US Patent 9,089,607: Scope, Claims, Expiration, Orange Book Status, and Levodopa Patent Landscape
US Patent No. 9,089,607 protects a multiparticulate, controlled-release oral formulation of levodopa and a decarboxylase inhibitor, typically carbidopa. The core invention combines immediate-release and two differently controlled-release levodopa/carbidopa populations with a separately coated carboxylic-acid component. The patent is directed to formulation architecture and resulting pharmacokinetic performance rather than to levodopa itself.
The patent is associated with the Impax Laboratories levodopa development program and the Rytary product family, now commercialized by Amneal Pharmaceuticals. Its principal commercial value is the combination of release-profile engineering, acid-mediated formulation performance, and stable levodopa exposure intended to reduce motor fluctuations in Parkinson's disease.
What does US Patent 9,089,607 cover?
The broadest independent claim, claim 1, requires all of the following elements:
| Required element |
Claim requirement |
| Active ingredient |
Levodopa |
| Decarboxylase inhibitor |
A decarboxylase inhibitor, with carbidopa expressly claimed in dependent claim 6 |
| First controlled-release component |
Levodopa, inhibitor, and rate-controlling excipients |
| Second controlled-release component |
Levodopa, inhibitor, and rate-controlling excipients |
| Relative composition |
The second controlled-release component has less levodopa and inhibitor than the first |
| Release behavior |
The two controlled-release components release levodopa and inhibitor at different rates |
| Immediate-release component |
Levodopa and decarboxylase inhibitor |
| Carboxylic-acid component |
A separate component containing a qualifying carboxylic acid and rate-controlling excipients |
| Enteric protection |
The carboxylic-acid component is coated with an enteric polymer |
| Physical form |
Components are beads or granules |
| Product architecture |
The components may be combined into a tablet, caplet, capsule, or multiparticulate product |
The claim is therefore a combination claim. A product that contains levodopa and carbidopa but lacks the separate enteric-coated carboxylic-acid component, or lacks two distinct controlled-release populations with different release rates, would not literally satisfy claim 1.
How broad is claim 1 of US 9,089,607?
Claim 1 is broad in the number of formulation options it permits but narrow in its required architecture.
The claim does not require:
- A particular carboxylic acid
- A particular enteric polymer
- A specific tablet strength
- A particular ratio of levodopa to carbidopa
- A particular release-rate polymer
- A specific capsule or tablet configuration
- A specific pharmacokinetic profile
The claim does require a distinct, enteric-coated acid component. That limitation is commercially important. A formulation containing tartaric acid blended directly with levodopa and carbidopa may not meet the claim if the acid is not in a distinct component and coated with an enteric polymer.
The claim also requires two controlled-release components with different release rates. A formulation with only one extended-release population and one immediate-release population may avoid literal infringement unless another component satisfies the second controlled-release limitation.
What formulations are protected by US 9,089,607?
The patent claims several dosage-form implementations.
Multiparticulate capsules
Claims 10 and 11 cover multiparticulate formulations in which the beads or granules are encapsulated. This is the most natural implementation for a product containing multiple bead populations with different release profiles.
A capsule could contain:
- Immediate-release levodopa/carbidopa beads.
- A higher-dose controlled-release levodopa/carbidopa bead population.
- A lower-dose controlled-release levodopa/carbidopa bead population.
- Enteric-coated carboxylic-acid beads or granules.
Tablets and caplets
Claims 7 through 9 cover tablets and caplets, including:
- Multilayer tablets
- Matrix tablets
- Matrix caplets
Claims 10 and 12 also cover multiparticulates pressed into a tablet. A compressed multiparticulate tablet can therefore fall within the claims even if the final dosage form is not a capsule.
Physical separation
Claim 26 requires the dicarboxylic acid to be physically separated from levodopa and the decarboxylase inhibitor. This limitation narrows the claim but provides a strong structural distinction from conventional blended formulations.
Which carboxylic acids are covered?
Claim 2 lists a broad group of acids:
- Tartaric acid
- Adipic acid
- Succinic acid
- Citric acid
- Benzoic acid
- Acetic acid
- Ascorbic acid
- Edetic acid
- Fumaric acid
- Lactic acid
- Malic acid
- Oleic acid
- Sorbic acid
- Stearic acid
- Palmitic acid
- Boric acid
Claims 3 and 4 separately cover polycarboxylic acids and dicarboxylic acids. Claim 5 narrows the invention to tartaric acid.
