United States Patent 6,770,623: Claim Scope, Expiration, Litigation Risk, and Parathyroid Hormone Patent Landscape

United States Patent No. 6,770,623 protects liquid, ready-to-administer parathyroid hormone formulations, particularly teriparatide, in vials and cartridges. Its core limitation is a non-lyophilized aqueous formulation containing human parathyroid hormone and an acidic buffer at a pH greater than 3 and less than 7. Narrow claims cover acetate-buffered teriparatide at 250 µg/mL with mannitol and metacresol, corresponding closely to the commercial Forteo formulation.

The patent is no longer an effective barrier to U.S. generic entry because its statutory term has expired. Its historical importance remains material: it was directed to the formulation and presentation of Forteo rather than to teriparatide itself.

What Does U.S. Patent 6,770,623 Protect?

The patent has four principal claim groups:

Claim group	Claims	Protected subject matter
Manufacturing processes	1-8	Preparing a liquid PTH solution, combining PTH with an acidic buffer, and sealing it in a vial or cartridge
Vial formulations	9-16, 26, 36-37, 39-48	Ready-to-use PTH solutions in sealed vials
Cartridge formulations	27-35, 38	Sterile liquid PTH solutions in cartridges for patient administration
Treatment method	18-25	Treating osteoporosis using a non-reconstituted liquid PTH solution

The claims are directed to formulation architecture and packaging. They do not broadly claim the discovery or use of parathyroid hormone as a molecule.

What Is the Core Technical Limitation?

The common technical elements are:

Human parathyroid hormone.
An aqueous liquid solution.
A buffer maintaining a pH above 3 and below 7.
Direct administration without patient reconstitution from a lyophilized powder.
In narrower claims, a vial or cartridge.
In the most specific claims, mannitol and metacresol.
For the narrowest formulation, PTH(1-34) at 250 µg/mL with acetate, mannitol, metacresol and water.

The patent therefore targets a ready-to-use liquid product rather than a conventional freeze-dried PTH product requiring reconstitution.

How Broad Are the Independent Claims?

Claim 1: Process for filling a vial or cartridge

Claim 1 requires a process comprising:

combining human PTH with a buffer;
maintaining pH from greater than 3 to less than 7;
forming a solution; and
sealing the solution in a vial or cartridge.

The claim does not require a specific PTH sequence, buffer identity, concentration, preservative, stabilizer, device or manufacturing temperature. It is therefore broad across liquid PTH formulations that meet the pH and container limitations.

The claim is narrower than a claim to any liquid PTH product because it requires a preparation and sealing process. A party that purchases prefilled cartridges rather than performs the claimed filling operation would require separate infringement analysis.

Claim 2: Non-lyophilized liquid formulation process

Claim 2 covers admixing human PTH with a buffer to form a solution that is not freeze-dried or reconstituted before patient use. This limitation distinguishes the claimed product from a lyophilized PTH product supplied as powder plus diluent.

The negative limitation is commercially important. A liquid formulation can fall within the claim even if the manufacturing process includes sterile filtration, filling, terminal processing or other conventional operations, provided the final patient-use product is not reconstituted from a freeze-dried powder.

Claims 3-8: Buffer, stabilizer and PTH sequence limitations

These claims narrow claim 2 by adding:

citrate, tartrate or acetate buffer;
a stabilizer;
mannitol as the stabilizer; and
PTH fragments including PTH(1-31), PTH(1-34), PTH(1-37), PTH(1-38), PTH(1-41) or PTH(1-84).

Claims 7 and 8 focus on PTH(1-84) and PTH(1-34), respectively. PTH(1-34) is teriparatide, the active peptide in Forteo.

What Formulations Are Protected by the Vial and Cartridge Claims?

Claims 9-16 and 27-34 cover the product presentation rather than its preparation.

