United States Patent 6,132,758: Loratadine Syrup Claims, Expiration, and Patent Landscape

U.S. Patent No. 6,132,758 protected stabilized loratadine liquid formulations containing an aminopolycarboxylic acid, particularly ethylenediaminetetraacetic acid, or EDTA. The patent also covered loratadine syrups defined by limits on hydroxymethyl-loratadine degradation products. It was issued to Schering Corporation on October 17, 2000, and expired in 2018 based on its earliest claimed priority date. The patent no longer creates an enforceable barrier to generic loratadine syrup products. [1]

What does U.S. Patent 6,132,758 protect?

The patent protects liquid loratadine formulations in which an aminopolycarboxylic acid reduces degradation during storage. Its technical focus is formulation stability rather than loratadine's antihistaminic activity.

The core inventive concept has four elements:

A syrup or liquid oral formulation.
Loratadine as the active antihistamine.
An aminopolycarboxylic acid or salt.
Stabilization of loratadine, measured either by the presence of the stabilizer or by limits on specified degradation products.

The patent's principal stabilizer is EDTA. The claims also identify iminodiacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, 1,2-diaminocyclohexanetetraacetic acid and N-hydroxyethylenediaminetriacetic acid.

Patent identification and legal timeline

Item	Detail
Patent	U.S. Patent No. 6,132,758
Title	Stabilized loratadine syrup
Patent type	Formulation and pharmaceutical composition
Patent holder at issuance	Schering Corporation
Filing date	1998
Earliest priority	1997
Issue date	October 17, 2000
Estimated statutory expiration	2018
Active status today	Expired
Primary product relevance	Loratadine oral syrup or oral solution
Principal stabilizer	EDTA and related aminopolycarboxylic acids

The patent term was governed by the 20-year term measured from the earliest effective nonprovisional filing date under the Uruguay Round Agreements Act. [1][2]

How many independent claims does the patent have?

The supplied claims contain four principal independent claim groups: claims 1, 11, 12 and 13.

Claim 1: quantified stabilizer formulation

Claim 1 covers:

an antihistaminic syrup;
loratadine; and
approximately 0.05 to approximately 5 mg/mL of an aminopolycarboxylic acid or salt.

This is the principal composition claim. A product generally would need to satisfy each element, including the syrup form, loratadine content and stabilizer concentration.

The use of "about" creates a range with some tolerance around the stated concentrations. The claim does not require EDTA specifically. It covers the defined chemical class of aminopolycarboxylic acids and their salts.

Claims 2 through 5: stabilizer and concentration limitations

These claims narrow claim 1 in several ways:

Claim	Limitation
2	Lists the permitted aminopolycarboxylic acids and combinations
3	Requires EDTA
4	Requires approximately 0.1 to 1 mg/mL stabilizer
5	Requires approximately 0.25 to 0.5 mg/mL stabilizer

Claim 5 is the narrowest concentration claim in the supplied set. An EDTA-containing loratadine syrup with 0.25 to 0.5 mg/mL EDTA would fall within the express scope of claims 3 and 5 if the remaining limitations were met.

Claims 6 through 10: combination cold medicines

Claims 6 through 10 extend the formulation to combination products containing:

pseudoephedrine;
phenylpropanolamine;
an analgesic;
an antitussive;
an expectorant; or
combinations of these ingredients.

These claims were directed to multisymptom cold products rather than loratadine-only syrups. Claim 8 specifically requires pseudoephedrine. Claims 9 and 10 address analgesic combinations, with claim 10 requiring both pseudoephedrine and an analgesic.

Because phenylpropanolamine was removed from the U.S. market as an over-the-counter nasal decongestant after FDA action concerning hemorrhagic stroke risk, its commercial relevance is limited. [3]

What do claims 11 and 12 protect?

Claims 11 and 12 are independent product claims defined by degradation-product limits:

Claim 11 covers a storage-stable loratadine syrup containing less than 0.49% by weight of 2-hydroxymethyl loratadine.
Claim 12 covers a storage-stable loratadine syrup containing less than 0.53% by weight of 4-hydroxymethyl loratadine.

Neither claim, as supplied, expressly requires EDTA or any other particular stabilizer. That makes these claims materially broader in one respect than claim 1. A formulation could potentially fall within claim 11 or 12 based on its impurity profile even if it used a different stabilization strategy.

Why the degradation-product claims matter

The claims target chemical outcomes rather than only ingredients. A manufacturer could avoid the express EDTA limitation in claim 1 but still face infringement questions under claims 11 or 12 if its loratadine syrup met the specified impurity thresholds and the product was storage-stable.

The practical scope would depend on:

the meaning of "storage-stable";
the analytical method used to quantify each hydroxymethyl-loratadine impurity;
whether the impurity percentage is measured on a specified basis;
the relevant storage period and conditions; and
whether the formulation satisfies the claim's syrup limitation.

