United States Patent 6,403,609: Scope, Claim Analysis, Expiration, and Ophthalmic Patent Landscape

U.S. Patent No. 6,403,609 covers liquid ophthalmic compositions that contain guar or a guar derivative, a borate compound, and water. The central technical concept is hydroxypropyl guar that remains sufficiently fluid in the bottle but thickens after contact with the eye. The patent was assigned to Alcon Laboratories, Inc., and issued on June 11, 2002.

The patent’s 20-year term from its earliest claimed priority date has ended. Based on the public priority and filing record, the patent expired in or around August 2019, subject to any patent-term adjustment or terminal-disclaimer information recorded by the USPTO. It therefore does not currently block manufacture or sale of a product that falls within the issued claims. Its claims remain relevant as prior-art evidence and as a technology marker for later hydroxypropyl-guar ophthalmic patents.

What does U.S. Patent 6,403,609 cover?

The patent protects a platform rather than a single commercial formulation. Its core limitations are:

Element	Principal scope
Dosage form	Topical ophthalmic liquid
Polymer	Guar or a guar derivative; narrower claims specify hydroxypropyl guar
Polymer concentration	0.1% to 5.0% w/v; narrower claims use 0.2% to 2.0% w/v or 0.1% to 3.0% w/v
Borate	0.05% to 5.0% w/v in the broad claims; narrower claims use 0.1% to 2.0% w/v
Borate species	Boric acid, sodium borate, potassium borate, or combinations
Vehicle	Water
pH	Claims require slightly acidic to neutral pH, or specifically pH 6.0 to 7.0
In-use behavior	Certain claims require thickening into a gel or partial gel after ocular administration
Use	Ocular lubrication, artificial tears, or delivery of an ophthalmic pharmaceutical agent
Sterility	Required by claims 14 through 37

The patent is directed to a liquid-to-gel or liquid-to-partial-gel transition. The composition is intended to be instilled as a drop and then increase viscosity in the ocular environment. That behavior can extend residence time, improve lubrication, and support delivery of active pharmaceutical ingredients.

How are the claims organized?

The claims fall into five functional groups.

Claims 1-13: Broad liquid compositions and ocular-use methods

Claim 1 is the principal composition claim. It requires:

A topical ophthalmic liquid.
0.1% to 5% w/v guar or a derivative.
0.05% to 5.0% w/v borate.
Water.
A pH that causes thickening into a gel or partial gel after one or more drops are administered to the eye.

Claims 2 through 7 narrow the formulation by adding pH, borate identity, hydroxypropyl guar, molar substitution, and concentration limitations.

Claims 8 and 9 expand the composition to include pharmaceutical agents. The listed therapeutic categories include glaucoma drugs, anti-allergy drugs, antimicrobials, anti-inflammatory drugs, analgesics, neuroprotective agents, and other ophthalmic agents.

Claims 10 through 12 add a pH of 6.0 to 7.0 and use as an ocular lubricant or artificial tear. Claim 13 covers the method of lubricating the eye with a claim 1-10 composition.

Claims 14-22: Sterile ophthalmic compositions

Claim 14 is an independent sterile-composition claim. It requires:

0.1% to 5% w/v of a galactomannan selected from guar and derivatives;
0.05% to 5.0% w/v borate; and
water.

Unlike claim 1, claim 14 does not expressly require the composition to thicken after administration. It also does not expressly require a particular pH. This makes claim 14 materially broader in some respects, even though it adds sterility.

Claims 15 through 22 narrow the galactomannan and borate identity, pH, active-agent content, artificial-tear use, and lubricating method.

Claims 23-27: Drug-delivery methods

Claim 23 covers topical delivery of a pharmaceutical agent using a sterile composition containing:

the active agent;
0.1% to 5% w/v guar or derivative;
0.05% to 5% w/v borate; and
water.

Claims 24 through 27 narrow the borate, polymer, concentration, and therapeutic-agent categories.

These claims are method-of-use claims. Infringement would depend on the accused party’s use of the composition to deliver a pharmaceutical agent, not merely on the composition’s physical presence in a package.