Limitation	Vial claims	Cartridge claims
Human PTH in solution	9	27
pH greater than 3 and less than 7	9	27
Citrate, tartrate or acetate	10	28
Stabilizer	11	29
Mannitol	12	30
PTH sequence limitations	13-15	31-33
PTH concentration of 25-1,000 µg/mL	16	34
Ready for administration without reconstitution	9, 39	27

The claims are not limited to Forteo’s delivery pen. A vial or cartridge can meet the limitations even if it is used with a different injector, provided the composition and container requirements are satisfied.

Are the Container Limitations Significant?

Yes. The vial and cartridge claims require a specified physical presentation. A bulk bottle, ampoule, syringe or other container may not fall within these claims unless it also satisfies the claim language or an asserted equivalent.

The distinction matters in generic litigation. A manufacturer may avoid a cartridge claim by using a prefilled syringe, but that strategy would not necessarily avoid the corresponding liquid-composition or method-of-use claims.

What Is the Narrowest Forteo-Type Claim?

Claim 17 is the most commercially specific vial claim. It requires:

Component	Claimed amount
Human PTH(1-34)	250 µg/mL
Glacial acetic acid	0.41 mg/mL
Anhydrous sodium acetate	0.10 mg/mL
Mannitol	45.4 mg/mL
Metacresol	3.0 mg/mL
Water	Required
pH	About 3 to 6

Claim 35 applies substantially the same composition to a cartridge.

Claims 37 and 38 are broader than claims 17 and 35 because they require PTH(1-34), a pH of about 3 to about 6, mannitol, metacresol and water, but do not require the precise concentrations of acetic acid, sodium acetate and mannitol.

From an enforcement perspective, claims 17 and 35 are easier to test analytically but narrower in scope. Claims 37 and 38 cover a wider range of liquid teriparatide formulations but may face greater validity scrutiny if prior art discloses similar compositions.

What Is the Patent’s Expiration Status?

Patent No. 6,770,623 is expired as of 2025. The patent’s ordinary term was tied to its earliest effective nonprovisional filing date, subject to any patent-term adjustment, patent-term extension, terminal disclaimer or other USPTO-record adjustment.[1]

Because the patent has expired:

it cannot block a current U.S. generic liquid teriparatide product;
new ANDA applicants do not face a live 30-month stay based solely on this patent;
infringement damages cannot accrue for post-expiration commercial activity;
the patent remains relevant to historical litigation and freedom-to-operate analysis for earlier periods.

The expiration date shown in commercial databases and regulatory records should be reconciled with the USPTO Patent Center record and the Orange Book listing history. The grant date, August 3, 2004, does not establish the patent term by itself.[1]

What Was the Orange Book Status of Patent 6,770,623?

Patent 6,770,623 was associated with Lilly’s Forteo regulatory and patent strategy because it covered the commercial liquid formulation of teriparatide. The relevant Orange Book analysis separates three concepts:

The patent’s presence in the Orange Book.
The patent’s expiration date.
Whether the patent was eligible to support a statutory stay after an ANDA Paragraph IV notice.

An Orange Book listing does not establish validity or infringement. It identifies patents submitted by the NDA holder or patent owner as relevant to the approved drug.[2]

The patent’s formulation focus made it relevant to ANDA applicants seeking approval for a ready-to-use teriparatide injection. An applicant using a materially different concentration, buffer, preservative, container or presentation could develop a non-infringement position, although the broader claims would still require analysis.

When Could Generic Manufacturers Challenge the Patent?

A generic teriparatide applicant could use several FDA pathways:

Pathway	Relevance
ANDA under Section 505(j)	Primary route for a therapeutically equivalent generic teriparatide injection
Paragraph IV certification	Challenge to listed patent validity, enforceability or infringement
Paragraph III certification	Acknowledge the patent and delay approval until expiration
Section 505(b)(2)	Potential route for a formulation or clinical-use difference not fully supported by an ANDA

A Paragraph IV certification would typically address:

anticipation by earlier liquid PTH formulations;
obviousness of combining teriparatide with an acidic buffer, mannitol and preservative;
written-description support for the broad PTH sequence genus;
enablement across the entire pH, concentration and sequence ranges;
indefiniteness in terms such as “stable,” “suitable for administration” and “therapeutically effective dose”; and
non-infringement based on formulation composition or container design.

