Details for Patent: 4,519,801
Summary for Patent: 4,519,801
| Title: | Osmotic device with wall comprising cellulose ether and permeability enhancer | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | An osmotic delivery system is disclosed for dispensing a useful agent. The system comprises a semipermeable wall surrounding a compartment housing the agent. The wall comprises a cellulose ether, an organic solvent soluble polymer, and optionally an aqueous soluble polymer. A passageway in the wall connects the interior of the system with the exterior for dispensing an agent from the system. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | David Edgren | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Alza Corp | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US06/397,517 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Patent Claim Types: see list of patent claims | Composition; Formulation; Compound; Delivery; Device; | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | United States Patent 4,519,801: Scope, Claims, Expiration, and Osmotic Drug-Delivery Patent LandscapeUnited States Patent No. 4,519,801 is an Alza osmotic-delivery platform patent directed to semipermeable cellulose-ether membranes containing permeability-enhancing polymers. The claims cover a device architecture with three required components: a semipermeable wall, an agent-containing compartment, and an osmotic passageway. The patent issued May 28, 1985, and its ordinary 17-year patent term expired May 28, 2002. It therefore presents no current U.S. patent-exclusivity barrier to generic or competing osmotic products. The patent is technically important as a membrane-composition patent, not as a drug-specific patent. Its claims do not require a particular active ingredient, dosage, indication, brand, or therapeutic class. The principal claim limitations concern the chemical composition and manufacturing treatment of the semipermeable wall. What does U.S. Patent 4,519,801 protect?The patent protects controlled-release osmotic systems in which an external fluid crosses a selectively permeable membrane, creates an osmotic pressure gradient inside the device, and drives a drug formulation through an opening in the membrane. The core architecture is:
The claims focus on the membrane rather than on the identity of the active pharmaceutical ingredient. A device could therefore fall within the technical concept of the patent regardless of whether it delivered a cardiovascular drug, stimulant, analgesic, hormone, or another active agent, provided that the membrane and osmotic-system limitations were satisfied. The patent identifies Alza Corporation as assignee and Felix Theeuwes as an inventor in the published patent record.[1] How many independent claims does Patent 4,519,801 contain?Claims 1 and 4 through 9 are independent claims. Claims 2 and 3 depend on claim 1.
Claims 8 and 9 are compositionally narrower than claim 1 because they require a cellulose ether combined with a specifically identified hydrophilic polymer. Claims 5 through 7 add process-related limitations involving energy application or reaction during coating. What membrane compositions are protected by the patent?Claim 1: cellulose ether plus permeability enhancerClaim 1 requires a semipermeable wall consisting essentially of:
The Markush group includes:
The membrane must be permeable to fluid but substantially impermeable to the useful agent. The claim also requires that the formulation be soluble in the external fluid entering the compartment. This combination distinguishes the claimed system from a conventional coated tablet or a simple diffusion-controlled membrane. The claimed release mechanism depends on osmotic influx and pressure-driven expulsion through a passageway. Claim 4: permeability enhancer plus aqueous-soluble polymerClaim 4 expands the membrane formulation. It requires a cellulose ether and one listed permeability enhancer, together with an aqueous-soluble polymer selected from:
The claim is directed to a more compositionally complex wall. The added aqueous-soluble component can modify hydration, permeability, pore development, or solvent exchange during use. Claim 5: in situ formation of a hydrophilic insoluble polymerClaim 5 requires:
The phrase "on the application of energy used to coat" is significant. It introduces a process-dependent limitation. A membrane containing the same final polymeric ingredients may not satisfy the claim if the required polymer formation did not occur through the claimed coating-related energy step. The claim does not expressly define the energy as heat, radiation, or another specific source in the text supplied. The specification and prosecution history would control the interpretation of that limitation. Claim 6: reaction of polyhydroxy and polycarboxy polymersClaim 6 is narrower in its chemical mechanism. It requires:
The claim is not satisfied merely by placing a cellulose ether, a polyhydroxy polymer, and a polycarboxy polymer in the same coating. The text requires reaction during coating and formation of the specified resulting polymer. Claim 7: reacted polymer system plus additional membrane componentClaim 7 incorporates the reacted water-soluble-polymer concept and adds a further member from a long list that includes:
The claim reaches a broad range of membrane modifiers and excipients, but every element must be assessed together. The additional component does not replace the requirement for the cellulose ether, the reacted hydrophilic polymer, the osmotic compartment, and the passageway. Claims 8 and 9: cellulose ether with polyethylene glycol or polyethylene oxideClaim 8 requires a wall consisting essentially of:
Claim 9 requires a wall consisting essentially of:
These claims are commercially relevant because polyethylene glycol and polyethylene oxide are common hydrophilic excipients. The claims still require the complete osmotic device, including the compartment and osmotic passageway. A conventional matrix tablet containing polyethylene glycol or polyethylene oxide would not, by that fact alone, satisfy the claims. What are the essential infringement elements?A potentially infringing device would need to satisfy the structural and functional limitations of at least one claim. The central elements are:
For claims containing "consisting essentially of," the analysis turns on whether an accused additional ingredient materially changes the basic and novel characteristics of the claimed membrane. The phrase generally permits components that do not materially affect those characteristics, while excluding additions that do. The claims use both "useful agent" and "beneficial agent." Those terms are broad and encompass drugs, but claims 1 and 4 through 9 are not limited to pharmaceuticals. Claim 2 expressly narrows claim 1 to a drug. When did U.S. Patent 4,519,801 lose exclusivity?The patent issued May 28, 1985.[1] For a pre-June 8, 1995 U.S. patent, the ordinary term was 17 years from issue under the former patent-term regime. On that basis, the patent expired May 28, 2002.[2]
