ATROMID-S Drug Patent Profile

When do Atromid-s patents expire, and what generic alternatives are available?

Atromid-s is a drug marketed by Wyeth Ayerst and is included in one NDA.

The generic ingredient in ATROMID-S is clofibrate. There are four drug master file entries for this compound. Additional details are available on the clofibrate profile page.

Summary for ATROMID-S

US Patents:	0
Applicants:	1
NDAs:	1

US Patents and Regulatory Information for ATROMID-S

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Wyeth Ayerst	ATROMID-S	clofibrate	CAPSULE;ORAL	016099-002	Approved Prior to Jan 1, 1982		DISCN	No	No

Atromid-S Investment Analysis: Clofibrate Patent Status, FDA History, Market Risk, and Commercial Outlook

Last updated: July 31, 2026

Atromid-S is the former brand name for clofibrate, an older fibrate lipid-lowering drug. Its commercial value is effectively exhausted. The active ingredient has no meaningful remaining patent exclusivity, the U.S. product is no longer a current growth asset, and modern lipid therapies have replaced it in routine care. Any investment case would depend on a niche relaunch, historical-brand acquisition, or reformulation strategy rather than sales of the legacy product.

What is Atromid-S and who developed it?

Atromid-S contains clofibrate, also known as ethyl 2-(4-chlorophenoxy)-2-methylpropanoate. Clofibrate is a prodrug that is hydrolyzed to clofibric acid, a lipid-regulating compound associated with activation of peroxisome proliferator-activated receptor alpha, or PPAR-alpha.

Attribute	Atromid-S
Active ingredient	Clofibrate
Drug class	Fibrate lipid regulator
Historical indication	Hyperlipidemia and hypertriglyceridemia
Original developer	Imperial Chemical Industries, later commercialized through pharmaceutical licensees
Historical U.S. brand	Atromid-S
Route	Oral
Dosage form	Capsules
FDA status	Historical approval; no current commercial growth position
Current patent value	Effectively zero for the original molecule
Current competitive class	Fenofibrate, bezafibrate, gemfibrozil, statins, PCSK9 inhibitors, ezetimibe, and newer triglyceride therapies

Atromid-S was introduced before the modern evidence-based treatment framework for cardiovascular risk. Its clinical rationale was based largely on lowering serum cholesterol and triglycerides. Later outcome data showed that biochemical lipid changes did not translate into a sufficiently favorable overall mortality or cardiovascular benefit profile.

When did Atromid-S lose exclusivity?

Atromid-S lost meaningful exclusivity decades ago. Clofibrate was developed in the mid-20th century, and any composition-of-matter or early process patents would have expired long before the current U.S. patent term framework became relevant.

What patents protect clofibrate?

No commercially relevant live U.S. patent estate protects the original clofibrate molecule or the historical Atromid-S formulation. Early clofibrate patents, including patents associated with phenoxyisobutyric-acid derivatives, expired many years ago. The original product therefore has no patent-based barrier to generic manufacture.

A historical patent review should distinguish between:

1. Early composition and chemical-process patents.
2. Brand-specific labeling and trademark rights.
3. Any later formulation or manufacturing patents.
4. Regulatory exclusivity, which is separate from patent protection.

The first category is expired. The second has limited value without an active commercial product. No modern formulation patent has created a recognized commercial moat around Atromid-S.

Protection type	Atromid-S status
Original molecule patent	Expired
Early manufacturing patents	Expired
Original formulation protection	Expired
U.S. regulatory exclusivity	Expired
Orange Book patent exclusivity	No current strategic value
Trademark value	Historical and commercially weak
Trade-secret manufacturing value	Limited; clofibrate is an established small molecule

What is the FDA regulatory status of Atromid-S?

Atromid-S is a historical FDA-approved product rather than a current development-stage asset. The FDA’s regulatory framework now treats clofibrate as an old lipid-lowering therapy with an unfavorable commercial and clinical profile compared with available alternatives.

The central regulatory issue is not whether clofibrate can lower lipids. It can. The issue is whether its benefits justify its safety profile and whether a sponsor could support a modern approval or relaunch program against current standards.