The process claims could also face difficulty if the accused manufacturer does not perform the claimed U.S. filling or sealing steps.

Which Companies Challenged Forteo Exclusivity?

The U.S. teriparatide market has included generic and follow-on competition from companies such as Teva and other manufacturers pursuing abbreviated or alternative approval pathways. Generic competition has focused on the active peptide and approved therapeutic use, while product-specific disputes have concerned formulation, device and regulatory exclusivity issues.

The commercial challenge to Forteo was broader than Patent 6,770,623. It involved:

patent expiry;
FDA exclusivity;
formulation and device patents;
pediatric exclusivity or other regulatory extensions where applicable;
settlements between Lilly and generic applicants; and
manufacturing and scale-up requirements for a sterile peptide injection.

A generic approval does not automatically establish freedom from all formulation or device patents. Each asserted patent must be evaluated separately.

Does Biosimilar Risk Apply to Teriparatide?

Traditional biosimilar risk is limited. Teriparatide is a peptide drug rather than a monoclonal antibody or other complex biologic. U.S. products have generally been pursued through the generic-drug framework or alternative 505(b)(2) pathways rather than through the principal biosimilar pathway under the Biologics Price Competition and Innovation Act.

The principal competitive risks are therefore:

ANDA approval;
therapeutic-equivalence determinations;
formulation workarounds;
device substitution;
manufacturing capacity; and
pricing after generic entry.

A follow-on product can compete without infringing this patent if it uses a different formulation or presentation that falls outside the surviving claims. Since the patent is expired, the issue is now historical rather than a current blocking risk.

How Strong Was the Patent Estate?

The patent estate was commercially strong during the period when Forteo was protected, but Patent 6,770,623 was narrower than a molecule patent.

Strength factor	Assessment
Commercial relevance	High because claims tracked a ready-to-use Forteo-type liquid
Chemical scope	Moderate because claims covered multiple PTH sequences and buffers
Formulation scope	Moderate to broad in claims 9, 27 and 39
Exact commercial formulation protection	Stronger in claims 17, 35, 37 and 38
Process enforcement	Fact-dependent and potentially difficult
Generic design-around potential	Material through concentration, preservative, buffer or container changes
Current blocking power	None after expiration

The broadest claims could be vulnerable to prior art directed to liquid peptide formulations, acidic buffering, protein stabilization and preservative systems. The narrow claims were more closely tied to the commercial product and therefore more useful in product-specific litigation.

What Manufacturing and Intellectual Property Barriers Remain?

Patent expiration does not remove practical barriers to market entry. A generic manufacturer still must establish:

peptide identity and purity;
aggregation and degradation controls;
sterility and particulate compliance;
container-closure integrity;
preservative compatibility;
cartridge or injector performance;
dose uniformity;
stability through the labeled shelf life; and
FDA therapeutic equivalence or alternative approval requirements.

Metacresol, mannitol and acetate buffering are not individually difficult to source. The greater technical challenge is maintaining teriparatide stability in a multidose, preserved liquid product over its full shelf life.

Device patents and trademarks can also remain relevant after formulation patent expiry. A competing product may avoid the Forteo pen, use a prefilled syringe or supply a different cartridge system.

How Does Patent 6,770,623 Compare With Other Teriparatide Protection?

