United States Patent 5,840,737: Scope, Claim Construction, Expiration, and Omeprazole Patent Landscape

U.S. Patent No. 5,840,737 covers an immediate-release oral liquid or suspension containing omeprazole or lansoprazole and a bicarbonate salt of sodium or potassium. The patent focuses on administering the proton-pump inhibitor and bicarbonate in one dose, without separately administering bicarbonate. The patent issued on November 24, 1998, and its 20-year patent term expired in 2016, subject to any applicable patent-term adjustment or extension. It no longer creates an enforceable U.S. patent barrier for generic omeprazole/sodium bicarbonate products.

What does U.S. Patent 5,840,737 protect?

The patent protects a treatment method with five principal technical elements:

A gastric-acid disorder is treated.
The active ingredient is omeprazole or lansoprazole.
The drug is in a pharmaceutically acceptable carrier consisting essentially of a Group IA metal bicarbonate.
The product is administered orally as a single dose.
The patient does not need a separate or additional administration of bicarbonate.

The central commercial concept is an immediate-release liquid dosage form in which bicarbonate both accompanies the proton-pump inhibitor and creates an alkaline environment. The bicarbonate is intended to protect the acid-labile proton-pump inhibitor during administration and permit delivery without the conventional enteric-coated granules or tablets associated with delayed-release omeprazole products.

The claims do not broadly cover every omeprazole product containing bicarbonate. They require the claimed administration method, including the single-dose and no-separate-bicarbonate limitations.

What are the key claim limitations in Patent 5,840,737?

Independent claim 1

Claim 1 is the controlling claim. It requires:

Claim element	Scope
Disease	Gastric acid disorder
Active drug	Omeprazole or lansoprazole
Carrier	Pharmaceutically acceptable carrier consisting essentially of a Group IA metal bicarbonate
Administration	Oral administration
Dosage form	Single dose of an aqueous solution or suspension
Bicarbonate delivery	No further administration of the bicarbonate salt is required

The phrase "consisting essentially of" generally permits components that do not materially affect the basic and novel characteristics of the claimed composition. It is narrower than "comprising" and broader than "consisting of." The principal issue would be whether additional excipients materially alter the single-dose bicarbonate delivery system.

The claim also uses "approximately," which gives the concentration limitations in dependent claims some measurement tolerance. It does not eliminate the need to prove that an accused product falls within the claimed concentration range.

Dependent claims 2 and 3

Claims 2 and 3 narrow the bicarbonate salt to:

Sodium bicarbonate; or
Potassium bicarbonate.

Sodium bicarbonate is the commercially significant embodiment. Potassium bicarbonate is separately claimed but has substantially less relevance to marketed omeprazole products.

Dependent claims 4 through 6

These claims specify omeprazole concentrations:

Claim	Omeprazole concentration
Claim 4	Approximately 0.5 to 6.0 mg/mL
Claim 5	Approximately 1.0 to 4.0 mg/mL, with potassium bicarbonate
Claim 6	Approximately 2.0 mg/mL, with potassium bicarbonate

Claims 5 and 6 are unusually narrow because they depend through claim 3 and therefore require potassium bicarbonate. A sodium bicarbonate product would not fall within those claims.

Dependent claims 7 through 9

These claims address bicarbonate concentration:

Claim	Bicarbonate concentration
Claim 7	Approximately 5.0% to 60.0%
Claim 8	Approximately 7.5% to 10.0%
Claim 9	Approximately 8.4%

The 8.4% concentration corresponds to a commercially practical high-bicarbonate formulation. The concentration is likely expressed as a weight/volume or comparable formulation percentage based on the patent disclosure. Product-by-product analysis would require review of the applicable specification, labeling, and manufacturing formula.

Dependent claims 10 and 11

These claims add bicarbonate-dose limitations:

Approximately 0.75 to 1.5 mEq of bicarbonate per milliliter.
Less than approximately 12 mEq per 20 mg omeprazole dose.

These limitations distinguish the claimed product from formulations that deliver substantially greater bicarbonate quantities. They also create potential claim-construction issues concerning whether the bicarbonate amount is measured in the administered dose, the reconstituted product, or the labeled dose volume.

Dependent claim 12

Claim 12 requires administration in a volume of approximately 10 to 20 mL. A commercial product administered in a materially larger volume could avoid this claim while still potentially implicating claim 1.

How does the claim set apply to commercial omeprazole products?

The patent is most relevant to a product with the following profile:

Product characteristic	Relevance
Omeprazole active ingredient	Required by claims 1 and 4-12
Lansoprazole active ingredient	Covered by claim 1, but not by claims specifically requiring omeprazole
Sodium bicarbonate	Covered by claim 2 and the broad claim 1
Potassium bicarbonate	Covered by claim 3 and claims 5-6
Immediate-release liquid	Strongly aligned with the claims
Aqueous solution or suspension	Required by claim 1
Single oral administration	Required by claim 1
Separate bicarbonate dose	The claim requires that no additional bicarbonate dose be needed
Enteric-coated capsule	Generally outside the express liquid/suspension limitation
Powder for reconstitution	Potentially within the claims after reconstitution, depending on the product presentation and administration method

A conventional delayed-release omeprazole capsule without bicarbonate would generally fall outside the claim language. A liquid omeprazole product using sodium bicarbonate could have presented a closer infringement question during the patent term.

