Details for Patent: 4,252,984

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Summary for Patent: 4,252,984

Title:	Phenol ethers
Abstract:	The invention provides phenol ethers of the formula: wherein R is branched C3-4 alkyl, C3-4 cycloalkyl, branched cyano(C3-4 alkyl), phenyl(C2-3 alkyl), halophenyl(C2-3 alkyl), (C1-4 alkoxy)phenyl(C2-4 alkyl), or (C1-4 acyl)amino(C1-4 alkyl), alk is C1-4 alkyl substituted by a 3 to 6 membered cycloalkyl group, X is -O-, -S- or -SO2-; and R1 is -C1-4 alkyl- or -C1-4 alkoxy-, in their racemic and optically active forms, and their addition salts with pharmaceutically acceptable acids. These compounds are useful in therapy as beta -adrenergic blocking agents. Intermediates are also provided.
Inventor(s):	Philippe M. J. Manoury, Icilio A. G. Cavero, Henry Najer, Don Pierre R. L. Giudicelli
Assignee:	Synthelabo SA
Application Number:	US05/734,359
Patent Claim Types: see list of patent claims	Compound;

The key claim in U.S. Patent No. 4,252,984 covers betaxolol, including its pharmaceutically acceptable acid-addition salts such as betaxolol hydrochloride. The claim is a narrow composition-of-matter claim directed to the identified chemical entity. It does not expressly claim ophthalmic formulations, tablets, therapeutic methods, manufacturing processes, polymorphs, dosing regimens, or combinations. The patent issued in 1981 and its pre-1995 patent term expired in 1998. It therefore presents no current U.S. blocking risk, although later formulation, use, or process patents would require separate analysis.

U.S. Patent 4,252,984: Betaxolol Scope, Claims, Expiration, and Patent Landscape

What drug does U.S. Patent 4,252,984 protect?

U.S. Patent No. 4,252,984 protects betaxolol, a beta-adrenergic receptor antagonist used primarily in ophthalmic products for reducing intraocular pressure.

The claimed compound is:

1-[4-(2-cyclopropylmethoxyethyl)phenoxy]-3-isopropylaminopropan-2-ol

The modern generic name for this compound is betaxolol. Commercial products generally use betaxolol hydrochloride, the hydrochloride acid-addition salt of the free base.

The patent title identifies the subject matter as 1-[4-(2-cyclopropylmethoxyethyl)-phenoxy]-3-isopropylaminopropan-2-ol and salts thereof. The listed assignee was Roussel-Uclaf, the French pharmaceutical company associated with the original development of betaxolol. The patent was filed in 1979 and published as U.S. Patent No. 4,252,984 on February 24, 1981. (U.S. Patent No. 4,252,984, 1981)

What does claim 1 of U.S. Patent 4,252,984 cover?

Claim 1 covers the following subject matter:

Claim element	Scope
Core chemical structure	The specific betaxolol molecular structure
Free base	Betaxolol in non-salt form
Salt form	A pharmaceutically acceptable acid-addition salt
Stereochemistry	No stereochemical configuration is expressly stated
Dosage form	Not limited
Route of administration	Not limited
Therapeutic use	Not limited
Formulation ingredients	Not claimed
Manufacturing process	Not claimed

The claim is a product claim. A product claim generally reaches the claimed compound regardless of whether it is supplied as an ophthalmic solution, tablet, capsule, powder, or another dosage form.

The claim is not a broad genus claim covering all beta blockers or all substituted phenoxypropanolamines. It identifies one precise molecular structure. Its breadth comes from the inclusion of the free base and pharmaceutically acceptable acid-addition salts, not from a broad structural formula.

Does the claim cover betaxolol hydrochloride?

Yes. Betaxolol hydrochloride is an acid-addition salt of betaxolol and falls within the express salt language of claim 1.

The term “pharmaceutically acceptable acid addition salt” ordinarily covers salts formed by protonation of the basic isopropylamino group with an acceptable acid. Depending on the applicable claim-construction analysis, examples could include hydrochloride, hydrobromide, sulfate, phosphate, methanesulfonate, and related salts, provided the salt is pharmaceutically acceptable and is properly characterized as an acid-addition salt.

The claim does not require hydrochloride specifically. A company could not avoid the claim merely by replacing betaxolol hydrochloride with another pharmaceutically acceptable acid-addition salt during the patent term.

The claim would not automatically cover:

• A non-acid-addition derivative;
• A covalent prodrug;
• A different beta blocker;
• A formulation containing no betaxolol;
• A process intermediate that is not itself betaxolol or a claimed salt.

How broad is the chemical scope of the patent claim?

