United States Patent 7,148,211 Patent Landscape: Scope, Claim Boundaries, and Formulation-Protection Coverage for Doxercalciferol Parenteral Compositions with Polysorbate 20, BHT, and Ethanol

United States Drug Patent 7,148,211 protects a specific parenteral formulation concept for doxercalciferol built around (i) a non-ionic solubilizer (polysorbate 20), (ii) a lipophilic antioxidant (butylated hydroxytoluene, BHT), and (iii) an optional (but often key) co-solvent (ethanol), in an aqueous vehicle. Claim 1 establishes the broad composition-with-range structure; dependent claims narrow to particular subranges and an exemplified “preferred” combination (polysorbate 20, BHT, and ethanol plus a doxercalciferol concentration suitable for secondary hyperparathyroidism).

This patent’s value is concentrated in formulation engineering: range-based infringement risk for competitors marketing injectable doxercalciferol products, especially those that preserve the same excipient stack and concentration windows. The tightest enforceable hooks are the ranges in claims 4–6 and the method-of-use framing in claim 6 (treatment of secondary hyperparathyroidism).

What is the claim scope of US Patent 7,148,211 for doxercalciferol injectable formulations?

Core protection theme. Claim 1 covers a parenteral aqueous formulation containing doxercalciferol plus a defined triad: polysorbate 20 (non-ionic solubilizer), BHT (lipophilic antioxidant), and an optional ethanol co-solvent, each with defined ranges, plus an aqueous vehicle.

Independent claim 1 (structural formula with concentration ranges). Claim 1 elements and boundaries:

Drug and dosage form context
- “A parenteral formulation”
- Lipophilic drug: doxercalciferol
Solubilizer
- Polysorbate 20 as non-ionic solubilizer
- Concentration: about 0.05% to about 5% w/w
Antioxidant
- BHT (butylated hydroxytoluene)
- Concentration: about 20 to about 2000 ppm
Optional agent
- Ethanol
- Concentration: 0 to about 30% w/w (optional)
Vehicle
- aqueous vehicle (implied water-based injectable medium)

Practical infringement reading. If a generic or branded competitor sells an injectable doxercalciferol formulation with polysorbate 20 and BHT within these windows, infringement risk rises sharply if ethanol is also present within 0–30% w/w (which is broad because it covers “0,” meaning absence of ethanol can still fall within claim 1). The claim is not limited to a specific manufacturing method or a specific route within “parenteral” (it is broad across injection modalities that fit the formulation definition).

How broadly does claim 1 cover polysorbate 20, BHT, and ethanol concentration ranges?

Range map for claim 1.

Component	Specified role	Claim 1 range	Enforcement impact
Doxercalciferol	lipophilic active	fixed (no range stated in claim 1)	Competition must use doxercalciferol to fall in scope
Polysorbate 20	non-ionic solubilizer	0.05% to 5% w/w	Key excipient window; many formulations land near 0.5–2.5%
BHT	lipophilic antioxidant	20 to 2000 ppm	Broad enough to capture common antioxidant levels
Ethanol	optional agent / co-solvent	0 to 30% w/w	Claim covers ethanol presence or absence; presence can strengthen allegation
Aqueous vehicle	vehicle	required	Competitors must remain aqueous/parenteral

Breadth consequence. Because claim 1 uses open-ended “about” language and ranges, literal infringement can be triggered by formulation adjustments that remain within these windows. Non-ionic solubilizer identity matters: claim 1 requires polysorbate 20 specifically, not a generic “polysorbate” or “surfactant.” Likewise, antioxidant identity is limited to BHT.

Which dependent claims narrow the formulation and increase infringement risk for competitors?

Claim 2: Ethanol lower subrange (0% to ~10% w/w)

Claim 2 constrains ethanol to 0% to about 10% w/w.

Scope effect. Claim 2 is narrower than claim 1, but it can be relevant in litigation where accused products clearly use ethanol at low-to-moderate levels. A product with ethanol at ~15% w/w can escape claim 2 but still fall under claim 1.

Claim 3: Ethanol midrange (~1% to ~3% w/w)

Claim 3 sets ethanol at about 1% to about 3% w/w.

