of absorption and dose consistency |
| Clinical demand | Specialty and selected patients | Broad hypothyroidism population |
| Patent leverage | Weak for old products | Weak for old products, but formulation disputes can arise |
Levothyroxine has a much larger prescription base and broader manufacturer participation. Liothyronine has a smaller market but potentially greater value per patient for differentiated delivery systems because its pharmacokinetic profile creates a clearer formulation problem.
What generic launch scenarios exist for liothyronine sodium?
Base case: continued generic supply
The most likely scenario is stable generic competition with modest price movement. Cytomel remains available as a branded alternative, while pharmacies substitute generic products where supply permits.
Shortage-driven pricing
A supplier withdrawal or manufacturing interruption can produce temporary price increases, allocation, and pharmacy switching. This scenario benefits manufacturers with validated capacity and inventory but can damage demand if prescribers move patients to levothyroxine or compounded alternatives.
Differentiated formulation launch
A sustained-release or combination product could command a premium if it demonstrates improved dosing convenience or tolerability. Such a launch would need to overcome payer resistance and the low-cost generic reference point.
Compounding expansion
Compounding may expand during shortages or when patients require nonstandard strengths. Compounded products can capture niche demand but face limitations in scale, consistency, reimbursement, and promotional reach.
What geographic markets matter for liothyronine sodium?
The United States is commercially important because of branded Cytomel, generic tablet availability, specialty prescribing, and a large regulated pharmacy market. European and other developed markets have different positions for liothyronine, with some countries restricting routine use more heavily than the U.S.
Geographic barriers include:
- Country-specific approval requirements
- Different reference products
- Local reimbursement rules
- Limited manufacturer participation
- API sourcing and import controls
- National shortage management
- Different clinical guidelines for T3 use
A manufacturer with a reliable global API and finished-dose supply chain can gain share without owning a strong patent estate.
How strong is the liothyronine sodium patent estate?
The patent estate for conventional liothyronine sodium is weak. The molecule is old, generic entry is established, and standard immediate-release tablets have limited defensible intellectual property.
The patent estate becomes stronger only when tied to a specific product innovation:
| Asset type | Patent strength | Commercial durability |
|---|---|---|
| Old molecule | Very low | None |
| Conventional immediate-release tablet | Low | Limited |
| Stable liquid formulation | Moderate | Product-specific |
| Sustained-release T3 | Moderate to potentially strong | Depends on claims and clinical data |
| T4/T3 combination | Moderate | Depends on ratio and formulation |
| Injectable presentation | Low to moderate | Manufacturing and regulatory barriers matter more |
| Genotype-specific method of use | Uncertain to moderate | Dependent on evidence and claim scope |
Patent strength should be assessed claim by claim. Broad claims covering the use of T3 in hypothyroidism are likely to face prior-art and obviousness challenges. Narrow claims directed to defined release profiles, pharmacokinetic targets, or validated patient populations have a better enforcement position.
Key Takeaways
- Liothyronine sodium is a mature, niche thyroid-hormone market.
- Cytomel has brand value, but no meaningful molecule-level exclusivity remains.
- Generic competition is established and limits long-term pricing power.
- Public companies generally do not disclose standalone liothyronine revenue.
- Financial performance is driven by supply reliability, shortages, pricing, and specialty formulations.
- No biosimilar pathway applies.
- Conventional immediate-release tablets have weak patent protection.
- The strongest IP opportunity is in sustained-release, liquid, injectable, or T4/T3 combination products.
- The main competitive risk is generic and supply-chain competition, not patent litigation.
- A differentiated formulation would likely require a 505(b)(2) or new-drug strategy, clinical support, and a payer-focused commercial plan.
FAQs
Is liothyronine sodium still under patent?
The active ingredient and conventional immediate-release tablet are long off patent. Any current patent risk would be product-specific and would most likely involve a newer formulation, combination product, or method of use.
Who manufactures generic liothyronine sodium?
Generic supply has historically included large and specialty manufacturers such as Hikma, Viatris or Mylan, Amneal, and other approved ANDA holders. Active commercial supply varies by strength, time period, and manufacturer decisions.
Can a company obtain FDA exclusivity for a new liothyronine formulation?
Yes. A differentiated product may qualify for regulatory exclusivity depending on its approval pathway. A 505(b)(2) product may obtain three years of exclusivity for certain new clinical investigations, although this does not create broad protection over the old active ingredient.
Why is liothyronine more difficult to commercialize than levothyroxine?
Liothyronine has a shorter half-life and faster concentration changes. Those characteristics complicate dosing and create a smaller guideline-supported market. They also increase the technical value of controlled-release formulations.
Does a liothyronine shortage create a durable investment opportunity?
Usually not by itself. Shortages can produce temporary pricing and share gains, but durable value generally requires reliable manufacturing, regulatory compliance, distribution capacity, or a differentiated formulation protected by defensible intellectual property.
References
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U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/
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U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
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U.S. Food and Drug Administration. (2022). Cytomel (liothyronine sodium) prescribing information. King Pharmaceuticals LLC.
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Jonklaas, J., Bianco, A. C., Bauer, A. J., Burman, K. D., Cappola, A. R., Celi, F. S., Cooper, D. S., Kim, B. W., Peeters, R. P., Rosenthal, M. S., & Sawka, A. M. (2014). Guidelines for the treatment of hypothyroidism. Thyroid, 24(12), 1670-1751.
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U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Generic drug facts. https://www.fda.gov/drugs/generic-drugs
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Pfizer Inc. (2024). Annual report. https://www.pfizer.com/investors/financial-reports-annual-reports
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