Details for Patent: 6,083,993
Summary for Patent: 6,083,993
| Title: | Method for treating bronchospasm using optically pure R(-) albuterol | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | The optically pure R(-) isomer of albuterol, which is substantially free of the S(+) isomer, is a potent bronchodilator for relieving the symptoms associated with asthma in individuals. A method is disclosed utilizing the optically pure R(-) isomer of albuterol for treating asthma while minimizing the side effects associated with albuterol. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | Timothy J. Barberich, James W. Young | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Sumitomo Pharma America Inc | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US09/466,107 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Patent Claim Types: see list of patent claims | Use; Delivery; Dosage form; | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | United States Drug Patent 6,083,993: Claim Scope, Expiration, and Levalbuterol Patent LandscapeU.S. Patent No. 6,083,993 covers methods of treating or preventing bronchospasm by administering the R(-) enantiomer of albuterol, now commonly called levalbuterol. Its claims distinguish levalbuterol from racemic albuterol by requiring specified optical purity, routes of administration, dosage ranges, and oral dosage forms. The patent is expired, so it no longer creates a current U.S. patent barrier to generic levalbuterol development or marketing. What does U.S. Patent 6,083,993 protect?The patent protects a therapeutic method, not the isolated chemical compound as such. The core invention is the use of optically pure R(-) albuterol in patients with reversible obstructive airway disease. The claims divide into two independent method categories:
Both independent claims require:
The dependent claims narrow the method by adding optical-purity thresholds, route of administration, dose, and oral dosage form. Claim 1: treatment of bronchospasmClaim 1 covers:
The claim does not specify a dose, route, dosage form, or particular disease diagnosis. The phrase “reversible obstructive airway disease” is broader than asthma alone and may encompass other airway disorders with reversible bronchoconstriction, subject to the evidence and claim construction applicable in a particular enforcement action. The claim requires a treatment purpose. Mere possession, manufacture, or sale of R(-) albuterol would not literally satisfy the method claim. Potential liability could instead arise under induced-infringement or contributory-infringement theories if a supplier intentionally encourages or materially supports the claimed administration method. Claim 10: prevention of bronchospasmClaim 10 is structurally parallel to claim 1 but covers prevention rather than treatment. The distinction matters because a product label directed only to relief of acute bronchospasm may present a different infringement analysis from labeling that expressly recommends prophylactic use. A label that includes both rescue and preventive language could implicate both independent claims if the remaining limitations are met. How do the dependent claims narrow the patent?Claims 2 through 9 depend from claim 1. Claims 11 through 17 depend from claim 10.
The claims therefore create several overlapping protection layers:
What does “optically pure R(-) albuterol” mean under the claims?R(-) albuterol is the pharmacologically active enantiomer of racemic albuterol. The S(+) enantiomer is the other optical isomer. Levalbuterol is generally used as the name for the R(-) form, often administered as levalbuterol hydrochloride. The patent’s dependent claims provide numerical purity thresholds:
A product containing 90% or more R(-) material would potentially fall within claims 2 or 11 if the therapeutic-use and disease limitations are also met. A product containing at least 99% R(-) material would potentially fall within claims 3 or 12. The numerical limitations do not automatically define the full scope of claims 1 and 10. The independent claims use “optically pure” without stating a percentage. In claim construction, the meaning of “optically pure” would be evaluated using the patent specification, prosecution history, technical meaning at the filing date, and any relevant judicial construction. The dependent claims may be relevant because they identify specific purity levels, but they do not necessarily eliminate broader scope from the independent claims. What formulations and routes are protected?The patent covers both inhaled and oral administration. Inhaled levalbuterolClaims 4, 5, 13, and 14 cover inhalation. The dose range is approximately 30 to 90 micrograms. The inhalation claims are not limited to a particular device in the claim text. They do not expressly require:
A product could therefore implicate the inhalation claims if it delivers the claimed R(-) albuterol dose to a qualifying patient for the claimed treatment or prevention purpose, even if the delivery device is materially different from the commercial product described in the patent. Oral levalbuterolClaims 6 through 9 and 15 through 17 cover oral administration. The specified oral dose is approximately 1 to 8 milligrams. Claims 8 and 17 identify tablets, capsules, and syrups. Claim 9 is narrower because it requires:
The patent does not claim every formulation property of an oral product. It claims the use of the specified R(-) active ingredient in the listed dosage forms and therapeutic settings. When did U.S. Patent 6,083,993 expire?U.S. Patent 6,083,993 is expired. Public patent and Orange Book records identify its effective patent term as ending in December 2017. Any applicable pediatric exclusivity would have extended regulatory marketing protection for six months, but that period also expired.
