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Details for Patent: 4,810,502
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Summary for Patent: 4,810,502
| Title: | Pseudoephedrine brompheniramine therapy | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | A dosage form is disclosed for delivering the beneficial drugs pseudoephedrine and brompheniramine to a biological environment of use. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | Atul D. Ayer, Lawrence G. Hamel | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Alza Corp | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US07/019,989 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Patent Claim Types: see list of patent claims | Compound; Delivery; Dosage form; | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | US Patent 4,810,502: Claim Scope, Expiration, and Osmotic Drug-Delivery Patent LandscapeUS Patent 4,810,502 covers a specific controlled-release oral dosage form combining pseudoephedrine and brompheniramine with an osmotic, semipermeable wall and an exterior drug-containing lamina. The patent requires either polyethylene oxide or carboxyvinyl polymer in the lamina, depending on the independent claim. Its statutory term expired on February 28, 2006, based on the patent’s February 28, 1989 issue date and the pre-URAA 17-year term applicable to the patent. It is not a current enforceable barrier to generic or branded products. What does US Patent 4,810,502 claim?The patent claims an improved osmotic dosage form for delivering pseudoephedrine and brompheniramine. The claimed product has five essential structural elements:
Claims 1 through 4 use polyethylene oxide in the exterior lamina. Claims 5 through 8 use carboxyvinyl polymer in that lamina. The claims therefore target two alternative formulations rather than a single composition. The patent is directed to a dosage-form architecture. It does not broadly claim pseudoephedrine, brompheniramine, their salts, or the concept of extended release without the specified wall, passageway, and lamina structure. [1] What is the claimed dosage-form architecture?The claimed architecture is an osmotic system with an external drug-containing coating or lamina.
The term "lamina" indicates a layer arranged with the exterior of the wall. The claims do not merely cover a polymer matrix mixed with drug throughout a conventional tablet. They require a layer in laminar arrangement with the wall’s exterior surface. What are the independent claims in US 4,810,502?Claims 1 and 5 are the independent claims. Claim 1: polyethylene oxide embodimentClaim 1 requires:
The stated purpose of polyethylene oxide is to improve the lamina’s mechanical integrity and drug-release pharmacokinetics. A product would need to satisfy the structural limitations and the stated functional relationship. Claim 5: carboxyvinyl-polymer embodimentClaim 5 has substantially the same dosage-form structure but substitutes carboxyvinyl polymer for polyethylene oxide. The claim requires carboxyvinyl polymer in the lamina to enhance mechanical integrity and pharmacokinetic properties. "Carboxyvinyl polymer" generally refers to crosslinked acrylic-acid polymers, commonly associated with carbomer-type materials. The claim language does not identify a particular commercial grade or molecular weight. How do the dependent claims narrow the patent scope?Claims 2, 3, 4, 6, 7, and 8 narrow the independent claims as follows:
The salt claims are broad as written. They do not limit pseudoephedrine or brompheniramine to one named salt, such as pseudoephedrine hydrochloride or brompheniramine maleate. The relevant salt must still be pharmaceutically acceptable. What products could fall within the literal scope?A product would present the closest literal claim issue if it had all of the following characteristics:
A conventional extended-release tablet using a hydrophilic matrix, coated multiparticulates, a bilayer tablet without a passageway, or a capsule with an erodible polymer coating would generally lack one or more express limitations. What formulation changes could avoid literal infringement?The most direct design-around approaches would change a required claim element, such as:
A design that uses a different coating may still raise a doctrine-of-equivalents question, but that analysis would depend on the specific formulation, prosecution history, and accused product. The expired status of US 4,810,502 removes that present enforcement issue in the United States. When did US Patent 4,810,502 expire?US Patent 4,810,502 issued on February 28, 1989. Because it issued before the transition to the 20-year term measured from the earliest effective nonprovisional filing date, its ordinary term was 17 years from issue under the pre-URAA framework.
The patent therefore cannot currently support an infringement action for post-expiration activity. Patent expiration does not erase the technical disclosure or its relevance to prior-art analysis, freedom-to-operate review, or prosecution history review. [1, 2] No patent-term-extension issue is apparent from the nature of this formulation patent. FDA regulatory exclusivity is separate from patent term and would not revive an expired patent. What is the Orange Book status of US Patent 4,810,502?US Patent 4,810,502 is not a current Orange Book exclusivity barrier. The Orange Book lists patents submitted by sponsors for approved drug products and does not operate as a complete registry of every patent that may relate technically to a drug or dosage form. [3] For pseudoephedrine/brompheniramine products, the relevant regulatory questions are product-specific:
An expired 1989 dosage-form patent does not block an ANDA filing. A generic applicant could still need to address separate, later patents covering a particular branded product, formulation, manufacturing process, or method of use. Does US Patent 4,810,502 create Paragraph IV risk?No current Paragraph IV risk arises from US Patent 4,810,502 itself because the patent expired in 2006. Historically, if the patent had been listed against an FDA reference product while active, an ANDA applicant could have filed a Paragraph IV certification alleging that the patent was invalid, unenforceable, or not infringed. A Paragraph IV notice can trigger Hatch-Waxman litigation and a potential 30-month stay under the statutory framework. [4] That pathway is no longer relevant to this patent as an active right. A current generic applicant would focus on later unexpired patents listed against the relevant reference product. Could a later patent recreate the same risk?Yes. A later patent could cover:
Such a later patent would need to be assessed independently. Expiration of US 4,810,502 does not invalidate later patents. How strong was the patent estate for the claimed technology?The patent’s claim strength was narrow but technically specific. StrengthsThe claims combine several limitations that can materially reduce literal overlap:
This combination would have been more difficult to read onto an ordinary sustained-release tablet than a claim directed only to a drug and a polymer. WeaknessesThe claims also contain limitations that constrain commercial coverage:
The use of functional language such as "enhancing" mechanical integrity and pharmacokinetic properties could have created claim-construction and enablement issues, depending on the prosecution record. The claims also contain drafting inconsistencies, including the phrase "pharmacokinetics properties" in claim 5 and the misspelling "psuedoephedrine" in claim 3. Those errors do not automatically invalidate the claims, but they could require interpretation in litigation. What is the relevant patent landscape around US 4,810,502?US 4,810,502 sits within the broader Alza and osmotic-drug-delivery patent field. The surrounding landscape includes several technology layers.