The patent predates the Uruguay Round Agreements Act patent-term transition. It therefore does not ordinarily receive a 20-year term measured from its earliest effective nonprovisional filing date. No current patent-term extension is relevant to this platform patent. Patent expiration terminates the right to exclude future making, using, selling, offering for sale, or importing of the claimed invention. It does not erase historical infringement claims accrued before expiration, subject to applicable damages limitations, including the six-year limitation in 35 U.S.C. § 286.[3] What is the Orange Book status of Patent 4,519,801?Patent 4,519,801 is not a drug-specific Orange Book patent. It claims a delivery-device platform and does not identify an approved active ingredient, dosage strength, dosage form, or therapeutic indication. The FDA Orange Book lists patents submitted for approved drug products under the Hatch-Waxman framework.[4] A platform patent of this type may be relevant to a drug product only if properly listed against that product and if it meets the statutory listing requirements. The patent number alone does not establish Orange Book listing status. Because the patent expired in 2002:
A generic applicant could still analyze the patent for historical freedom-to-operate, prior-art, or litigation context, but the expired patent does not block commercial launch. Are Paragraph IV challenges or generic-entry risks relevant?A current Paragraph IV challenge to Patent 4,519,801 has no practical exclusivity effect because the patent is expired. Paragraph IV certification is relevant to unexpired patents listed for an approved drug product. The statutory framework permits an ANDA applicant to assert that a listed patent is invalid, unenforceable, or will not be infringed.[5] For this patent, the relevant risk profile is:
The principal current risk would come from later, unexpired patents covering a particular osmotic product, formulation, manufacturing process, dosage form, or drug-specific use. How does the patent compare with later OROS and osmotic-delivery patents?Patent 4,519,801 occupies an early layer of the osmotic-delivery patent estate. Earlier Alza patents established the general osmotic-dispenser architecture. Later patents moved toward more specialized systems, including push-pull systems, multilayer cores, controlled-orifice structures, drug-specific formulations, and product-specific dosing profiles.
The claims supplied for Patent 4,519,801 are broad in drug identity but relatively specific in membrane chemistry. A later osmotic product could avoid literal infringement by using a different membrane polymer system, a different release mechanism, or a non-osmotic delivery architecture. Conversely, a product using the claimed cellulose-ether and polyethylene glycol or polyethylene oxide membrane may have historically implicated claims 8 or 9 if the remaining device limitations were present. What formulation and manufacturing barriers did the patent create?The patent’s technical barriers were concentrated in membrane engineering:
Claims 5 through 7 are particularly tied to manufacturing. They require polymer transformation or reaction associated with the coating process. This makes process records, coating conditions, polymer identity, molecular weight, solvent system, curing conditions, and analytical characterization important in any historical infringement analysis. The patent does not claim every osmotic device. It does not expressly cover all semipermeable membranes, all cellulose derivatives, all hydrophilic excipients, or all controlled-release dosage forms. The composition and, for some claims, the coating-reaction limitations materially constrain the scope. What is the patent strength of U.S. Patent 4,519,801?Historical strengthThe patent had meaningful historical value because it combined:
Its strongest historical claims were likely claims 8 and 9 for products using cellulose ether with polyethylene glycol or polyethylene oxide, assuming the full osmotic-device structure was present. Claims 5 through 7 could have been difficult to assess without detailed manufacturing evidence because they depend on how polymers were formed or reacted during coating. Current strengthThe current legal strength is zero as an exclusion right because the patent expired. Its remaining value is historical and technical:
Which companies challenged or licensed this technology?Alza Corporation was the principal patent owner associated with this technology.[1] Alza commercialized osmotic delivery platforms and licensed or partnered with other pharmaceutical companies across its broader OROS portfolio. Patent 4,519,801 itself is not a drug-specific patent, and the patent document does not establish a current license, settlement, or product-specific royalty arrangement. Any licensing analysis must distinguish this patent from later Alza patents and from commercial agreements covering the broader OROS platform. No current Paragraph IV dispute can affect launch based solely on this expired patent. Historical litigation or settlement agreements would need to be tied to a specific product, later patent, or commercial license rather than inferred from Patent 4,519,801’s claims. What revenue exposure was associated with this patent?The patent did not claim a particular revenue-generating drug. Revenue exposure therefore cannot be assigned directly from the patent number. Its commercial value was platform-based. Potential products using related osmotic technology included controlled-release oral products marketed under different brand and license arrangements. Those products generally depended on layered patent protection:
Expiration of Patent 4,519,801 did not automatically eliminate protection for any particular product. Later patents could continue to protect a product after this platform patent expired. Key Takeaways
FAQs About U.S. Patent 4,519,801Does Patent 4,519,801 cover OROS products?It covers an osmotic delivery architecture and specific membrane compositions associated with osmotic systems. It does not automatically cover every OROS product because infringement requires satisfaction of all limitations in at least one claim. Can a generic company launch a cellulose-ether osmotic tablet today?Patent 4,519,801 alone does not prevent launch because it expired in 2002. The product must still be evaluated against later unexpired patents and applicable FDA requirements. Does the patent cover polyethylene glycol and polyethylene oxide separately?Yes. Claim 8 identifies polyethylene glycol, while claim 9 identifies polyethylene oxide. Each claim also requires the claimed cellulose-ether membrane and complete osmotic delivery-system structure. Are claims 5, 6, and 7 product claims or process claims?They are drafted as system claims but include process-dependent limitations. Their scope turns partly on whether the required hydrophilic polymer was formed or reacted during the coating operation. Does expiration of this patent invalidate later OROS patents?No. Expiration eliminates this patent’s exclusion right. It does not invalidate later patents that independently satisfy novelty, nonobviousness, written-description, enablement, and other statutory requirements. References
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Drugs Protected by US Patent 4,519,801
| 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 |
