US Patent 7,572,834: Rasagiline Mesylate Formulation Claims, Patent Scope and Generic Risk

US Patent No. 7,572,834 protects pharmaceutical compositions containing rasagiline mesylate, a pharmaceutically acceptable carrier, and a narrowly defined concentration of a chlorination-derived rasagiline impurity. The patent does not broadly cover rasagiline, rasagiline mesylate, or every rasagiline formulation. Its enforceable scope depends on the presence of the identified impurity within specified parts-per-million ranges and, for dependent claims, on particular excipient combinations or exclusions.[1]

The patent is associated with Teva’s Azilect product, which contains rasagiline mesylate for Parkinson’s disease. The principal commercial risk was directed at generic formulations that reproduced the Azilect excipient system and impurity profile. The patent’s ordinary 20-year term is tied to a December 23, 2004 priority date, placing the expected expiration in December 2025, subject to the USPTO’s final term calculation and any applicable adjustment.[1][2]

What drug and formulation does US Patent 7,572,834 protect?

The patent concerns rasagiline mesylate, chemically identified in the claims as N-propargyl-1(R)-aminoindan mesylate. Rasagiline is a selective monoamine oxidase-B inhibitor approved in the United States as Azilect for Parkinson’s disease.[3]

The supplied claim text does not reproduce the chemical structure drawing referenced in claim 1. The analysis therefore treats the claimed impurity as the chlorination-derived compound defined by the patent rather than assigning it a specific ring position.

Core claim elements

Claim 1 requires all of the following:

A pharmaceutical composition.
N-propargyl-1(R)-aminoindan mesylate.
A pharmaceutically acceptable carrier.
More than 0.7 ppm and less than 30 ppm, in total, of the specified chlorination-derived compound and its salts.
The compound must be formed by chlorination of N-propargyl-1(R)-aminoindan in the rasagiline mesylate product.

The claim is therefore a composition claim with an impurity-profile limitation. It is not a conventional active-ingredient claim.

Scope of the impurity limitation

The concentration range is central:

Claim	Required total impurity concentration
Claim 1	More than 0.7 ppm and less than 30 ppm
Claim 2	More than 2 ppm and less than 30 ppm
Claim 3	More than 4 ppm and less than 30 ppm
Claim 4	More than 7 ppm and less than 30 ppm
Claim 9	More than 0.7 ppm and less than 20 ppm

The claims use open-ended lower thresholds and closed upper boundaries in practical terms. A formulation containing exactly 0.7 ppm would not satisfy the “greater than 0.7 ppm” requirement. A formulation containing exactly 30 ppm would not satisfy the “less than 30 ppm” requirement.

The patent’s commercial theory appears to be that controlled, low-level chlorination impurities can be present in a finished rasagiline mesylate product while remaining below a maximum concentration. That creates an unusual claim profile: a product with too little impurity may fall outside the claims, while a product with too much impurity also falls outside them.

How do claims 1 through 12 differ?

Claims 2 through 4 narrow claim 1 by raising the minimum impurity concentration. Claim 9 creates a separate narrower range with a 20 ppm maximum.

Carrier limitations

Claim 5 excludes magnesium stearate from the carrier system.

Claim 6 identifies the permitted carrier classes as one or more of:

Mannitol
Starch
Pregelatinized starch
Colloidal silicon dioxide
Stearic acid
Talc

Claim 7 requires the listed carrier system to contain all six excipients.

Claim 8 excludes the following materials:

Maltodextrin
Croscarmellose sodium
Citric acid
Lactose
Glyceryl behenate
Hydrogenated vegetable oil type I

Claims 10 through 12 combine the concentration limitations from claims 2 through 4 or 9 with the carrier restrictions in claims 6 through 8.

Claim	Principal limitation
1	Rasagiline mesylate, carrier, and >0.7 to <30 ppm impurity
2	Claim 1 with more than 2 ppm impurity
3	Claim 1 with more than 4 ppm impurity
4	Claim 1 with more than 7 ppm impurity
5	No magnesium stearate
6	Specified carrier class
7	All six specified carriers
8	Exclusion of six named excipients
9	More than 0.7 ppm and less than 20 ppm impurity
10	Claims 2-4 or 9 plus claim 6 carrier limitation
11	Claims 2-4 or 9 plus all six carriers
12	Claims 2-4 or 9 plus claim 8 exclusions

What formulations are protected by US 7,572,834?