Foundational osmotic patents from the Theeuwes and Alza research programs established the use of semipermeable membranes and delivery orifices for controlled drug release. Examples include US Patent 4,111,202 and US Patent 4,327,725. Those patents are relevant as platform prior art but do not establish that every osmotic dosage form falls within US 4,810,502. [5, 6] The key distinction is that US 4,810,502 is not a broad claim to an osmotic pump. It is an improvement claim directed to a particular combination of actives and a particular external lamina. Are biosimilar issues relevant to pseudoephedrine and brompheniramine?No. Pseudoephedrine and brompheniramine are small-molecule active ingredients. Products containing them proceed through generic-drug pathways, usually an ANDA pathway where an applicable reference listed drug exists, rather than the biosimilar pathway under section 351(k) of the Public Health Service Act. The relevant competitive risks are:
Biosimilar litigation, reference-product biologic exclusivity, and patent dance procedures do not apply to this patent technology. Which companies could be relevant competitors?The historical osmotic-delivery field was associated with Alza Corporation, later acquired by Johnson & Johnson. Companies active in generic and controlled-release oral dosage forms have included major ANDA manufacturers such as Teva, Perrigo, Mylan, Sandoz, and Impax, although the existence of a company in this field does not establish that it marketed a product practicing US 4,810,502. The commercial competitive set should be separated into three groups:
The third group is commercially competitive but would not satisfy the patent’s requirement for brompheniramine. What manufacturing and intellectual-property barriers remain?The expired patent does not create a current U.S. manufacturing barrier. Technical barriers may still include:
These are manufacturing and regulatory-development issues, not surviving rights under US 4,810,502. Later patents may protect manufacturing steps or specific formulations even when the underlying platform patent has expired. A freedom-to-operate review should therefore examine the complete current patent family, continuations, divisionals, reissues, and later patents citing or improving the formulation. What generic launch scenarios exist?Immediate launch against US 4,810,502A generic or reformulated product can launch without waiting for this patent because the patent expired in 2006. No Paragraph IV certification is required solely because of an expired patent unless an FDA-listed product patent or other regulatory issue creates a separate certification obligation. Launch using a non-osmotic dosage formA matrix tablet, coated multiparticulate, or extended-release capsule could avoid the express osmotic-wall and passageway limitations. The product would still require FDA approval and must satisfy applicable performance, stability, bioequivalence, and manufacturing requirements. Launch using an osmotic dosage formAn osmotic product could potentially practice the disclosed technology without patent infringement from this patent because the patent has expired. Later patents covering specific membrane compositions, release profiles, or manufacturing processes would remain relevant. What revenue exposure is associated with US Patent 4,810,502?Current direct revenue exposure is zero from this patent because it is expired and cannot produce future patent royalties or block U.S. market entry. Historical exposure cannot be reliably assigned to the patent from the claim text alone. Revenue would depend on:
The patent’s commercial value was therefore historical and product-specific rather than an ongoing exclusivity asset. Key Takeaways
FAQs About US Patent 4,810,502Is US Patent 4,810,502 still enforceable?No. Its ordinary patent term expired on February 28, 2006. Does the patent cover all extended-release pseudoephedrine products?No. It requires pseudoephedrine and brompheniramine in a specific osmotic dosage form with a defined wall, passageway, and external lamina. Does the patent cover brompheniramine maleate?It can cover pharmaceutically acceptable brompheniramine salts under dependent claim 4 or claim 8, provided all other claim limitations are met. The claim text does not name brompheniramine maleate specifically. Is polyethylene oxide required in every claim?No. Polyethylene oxide is required by claim 1 and its dependent claims. Claims 5 through 8 instead require carboxyvinyl polymer. Can a generic company use the disclosed osmotic technology?Yes, with respect to US Patent 4,810,502, because the patent expired. Current patents covering a particular formulation, manufacturing process, or reference product must still be assessed. Does an expired patent remain relevant to FDA approval?Yes, as a technical disclosure and possible prior-art reference. It does not provide active patent exclusivity or independently prevent FDA approval of a generic product. References
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Drugs Protected by US Patent 4,810,502
| 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 4,810,502
| Country | Patent Number | Estimated Expiration | Supplementary Protection Certificate | SPC Country | SPC Expiration |
|---|---|---|---|---|---|
| Australia | 602020 | ⤷ Start Trial | |||
| Australia | 8093487 | ⤷ Start Trial | |||
| Canada | 1297026 | ⤷ Start Trial | |||
| Germany | 3769307 | ⤷ Start Trial | |||
| European Patent Office | 0281708 | ⤷ Start Trial | |||
| >Country | >Patent Number | >Estimated Expiration | >Supplementary Protection Certificate | >SPC Country | >SPC Expiration |