Claims 28-37: Narrow artificial-tear claims

Claim 28 is an independent claim directed to sterile ocular-lubricant or artificial-tear compositions. It narrows the concentration ranges to:

0.1% to 3.0% w/v galactomannan; and
0.1% to 2.0% w/v borate.

Claims 29 through 34 narrow the chemical identities and pH. Claims 35 through 37 cover methods of lubricating the eye with those formulations.

This group is narrower in concentration and intended use than claim 14, but it does not necessarily require the gel-transition language found in claim 1.

What are the strongest and weakest claim limitations?

The strongest commercial coverage is concentrated in the combination of hydroxypropyl guar and borate at ophthalmically useful concentrations.

Strong limitations

The following limitations are technically distinctive when combined:

Hydroxypropyl guar rather than generic viscosity agents.
Boric acid or another listed borate compound.
A liquid formulation that thickens after ocular administration.
pH 6.0 to 7.0.
Sterile ophthalmic presentation.
Concentration ranges that correspond to commercial artificial-tear formulations.

The gel-transition limitation can distinguish the claims from ordinary liquid tears containing cellulose derivatives, polyvinyl alcohol, polyethylene glycol, or simple saline.

Broad or vulnerable limitations

Several limitations create potential validity or construction issues:

“Guar or a derivative thereof” is broad.
“Borate compound” includes multiple salts and combinations.
“Water” does not exclude buffers, preservatives, electrolytes, surfactants, or active ingredients.
“Slightly acidic to neutral pH” is less precise than the pH 6.0-7.0 limitation.
Claims 14 and 28 do not expressly require the gel-transition result.
The use of “comprising” permits additional ingredients.

A prior-art formulation containing guar, borate, and water could present an anticipation issue if it also falls within the claimed concentration and sterility ranges. For an obviousness challenge, the relevant question would be whether a skilled formulator would have combined guar or hydroxypropyl guar with borate to obtain a liquid ophthalmic composition that thickens under ocular conditions.

What is the significance of the hydroxypropyl-guar limitation?

Hydroxypropyl guar is the principal commercial and technical species in the patent. The claims identify hydroxypropyl guar and, in claim 5, specify a molar substitution of less than 0.6.

Molar substitution affects hydration, rheology, compatibility with borate, and the degree of viscosity increase after administration. A low-substitution hydroxypropyl guar can provide a formulation that is pourable or drop-dispensable in the container but more viscous after exposure to the eye.

The patent does not claim every hydroxypropyl-guar formulation. A product analysis would need to address:

whether the polymer is chemically a guar derivative;
whether the molar substitution is below 0.6 when claim 5 is asserted;
the polymer and borate concentrations;
the formulation pH;
sterility;
whether the product is an artificial tear or drug-delivery composition; and
whether the composition exhibits the claimed in-eye thickening behavior.

What is the scope of the pH and gel limitations?

The pH limitations have different legal functions.

Claim 1 requires a pH “such that” the liquid thickens after ocular administration. This is a functional limitation tied to actual formulation performance. Testing may be required to determine whether a product satisfies the limitation.

Claims 2, 10, 11, 19, 33, and 34 impose more specific pH restrictions. The most concrete limitation is pH 6.0 to 7.0.

The gel limitation is not equivalent to simply having a high viscosity. The claim language targets a change after topical administration. A product that is viscous in the bottle but does not materially thicken on the eye may fall outside claim 1, although it could still fall within claims 14 or 28 if the remaining limitations are met.

What patent claims protect artificial tears using hydroxypropyl guar and borate?

The issued claims protect several artificial-tear configurations:

Claim group	Product concept	Key limitations
1-7	Liquid in-bottle formulation that thickens on the eye	Guar derivative, borate, water, pH-dependent gel formation
10-12	pH-controlled ocular lubricant	pH 6.0-7.0 and artificial-tear use
14-22	Sterile guar-borate ophthalmic composition	Sterility, galactomannan, borate, water
28-34	Narrow sterile artificial tear	0.1%-3.0% galactomannan and 0.1%-2.0% borate
13, 22, 35-37	Lubrication methods	Topical application of qualifying compositions
23-27	Drug delivery	Active agent plus sterile guar-borate formulation

A commercial product containing hydroxypropyl guar and boric acid may be within the technical field, but claim coverage depends on the exact quantitative formulation and the applicable claim group.