Tartaric acid is commercially significant because it is the specifically claimed dicarboxylic acid most closely associated with the disclosed levodopa formulation approach. Claims 17 through 21 impose narrower molar-ratio ranges between dicarboxylic acid and levodopa.
| Claim |
Dicarboxylic-acid-to-levodopa ratio |
| 17 |
Less than 4:1 |
| 18 |
Greater than 1:4 and less than 3:2 |
| 19 |
Greater than 1:2 and less than 4:3 |
| 20 |
Greater than 2:3 and less than 5:4 |
| 21 |
Greater than 1:1 and less than 4:3 |
These overlapping ranges may provide fallback positions if the broad formulation claims face validity or infringement challenges.
What pharmacokinetic profiles are claimed?
Claims 27 through 43 protect pharmacokinetic outcomes in addition to structural formulation features.
The claims focus on maintaining levodopa exposure after the maximum concentration is reached. Claim 27 requires the minimum concentration occurring after the maximum and within approximately six hours of administration to be at least 50% of the maximum concentration.
Other claimed characteristics include:
| Pharmacokinetic limitation |
Claimed range |
| Early concentration |
At least 50% of maximum within approximately 90 minutes |
| Later concentration |
At least 50% of maximum within approximately six hours |
| Alternative stability threshold |
At least 60% at early and later time points |
| Mean AUC for 380 mg levodopa |
4,330 to 8,000 ng·h/mL |
| Narrower mean AUC |
5,000 to 7,000 ng·h/mL |
| AUC-to-dose ratio |
11:1 to 25:1 |
| Narrower AUC-to-dose ratio |
14:1 to 19:1 |
| Maximum concentration for 380 mg |
825 to 1,505 ng/mL |
| Maximum-concentration-to-dose ratio |
3:1 to 5:1 |
| AUC-to-maximum-concentration ratio |
9:2 to 6:1 |
These claims create potential infringement issues for products that use a different physical design but produce a substantially similar plasma profile. Enforcement would depend on claim construction, testing protocols, and whether the accused product meets the structural limitations inherited from claim 1.
What therapeutic uses are protected?
Claims 44 through 56 cover methods of administering the claimed formulation for dopaminergic disorders and Parkinson's disease outcomes.
The claimed methods include:
- Reducing motor fluctuations
- Reducing "off" time
- Increasing "on" time
- Reducing time to "on"
- Enhancing dopamine levels
- Providing a stable median plasma levodopa concentration
- Limiting plasma fluctuations to no more than 40% over the specified period
The disease claims include:
- Parkinson's disease
- Secondary Parkinsonism
- Alzheimer's disease
- Dystonia
- Schizophrenia
- Conditions resulting from brain injury
- Carbon monoxide intoxication
- Manganese intoxication
The method claims depend on administration of a formulation falling within claim 1. They do not independently cover administration of any levodopa product for Parkinson's disease.
What are the key infringement choke points?
A competing product is most exposed when it has the following combination:
- Levodopa plus carbidopa.
- Immediate-release beads or granules.
- Two separate controlled-release bead or granule populations.
- Different levodopa and carbidopa loading between the controlled-release populations.
- Different release rates.
- A separate carboxylic-acid population.
- Enteric coating on the acid population.
- A capsule or multiparticulate dosage form.
The most defensible design-around strategies would generally involve removing or changing one of those structural limitations, such as:
- Using only one controlled-release population.
- Using a single blended matrix instead of separate bead populations.
- Incorporating the acid directly into the drug-containing beads.
- Omitting the enteric coating from the acid component.
- Using a formulation without a separately identifiable acid component.
- Using a non-particulate monolithic dosage form.
- Using a release system that does not provide different release rates for two controlled-release populations.
A design-around must be assessed against the full claim set, including equivalents and any narrower claims that may be asserted if claim 1 is avoided.
When does US Patent 9,089,607 lose exclusivity?
Public patent records associate the patent family with an expiration date in or around November 2029. The reported term is generally November 20, 2029, subject to the controlling patent-term calculation, any terminal disclaimer, patent-term adjustment, and applicable statutory extensions.
| Event |
Date or status |
| Patent issued |
July 28, 2015 |
| Patent number |
US 9,089,607 |
| Patent type |
Utility patent |
| Principal technology |
Controlled-release levodopa/carbidopa multiparticulates |
| Reported patent-term endpoint |
November 20, 2029 |
| Regulatory exclusivity |
Separate from patent term |
| Generic entry |
Controlled by patent rights, settlements, and FDA approval requirements |
Patent expiration does not by itself establish immediate generic market entry. A generic applicant may launch before the expiration date if it prevails in litigation, obtains a favorable settlement license, or relies on an approved non-infringing formulation.
What is the Orange Book status of US 9,089,607?