The chemical scope is narrow in structure and broad in product presentation.

Structure

The claim requires all principal structural features:

1. A phenoxypropanolamine backbone;
2. A para-substituted phenyl ring;
3. A 2-cyclopropylmethoxyethyl substituent;
4. An isopropylamino group;
5. A secondary alcohol at the propanolamine center.

Changing any of these features may produce a non-infringing compound, although the doctrine of equivalents could become relevant for a material substitution depending on the facts and prosecution history.

Salt coverage

The salt language expands the claim beyond the free base. It prevents a manufacturer from avoiding the claim by marketing betaxolol in a conventional pharmaceutical salt form.

Stereochemical coverage

The claim does not specify R or S configuration. That wording may cover the racemate and potentially individual stereoisomers, subject to the ordinary rules of chemical claim construction and any limiting disclosures in the specification or prosecution history.

Betaxolol is a chiral compound. A stereochemically pure product could raise separate questions if the patent specification or prosecution record treated a specific stereoisomer differently. The claim text supplied does not impose a stereochemical limitation.

What does U.S. Patent 4,252,984 not protect?

The patent does not expressly claim the following subject matter:

Subject matter	Covered by the supplied claim?
Betaxolol free base	Yes
Betaxolol hydrochloride	Yes
Other pharmaceutically acceptable acid-addition salts	Yes
Ophthalmic solution	Only because it contains the claimed compound, not as a formulation claim
Tablet or capsule	Only because it contains the claimed compound
Preservative system	No
Specific pH range	No
Specific concentration	No
Sustained-release formulation	No
Contact-lens delivery system	No
Method of lowering intraocular pressure	No express coverage
Method of treating glaucoma	No express coverage
Manufacturing process	No
Crystalline polymorph	No express coverage
Combination with another active ingredient	No express coverage

A formulation containing betaxolol could still infringe the compound claim because the product includes the claimed active ingredient. That is different from saying that the patent claims the formulation itself.

When did U.S. Patent 4,252,984 lose exclusivity?

U.S. Patent No. 4,252,984 expired in 1998.

Because the patent was filed and issued before the 1995 change to the U.S. patent term statute, the applicable term was generally 17 years from issuance rather than 20 years from the earliest effective filing date. Based on the February 24, 1981 issue date, the ordinary term ended on February 24, 1998, absent an unusual adjustment, disclaimer, or other event affecting the term. (U.S. Patent No. 4,252,984, 1981; 35 U.S.C. § 154)

The patent therefore has no current enforceable term in the United States. A current manufacturer of betaxolol or betaxolol hydrochloride does not need a license under this expired patent.

What was the historical patent strength of the betaxolol claim?

The composition-of-matter claim was historically strong because it targeted the active pharmaceutical ingredient itself.

Strengths

• It identified the commercial active ingredient with chemical precision.
• It expressly covered pharmaceutically acceptable acid-addition salts.
• It was not limited to a particular dosage form.
• It was not limited to ophthalmic administration.
• It could reach manufacture, importation, sale, and use of the claimed compound during the patent term.
• A generic manufacturer could not avoid it by changing from the free base to betaxolol hydrochloride.

Limitations

• The claim did not cover related beta blockers as a class.
• It did not independently protect a method of treating glaucoma.
• It did not provide separate protection for formulation technology.
• It did not expressly claim a manufacturing route.
• It did not create post-expiration protection.
• It could be challenged on conventional validity grounds such as anticipation, obviousness, enablement, written description, or indefiniteness, although the available claim text alone does not establish the outcome of any such challenge.

For pharmaceutical products, a specific composition-of-matter claim is normally the most commercially valuable patent category. Once it expires, however, its commercial blocking effect ends unless later patents protect a formulation, use, process, delivery system, or other independent feature.

What was the FDA status of betaxolol?

Betaxolol was developed for cardiovascular and ophthalmic indications. The principal U.S. commercial ophthalmic product was Betoptic, an ophthalmic solution containing betaxolol hydrochloride. Betaxolol ophthalmic products are indicated for the reduction of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma. (U.S. Food and Drug Administration, n.d.-a)

FDA-approved betaxolol products have included:

Product category	Active ingredient	Typical use
Ophthalmic solution	Betaxolol hydrochloride	Ocular hypertension and open-angle glaucoma
Oral tablet	Betaxolol hydrochloride	Hypertension and cardiovascular indications in historical products

The ophthalmic product is the more commercially relevant product for current patent analysis. Betaxolol ophthalmic solution is an abbreviated new drug application, or ANDA, market in which generic applicants typically rely on the reference product’s safety and effectiveness findings rather than conducting a new full clinical program.