When did U.S. Patent 6,403,609 expire?

The patent issued June 11, 2002. Public patent records identify an earliest priority date in August 1999 and a nonprovisional filing in August 2000. The ordinary patent term therefore ran approximately 20 years from the earliest effective nonprovisional filing date, placing expiration in approximately August 2019, before any adjustment.

Event	Date or period
Earliest claimed priority	August 1999
U.S. nonprovisional filing	August 2000
Patent issued	June 11, 2002
Expected ordinary term endpoint	Approximately August 2019
Current status	Expired; verify any recorded PTA or terminal disclaimer in USPTO Patent Center

Because the patent has expired, the claims do not create a current U.S. exclusionary right. Expiration does not erase the patent’s relevance to prior-art analysis, freedom-to-operate history, or interpretation of later Alcon patent filings.

What was the FDA and Orange Book status?

U.S. Patent 6,403,609 is not best understood as an Orange Book patent protecting a conventional prescription drug product.

The claims cover ophthalmic formulations, artificial tears, and broad categories of potential active agents. Many commercial artificial tears are marketed under the FDA’s OTC ophthalmic framework rather than through an NDA. Products marketed under an OTC monograph generally do not have the same Orange Book patent-listing structure as approved prescription products.

The patent therefore should not be treated as an Orange Book barrier to an ANDA unless a specific prescription product and NDA listing connected it to the patent. The principal regulatory pathway for an artificial tear depends on the active ingredient and labeling. A hydroxypropyl-guar formulation used as a lubricant may be assessed under the applicable OTC ophthalmic monograph, while an active-drug formulation may require an NDA or another FDA pathway.

Were there Paragraph IV challenges or patent litigation?

No reliable conclusion about a specific Paragraph IV certification or litigation matter follows from the patent number alone. The claims are broad enough to have commercial significance for artificial tears and ophthalmic drug-delivery products, but Paragraph IV activity would depend on a drug-specific ANDA, an NDA patent listing, and a litigation docket.

The patent’s expiration also changes the litigation analysis. A Paragraph IV dispute directed solely to U.S. Patent 6,403,609 would no longer provide a live infringement controversy after expiration. Later patents covering specific formulations, delivery systems, preservatives, packaging, or active ingredients could still create separate litigation risk.

Which companies were most exposed to this patent technology?

Alcon is the central commercial entity associated with the patent and the hydroxypropyl-guar/borate technology. The technology is associated with the Systane family of ocular-lubricant products, although a particular product’s formulation, labeling, and patent coverage must be evaluated separately.

Relevant competitive categories include:

Company or category	Commercial relevance
Alcon	Originator associated with the patented guar-borate platform and Systane products
Bausch + Lomb	Competing artificial-tear and ocular-lubricant products using different or overlapping viscosity technologies
Johnson & Johnson Vision and related brands	Competing over-the-counter ocular-lubricant products
Generic and private-label manufacturers	Potential formulators of guar-based or alternative polymer artificial tears
Prescription ophthalmic-drug companies	Potential users of the drug-delivery claims where an active agent is included

A competing product can avoid the patent’s technical scope by omitting guar, replacing borate with another crosslinking or viscosity system, using a concentration outside the relevant range, or relying on a different delivery mechanism. Those alternatives may be covered by later patents.

How strong is the patent estate after expiration?

The enforceable strength of U.S. Patent 6,403,609 is effectively zero because the patent term has ended. Its historical claim breadth was substantial, particularly for formulations containing hydroxypropyl guar, borate, water, and a pH-controlled viscosity response.

The remaining commercial risk lies in later patent families, not in the expired patent itself. A current freedom-to-operate review should separate:

expired platform patents;
live formulation patents;
live method-of-use patents;
product-specific patents listed for prescription products;
manufacturing and sterilization patents;
packaging and multidose-dispenser patents; and
foreign rights that may have different expiration or maintenance outcomes.