The strongest practical formulation target is a tablet containing rasagiline mesylate with the following excipient system:

Mannitol
Starch
Pregelatinized starch
Colloidal silicon dioxide
Stearic acid
Talc

A formulation using this combination, without magnesium stearate, and containing the claimed chlorination-derived impurity within the specified concentration range is positioned closest to claims 7 and 11.

Claims 8 and 12 provide a second route to infringement. A formulation may fall within those claims if it contains the claimed impurity range and omits maltodextrin, croscarmellose sodium, citric acid, lactose, glyceryl behenate, and hydrogenated vegetable oil type I.

Does the patent cover every rasagiline tablet?

No. A rasagiline tablet may avoid the patent if one or more required elements is absent. Potential design-around variables include:

Using a different impurity profile.
Reducing the specified impurity to 0.7 ppm or below.
Increasing the impurity to 30 ppm or above, although this may raise regulatory and safety problems.
Using a carrier system outside the dependent-claim combinations.
Including an excluded excipient where a negative limitation is required.
Using a different manufacturing route that does not produce the claimed compound, subject to claim construction.
Demonstrating that the relevant impurity is not the compound defined in the patent.

The most commercially realistic design-around is control of the impurity profile or use of a materially different formulation. Deliberately increasing a potentially genotoxic or otherwise regulated impurity would generally be unattractive from a quality and regulatory standpoint.

How strong is the patent estate for rasagiline?

US 7,572,834 is a secondary formulation and impurity patent. It is narrower than the earlier patents covering rasagiline and rasagiline mesylate as active pharmaceutical substances.

Patent category	Subject matter	Competitive significance
Core compound patents	Rasagiline and related propargyl aminoindan compounds	Historically prevented early generic entry
Salt and pharmaceutical composition patents	Rasagiline mesylate and medicinal compositions	Covered active form and dosage products
US 7,572,834	Chlorination-derived impurity range and excipient system	Creates a narrower formulation barrier
Method-of-use patents	Treatment of Parkinson’s disease and related indications	May affect label strategy and induced-infringement risk
Manufacturing patents	Production, purification, salt formation, and impurity control	May restrict API or finished-dose manufacturing routes

The 7,572,834 patent has meaningful claim specificity but limited breadth. Its enforceability depends heavily on analytical evidence. A patent owner would need to establish the identity and quantity of the specified impurity, the presence of rasagiline mesylate, the carrier composition, and the claimed formation relationship.

When does US Patent 7,572,834 lose exclusivity?

The patent’s expected ordinary expiration is December 23, 2025, based on the December 23, 2004 priority date and the standard 20-year patent term.[1][2]

Event	Date or status
Earliest identified priority date	December 23, 2004
US patent grant	August 11, 2009
Expected ordinary expiration	December 23, 2025
Patent term extension	No extension is identified here
Patent term adjustment	Final USPTO calculation controls
Post-expiration position	Claims generally cannot block new US sales based solely on this patent

Patent expiration does not eliminate regulatory exclusivity, pending litigation remedies, or damages claims for pre-expiration infringement. It does remove the forward-looking exclusionary right once the statutory term ends.

The earlier rasagiline patent estate had substantially earlier expiration dates. The principal commercial importance of US 7,572,834 was therefore its ability to extend formulation-related protection beyond the core compound patents.

What is the Orange Book status of US 7,572,834?

FDA Orange Book listings identify patents that a listed drug sponsor submits as applicable to an approved drug. Azilect is the relevant reference product for rasagiline mesylate.[2][3]

US 7,572,834 has been associated with the Azilect patent listing and is relevant to abbreviated new drug application review. An ANDA applicant challenging a listed patent can file a Paragraph IV certification stating that the patent is invalid, unenforceable, or will not be infringed.[2][4]

The listing does not establish that every rasagiline generic infringes. It determines the statutory certification and litigation framework. The applicant’s proposed formulation, manufacturing process, impurity specification, and labeling remain decisive.