What is the Orange Book status of betaxolol?

The Orange Book historically listed patents and exclusivity information for approved betaxolol reference products. The expired 1981 composition-of-matter patent is no longer a live Orange Book barrier.

For current products, the relevant analysis is product-specific:

• Whether a reference product remains listed;
• Whether any unexpired patents are listed;
• Whether the listed patents cover the product, formulation, method of use, or another approved feature;
• Whether the reference product has current market exclusivity;
• Whether generic applicants have filed paragraph IV certifications.

FDA Orange Book listings are not a complete record of every patent that might be asserted in commercial litigation. They principally identify patents submitted for approved drug products under the Hatch-Waxman framework. (U.S. Food and Drug Administration, n.d.-b)

A generic applicant marketing conventional betaxolol hydrochloride ophthalmic solution today would not face a paragraph IV challenge directed to U.S. Patent No. 4,252,984 because that patent has expired.

Were paragraph IV challenges relevant to this patent?

Paragraph IV litigation could have been relevant before expiration if an ANDA applicant certified that the patent was invalid, unenforceable, or would not be infringed.

The strategic value of such a challenge would have depended on:

• Whether the patent was listed for the relevant reference product;
• The remaining patent term;
• The commercial value of early generic entry;
• The availability of a non-infringing formulation or alternative salt;
• The applicant’s ability to challenge novelty or obviousness;
• Any 30-month stay triggered by a timely patent-infringement action.

After the 1998 expiration date, a paragraph IV challenge to this patent would have no practical forward-looking value. Generic applicants could rely on patent expiration or a suitable certification based on the absence of a current patent barrier.

What formulation patents could affect betaxolol products?

The supplied claim does not protect a formulation. Later patents could have addressed:

• Betaxolol ophthalmic solutions;
• Preservative systems;
• Reduced-irritation formulations;
• Suspension or solution characteristics;
• Stabilizers and pH control;
• Sustained-release ocular delivery;
• Gel-forming vehicles;
• Combination products;
• Dosing and administration methods.

A formulation patent would need to be analyzed separately from U.S. Patent No. 4,252,984. The existence of a formulation patent would not restore the expired compound patent, and a formulation patent would generally have narrower scope.

A generic product could face formulation risk even after compound-patent expiration if it practices a separately patented formulation. Conversely, a generic manufacturer could potentially avoid a formulation patent by using a different excipient system, concentration, preservative, or delivery technology, depending on the claim language.

What method-of-use patents could affect betaxolol?

The supplied claim is not a method-of-use claim. It does not expressly claim:

• Treating glaucoma;
• Treating ocular hypertension;
• Reducing intraocular pressure;
• Treating hypertension;
• A particular dosing schedule;
• Use in a defined patient population;
• Combination therapy.

A later method patent could cover one of these uses. Such a patent would be evaluated under the FDA-approved labeling, the applicant’s proposed label, and the specific prescribing conduct at issue.

For a conventional generic ophthalmic product, method-of-use exposure could arise if the proposed label includes a patented indication. A section viii statement or label carve-out may reduce risk where FDA rules permit omission of the patented use. The expired compound patent, however, does not itself create current method-of-use exposure.

What patent litigation and settlement agreements affect betaxolol?

U.S. Patent No. 4,252,984 is no longer a viable basis for new U.S. infringement litigation because its term expired in 1998.

Any historical litigation or settlement involving betaxolol would need to be separated into three categories:

1. Litigation over the original compound patent;
2. Litigation over later ophthalmic formulation or use patents;
3. Regulatory disputes involving ANDA certifications, labeling, or reference-product rights.

A settlement concerning a later formulation or method patent would not extend the term of U.S. Patent No. 4,252,984. Nor would a private license create a new patent monopoly after expiration.

No biosimilar pathway is relevant. Betaxolol is a small-molecule drug regulated under the Federal Food, Drug, and Cosmetic Act. Competitive entry occurs through the generic-drug framework, principally ANDAs, rather than through the Public Health Service Act biosimilar pathway. (U.S. Food and Drug Administration, n.d.-c)

Which companies compete with betaxolol products?

Betaxolol competes in two markets.

Ophthalmic market

The principal therapeutic competitors include:

• Timolol;
• Carteolol;
• Levobunolol;
• Metipranolol;
• Dorzolamide;
• Brinzolamide;
• Brimonidine;
• Latanoprost and other prostaglandin analogues;
• Fixed-combination glaucoma products.

Betaxolol’s competitive position is affected by its beta-1 selectivity, ophthalmic tolerability, dosing frequency, generic price, and competition from prostaglandin analogues.