When did U.S. Patent 5,840,737 expire?

The patent issued on November 24, 1998. Public patent records identify an August 28, 1996 priority date and a 20-year term measured from the relevant nonprovisional filing framework. The ordinary expiration date was August 28, 2016, absent an effective patent-term adjustment or extension.[1]

Event	Date
Earliest identified priority date	August 28, 1996
Patent issued	November 24, 1998
Ordinary 20-year expiration	August 28, 2016
Current enforceability	Expired

The patent was not eligible for the type of pediatric exclusivity that can extend a patent right for six months. Patent-term extension under 35 U.S.C. § 156 is generally associated with regulatory review of qualifying products and would need to be separately reflected in the patent and FDA records. No current enforceable term for Patent 5,840,737 should be assumed.

What was the Orange Book status of Patent 5,840,737?

Patent 5,840,737 was associated with the omeprazole/sodium bicarbonate product Zegerid, marketed by Santarus, Inc., and later associated with successor commercial rights. Zegerid was approved by the FDA as an omeprazole and sodium bicarbonate product, including powder-for-suspension presentations.[2]

The patent’s relevance to Orange Book analysis was limited by three factors:

The patent claims a method of treatment rather than a broad composition claim.
The claims focus on liquid or suspension administration.
The patent expired in 2016.

After expiration, the patent could no longer support a current Paragraph IV litigation strategy or block FDA approval based on an unexpired patent right. FDA listing status and patent enforceability are separate questions. An expired patent may remain visible in historical Orange Book records while having no remaining exclusionary term.

Were Paragraph IV challenges or generic litigation associated with this patent?

A Paragraph IV certification would have been relevant while the patent was listed and unexpired. A generic applicant could have argued that:

The proposed product did not contain the claimed bicarbonate concentration.
The product was not administered as a single aqueous solution or suspension.
The product required a separate bicarbonate administration.
The product used a dosage volume outside the 10-to-20 mL range.
The patent claims were invalid for anticipation, obviousness, lack of written description, or indefiniteness.
The patent was unenforceable or improperly listed.

The commercial Zegerid patent dispute environment also included later patents directed to omeprazole/bicarbonate formulations and methods. Those later patents, rather than Patent 5,840,737 alone, were more likely to drive ANDA litigation and settlement negotiations for later generic entrants.

The expiration of Patent 5,840,737 eliminates the need for a current Paragraph IV challenge to this patent. Any ongoing generic risk analysis must instead examine later unexpired patents, regulatory exclusivity, trade secrets, manufacturing controls, and product-specific Orange Book listings.

What later patents protected Zegerid and omeprazole/sodium bicarbonate products?

Patent 5,840,737 was an early patent in the commercial estate surrounding immediate-release omeprazole with bicarbonate. The broader landscape included later patents directed to:

Omeprazole/bicarbonate compositions.
Powder-for-suspension products.
Dosage strengths and administration methods.
Stability and reconstitution.
Methods for treating nocturnal acid breakthrough.
Manufacturing processes and formulation performance.

Publicly associated later U.S. patents include U.S. Patent Nos. 6,489,346 and 6,645,988, which were linked to the commercial Zegerid patent estate in historical regulatory and litigation materials.[2][3] Their enforceability and expiration dates must be analyzed separately from Patent 5,840,737. A later patent cannot revive the expired claims of the ’737 patent, but it can create a separate barrier if its claims cover a generic product.

How strong was the patent estate for the claimed technology?

During its term, Patent 5,840,737 had meaningful practical coverage but limited breadth.

Strengths

It covered both omeprazole and lansoprazole in claim 1.
It captured a single-dose liquid or suspension format.
It expressly covered sodium and potassium bicarbonate.
It addressed a commercially useful concentration range.
It targeted the formulation architecture that differentiated immediate-release omeprazole products from standard delayed-release products.

Limitations

The independent claim required a method of treatment, not merely manufacture or sale.
The claim required an aqueous solution or suspension.
The single-dose and no-further-bicarbonate limitations could create factual defenses.
The dependent claims were narrow and internally differentiated by bicarbonate salt.
The claims did not broadly cover all oral omeprazole/bicarbonate formulations.
Expiration removed the patent’s current enforcement value.

The patent therefore had stronger relevance against an immediate-release liquid competitor than against a conventional enteric-coated omeprazole product.

What generic launch risks exist after expiration?