The issue date does not control the patent’s expiration. For modern utility patents, the term generally runs from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, and relevant transition rules. The U.S. Patent and Trademark Office and FDA Orange Book records are the controlling sources for term calculations and listed regulatory exclusivity. (U.S. Patent and Trademark Office, n.d.; FDA, 2024a) What is the FDA regulatory status of levalbuterol?Levalbuterol was developed as the single-enantiomer alternative to racemic albuterol. The FDA approved Xopenex inhalation solution for treatment or prevention of bronchospasm in patients with reversible obstructive airway disease, including pediatric patients within the approved labeling parameters. The FDA later approved inhalation-aerosol presentations. The relevant regulatory distinction is:
Levalbuterol and racemic albuterol are related but are not the same active ingredient for product-development and regulatory purposes. A generic levalbuterol applicant must address the reference product’s active ingredient, dosage form, route, strength, and bioequivalence or performance requirements under the applicable FDA pathway. What is the Orange Book status of Patent 6,083,993?The patent was historically associated with the Xopenex product franchise and its listed method-of-use protection. Because the patent expired in 2017, it is no longer a live Orange Book patent obstacle to an ANDA applicant. An expired Orange Book patent can remain relevant historically because it may explain:
It does not, by itself, support a current injunction or delay a new generic approval. Orange Book analysis must distinguish between:
The expiration of 6,083,993 does not establish that every patent associated with every levalbuterol presentation has expired. It establishes only that this patent no longer provides enforceable U.S. protection. How many patents cover levalbuterol?The commercial levalbuterol estate historically included more than one U.S. patent family. Patent 6,083,993 is the principal method-of-use patent reflected in the claims supplied here, but it should not be treated as a complete representation of the former estate. Potentially relevant patent categories include:
The supplied claims do not cover a manufacturing process, a composition per se, a container, an inhaler device, or a specific excipient system. A separate unexpired patent in one of those categories could have created a residual barrier after the expiration of 6,083,993. Patent 6,083,993 alone does not establish such a barrier. What Paragraph IV challenges affected levalbuterol?A Paragraph IV certification is relevant when an ANDA applicant asserts that a listed patent is invalid, unenforceable, or not infringed. For a method-of-use patent, an applicant may use a section viii statement to carve out the patented use if an approved noninfringing use remains. For levalbuterol, the strategic options included:
Because Patent 6,083,993 is expired, it no longer supports a current Paragraph IV launch delay. Historical ANDA litigation and settlement agreements may still be relevant to the chronology of generic entry, but they do not revive the expired claims. Which companies challenged or commercialized generic levalbuterol?Generic levalbuterol inhalation-solution products entered the U.S. market after the Xopenex exclusivity and patent period. FDA approval records identify multiple generic sponsors over time, including major generic manufacturers and specialty respiratory-product companies. The competitive field has included:
The key commercial competition is not limited to levalbuterol versus levalbuterol. Racemic albuterol remains a major substitute because it is widely available, familiar to prescribers, and generally lower priced. How strong is the patent estate for levalbuterol?Patent 6,083,993 was commercially meaningful while enforceable but is now legally weak as an exclusionary asset because it has expired.