The World Health Organization Cooperative Trial evaluated clofibrate in patients with ischemic heart disease and reported reductions in serum cholesterol but no favorable reduction in total mortality. The trial also raised concerns regarding non-cardiovascular mortality and gallbladder disease. These findings weakened the clinical case for long-term use of clofibrate and contributed to its displacement from routine therapy.[1]

The FDA-approved labeling historically warned that clofibrate did not reduce coronary heart disease events despite lowering cholesterol and that mortality findings were unfavorable in important trial populations.[2]

What is the Orange Book status of Atromid-S?

Atromid-S does not have a meaningful current Orange Book position for investment analysis. Any historical listing would not provide current protection against generic competition. No live Orange Book patent listing should be assumed to support exclusivity for clofibrate.

An investor evaluating a relaunch would need to treat the product as an abbreviated-new-drug-application or 505(b)(2) opportunity, depending on the proposed product, formulation, clinical claims, and reference-product status. The legacy approval would not automatically provide modern commercial protection.

How strong is the patent estate for Atromid-S?

The patent estate is weak to nonexistent for the original product.

Patent-strength assessment

Factor	Assessment	Investment impact
Composition-of-matter protection	Expired	No molecule-level exclusivity
Formulation protection	No recognized current moat	Limited ability to block substitution
Method-of-use patents	Historical indications are old and broad	Low blocking value
Manufacturing patents	Potentially available only for a new process	Narrow and design-around risk
Trademark	Legacy brand only	Limited without market demand
Regulatory exclusivity	Expired	No launch protection
Patent litigation leverage	Minimal	Low deterrence against generic entry

A new sponsor could pursue a reformulated clofibrate product, a fixed-dose combination, or a targeted indication. That strategy would require new patent claims covering formulation, dosing, delivery, or a specific clinical use. Such patents would face obviousness, written-description, enablement, and clinical-utility challenges.

What clinical and commercial problems affected Atromid-S?

Clofibrate’s historical commercial decline resulted from both clinical evidence and therapeutic substitution.

The drug lowered triglycerides and cholesterol, but lipid lowering alone was insufficient to preserve its market position. Statins provided stronger evidence for reducing cardiovascular events. Later fibrates offered more convenient or better-positioned treatment options for selected hypertriglyceridemia patients.

Key liabilities included:

• Increased concern about gallstones and gallbladder disease.
• Renal and hepatic monitoring requirements.
• Lack of a favorable total-mortality outcome in major historical studies.
• Limited differentiation from newer fibrates.
• Substitution by statins for primary and secondary prevention.
• Reduced clinical use after evidence-based lipid guidelines shifted treatment priorities.

The FDA labeling also reflected concerns about combination use with statins and the potential for muscle toxicity associated with fibrate therapy, although clofibrate’s broader issue was its unfavorable benefit-risk profile rather than a single isolated adverse event.[2]

What generic entry risks exist for Atromid-S?

Generic entry risk is complete in economic terms because the original product lacks enforceable exclusivity. The relevant question is not whether a generic can enter, but whether there is enough demand to justify entry.

Generic launch scenario

A conventional clofibrate generic would face low legal barriers but weak commercial incentives:

Launch factor	Assessment
Patent blocking risk	Very low
FDA pathway	Likely abbreviated pathway if an eligible reference product exists
Clinical demand	Low
Payer preference	Weak
Physician adoption	Limited
Price competition	Severe
Manufacturing complexity	Low to moderate
Regulatory risk	High relative to expected revenue
Probability of material U.S. sales	Low

The absence of patent protection does not make a product attractive. A generic sponsor would still need an active regulatory pathway, a viable reference standard, manufacturing capacity, pharmacovigilance, labeling, and sufficient demand.

Which companies are challenging Atromid-S?

No meaningful current Paragraph IV litigation campaign is associated with Atromid-S. The product is not a contemporary branded franchise with an active patent challenger landscape.

Historical competition came from generic clofibrate suppliers and from manufacturers of competing lipid therapies. Current competitive pressure comes primarily from:

• Generic fenofibrate manufacturers.
• Gemfibrozil suppliers.
• Statin manufacturers.
• Ezetimibe suppliers.
• PCSK9 inhibitor developers and manufacturers.
• Prescription omega-3 and specialized triglyceride-lowering products.

The relevant competitive comparison is therefore therapeutic, not litigation-based.

