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Details for Patent: 4,690,825
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Summary for Patent: 4,690,825
| Title: | Method for delivering an active ingredient by controlled time release utilizing a novel delivery vehicle which can be prepared by a process utilizing the active ingredient as a porogen | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | Delivery vehicles comprised of a polymeric bead having a network of pores with an active ingredient held within the network are provided for use in a method to provide controlled release of the active ingredient. The network of pores is substantially non-collapsible upon removal of the active ingredient and the delivery vehicles are polymerized by a process in which the active ingredient also comprises the porogen during formation of the network of pores. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | Richard Won | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Heron Therapeutics LLC | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US06/784,382 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Patent Claim Types: see list of patent claims | Use; Composition; Process; Delivery; | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | # U.S. Patent 4,690,825: Claim Scope, Expiration, Patent Landscape, and Generic-Entry Risk U.S. Patent 4,690,825 covers porous cross-linked polymer beads that retain an active ingredient in a substantially non-collapsible pore network, together with methods for making and using those beads for controlled release. The patent issued on September 1, 1987, and, under the pre-Uruguay Round patent-term rule, its 17-year term ran to approximately September 1, 2004. It is therefore expired and cannot presently block manufacture, sale, or use in the United States.[1][2] The patent is a platform-technology patent, not a drug-specific patent. Its claims focus on particle structure, polymer chemistry, porogen retention, particle size, loading, manufacturing conditions, and release mechanisms. The principal commercial relevance is historical or technical: it may remain useful as prior art against later patents claiming similar porous polymer microspheres, controlled-release beads, or mineral-oil delivery systems. What does U.S. Patent 4,690,825 cover?The patent claims three connected subject-matter categories:
The broadest recurring limitation is a porous polymeric bead with:
The claims also repeatedly recite particle diameters of approximately 10 to 100 microns, cross-linking density above approximately 10%, and active-ingredient loading between approximately 5% and 60% by weight. The claim set is drafted as a layered platform. The broad claims are followed by narrower claims directed to specific monomer systems, mineral oil, particle size, release mechanisms, and manufacturing steps. How many independent claims does Patent 4,690,825 contain?Patent 4,690,825 contains eight independent claims based on the claim text provided:
Claim 68 is also drafted as an independent delivery-method claim, bringing the total to nine independent claims if claim dependency and punctuation are assessed according to the supplied text. The independent claims divide into two principal families:
What polymer systems are protected?The claims identify three principal polymer systems.
The claims also refer to “styrene and divinylbenzene” as a comonomer pair and require an initiator soluble in the monomer system in certain embodiments. The process claims therefore reach beyond the finished bead and cover specific suspension-polymerization approaches. The principal structural distinction is the use of cross-linking to maintain pore geometry after removal of the porogen or loaded active ingredient. A non-cross-linked or weakly cross-linked polymer particle may fall outside the claims if it lacks the required substantially non-collapsible pore network. What limitations define the strongest claim scope?The strongest practical limitations are the following: Porous polymeric beadThe claims require a bead rather than an arbitrary porous polymer article. A formulation using a porous film, capsule, fiber, granule, or monolithic matrix would require a close analysis of whether it satisfies the “bead” limitation. Non-collapsible pore networkThis is the central structural limitation. The pore network must remain substantially non-collapsible when the active ingredient is removed. A product with pores formed only by temporary solvent extraction and substantial pore collapse may present a non-infringement position. Active ingredient retained in the poresThe claims require the active ingredient to be held within the pore network. A coating or surface-adsorbed ingredient that does not reside within the internal pore structure may fall outside the literal claim language. Cross-linkingSeveral dependent claims require calculated cross-linking density above approximately 10%. This limitation narrows the claims but also identifies the technology’s principal engineering mechanism. A competing product with a different pore-stabilization mechanism could avoid those dependent claims while still requiring analysis under broader claims 1, 8, 16, 28, 34, 40, 51, 60, or 68. Particle sizeThe 10-to-100-micron range is a dependent limitation. Products outside that range are not automatically outside the patent because the independent claims do not uniformly require that size range. Release mechanismClaims 22-25 and 46-49 recite pressure release, diffusion, volatilization, and gradual continuous release. These claims are narrower than the underlying composition claims. A product using another release mechanism may avoid these specific dependent claims but could still implicate an independent composition claim if the bead structure is present. What does the process claim cover?The process claims generally require:
This is a suspension-polymerization process. A manufacturer using a materially different process, such as emulsion polymerization, microfluidic droplet generation, phase separation, spray drying, templating, or post-polymerization pore formation, would need to determine whether all required process steps are present. The process claims are narrower than a pure product claim because infringement requires performance of the claimed steps. They may nevertheless have been commercially important when manufacturing methods were less standardized and process evidence was available from batch records, technical specifications, or reverse engineering. What is the significance of the mineral-oil claims?Mineral oil appears as both:
Claims 5, 11, 19, 31, 35, 43, 54, 56, 63, 70, and 73 specifically recite mineral oil. This creates a narrow but commercially recognizable subfamily. A formulation containing mineral oil in cross-linked porous beads may satisfy several dependent claims if the remaining structural and process limitations are met. Mineral oil is not itself a drug active ingredient in the conventional pharmaceutical sense. The patent’s “active ingredient” terminology is broad enough to encompass carriers, agents, cosmetic ingredients, volatile materials, and other releasable substances. Claim 26 and claim 50 expressly recognize an active ingredient comprising a carrier and an agent. That language supports applications in which the bead carries another substance rather than acting as a conventional oral pharmaceutical dosage form. What is the scope of the release-test claims?Claims 51-80 add a functional release requirement. The composition must have a calculated cross-linking density and active-ingredient concentration such that substantially all of the active ingredient is released when the bead is placed in a solvent in which the active ingredient is soluble and the bead is wetted. Claim 52 narrows the requirement to release within approximately five minutes under moderate agitation. These claims are potentially useful for distinguishing a controlled-release bead from a permanently loaded absorbent particle. They also create proof issues. A party assessing infringement would need to determine:
The performance-based language may also create validity and construction issues if the specification does not provide sufficiently objective test protocols. Those issues depend on the patent specification, prosecution history, expert testimony, and applicable claim-construction law. When did U.S. Patent 4,690,825 lose exclusivity?The patent issued September 1, 1987. Because it was granted before June 8, 1995, its term was generally 17 years from issuance rather than 20 years from the earliest effective U.S. nonprovisional filing date.[2]
Any terminal disclaimer, patent-term adjustment, reissue, or unusual maintenance-fee event would need to be checked against the official USPTO file. Those mechanisms ordinarily do not extend a pre-1995 patent beyond the governing statutory term absent a specific statutory basis. What is the Orange Book status of Patent 4,690,825?Patent 4,690,825 is not a conventional Orange Book drug patent. Its claims do not identify:
The FDA Orange Book lists patents submitted for approved drug products under the Hatch-Waxman framework. A broad controlled-release bead platform patent of this type would not ordinarily appear as an Orange Book-listed patent unless it had been submitted for a particular approved drug product and accepted by FDA under the applicable listing rules.[3] There is therefore no meaningful Orange Book or Paragraph IV challenge pathway directed specifically to Patent 4,690,825 today. Any generic applicant could not receive a current patent-term barrier from this expired patent. What FDA exclusivity applies?No FDA regulatory exclusivity can be inferred from Patent 4,690,825. Patent protection and FDA exclusivity are separate rights. The patent does not itself establish:
The claims could have been used in a drug-delivery product, topical product, cosmetic product, agricultural product, or industrial release system. Regulatory exclusivity would depend on the product and regulatory submission, not on the patent’s generic delivery-vehicle claims. Which companies are challenging Patent 4,690,825?There is no current Paragraph IV challenger landscape for this patent because its term expired approximately two decades ago. A Paragraph IV certification is relevant to an unexpired patent listed for an approved drug product. Patent 4,690,825 does not present that current litigation profile. Historical competitive activity is more likely to have occurred through:
Those later rights must be analyzed independently. Expiration of Patent 4,690,825 does not eliminate later patents covering a specific drug, particle coating, manufacturing process, excipient combination, or approved formulation. How strong is the patent estate for this technology?As a current enforcement estate, it is weak because the patent is expired. As prior art, it is potentially significant.