These claims would have required product testing, formulation records and stability data in an infringement dispute.

What do claims 13 through 16 protect?

Claim 13 broadly covers an antihistaminic syrup containing loratadine and an aminopolycarboxylic acid. Unlike claim 1, it does not state a concentration range.

Claim 14 adds the functional requirement that the aminopolycarboxylic acid be present in an amount sufficient to inhibit loratadine degradation. Claim 15 limits the stabilizer to EDTA. Claim 16 combines EDTA with the requirement that it be present in an amount sufficient to inhibit degradation.

The relationship between claims 1 and 13 is important:

Feature	Claim 1	Claim 13
Loratadine	Required	Required
Syrup	Required	Required
Aminopolycarboxylic acid	Required	Required
Concentration range	0.05 to 5 mg/mL	None stated
EDTA required	No	No, except claim 15
Antihistaminic formulation	Yes	Yes
Functional stabilization requirement	Not expressly stated	Added in claim 14

Claim 13 could cover formulations outside claim 1's stated concentration range, subject to the scope of the term "aminopolycarboxylic acid" and other claim-construction issues. Claims 14 and 16 introduce a functional limitation that would likely require technical evidence showing inhibition of degradation.

What formulations are protected by U.S. Patent 6,132,758?

The strongest literal-read coverage applies to loratadine oral syrups containing EDTA at concentrations within the claimed range.

Formulations most directly exposed

Formulation	Likely claim exposure during patent term
Loratadine syrup with 0.25-0.5 mg/mL EDTA	High, under claims 1, 3 and 5
Loratadine syrup with 0.1-1 mg/mL EDTA	High, under claims 1, 3 and 4
Loratadine syrup with 0.05-5 mg/mL nitrilotriacetic acid	Potentially within claims 1 and 2
Loratadine-pseudoephedrine syrup with EDTA	Potentially within claims 1, 6, 7 and 8
Loratadine syrup with an analgesic and EDTA	Potentially within claims 1, 9 and 10
Loratadine syrup with no EDTA but less than 0.49% 2-hydroxymethyl loratadine	Potentially within claim 11
Loratadine syrup with no EDTA but less than 0.53% 4-hydroxymethyl loratadine	Potentially within claim 12
Loratadine tablet, capsule or orally disintegrating tablet	Generally outside the syrup limitations
Loratadine solution without an aminopolycarboxylic acid	Outside claims 1 and 13, but impurity claims require separate analysis

The patent did not broadly claim every loratadine dosage form. Tablets, capsules and other solid formulations generally would not meet the syrup limitation. A liquid product marketed as an oral solution could still raise claim-construction questions if "syrup" were disputed, particularly where the product had low viscosity or lacked conventional syrup excipients.

How strong was the patent estate?

The estate was technically focused but commercially relevant during the period when loratadine syrup was sold as a branded or generic liquid product.

Strengths

Claims 1 and 13 directly targeted the formulation architecture.
EDTA was expressly identified and separately claimed.
The concentration ranges covered commercially practical stabilizer levels.
Claims 11 and 12 used impurity thresholds that could reach products using non-EDTA stabilization methods.
Combination-product claims addressed loratadine and decongestant or analgesic products.

Limitations

The claims were limited to syrups.
The patent did not claim loratadine itself.
The patent did not control solid oral loratadine products.
A generic manufacturer could potentially design around the expressly claimed stabilizer concentrations.
Claims 11 and 12 depended on analytical measurements and the meaning of storage stability.
The patent has expired, eliminating current infringement risk.

The patent therefore represented a formulation barrier, not a basic active-ingredient barrier.

What was the FDA and Orange Book status?

Loratadine became an over-the-counter antihistamine in the United States after FDA approval of the switch from prescription to nonprescription status. Claritin products included tablets, chewable tablets and liquid formulations. [4]

The Orange Book lists patents and regulatory exclusivity associated with approved prescription products and certain listed drug products. Orange Book relevance depends on the specific approved product, dosage form and patent submission. [5]

U.S. Patent 6,132,758 is no longer a live Orange Book exclusivity barrier because its patent term expired in 2018. Even if it was previously listed for a loratadine liquid product, an expired listing cannot block approval or commercial launch of an otherwise compliant generic or private-label product.

Which companies challenged loratadine patent protection?

The principal U.S. generic competition to loratadine developed around the expiration and litigation of earlier patents covering loratadine and branded Claritin products. Companies including Teva, Mylan and other generic manufacturers entered the loratadine market after the relevant exclusivity barriers ended.