US 9,089,607 has been associated with the Rytary levodopa/carbidopa extended-release product and the Impax/Amneal product line. The relevant reference product is Rytary, approved by the FDA in 2015 for Parkinson's disease, postencephalitic parkinsonism, and parkinsonism following carbon monoxide or manganese intoxication.[1]
Rytary's Orange Book patent estate has included multiple formulation patents rather than a single blocking patent. Publicly reported Rytary-related patents include:
| Patent |
General subject matter |
| US 8,778,390 |
Controlled-release levodopa formulation technology |
| US 8,877,776 |
Levodopa/carbidopa controlled-release formulations |
| US 9,089,607 |
Multiparticulate formulation with differing release components |
| US 9,192,644 |
Related controlled-release formulation claims |
| US 9,402,806 |
Additional formulation and performance claims |
The exact Orange Book listing and delisting status should be determined from the FDA’s current Approved Drug Products with Therapeutic Equivalence Evaluations database and the applicable NDA patent listing history.[2]
Which companies have challenged the Rytary patent estate?
Rytary has attracted generic competition because its formulation differs materially from conventional immediate-release Sinemet and older sustained-release levodopa products.
Public patent disputes have involved generic applicants, including Actavis and other ANDA sponsors, in litigation concerning Rytary-related patents. The disputes have centered on:
- Paragraph IV assertions
- Invalidity
- Non-infringement
- Obviousness
- Written description and enablement
- The scope of the multiparticulate formulation claims
Impax and related entities have also used patent litigation to protect Rytary against ANDA filings. After Amneal acquired Impax, Amneal became the principal commercial successor for the product and related intellectual-property assets.[3]
What is a Paragraph IV challenge to this patent estate?
A generic applicant filing an ANDA may certify under Paragraph IV that a listed patent is invalid, unenforceable, or will not be infringed by the proposed product.[4]
For US 9,089,607, a Paragraph IV case would likely examine:
- Whether the proposed product has two separate controlled-release components.
- Whether those components release drug at different rates.
- Whether the acid is in a distinct component.
- Whether the acid component is coated with an enteric polymer.
- Whether the proposed product contains beads or granules.
- Whether the applicant’s formulation meets the limitations under the doctrine of equivalents.
- Whether the claims are obvious over earlier levodopa controlled-release technologies.
A Paragraph IV notice can trigger a 45-day period for the patent holder to file suit. A timely suit may result in a 30-month stay of FDA approval, subject to statutory exceptions and court rulings.
How strong is the patent estate for US 9,089,607?
The patent has meaningful commercial strength because its principal claim combines several independently identifiable product characteristics. A competitor may avoid one limitation but still fall within a narrower dependent claim or a related patent in the same estate.
Strengths
- Claim 1 covers a product architecture rather than only a specific excipient.
- The claim covers capsules, tablets, caplets, and multiparticulates.
- The carboxylic-acid component is separately protected.
- The release-profile requirement can reach products with multiple controlled-release populations.
- Claims 27 through 43 provide pharmacokinetic fallback positions.
- Method claims support infringement theories based on labeled use.
Vulnerabilities
- The claim requires a complex combination of structural elements.
- The acid component must be distinct and enterically coated.
- Different release rates may require detailed analytical testing.
- Pharmacokinetic claims may be difficult to enforce without controlled clinical or laboratory data.
- The technology is built on known levodopa, carbidopa, multiparticulate, and controlled-release concepts.
- Obviousness arguments may combine prior-art teachings on immediate-release and sustained-release levodopa products.
The patent is stronger against a close copy of the Rytary architecture than against a monolithic controlled-release tablet or a formulation using a fundamentally different delivery system.
How does US 9,089,607 compare with competing levodopa products?
| Product |
Sponsor or manufacturer |
Delivery approach |
Relationship to US 9,089,607 |
| Sinemet |
Merck historically; generic manufacturers |
Immediate-release levodopa/carbidopa |
Does not ordinarily replicate the claimed multi-component architecture |
| Sinemet CR |
Merck historically; generic manufacturers |
Controlled-release tablet |
Potentially relevant prior art, but not necessarily within claim 1 |
| Rytary |
Amneal, formerly Impax |
Extended-release multiparticulate levodopa/carbidopa |
Closest commercial product association |
| Duopa |
AbbVie |
Continuous intestinal gel infusion |
Different delivery route and formulation |
| Crexont |
Amneal |
Extended-release levodopa/carbidopa capsule |
Competing Amneal product with separate intellectual-property coverage |
| Inbrija |
Acorda |
Inhaled levodopa powder |
Different active-delivery route and no direct claim overlap |
Crexont is commercially relevant because it represents a newer extended-release levodopa/carbidopa product from Amneal. Its patent estate and formulation architecture should be analyzed separately. Product-level overlap with US 9,089,607 cannot be inferred from the shared active ingredients.
What manufacturing and intellectual-property barriers matter?
The patent can create manufacturing barriers even where the active ingredients are off-patent. A commercial entrant may need to develop and validate:
- Multiple bead or granule populations.