How does Atromid-S compare with modern lipid drugs?

Product or class	Main use	Evidence position	Patent position	Commercial status
Clofibrate / Atromid-S	Historical lipid lowering	Weak relative to modern standards	Expired	Legacy
Gemfibrozil	Selected hypertriglyceridemia use	Established but interaction-limited	Generic
Fenofibrate	Hypertriglyceridemia and mixed dyslipidemia	More practical fibrate option	Largely generic, with historical formulation patents
Statins	LDL reduction and cardiovascular-risk reduction	Strong	Mostly generic, except newer products
Ezetimibe	LDL reduction	Strong adjunctive evidence	Generic
PCSK9 inhibitors	High-risk LDL reduction	Strong	Active biologic and formulation estates for some products
Icosapent ethyl	Selected triglyceride-related risk reduction	Outcome-supported in defined populations	Product-specific patent litigation history

Clofibrate is disadvantaged because its historical evidence does not support the broad cardiovascular-prevention role occupied by statins and other modern therapies.

What formulation patents could support an Atromid-S relaunch?

A relaunch would need a differentiated technical product. Potential targets could include:

1. Modified-release capsules designed to reduce dosing frequency.
2. A formulation intended to improve gastrointestinal tolerability.
3. A fixed-dose combination with another lipid-lowering agent.
4. A liquid or sprinkle formulation for patients with swallowing limitations.
5. A formulation designed to reduce conversion variability or improve pharmacokinetics.
6. A narrow-use product for severe hypertriglyceridemia.

These concepts would not automatically create investable value. A sponsor would need to demonstrate that the formulation produces a clinically meaningful benefit, not merely a different release profile. Patent claims could be vulnerable if they rely on routine excipients, conventional release technologies, or predictable pharmacokinetic optimization.

A 505(b)(2) strategy could reduce development requirements for a reformulated product, but the sponsor would still face clinical, labeling, safety, and market-access barriers. New three-year clinical exclusivity might be available for certain approval-supporting investigations, but it would not restore broad molecule-level exclusivity.

What patent litigation affects Atromid-S?

No active litigation materially affects Atromid-S as a commercial asset. The historical product does not present the usual branded-drug litigation profile involving:

• Paragraph IV notices.
• Hatch-Waxman infringement actions.
• Orange Book patent disputes.
• Settlement agreements restricting generic launch.
• Authorized-generic strategy.
• Biosimilar litigation.

The biosimilar category is not relevant because clofibrate is a chemically synthesized small molecule, not a biologic. Any future competition would arise through generic-drug pathways rather than biosimilar applications.

Does Atromid-S have licensing or acquisition value?

A legacy brand acquisition would have limited value unless it included a viable regulatory file, a recognized market outside the United States, or rights to a differentiated reformulation.

Potential transaction structures include:

Transaction type	Strategic value
Purchase of historical trademark	Low
Acquisition of old product rights	Low without active sales
Regional licensing	Possible only in narrow markets
Reformulation license	Potentially meaningful if supported by data
Manufacturing license	Limited because the molecule is established
Combination-product partnership	Higher development risk
Rights to clinical data	Mostly historical and insufficient for broad relaunch

A buyer should not value Atromid-S using historical peak sales. The relevant valuation variables are the cost of regulatory redevelopment, probability of approval, reimbursement access, evidence requirements, and the size of any defensible niche.

What revenue exposure does Atromid-S create?

Atromid-S has no evident current revenue exposure comparable to an active branded cardiovascular franchise. Any historical revenue was generated before the widespread adoption of statins and before current lipid-management guidelines.

For an investment model, the base case should assign:

• No recurring branded revenue from the legacy U.S. product.
• No patent-expiry revenue cliff because exclusivity ended long ago.
• No material litigation liability tied to an active Orange Book estate.
• No biosimilar exposure.
• Low probability of a commercially significant relaunch without new clinical and formulation investment.
• High sensitivity to regulatory rejection, weak reimbursement, and physician reluctance.

A relaunch model should be treated as a high-risk specialty generic or 505(b)(2) development project, not as a protected pharmaceutical franchise.

What manufacturing and intellectual-property barriers remain?

Clofibrate is a mature small molecule with relatively limited manufacturing differentiation. The molecule’s synthesis is not expected to create the same barrier as a complex biologic, sterile injectable, or highly specialized drug-delivery system.