FDA pathway and exclusivity

Rasagiline is a small-molecule drug. Generic competition proceeds through the ANDA pathway under section 505(j) of the Federal Food, Drug, and Cosmetic Act. A biosimilar application under section 351(k) is not relevant.[4]

Regulatory issue	Relevance
Reference product	Azilect
Active ingredient	Rasagiline mesylate
Generic pathway	ANDA
Patent certification	Paragraph IV may be used
Biosimilar risk	None; rasagiline is not a biologic
Formulation review	Bioequivalence, CMC, impurity, and stability data
Label strategy	Carve-outs may be relevant for patented methods of use

Which companies challenged rasagiline patents?

Multiple generic companies pursued rasagiline products after the core Azilect exclusivity period. Public FDA records and Hatch-Waxman litigation records should be read together because Orange Book certification data identifies patent challenges, while court dockets establish the litigation outcome and settlement terms.[2][4]

The principal competitive groups included large generic manufacturers and specialty generic filers. Publicly reported rasagiline generic activity has involved companies such as Teva, Mylan, Apotex, Dr. Reddy’s Laboratories, Sandoz, and Zydus, although the specific patent challenged and the ultimate settlement terms must be attributed at the individual ANDA level.

A Paragraph IV challenge to US 7,572,834 would likely focus on:

Anticipation by prior formulations containing the impurity.
Obviousness of controlling the impurity within the claimed range.
Lack of written description for the claimed ppm windows.
Enablement of the analytical and manufacturing requirements.
Indefiniteness in the identity, quantification, or source of the impurity.
Noninfringement based on a different impurity or excipient profile.
Lack of proof that the impurity was formed by chlorination.

What patent litigation affects US 7,572,834?

The patent creates a litigation issue distinct from the core rasagiline patents. A generic applicant may avoid direct infringement by demonstrating that its product does not contain the identified impurity in the claimed range, even if it contains rasagiline mesylate and is therapeutically equivalent to Azilect.

The key evidence would include:

Batch-release specifications.
Stability data.
High-performance liquid chromatography or mass-spectrometry methods.
Impurity reference standards.
API and finished-product manufacturing records.
Excipient certificates and quantitative composition.
Expert analysis of whether the impurity was produced by chlorination.

Because the claims use “in total,” aggregation of the compound and its salts matters. The analytical method must distinguish the claimed compound from unrelated degradation products, process impurities, and assay artifacts.

What settlement agreements mean for generic entry

A settlement may permit launch before patent expiration, impose a later-entry date, provide a license, or allocate manufacturing and supply rights. A settlement does not necessarily confirm validity or infringement. The commercial result depends on the agreed launch date and any acceleration provisions.

For rasagiline, generic entry has already occurred in the US market through ANDA-approved products. The remaining significance of US 7,572,834 is therefore primarily:

Pre-expiration damages exposure.
Risk to products launched before December 2025.
Contractual settlement obligations.
Manufacturing changes required to maintain a noninfringing formulation.
Residual litigation over earlier sales.

What generic launch risks exist for rasagiline?

Launch before patent expiration

A generic launch before expiration could create substantial risk if the product contains:

Rasagiline mesylate.
The specified chlorination-derived impurity above 0.7 ppm and below 30 ppm.
One of the claimed carrier systems.
No excluded excipients where claims 8 or 12 apply.

A Paragraph IV launch may proceed after the statutory stay expires or after litigation resolves, but the sponsor remains exposed to damages and injunctive relief if the patent is upheld and infringed.

Launch after patent expiration

After expiration, US 7,572,834 should no longer block ordinary commercial sale based solely on its claims. FDA approval, manufacturing compliance, bioequivalence, labeling, and other unexpired patents remain separate issues.

Risk matrix

Generic product characteristic	Risk under US 7,572,834
Rasagiline without the claimed impurity	Low under this patent
Impurity at or below 0.7 ppm	Low under claim 1
Impurity above 0.7 ppm and below 20 ppm	High if other elements match
Impurity 20-30 ppm	Potential claim 1 risk; claims 9-12 may not apply
Impurity at or above 30 ppm	Low under the stated concentration claims, subject to other issues
Magnesium stearate present	May avoid claims 5, 7, and 11, but not claim 1
Different carrier system	May avoid dependent carrier claims
Excluded excipient present	May avoid claims 8 and 12
Same formulation after expiration	No prospective infringement risk from this patent

How does US 7,572,834 compare with core rasagiline patents?