The strongest historical claims were likely the composition claims directed to the porous bead itself because they did not require proof of a particular manufacturing route. The process claims could be avoided by changing the manufacturing pathway. The method claims required application of the delivery vehicle to a surface and release of the active ingredient, which narrowed their relevance to particular commercial uses. What patent landscape surrounds the claimed technology?The relevant landscape has five technical clusters: Cross-linked porous polymer beadsThese patents typically claim bead composition, pore volume, pore size, cross-link density, particle diameter, and loading capacity. Microcapsules and microparticlesMicrocapsule patents often claim a discrete shell surrounding a core, which differs structurally from a bead containing a connected internal pore network. Controlled-release pharmaceutical particlesLater pharmaceutical patents may claim a particular active ingredient, polymer blend, coating, dissolution profile, or dosage form. Those claims can remain enforceable even though Patent 4,690,825 has expired. Topical and cosmetic delivery systemsThe surface-application claims in Patent 4,690,825 make topical, cosmetic, fragrance, pesticide, and coating uses relevant. Later products may use polymer particles to release emollients, fragrances, preservatives, sunscreens, or active agents. Manufacturing and scale-up patentsLater rights may focus on droplet-size control, surfactants, initiators, solvent extraction, residual monomer removal, sterilization, and pharmaceutical-grade manufacturing. These process patents are more likely to create current freedom-to-operate issues than Patent 4,690,825 itself. What generic launch risks remain?Patent 4,690,825 creates no current generic-launch risk because it is expired. The relevant risks are second-generation rights. A generic or follow-on manufacturer using porous polymer beads should assess:
A product can be free of Patent 4,690,825 yet infringe a later patent claiming a particular drug-loaded porous particle or controlled-release dosage form. Key Takeaways
FAQs About U.S. Patent 4,690,825Can an expired patent still affect a new controlled-release formulation?Yes. The expired patent cannot be enforced, but it can be cited as prior art against later patent applications. It may also help establish that certain bead structures or release concepts were publicly disclosed before later filings. Does the patent cover all polymeric microspheres?No. The claims require a porous polymeric bead with an internal pore network holding the active ingredient. Nonporous microspheres, shell-core microcapsules, liposomes, and matrices lacking the claimed structure are not automatically covered. Does use of mineral oil create infringement risk today?No infringement risk arises from this patent because the patent is expired. Mineral-oil formulations may still implicate later patents covering a specific particle architecture, cosmetic formulation, pharmaceutical use, or manufacturing method. Are the 10-to-100-micron particle limits present in every claim?No. The particle-size range appears in dependent claims. It narrows those claims but does not apply uniformly to the independent claims. Does the patent cover oral drug-delivery products?The claim language is broad enough to encompass delivery applications, but the asserted method claims expressly require mixing the vehicle with a medium and applying the mixture to a surface. The patent does not expressly claim a conventional oral tablet, capsule, or specific FDA-approved drug product. References
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Drugs Protected by US Patent 4,690,825
| 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 4,690,825
| Country | Patent Number | Estimated Expiration | Supplementary Protection Certificate | SPC Country | SPC Expiration |
|---|---|---|---|---|---|
| Austria | 68965 | ⤷ Start Trial | |||
| Australia | 591264 | ⤷ Start Trial | |||
| Australia | 7132287 | ⤷ Start Trial | |||
| Germany | 3774266 | ⤷ Start Trial | |||
| European Patent Office | 0285694 | ⤷ Start Trial | |||
| >Country | >Patent Number | >Estimated Expiration | >Supplementary Protection Certificate | >SPC Country | >SPC Expiration |