The method-claim structure could have permitted design-around strategies based on label language, patient population, dose, route, or noninfringing use. Those strategies would have depended on the complete patent specification, prosecution history, FDA labeling, and the facts surrounding a particular generic product. What generic launch risks exist after expiration?Current launch risk from Patent 6,083,993 is low because the patent has expired. Remaining risks would arise from other sources, including:
A generic applicant also must assess whether its proposed label includes the treatment and prevention uses recited in claims 1 and 10. That issue was more important before expiration. Today, the patent’s expired status removes the principal legal consequence of that comparison. What licensing and settlement issues are relevant?During the patent term, a sponsor could have used licensing or settlement agreements to control the timing of generic entry. Such agreements could address:
No current license can extend the statutory enforceability of expired claims against third parties. A contract may allocate commercial rights between its parties, but it cannot restore Patent 6,083,993 as an enforceable patent monopoly. Does Patent 6,083,993 create biosimilar risk?No. Biosimilars are relevant to biologic products regulated under the Public Health Service Act. Levalbuterol is a small-molecule drug, not a biologic. The relevant competitive pathway is the ANDA pathway for generics, not the biosimilar pathway under the Biologics Price Competition and Innovation Act. What geographic coverage does the patent have?U.S. Patent 6,083,993 provided protection only in the United States. Foreign counterparts, if granted, required separate national enforcement and had separate expiration dates, prosecution histories, and claim scopes. U.S. expiration does not determine the status of corresponding patents in Europe, Canada, Japan, or other jurisdictions. International freedom-to-operate analysis must review each national patent family member and applicable supplementary protection, pediatric, or other term adjustment. Key Takeaways
FAQsIs levalbuterol the same drug as albuterol?No. Levalbuterol is the R(-) enantiomer of albuterol, while conventional albuterol products generally contain the racemic mixture of R(-) and S(+) enantiomers. Can a generic manufacturer sell levalbuterol without infringing Patent 6,083,993?Yes, Patent 6,083,993 is expired. A manufacturer must still assess other patents, FDA requirements, labeling, and formulation or device rights. Does Patent 6,083,993 cover levalbuterol inhalers specifically?It covers inhaled administration within the recited dose range, but the supplied claims do not require a particular inhaler, propellant, device, or formulation. Can an expired Orange Book patent block an ANDA?No. An expired patent does not create a current statutory patent-based approval delay, although historical Orange Book listings may remain relevant to prior litigation and entry chronology. Are levalbuterol products subject to biosimilar competition?No. Levalbuterol is a small-molecule drug. Competition is generally through abbreviated new drug applications and generic products. References
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Drugs Protected by US Patent 6,083,993
| Applicant | Tradename | Generic Name | Dosage | NDA | Approval Date | TE | Type | RLD | RS | Patent No. | Patent Expiration | Product | Substance | Delist Req. | Patented / Exclusive Use | Submissiondate |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| >Applicant | >Tradename | >Generic Name | >Dosage | >NDA | >Approval Date | >TE | >Type | >RLD | >RS | >Patent No. | >Patent Expiration | >Product | >Substance | >Delist Req. | >Patented / Exclusive Use | >Submissiondate |
International Family Members for US Patent 6,083,993
| Country | Patent Number | Estimated Expiration | Supplementary Protection Certificate | SPC Country | SPC Expiration |
|---|---|---|---|---|---|
| Austria | 135908 | ⤷ Start Trial | |||
| Australia | 7174191 | ⤷ Start Trial | |||
| Canada | 2073181 | ⤷ Start Trial | |||
| Germany | 69118359 | ⤷ Start Trial | |||
| Denmark | 0509036 | ⤷ Start Trial | |||
| European Patent Office | 0509036 | ⤷ Start Trial | |||
| Spain | 2085468 | ⤷ Start Trial | |||
| >Country | >Patent Number | >Estimated Expiration | >Supplementary Protection Certificate | >SPC Country | >SPC Expiration |