US 7,572,834 is narrower but technically more targeted than a compound patent. A core patent can prevent use of the active ingredient across formulations. The 7,572,834 claims reach only compositions meeting the impurity and excipient limitations.

Feature	Core rasagiline patent	US 7,572,834
Active ingredient coverage	Broad	Required, but not sufficient
Formulation specificity	Usually limited	High
Impurity limitation	Generally absent	Central
Design-around potential	Lower before expiration	Higher
Dependence on analytical testing	Moderate	High
Biosimilar relevance	None	None
ANDA relevance	High	High
Primary risk period	Earlier patent term	Through expected December 2025 expiration

What manufacturing and IP barriers remain?

The main manufacturing barrier is impurity control. The patent links the claimed impurity to chlorination of the rasagiline intermediate. A manufacturer must control chlorinating reagents, reaction conditions, raw-material purity, solvent systems, workup, crystallization, and storage.

The principal freedom-to-operate questions are:

Whether the API contains the claimed impurity before tableting.
Whether the impurity concentration changes during granulation or compression.
Whether the impurity is present as a free compound, salt, or both.
Whether the analytical assay measures total relevant material.
Whether the finished formulation uses the claimed excipients.
Whether the same impurity can arise through a nonchlorination pathway.

Geographic coverage is limited by jurisdiction. US 7,572,834 can support a US infringement action, but it does not directly prevent manufacture or sale in Europe, Canada, Japan, or other countries. Parallel family members must be reviewed independently for claim scope, prosecution history, term, and legal status.

Key Takeaways

US 7,572,834 is a narrow rasagiline mesylate composition patent focused on a chlorination-derived impurity.
Claim 1 requires more than 0.7 ppm and less than 30 ppm of the claimed compound and its salts.
Claims 2 through 4 raise the minimum impurity threshold to more than 2, 4, or 7 ppm.
Claim 9 narrows the upper limit to less than 20 ppm.
Claims 5 through 12 add excipient restrictions, including a magnesium stearate exclusion and a six-excipient formulation.
The closest commercial target is a tablet containing mannitol, starch, pregelatinized starch, colloidal silicon dioxide, stearic acid, and talc.
The patent does not broadly cover all rasagiline products.
Generic risk depends on impurity identity, ppm concentration, excipient composition, and proof of chlorination origin.
The expected ordinary expiration is December 23, 2025, subject to the USPTO’s final term calculation.
Rasagiline is a small molecule, so biosimilar analysis is not applicable.
Generic products are reviewed through the ANDA pathway and may use Paragraph IV certifications against listed patents.

FAQs About US Patent 7,572,834

Does US 7,572,834 cover rasagiline mesylate itself?

No. It requires rasagiline mesylate plus a specified chlorination-derived compound within a defined concentration range and a pharmaceutically acceptable carrier.

Can a generic avoid this patent by using magnesium stearate?

Magnesium stearate may avoid claims that expressly exclude or omit it, but it does not automatically avoid claim 1, which does not contain the magnesium stearate limitation.

Is a formulation with less than 0.7 ppm of the impurity covered?

The stated claims require more than 0.7 ppm. A formulation at or below 0.7 ppm would not satisfy that concentration limitation.

Does the patent create biosimilar risk for rasagiline?

No. Rasagiline is a chemically synthesized small molecule. Competition uses the ANDA pathway rather than the biosimilar pathway.

What is the most important evidence in a US 7,572,834 dispute?

The critical evidence is the validated analytical result for the claimed impurity, the total concentration of the compound and its salts, the finished-product excipient composition, and manufacturing evidence concerning chlorination.

References

U.S. Patent No. 7,572,834. (2009). Pharmaceutical composition comprising N-propargyl-1(R)-aminoindan mesylate. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
U.S. Food and Drug Administration. (2006). Azilect (rasagiline mesylate) prescribing information. FDA.
U.S. Food and Drug Administration. (2024). Abbreviated new drug application approvals and patent certification procedures. FDA.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Teva	AZILECT	rasagiline mesylate	TABLET;ORAL	021641-001	May 16, 2006	AB	RX	Yes	No	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
Teva	AZILECT	rasagiline mesylate	TABLET;ORAL	021641-002	May 16, 2006	AB	RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Details for Patent: 7,572,834

Which drugs does patent 7,572,834 protect, and when does it expire?

Summary for Patent: 7,572,834