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Details for Patent: 3,882,246
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Summary for Patent: 3,882,246
| Title: | Treatment of skeletal muscle disorders with cyclobenzaprine | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | The present invention relates to a pharmaceutical composition providing a dosage unit of from 1 to 20 mg. of cyclobenzaprine and salts thereof useful as a skeletal muscle relaxant. It also relates to a method of treating muscular spasm and other similar muscular disorders associated with or caused by injury or arising spontaneously with no known cause by the administration of a pharmaceutical composition containing cyclobenzaprine or a salt thereof as one of the active ingredients. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | Nathan Norman Share | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Merck and Co Inc | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US459748A | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Patent Claim Types: see list of patent claims | Delivery; | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | United States Patent 3,882,246: Cyclobenzaprine Claims, Scope, Expiration, and Patent LandscapeU.S. Patent No. 3,882,246 protected methods of treating skeletal-muscle hypertonic disorders with cyclobenzaprine, including muscle spasm, spasticity, rigidity, and muscle splinting. The patent issued on May 6, 1975, under the pre-Uruguay Round patent-term regime. Its 17-year term from issuance therefore ended on May 6, 1992, absent an unusual terminal adjustment or restoration. The patent is expired and does not create current U.S. exclusivity for cyclobenzaprine products. [1] The patent was a method-of-use patent. It did not, based on the supplied claims, claim the cyclobenzaprine molecule as a composition, a particular tablet formulation, a sustained-release dosage form, or a manufacturing process. What does U.S. Patent 3,882,246 cover?The patent covers administering cyclobenzaprine to patients with selected disorders involving skeletal-muscle hypertonic activity. Its protection is defined by five claims:
The formula reproduced in claim 1 identifies cyclobenzaprine, commonly described as 5-(3-dimethylaminopropylidene)-10,11-dihydro-5H-dibenzo[a,d]cycloheptene. Commercial products generally use cyclobenzaprine hydrochloride. What disorders are within claim 1?Claim 1 uses a closed group of indications:
The phrase “selected from the group consisting of” generally limits the claimed disorder to the listed conditions rather than every condition involving abnormal muscle tone. A treatment for a different indication, such as fibromyalgia, insomnia, depression, or neuropathic pain, would not fall within the literal disorder limitation unless the claim were construed more broadly under the applicable facts. The claim also requires that the condition involve skeletal-muscle hypertonic activity. That limitation distinguishes the claim from a broad claim covering any use of cyclobenzaprine. How do the dependent claims narrow the patent scope?Claim 2 narrows claim 1 to a unit dosage of 1 to 20 mg. It does not necessarily require that the total daily dose be between 1 and 20 mg. The phrase “unit dosage” ordinarily focuses on the amount contained in each administered unit, such as a tablet, capsule, or injection. Claim 3 requires oral administration and incorporates claim 2’s 1-to-20-mg unit-dose range. A typical 5-mg or 10-mg oral cyclobenzaprine tablet would fall within the textual boundaries of claim 3 if the underlying disorder and therapeutic-use limitations were satisfied. Claim 4 covers parenteral administration at the same 1-to-20-mg unit-dose range. Parenteral administration generally includes routes such as intravenous, intramuscular, or subcutaneous delivery, although the patent specification and prosecution history would control the precise construction. Claim 5 requires the hydrochloride salt but does not depend on claim 2. On the supplied claim structure, claim 5 covers cyclobenzaprine hydrochloride treatment under claim 1 without an express 1-to-20-mg limitation. What is the practical difference between claims 3, 4, and 5?Claim 3 is route-specific and dose-specific. Claim 4 is also route-specific and dose-specific. Claim 5 is salt-specific but does not add the dose limitation found in claim 2.
When did U.S. Patent 3,882,246 expire?U.S. Patent 3,882,246 issued on May 6, 1975. Patents filed before June 8, 1995 generally received a term of 17 years from issuance under the pre-URAA system. On that basis, the patent expired on May 6, 1992. [1][2] The expiration analysis is important because current patent enforceability does not depend on whether the original claim language could have covered a modern cyclobenzaprine product. Once the patent term ended, the claims ceased to provide an enforceable exclusionary right in the United States. Did the patent receive pediatric exclusivity or patent-term extension?There is no basis in the supplied patent record to treat U.S. Patent 3,882,246 as having received pediatric exclusivity or a Hatch-Waxman patent-term extension. Those mechanisms became relevant under later statutory frameworks and would not ordinarily convert a 1975-issued method-of-use patent into a currently enforceable right. What is the Orange Book status of cyclobenzaprine?Cyclobenzaprine products have been approved through FDA drug applications, including immediate-release tablets and extended-release capsules. The original Flexeril product was approved for short-term use as an adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions. [3] The relevant regulatory categories include:
Patent 3,882,246 is not a current Orange Book exclusivity barrier. Any Orange Book listing associated with a later cyclobenzaprine product would relate to a separate patent, formulation, delivery system, or method-of-use right, not to the expired 1975 patent itself. FDA Orange Book listings must be evaluated by product, NDA, patent number, and listed use. [4] What Paragraph IV challenges affected cyclobenzaprine?Paragraph IV certifications are relevant to unexpired patents listed for an FDA-approved reference product. They are not a current challenge pathway for Patent 3,882,246 because that patent expired decades ago. Historical generic entry into immediate-release cyclobenzaprine was driven by the expiration of the original exclusivity and by ANDA approvals. A generic applicant would not need to make a commercially meaningful Paragraph IV challenge to an expired patent. For later extended-release products, generic applicants could face separate formulation, drug-delivery, or method-of-use patents listed against the applicable reference product. A Paragraph IV analysis therefore must distinguish:
What formulations are protected by later cyclobenzaprine patents?Patent 3,882,246 does not claim a formulation. Its claims do not specify:
The principal later patent risk historically associated with cyclobenzaprine involved extended-release delivery rather than the basic use of the active ingredient for muscle spasm. Extended-release products such as Amrix required separate technical and regulatory analysis because a formulation patent can protect a dosage form even after a basic method-of-use patent expires. An immediate-release generic tablet generally does not infringe an expired method-of-use patent. An extended-release product may still face a patent review if a current patent claims its release mechanism, capsule construction, formulation composition, or labeled indication. Does claim 5 cover every cyclobenzaprine hydrochloride product?No. Claim 5 is a method claim, not a product claim. It requires administration of cyclobenzaprine hydrochloride to a patient afflicted with one of the specified disorders. It does not prohibit making, selling, or possessing cyclobenzaprine hydrochloride independently of the claimed treatment method. The claim also expired in 1992. It therefore does not currently restrict commercial manufacture or sale of cyclobenzaprine hydrochloride in the United States. How strong was the patent estate for cyclobenzaprine?The original patent estate had practical value during the early commercialization period because it linked cyclobenzaprine to a therapeutic use in skeletal-muscle hypertonic disorders. Its strength was limited by several factors:
The strongest historical claim was likely claim 1 because it lacked the express 1-to-20-mg, oral, parenteral, or hydrochloride limitations found in the dependent claims. Its scope remained constrained by the requirement that the patient have a covered skeletal-muscle hypertonic disorder and that cyclobenzaprine be administered at a therapeutically effective and safe dosage. What patent litigation affects cyclobenzaprine?Patent 3,882,246 is not a current litigation risk because it expired in 1992. Any historical litigation involving cyclobenzaprine must be separated from current disputes involving later products. The commercially relevant litigation questions for cyclobenzaprine have generally concerned:
No current infringement action can be based on an expired patent. A settlement agreement that once delayed generic entry would not revive the patent or extend its term. Which companies challenged or competed with the original cyclobenzaprine products?The immediate-release cyclobenzaprine market became highly genericized. Competition has involved major generic manufacturers and distributors, including companies operating under the Actavis, Teva, Mylan, Sandoz, and related commercial names. Product-specific participation has changed over time and must be tied to individual ANDA records rather than inferred from the existence of a generic market. The relevant competitive structure is:
Cyclobenzaprine competes primarily in the short-term treatment of acute painful musculoskeletal conditions. FDA labeling states that use beyond two or three weeks is generally not recommended because adequate evidence for prolonged use is limited. [3] What generic launch risks exist for cyclobenzaprine?For immediate-release cyclobenzaprine, patent-related launch risk is low because the foundational patent expired in 1992 and generic competition is established. For an extended-release product, launch risk can remain higher because the applicant may need to address:
The risk profile is therefore product-specific:
Does cyclobenzaprine have biosimilar risk?No. Cyclobenzaprine is a small-molecule drug, not a biologic. The relevant FDA pathway is the ANDA pathway under section 505(j) of the Federal Food, Drug, and Cosmetic Act, not the biosimilar pathway under section 351(k) of the Public Health Service Act. The competitive threat is generic substitution, not biosimilar competition. For immediate-release tablets, the principal commercial barriers are manufacturing scale, FDA compliance, supply reliability, reimbursement, and price erosion. What licensing deals are relevant to Patent 3,882,246?The supplied patent claims do not establish a licensing arrangement. Patent ownership and commercial licensing must be distinguished from product marketing rights. A patent may have been assigned, licensed, or used by a commercial affiliate, but the claims alone do not prove the existence, scope, consideration, territory, or duration of any agreement. Because Patent 3,882,246 expired in 1992, any historical license associated with it would not create present-day patent exclusivity. A surviving trademark, manufacturing agreement, supply contract, or regulatory license would be legally distinct from the expired patent rights. How does U.S. Patent 3,882,246 compare with later cyclobenzaprine protection?
Key Takeaways
FAQs About U.S. Patent 3,882,246 and Cyclobenzaprine ExclusivityCan an expired cyclobenzaprine method patent block a generic tablet?No. An expired patent cannot support a current patent-infringement claim. Generic launch may still require FDA approval and compliance with any unexpired patents listed for the applicable reference product. Does U.S. Patent 3,882,246 cover Flexeril as a product?No. The supplied claims cover methods of administering cyclobenzaprine. They do not claim Flexeril as a composition or trademarked product. Does the patent cover cyclobenzaprine for fibromyalgia?The claims identify muscle spasm, muscle spasticity, muscle rigidity, and muscle splinting associated with skeletal-muscle hypertonic activity. Fibromyalgia is not expressly listed in the supplied claims. Is an extended-release cyclobenzaprine capsule automatically covered by this patent?No. Patent 3,882,246 does not claim an extended-release formulation. Any relevant protection would have to arise from a separate formulation, delivery, dosage, or method-of-use patent. What FDA pathway applies to a generic cyclobenzaprine tablet?A generic cyclobenzaprine tablet is generally submitted through an abbreviated new drug application under section 505(j), subject to pharmaceutical equivalence, bioequivalence, manufacturing, labeling, and other FDA requirements. References
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Drugs Protected by US Patent 3,882,246
| Applicant | Tradename | Generic Name | Dosage | NDA | Approval Date | TE | Type | RLD | RS | Patent No. | Patent Expiration | Product | Substance | Delist Req. | Patented / Exclusive Use | Submissiondate |
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| >Applicant | >Tradename | >Generic Name | >Dosage | >NDA | >Approval Date | >TE | >Type | >RLD | >RS | >Patent No. | >Patent Expiration | >Product | >Substance | >Delist Req. | >Patented / Exclusive Use | >Submissiondate |
