Details for Patent: 4,870,105
Summary for Patent: 4,870,105
| Title: | Phosphorus binder | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | A composition for oral administration to an individual for the purpose of inhibiting gastrointestinal absorption of phosphorous, which includes calcium acetate. A method of inhibiting gastrointestinal absorption of phosphorous, comprising administering orally the composition, preferably close in time to food and beverage consumption. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | John S. Fordtran | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Fresenius Medical Care Holdings Inc | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US07/035,341 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Patent Claim Types: see list of patent claims | Use; Dosage form; | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | United States Patent 4,870,105: Scope, Claims, Expiration, and Calcium Acetate Patent LandscapeU.S. Patent No. 4,870,105 covers oral use of calcium acetate as a gastrointestinal phosphate binder. Its claims are method-of-treatment claims directed to reducing phosphorus absorption, with dependent claims covering a calcium dose of 10 to 200 milliequivalents, administration at mealtimes, tablets, and gelatin capsules. The patent issued on September 26, 1989, and its 17-year term expired in September 2006. It therefore presents no current U.S. patent barrier to generic calcium acetate products. The patent has historical importance for calcium acetate products such as PhosLo, but its claims do not cover the calcium acetate molecule, a particular formulation, a manufacturing process, or a brand-specific product. The principal commercial risk during the patent term was infringement by products using calcium acetate as a phosphate binder, particularly products administered with meals to patients with renal impairment. What does U.S. Patent 4,870,105 claim?The patent claims a treatment method in which an individual orally ingests calcium acetate in a quantity sufficient to bind phosphorus in the gastrointestinal tract.
Claims 1 and 5 are the two operative claim categories. Claim 1 requires calcium acetate in an amount sufficient to bind gastrointestinal phosphorus. Claim 5 adds the timing limitation that administration occurs at mealtimes. The dependent claims do not create independent product claims. They narrow the method claims by specifying dose, dosage form, or timing. How broad is the scope of U.S. Patent 4,870,105?The patent’s scope is functional and use-based rather than composition-based. It does not claim every calcium acetate product regardless of use. A potentially infringing product would need to be used in the claimed method, including oral administration for the purpose of inhibiting gastrointestinal phosphorus absorption. Claim 1: General calcium acetate phosphate-binding methodClaim 1 requires four material elements:
The claim does not require:
The phrase "sufficient to bind with phosphorous in the gastrointestinal tract" is a functional limitation. It ties the claimed activity to the amount administered and the intended treatment result. The claim is broad as to formulation and patient population but narrower than a claim covering calcium acetate as a chemical composition. Claim 5: Mealtime administrationClaim 5 is similar to claim 1 but expressly requires administration "at mealtimes." This limitation tracks the clinical use of phosphate binders, which are generally taken with food so that calcium acetate is present when dietary phosphorus reaches the gastrointestinal tract. A product label or prescribing instruction directing patients to take calcium acetate with meals would have been commercially significant during the patent term. Because the patent expired, that limitation no longer creates current U.S. infringement exposure. Claims 2 and 6: 10 to 200 mEq of calciumClaims 2 and 6 cover administration of calcium acetate in an amount sufficient to provide between 10 and 200 milliequivalents of calcium. This range is broad. It encompasses ordinary clinical doses and extends well beyond typical daily dosing for calcium acetate phosphate binders. For calcium, milliequivalents are calculated using calcium’s valence of two: [ \text{mEq calcium} = \frac{\text{mg elemental calcium}}{20.04} ] Calcium acetate contains approximately 25.3% elemental calcium by weight. Accordingly:
A 667 mg calcium acetate capsule contains approximately 169 mg of elemental calcium, or about 8.4 mEq of calcium. A common three-meal regimen of one 667 mg capsule at each meal would provide approximately 25 mEq of calcium daily. Two capsules at each of three meals would provide approximately 50 mEq. The 10-to-200 mEq range therefore captures ordinary commercial dosing but is not limited to a particular marketed strength. Claims 3, 4, 7, and 8: Dosage-form limitationsThe tablet claims cover calcium acetate administered in tablet form. The gelatin capsule claims cover calcium acetate in a gelatin capsule. These claims do not specify:
A tablet or gelatin capsule used in the claimed phosphate-binding method would have fallen within the relevant dependent claim during the patent term if the other limitations were satisfied. What does the patent not cover?U.S. Patent 4,870,105 does not claim the following subject matter as such:
The patent also does not create patent rights in foreign jurisdictions. A U.S. patent can be enforced only against conduct within the scope of U.S. patent law. Any corresponding foreign rights would require separate national patents and separate term analyses. When did U.S. Patent 4,870,105 expire?The patent issued on September 26, 1989. For a pre-June 8, 1995 application, the applicable U.S. patent term was generally 17 years from the issue date, subject to statutory adjustments or terminal disclaimers. On that basis, the patent term expired in September 2006.