The 6,403,609 patent does not by itself establish a current U.S. monopoly over hydroxypropyl guar artificial tears.

What manufacturing and formulation barriers remain?

Even after patent expiration, technical and regulatory barriers can remain. A manufacturer must control:

polymer hydration and batch-to-batch viscosity;
hydroxypropyl substitution level;
borate concentration and buffering;
osmolality and ocular tolerability;
preservative compatibility;
sterility assurance;
container-closure integrity;
drop size and dispensing performance;
viscosity change after administration; and
stability over the labeled shelf life.

The patent’s manufacturing disclosure may also remain relevant as prior art. A later patent cannot validly recapture the same disclosed combination merely by restating it, although a genuinely new formulation, use, process, or device may support separate patent rights.

Key Takeaways

U.S. Patent 6,403,609 covers guar or guar-derivative ophthalmic liquids containing borate and water.
The principal commercial concept is hydroxypropyl guar that thickens after administration to the eye.
Claims cover compositions, sterile compositions, artificial tears, lubrication methods, and drug-delivery methods.
Claims 14 and 28 are important because they do not expressly require the gel-transition limitation in claim 1.
Claim 5 narrows hydroxypropyl guar to a molar substitution below 0.6.
The patent issued June 11, 2002 and expired in approximately August 2019 based on its 1999 priority record.
It is not a current U.S. exclusionary barrier.
Artificial tears marketed under OTC pathways generally do not present the same Orange Book listing issues as prescription NDA products.
Current freedom-to-operate risk must be assessed against later formulation, delivery, packaging, manufacturing, and active-ingredient patents.
A product comparison requires exact composition, pH, sterility, polymer identity, concentration, intended use, and in-eye rheology.

FAQs

Does U.S. Patent 6,403,609 cover all artificial tears containing hydroxypropyl guar?

No. The product must satisfy the applicable claim limitations, including borate content, concentration ranges, water, sterility where required, pH or intended use, and, for certain claims, post-administration thickening.

Can a company launch a hydroxypropyl-guar artificial tear after expiration of this patent?

Yes, expiration removes the patent’s current U.S. exclusionary effect. The product may still implicate later patents or regulatory requirements.

Is boric acid interchangeable with sodium borate under the claims?

The claims expressly identify boric acid, sodium borate, potassium borate, and combinations. A product must still satisfy the concentration and other claim limitations.

Does a product need to contain a pharmaceutical active ingredient to infringe?

No. Claims 1-22 and 28-37 cover lubricant and artificial-tear compositions without requiring an active drug. Claims 23-27 specifically address delivery of a pharmaceutical agent.

Does the claim 18 dependency error eliminate the entire patent?

No. Claim 18 appears to refer to claim 18 instead of claim 17. That drafting defect affects the interpretation and enforceability of claim 18, but it does not automatically eliminate the other claims or the patent as a whole.

References

Alcon Laboratories, Inc. (2002). Ophthalmic compositions containing guar and borate (U.S. Patent No. 6,403,609). U.S. Patent and Trademark Office.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. FDA.
U.S. Food and Drug Administration. (n.d.). Ophthalmic drug products for over-the-counter human use. Code of Federal Regulations, 21 C.F.R. Part 349.
U.S. Patent and Trademark Office. (n.d.). Patent Center: Patent prosecution and maintenance records. USPTO.
U.S. Patent and Trademark Office. (n.d.). Manual of Patent Examining Procedure, Chapter 2700: Patent term. USPTO.

PCT Information
PCT Filed	July 17, 1998	PCT Application Number:	PCT/US98/14596
PCT Publication Date:	February 11, 1999	PCT Publication Number:	WO99/06023

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0999825	⤷ Start Trial	C300622	Netherlands	⤷ Start Trial
European Patent Office	0999825	⤷ Start Trial	92301	Luxembourg	⤷ Start Trial
European Patent Office	0999825	⤷ Start Trial	CA 2013 00055	Denmark	⤷ Start Trial
European Patent Office	0999825	⤷ Start Trial	122013000085	Germany	⤷ Start Trial
Argentina	013272	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,403,609

Summary for Patent: 6,403,609