Remaining barriers include:

• Validation of current-good-manufacturing-practice production.
• Control of impurities and degradation products.
• Stability data for the proposed dosage form.
• Bioequivalence or bridging studies.
• Current toxicology and pharmacovigilance expectations.
• Supply-chain economics at low volumes.
• Regulatory acceptance of an old reference product and historical clinical record.

These are execution barriers, not durable competitive barriers. A sponsor could potentially obtain process patents, but competitors may design around them unless the process produces a material cost or quality advantage.

What is the investment scenario for Atromid-S?

Base case

Atromid-S remains a noncommercial legacy drug with no meaningful patent value, no active branded-market position, and no clear pathway to material revenue. This is the most supportable scenario.

Upside case

A sponsor identifies a narrowly defined unmet need, develops a differentiated formulation, secures a modern regulatory pathway, and obtains limited regulatory or formulation-based exclusivity. The upside would depend on premium pricing and successful physician adoption despite the molecule’s unfavorable history.

Downside case

A relaunch fails because modern lipid therapies offer better outcomes, regulators demand additional evidence, prescribers reject the historical safety profile, or payers refuse reimbursement. Generic competition would prevent premium pricing if the product is approved without meaningful differentiation.

Investment criterion	Rating
Patent protection	Very weak
Regulatory certainty	Weak
Clinical differentiation	Weak
Manufacturing complexity	Low
Market size	Low for the legacy indication
Competitive intensity	High
Litigation protection	None of practical significance
Licensing appeal	Low
Relaunch optionality	Possible but speculative
Overall investment quality	Poor without a new, validated product concept

Key Takeaways

• Atromid-S is the historical brand for clofibrate, an obsolete fibrate lipid-lowering drug.
• Original molecule, formulation, and regulatory exclusivity have expired.
• No active patent estate provides a meaningful barrier to generic competition.
• No current Paragraph IV, Orange Book, biosimilar, or settlement activity materially affects the asset.
• Historical clinical evidence weakened clofibrate’s benefit-risk profile.
• Statins, fenofibrate, ezetimibe, PCSK9 inhibitors, and newer triglyceride therapies dominate the relevant market.
• The legacy product has little current revenue value.
• Investment value would require a new formulation, combination, delivery system, or narrowly defined indication supported by modern clinical evidence.
• A conventional generic launch would face low legal barriers but weak commercial demand.
• Atromid-S should be valued as a redevelopment option, not as an active pharmaceutical franchise.

FAQs About Atromid-S and Clofibrate

Is Atromid-S still available in the United States?

Atromid-S is not a current U.S. growth product. The brand is historical, and clofibrate does not occupy a meaningful position in current U.S. lipid-treatment practice.

Is clofibrate the same as fenofibrate?

No. Both are fibrates, but clofibrate and fenofibrate are different chemical compounds with different clinical histories, formulations, and market positions. Fenofibrate has replaced clofibrate in many fibrate-treatment settings.

Can a company still patent clofibrate?

A company cannot obtain a new composition-of-matter patent on the old clofibrate molecule. It could seek patents for a novel formulation, delivery method, combination, manufacturing process, or narrowly defined method of use.

Does Atromid-S have biosimilar risk?

No. Clofibrate is a small-molecule chemical drug. Competition would occur through generic-drug pathways, not biosimilar applications.

Would a clofibrate reformulation qualify for new FDA exclusivity?

A reformulated or otherwise modified product could potentially qualify for limited regulatory exclusivity if it meets the statutory requirements and is supported by qualifying clinical investigations. That exclusivity would apply to the approved innovation, not to the old clofibrate molecule broadly.

References

1. World Health Organization Cooperative Trial Committee. (1978). WHO cooperative trial on primary prevention of ischaemic heart disease using clofibrate to lower serum cholesterol: Final report. British Heart Journal, 40(10), 1069-1118.

2. U.S. Food and Drug Administration. (n.d.). Clofibrate prescribing information and historical labeling. U.S. Department of Health and Human Services.

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.

4. National Library of Medicine. (n.d.). Clofibrate. PubChem compound database. National Center for Biotechnology Information.

5. U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs. U.S. Department of Health and Human Services.