Protection category	Patent 6,770,623	Typical competing protection
Active molecule	Does not broadly claim teriparatide itself	Composition-of-matter and peptide sequence patents
Liquid formulation	Central focus	Alternative buffers, stabilizers and preservatives
Lyophilized products	Generally excluded by the no-reconstitution limitations	Freeze-dried formulation patents
Container	Vials and cartridges	Pens, syringes, cartridges and delivery devices
Osteoporosis treatment	Claims use of liquid PTH	Dosing schedules, treatment duration and patient populations
Manufacturing	Filling and sealing liquid PTH	Peptide synthesis, purification and sterile processing

The patent was therefore one layer in a larger Forteo protection strategy. It did not independently cover every teriparatide product.

What Generic Launch Scenarios Exist?

Three launch models were commercially plausible:

Direct formulation match. A generic reproduces the liquid PTH composition and relies on patent expiration or a successful Paragraph IV challenge.
Formulation design-around. A manufacturer changes the buffer, concentration, preservative or container while preserving the same active ingredient and therapeutic use.
Alternative presentation. A manufacturer uses a syringe or injector configuration that avoids the cartridge claims while addressing applicable liquid-composition claims separately.

After expiration, the first model became legally available, subject to FDA approval and non-patent barriers.

Key Takeaways

Patent 6,770,623 protects ready-to-use liquid human PTH formulations, especially teriparatide.
Its central limitation is an aqueous PTH solution buffered at a pH greater than 3 and less than 7.
The patent covers preparation processes, vials, cartridges and osteoporosis treatment methods.
Claims 17, 35, 37 and 38 most closely track the commercial Forteo formulation.
The broad claims cover multiple PTH sequences, including PTH(1-34) and PTH(1-84).
The patent does not broadly claim teriparatide as a molecule.
It is expired as of 2025 and no longer provides a current U.S. blocking right.
Historical Paragraph IV risk centered on obviousness, anticipation, enablement, written description, formulation differences and container design.
Teriparatide competition is primarily a generic or 505(b)(2) issue, not a conventional biosimilar issue.
Manufacturing, stability, sterile filling and delivery-device requirements remain practical barriers after patent expiry.

FAQs About U.S. Patent 6,770,623

Does Patent 6,770,623 cover Forteo?

Yes. Its claims cover liquid teriparatide formulations and presentations that correspond closely to Forteo, including acetate-buffered PTH(1-34) with mannitol and metacresol.

Does the patent cover all teriparatide products?

No. The claims require specified liquid, pH, container, concentration or formulation characteristics. A lyophilized product or materially different formulation may fall outside the claims.

Is a teriparatide biosimilar required to use the BPCIA pathway?

Not necessarily. Teriparatide has primarily been treated as a peptide drug subject to generic or 505(b)(2) regulatory strategies rather than as a conventional biologic biosimilar product.

Could a different injector avoid the patent?

Potentially. A different injector may avoid cartridge-specific claims, but it would not necessarily avoid claims directed to the liquid composition or osteoporosis treatment method.

Does expiration eliminate all Forteo intellectual property risk?

No. Expiration eliminates the blocking effect of this patent, but trademarks, device patents, manufacturing know-how, regulatory exclusivity and other patent families may remain relevant.

References

United States Patent and Trademark Office. (2004). U.S. Patent No. 6,770,623, Liquid parathyroid hormone formulations.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Orange Book.
U.S. Food and Drug Administration. (2024). Approved drug products database and patent and exclusivity information.
Eli Lilly and Company. (2002). Forteo prescribing information.
United States Congress. (1984). Drug Price Competition and Patent Term Restoration Act of 1984, 21 U.S.C. § 355 and 35 U.S.C. §§ 154, 156.

PCT Information
PCT Filed	December 08, 1998	PCT Application Number:	PCT/US98/26043
PCT Publication Date:	June 17, 1999	PCT Publication Number:	WO99/29337

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	018526	⤷ Start Trial
Austria	260113	⤷ Start Trial
Australia	1717799	⤷ Start Trial
Australia	759726	⤷ Start Trial
Brazil	9813463	⤷ Start Trial
Canada	2314313	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,770,623

Summary for Patent: 6,770,623