- Separate drug loading for the two controlled-release components.
- Different release-rate profiles.
- Enteric coating of the acid component.
- Consistent particle-size distributions.
- Uniform blending or capsule filling.
- Stability of levodopa and carbidopa.
- Dissolution performance across pH conditions.
- Batch-to-batch pharmacokinetic consistency.
The manufacturing process may also be protected by related patents, trade secrets, development know-how, or regulatory data. Avoiding US 9,089,607 does not eliminate risk from related Rytary patents or from patents covering specific polymers, coating processes, bead structures, or release profiles.
What generic launch scenarios exist?
Three practical launch scenarios are most relevant.
Launch after patent expiry
A generic applicant may wait until the reported November 2029 patent endpoint. This is the lowest litigation-risk scenario but may leave substantial commercial value on the table.
Launch under a settlement license
A Paragraph IV applicant may obtain a negotiated entry date before patent expiration. The entry date may depend on the settlement terms, other patents, regulatory approval, and antitrust constraints.
At-risk launch
A generic company may launch before final resolution of all patent disputes. This creates potential damages exposure, an injunction risk, and possible liability under 35 U.S.C. § 271(e)(4).
The practical entry date is determined by the full patent estate, not by US 9,089,607 alone.
What is the revenue exposure associated with this patent?
Rytary was a commercially important product for Impax and later Amneal. The patent’s economic value derives from protecting an extended-release formulation with differentiated dosing and symptom-control characteristics in a large Parkinson's disease market.
Revenue exposure depends on:
- Rytary prescription volume.
- Net price and payer rebates.
- The number of approved generic strengths.
- The number of generic applicants.
- Settlement entry dates.
- Substitution rates.
- The enforceability of related patents.
- The commercial performance of Crexont and other competing levodopa products.
Because Rytary’s value is distributed across a patent family, invalidation or non-infringement of US 9,089,607 would not necessarily eliminate all protection. It could, however, reduce barriers to a close multiparticulate copy.
Key Takeaways
- US 9,089,607 protects a complex multiparticulate levodopa/carbidopa formulation.
- Claim 1 requires immediate-release material, two distinct controlled-release populations, and a separate enteric-coated carboxylic-acid component.
- The patent covers capsules, tablets, caplets, multilayer tablets, matrix systems, and compressed multiparticulates.
- Tartaric acid and specific acid-to-levodopa ratios are protected by dependent claims.
- Claims 27 through 43 protect defined levodopa plasma profiles and exposure metrics.
- Claims 44 through 56 cover treatment of motor fluctuations, off time, reduced on time, and related dopaminergic conditions.
- The patent is associated with the Rytary product family and the Impax/Amneal levodopa program.
- The reported patent-term endpoint is November 20, 2029.
- The principal design-around opportunities involve eliminating the separate acid component, using one controlled-release population, or adopting a non-multiparticulate delivery system.
- Generic launch timing depends on the entire Rytary patent family, Paragraph IV litigation, and any settlement licenses.
FAQs About US Patent 9,089,607
Does US 9,089,607 cover ordinary Sinemet tablets?
No. Ordinary immediate-release levodopa/carbidopa tablets generally lack the two distinct controlled-release components and the separate enteric-coated carboxylic-acid component required by claim 1.
Does using tartaric acid automatically infringe US 9,089,607?
No. Tartaric acid alone is insufficient. The product must also satisfy the required bead or granule structure, controlled-release populations, immediate-release component, enteric coating, and other claim limitations.
Can a single extended-release matrix tablet avoid US 9,089,607?
Potentially. A single matrix system may avoid the requirement for two separate controlled-release components with different release rates, although related patents and dependent claims must be assessed separately.
Does a similar levodopa plasma profile create infringement risk?
Yes, but a similar pharmacokinetic profile alone does not establish infringement. The asserted claim may also require the structural formulation elements inherited from claim 1.
Are biosimilar rules relevant to Rytary?
No. Rytary contains small-molecule levodopa and carbidopa, so competing products proceed through the ANDA or other small-molecule FDA pathways rather than the biosimilar pathway under the Public Health Service Act.
References
-
U.S. Food and Drug Administration. (2015). Rytary (carbidopa and levodopa) extended-release capsules prescribing information. FDA.
-
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA.
-
Amneal Pharmaceuticals, Inc. (2018). Amneal Pharmaceuticals completes merger with Impax Laboratories. Company filing and investor materials.
-
U.S. Code. (2024). 21 U.S.C. § 355(j) and 35 U.S.C. § 271(e): Abbreviated new drug applications and patent certifications.
-
United States Patent and Trademark Office. (2015). U.S. Patent No. 9,089,607: Controlled release levodopa formulations. Washington, DC.