Patent 5,840,737 presents no current U.S. patent-blocking risk because it expired in 2016. Generic and follow-on product risks now depend on other factors:

Risk category	Current significance
’737 patent infringement	None after expiration
Later formulation patents	Product-specific
Method-of-use patents	Potentially relevant if listed and unexpired
FDA approval	Depends on ANDA, 505(b)(2), or other pathway
Bioequivalence	Relevant to oral liquid and suspension products
Manufacturing know-how	May affect product quality and stability
Trade secrets	May protect process information but do not create patent exclusivity
Trademark	Zegerid branding remains separate from patent rights
Biosimilar pathway	Not applicable because omeprazole is a small molecule
Regulatory exclusivity	Must be checked independently of patent expiration

A generic company could pursue an ANDA for a therapeutically equivalent product where the reference product and dosage form support an ANDA pathway. A materially different liquid formulation, strength, administration method, or indication could require a 505(b)(2) application.

What manufacturing and formulation barriers remain?

The expired patent does not eliminate technical barriers. Immediate-release omeprazole is sensitive to acidic conditions and can degrade without adequate alkalinity. A competing product must address:

Omeprazole stability in the presence of water.
Adequate bicarbonate loading.
Uniform dose delivery after reconstitution.
Suspension settling and redispersion.
Palatability and sodium load.
Container closure and moisture control.
Reconstitution time and labeled storage period.
Dose-volume accuracy.
Compatibility with oral syringes and administration devices.

These issues may support process patents or trade-secret protection even where the core ’737 claims are expired. They do not, however, extend the term of Patent 5,840,737.

Does Patent 5,840,737 create biosimilar risk?

No. Omeprazole and lansoprazole are chemically synthesized small-molecule drugs, not biologics. The relevant competitive pathways are ANDA and, for certain modified products, 505(b)(2). Biosimilar approval under the Public Health Service Act is not the applicable route.

What licensing and commercial rights were associated with the technology?

The commercial exploitation of the technology was associated with Santarus and the Zegerid product franchise. Santarus later became part of Salix Pharmaceuticals through a transaction involving Salix and Valeant Pharmaceuticals.[4] Those corporate transactions affected commercial ownership and licensing relationships but did not extend the patent term.

A current licensing decision should distinguish:

The expired patent rights under Patent 5,840,737.
Any surviving later patents.
Product trademarks and brand rights.
Regulatory reference-product rights.
Manufacturing know-how and confidential formulation information.
Settlement or license agreements tied to later patents.

Key Takeaways

Patent 5,840,737 covers a single oral dose of omeprazole or lansoprazole in an aqueous solution or suspension containing a Group IA metal bicarbonate.
Sodium bicarbonate is the commercially important embodiment.
The patent requires that the patient not receive a separate bicarbonate administration.
Dependent claims narrow the invention by drug concentration, bicarbonate concentration, bicarbonate equivalents, and 10-to-20 mL administration volume.
The patent issued on November 24, 1998, and expired in 2016 under the ordinary patent-term calculation.
It no longer presents an enforceable U.S. patent barrier.
Later Zegerid and omeprazole/bicarbonate patents require separate analysis.
No biosimilar pathway applies because omeprazole is a small molecule.
Current competition is driven by later patents, FDA pathway selection, formulation stability, manufacturing know-how, and commercial execution.

FAQs About U.S. Patent 5,840,737

Can a generic company launch an omeprazole and sodium bicarbonate liquid after expiration of Patent 5,840,737?

Yes, the ’737 patent itself does not prevent launch after expiration. The applicant must still address later patents, FDA requirements, bioequivalence, labeling, and any applicable method-of-use restrictions.

Does Patent 5,840,737 cover Zegerid capsules?

The claim language is directed to an aqueous solution or suspension administered as a single dose. A conventional capsule product would not automatically fall within the claims and requires product-specific analysis.

Does the patent cover sodium bicarbonate separately from omeprazole?

No. The claims require a pharmaceutical composition containing omeprazole or lansoprazole together with the bicarbonate carrier. Sodium bicarbonate alone is outside the claimed method.

Could a product avoid the patent by using calcium carbonate instead of sodium bicarbonate?

During the patent term, calcium carbonate would not literally satisfy the Group IA metal bicarbonate limitation. It could raise a doctrine-of-equivalents issue depending on the facts, but the patent has expired.

Are Patent 5,840,737 claims composition claims or method claims?

They are method-of-treatment claims. Each claim requires administering the specified pharmaceutical composition to a patient for a gastric acid disorder.

References

United States Patent and Trademark Office. (1998). U.S. Patent No. 5,840,737: Pharmaceutical composition and method for treating gastric acid disorders. U.S. Department of Commerce.
U.S. Food and Drug Administration. (n.d.). Orange Book: Approved drug products with therapeutic equivalence evaluations. FDA.
United States Patent and Trademark Office. (2002). U.S. Patent No. 6,489,346: Pharmaceutical compositions and methods involving omeprazole and bicarbonate. U.S. Department of Commerce.
Salix Pharmaceuticals, Ltd. (2014). Annual report on Form 10-K. U.S. Securities and Exchange Commission.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	038157	⤷ Start Trial
Austria	340574	⤷ Start Trial
Australia	1907100	⤷ Start Trial
Australia	2002330863	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,840,737

Summary for Patent: 5,840,737