The expired patent cannot support a current injunction, damages claim, or Paragraph IV litigation strategy against a new generic calcium acetate entrant. What was the historical patent strength?During its enforceable period, the patent had meaningful commercial reach because the independent claims targeted the therapeutic use of calcium acetate rather than a narrow formulation. Its historical strengths were:
Its limitations were equally important:
The most commercially important claim combination was claim 5, together with claims 6 and 7 or 8: oral calcium acetate, administered at mealtimes, in the specified calcium range, in tablet or gelatin capsule form. What is the Orange Book status of U.S. Patent 4,870,105?The patent is no longer a live Orange Book patent barrier because its term expired in 2006. Any historical listing associated with an approved calcium acetate product would not prevent FDA approval of a competing product today. For small-molecule products, an ANDA applicant addresses listed patents through the applicable certification framework:
For Patent 4,870,105, the relevant current posture is expiration. A new ANDA applicant would not need to mount a present-tense Paragraph IV challenge to this patent because the patent term has already ended. The patent also does not create current pediatric, regulatory, or market exclusivity. Patent expiration and FDA regulatory exclusivity are separate concepts. An expired patent does not preserve an exclusivity period under the Hatch-Waxman statute. What Paragraph IV challenges and litigation affected calcium acetate products?The supplied claim set identifies the patent’s substantive scope but does not establish a complete historical docket of ANDA certifications, district court actions, settlements, or licensed launches. The patent’s expiration eliminates any current Paragraph IV exposure attributable to Patent 4,870,105. During the patent term, a generic applicant seeking approval of calcium acetate capsules or tablets could have faced an infringement allegation based on the use instructions associated with the product. The relevant issue would have been whether the generic label induced the claimed method of administering calcium acetate to inhibit gastrointestinal phosphorus absorption, particularly at mealtimes. After expiration:
No biosimilar pathway applies. Calcium acetate is a small-molecule active ingredient regulated through the generic drug framework, not the biologics license application and biosimilar framework. What FDA products and formulations are relevant?Calcium acetate phosphate binders have been marketed primarily as oral capsules and tablets. A commonly used unit strength is 667 mg calcium acetate, equivalent to approximately 169 mg elemental calcium. The commercial product category includes:
The patent claims reach the therapeutic method rather than a particular approved product. A generic product could avoid any product-specific patent claim if it used a different composition or manufacturing process, but Patent 4,870,105 was broad enough during its term to create potential method-of-use issues for products carrying a phosphate-binding label. How does Patent 4,870,105 compare with competing phosphate-binder patents?
The patent does not block alternative phosphate binders. It also does not prevent formulation or manufacturing innovation involving calcium acetate after expiration, provided that no separate unexpired patent covers the specific product or process. What manufacturing and IP barriers remain?Patent 4,870,105 creates no current manufacturing barrier. A manufacturer today would still need to address non-patent requirements, including:
Potential patent risk may still arise from later patents covering a specific formulation, packaging system, manufacturing process, or combination product. Those rights cannot be inferred from Patent 4,870,105 itself. The expired patent should therefore be treated as historical prior art and market background, not as a current freedom-to-operate clearance for every calcium acetate product. What licensing deals are associated with the patent?The patent record and claim language alone do not establish the commercial terms of any license, assignment, co-development agreement, or settlement. Patent ownership and product commercialization are separate questions. Because the patent expired, any historical license concerning Patent 4,870,105 would have no continuing exclusionary effect against new U.S. calcium acetate entrants. A license could still have had commercial relevance during the patent term, including rights to market an approved calcium acetate product, but the expired patent cannot now support a royalty obligation unless a separate surviving contractual obligation applies. What generic launch scenarios exist today?The patent supports no current delayed-launch scenario. Generic calcium acetate entry is not blocked by Patent 4,870,105. The relevant current scenarios are:
Commercial constraints are more likely to involve pricing, supply reliability, API sourcing, FDA compliance, and market concentration than Patent 4,870,105. Key Takeaways
FAQs About U.S. Patent 4,870,105Does Patent 4,870,105 cover calcium acetate capsules sold today?No. The patent expired in 2006. Its historical claims covered the use of calcium acetate in oral phosphate-binding treatment, including gelatin capsules, but it no longer provides an enforceable U.S. exclusion right. Does the patent cover calcium carbonate phosphate binders?No. The claims require calcium acetate. Calcium carbonate and other phosphate binders fall outside the express active-ingredient limitation. Can a generic calcium acetate label instruct patients to take the product with meals?Yes, as far as this expired patent is concerned. The mealtime claims are no longer enforceable. Does the patent cover calcium acetate API manufacturing?No. The patent claims therapeutic methods. It does not claim a calcium acetate manufacturing process, purification method, polymorph, or API specification. Is a Paragraph IV certification required for this patent?Not to address a current blocking right. The patent expired in 2006, so it cannot presently delay FDA approval or support a new patent-term litigation stay. References
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Drugs Protected by US Patent 4,870,105
| 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 4,870,105
| Country | Patent Number | Estimated Expiration | Supplementary Protection Certificate | SPC Country | SPC Expiration |
|---|---|---|---|---|---|
| Canada | 1333884 | ⤷ Start Trial | |||
| >Country | >Patent Number | >Estimated Expiration | >Supplementary Protection Certificate | >SPC Country | >SPC Expiration |