The supplied record does not establish a specific Paragraph IV case directed solely to claims 1 through 16 of U.S. Patent 6,132,758. Paragraph IV certifications are ANDA-specific and depend on the patents listed for the particular reference product. A Paragraph IV certification against this patent would have been relevant only while the patent was listed and unexpired. After 2018, a certification against the patent could not create a current launch-blocking patent dispute. [5][6]

What litigation and settlement agreements affect the patent?

No current litigation threat arises from U.S. Patent 6,132,758 because the patent expired. The patent's expiration also removes the commercial significance of any historical settlement that may have governed launch timing during the patent term.

No licensing transaction specifically tied to this patent is identified in the patent record or the FDA listing materials. Schering Corporation's commercial rights later became associated with the broader Schering-Plough and Merck corporate structure, but corporate succession did not extend the patent term.

What generic launch risks exist today?

The patent creates no current generic launch bar. Current risk is regulatory and commercial rather than patent-based.

A competing loratadine syrup would still need to address:

FDA requirements for the applicable OTC monograph or approved application;
active-ingredient identity and assay;
impurity specifications;
preservative effectiveness;
microbial quality;
shelf-life and stability;
labeling and dosing;
excipient safety; and
manufacturing controls under current good manufacturing practice requirements.

A manufacturer using EDTA may obtain formulation and stability benefits without facing an enforceable patent claim from this patent. Separate patents, trademarks, trade dress, formulation know-how or manufacturing patents would require independent review.

How does this patent compare with the broader loratadine patent estate?

Patent category	Commercial effect
Basic loratadine compound patents	Controlled early market exclusivity
Loratadine synthesis patents	Could affect manufacturing routes
Loratadine syrup stabilization patent	Targeted liquid-formulation protection
Method-of-use patents	Could cover particular therapeutic uses
Pediatric exclusivity	Temporary FDA approval delay, not a patent right
Trademark protection for Claritin	Brand protection remains separate from patent expiration
Trade secrets and manufacturing know-how	May remain relevant after patent expiry

U.S. Patent 6,132,758 did not provide broad protection for the loratadine molecule, its antihistamine mechanism or all dosage forms. Its value was concentrated in liquid formulation stability and combination syrup products.

Key Takeaways

U.S. Patent 6,132,758 covers stabilized loratadine syrups.
EDTA is the principal claimed stabilizer.
Claims 1 and 13 are the central composition claims.
Claims 11 and 12 cover impurity-defined storage-stable syrups without expressly requiring EDTA.
Claims 6 through 10 cover decongestant, analgesic, antitussive and expectorant combinations.
The patent was issued on October 17, 2000, and expired in 2018.
It no longer blocks generic loratadine syrup approval or launch.
The patent was a formulation patent, not a basic loratadine compound patent.
Current competitive exposure depends on FDA compliance, formulation performance, manufacturing cost and separate intellectual-property rights.

FAQs

Does U.S. Patent 6,132,758 cover loratadine tablets?

No. The supplied claims are directed to syrups. A tablet, capsule or other solid dosage form generally would not satisfy the syrup limitation.

Does using EDTA in a loratadine syrup infringe the patent today?

No enforceable infringement liability arises from this patent today because the patent expired in 2018. During its term, EDTA-containing syrups within the claimed concentration ranges presented the greatest exposure.

Did the patent cover loratadine itself?

No. It covered stabilized liquid formulations containing loratadine and an aminopolycarboxylic acid. It did not claim the loratadine molecule generally.

Could a loratadine syrup avoid the patent by using a different stabilizer?

During the patent term, a different stabilizer could avoid claims requiring EDTA or a listed aminopolycarboxylic acid, but claims 11 and 12 required separate analysis because they were defined by degradation-product limits rather than a named stabilizer.

Is a Paragraph IV challenge still required for this patent?

No current launch-blocking Paragraph IV issue exists for an expired patent. The relevance of any historical Paragraph IV certification depended on the specific ANDA, reference product and Orange Book listing in effect before expiration.

References

United States Patent and Trademark Office. (2000). U.S. Patent No. 6,132,758, Stabilized loratadine syrup.
United States Code, 35 U.S.C. § 154. Patent term.
U.S. Food and Drug Administration. (2000). FDA proposes removal of phenylpropanolamine from over-the-counter products.
U.S. Food and Drug Administration. (2002). FDA approves nonprescription use of Claritin and other loratadine products.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations.
U.S. Food and Drug Administration. (2024). Abbreviated new drug application approvals and patent certifications.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	019147	⤷ Start Trial
Austria	257705	⤷ Start Trial
Australia	4308599	⤷ Start Trial
Australia	754469	⤷ Start Trial
Canada	2333528	⤷ Start Trial
Colombia	5011119	⤷ Start Trial
Costa Rica	6035	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,132,758

Summary for Patent: 6,132,758