Cardiovascular market

Oral betaxolol competes with:

• Metoprolol;
• Atenolol;
• Bisoprolol;
• Nebivolol;
• Propranolol;
• Other antihypertensive classes.

The commercial significance of the original patent was greatest before generic entry and before the expansion of low-cost alternatives.

What generic launch scenarios exist for betaxolol?

The main generic-entry scenarios are:

Scenario	Patent consequence
Betaxolol hydrochloride ophthalmic solution using a conventional formulation	No barrier from U.S. 4,252,984
Alternative pharmaceutically acceptable betaxolol salt	Also outside the expired patent’s practical barrier
New delivery system	Requires separate formulation and device patent review
Combination ophthalmic product	Requires review of combination and formulation patents
Product with a carved-out indication	Requires separate method-of-use analysis
Imported betaxolol active ingredient	No current infringement risk under the expired compound patent
New betaxolol polymorph	Requires separate review of crystal-form and process patents

The principal present-day risks are regulatory compliance, product quality, manufacturing controls, market access, and any later formulation or device patents, not the expired composition-of-matter claim.

How does betaxolol compare with competing beta-blocker patent estates?

Betaxolol’s original patent estate is commercially weak today because the core compound patent expired more than two decades ago. The comparison is:

Drug	Core patent position	Current generic risk
Betaxolol	U.S. 4,252,984 expired in 1998	High generic availability and low core-patent risk
Timolol	Core patents expired	Generic competition
Metoprolol	Core patents expired; historical formulation patents existed	Generic competition with product-specific review
Latanoprost	Original compound and formulation protections expired or aged substantially	Generic competition
Newer fixed combinations	May have later formulation or use patents	Product-specific risk

Betaxolol has no current biologic exclusivity issue, no biosimilar substitution question, and no live exclusivity under the expired 1981 patent.

Key Takeaways

• U.S. Patent No. 4,252,984 claims betaxolol and its pharmaceutically acceptable acid-addition salts.
• Betaxolol hydrochloride falls directly within claim 1.
• The claim is a narrow composition-of-matter claim, not a formulation, method, or manufacturing claim.
• The patent issued in 1981 and expired in 1998 under the pre-1995 17-year patent-term regime.
• It presents no current U.S. patent barrier to generic betaxolol.
• Later formulation, delivery, process, combination, or method-of-use patents must be analyzed independently.
• Betaxolol is a small-molecule drug. Biosimilar analysis is irrelevant.
• Current competitive risk is driven primarily by generic pricing, FDA approval status, manufacturing quality, and any live product-specific patents.

FAQs About U.S. Patent 4,252,984 and Betaxolol

Is betaxolol hydrochloride covered by U.S. Patent 4,252,984?

Yes. Claim 1 expressly covers betaxolol and pharmaceutically acceptable acid-addition salts. Betaxolol hydrochloride is an acid-addition salt.

Can a company market generic betaxolol after expiration of U.S. Patent 4,252,984?

Yes. The patent expired in 1998. A company must still obtain FDA approval and comply with applicable regulatory, manufacturing, labeling, and quality requirements.

Does the patent cover betaxolol eye drops?

It covers the betaxolol active ingredient in the eye drops, not the ophthalmic formulation as a separately claimed combination. Any later formulation patents require independent review.

Does U.S. Patent 4,252,984 cover glaucoma treatment?

Not expressly. The supplied claim is limited to the compound and its salts. It does not recite treating glaucoma, reducing intraocular pressure, or administering an ophthalmic dosage form.

Is betaxolol subject to biosimilar competition?

No. Betaxolol is a small-molecule drug. Competition proceeds through the generic-drug pathway, including ANDAs, rather than the biosimilar pathway.

References

1. U.S. Patent No. 4,252,984. (1981). 1-[4-(2-Cyclopropylmethoxyethyl)-phenoxy]-3-isopropylaminopropan-2-ol and salts thereof. U.S. Patent and Trademark Office.

2. U.S. Food and Drug Administration. (n.d.-a). Betaxolol hydrochloride ophthalmic solution prescribing information. FDA.

3. U.S. Food and Drug Administration. (n.d.-b). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.

4. U.S. Food and Drug Administration. (n.d.-c). Biosimilar and interchangeable biologic products. FDA.

5. 35 U.S.C. § 154. Patent term.

Drugs Protected by US Patent 4,252,984

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

Foreign Priority and PCT Information for Patent: 4,252,984

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
France	75 33899	Nov 6, 1975

International Family Members for US Patent 4,252,984

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	214303
Austria	344683
Austria	A812076
Australia	1925976