Litigation hook. Many injectables use ethanol in low single digits to manage solubilization and extraction-related stability. If an accused product matches this midrange, claim 3 becomes a strong “fit” for infringement arguments.

Claim 4: Three-component “stack” exemplified

Claim 4 requires:

0.5%–2.5% w/w polysorbate 20
20 ppm BHT
2.5% w/w ethanol

This is the sharpest composition signature in the claim set, because it ties all three excipients to specific numeric anchor values (not just ranges). It functions as the “preferred embodiment claim.”

Scope effect.

Competitors using polysorbate 20 within 0.5–2.5% and BHT at 20 ppm and ethanol at 2.5% are positioned closest to literal infringement of claim 4.

Claim 5: Doxercalciferol potency range

Claim 5 sets doxercalciferol concentration at 2–10 μg/mL.

Scope effect. This is potency-specific. If an accused product has doxercalciferol outside 2–10 μg/mL, it may avoid claim 5 while still potentially falling within claim 1 (which does not specify doxercalciferol concentration).

Claim 6: Treatment indication with a defined formulation

Claim 6 depends on claim 1 and specifies a formulation “suitable for treatment of secondary hyperparathyroidism comprising”:

2–10 μg/mL doxercalciferol
0.5%–2.5% w/w polysorbate 20
20 ppm BHT
2.5% w/w ethanol

Scope effect.

Claim 6 is the most litigable combination: it anchors both the formulation composition (polysorbate range, BHT fixed at 20 ppm, ethanol fixed at 2.5%) and the doxercalciferol concentration and ties it to a specific therapeutic use.

What does the “secondary hyperparathyroidism” language in claim 6 do legally and practically?

Claim 6 includes a therapeutic statement: “suitable for treatment of secondary hyperparathyroidism.” In US patent practice, such language can operate as a limitation depending on how the claim is construed and whether it is tied to a specific formulation concentration window that supports the claimed use.

Practical use in enforcement.

If a competitor’s product is marketed for secondary hyperparathyroidism and the formulation matches the numeric constraints in claim 6, the indication language supports a narrower infringement narrative.
If the formulation matches but the competitor uses a different marketed indication, infringement may still be argued under claim 1 (which lacks the indication limitation), but claim 6 becomes less clean as a “fit.”

Numeric anchor importance. Claim 6’s true strength is the tight excipient combination plus doxercalciferol potency range, which reduces the degrees of freedom for design-around.

What formulation design-arounds are plausibly outside claim 7,148,211 (based on claim boundaries alone)?

Because the claim set requires specific excipient identities (polysorbate 20 and BHT) and imposes numeric ranges, the most straightforward design-arounds in litigation tend to exploit one of the following:

1) Replace polysorbate 20

Substitution to another solubilizer (e.g., different polysorbate or non-ionic surfactant) aims to avoid the “polysorbate 20” limitation in claim 1 and all dependents.

2) Replace or omit BHT

Changing antioxidant identity to something other than BHT, or using BHT outside 20–2000 ppm (or not at 20 ppm for claims 4/6) targets the antioxidant requirement.

3) Move ethanol outside the “fixed” embodiment

Avoid claim 4/6 by changing ethanol from 2.5% w/w to something materially different. However, claim 1 still covers ethanol from 0 to 30% w/w, so the competitor must consider both claim 1 and dependents.

4) Shift doxercalciferol potency outside 2–10 μg/mL

Avoid claim 5/6 by formulating at concentrations outside the 2–10 μg/mL window. This does not avoid claim 1 if doxercalciferol is present, since claim 1 itself does not constrain doxercalciferol concentration.

Net design-around principle. The hardest changes to implement without affecting clinical dosing and solubility stability usually involve swapping polysorbate 20 and/or BHT identity. Range-jitter on ethanol and potency can reduce exposure to dependent claims but may not remove claim 1 risk.

How many claims are “directly composition-limited” vs “range-limited,” and what does that mean for enforcement?

Composition-limited to specific ingredients.

Polysorbate 20 is required by claim 1.
BHT is required by claim 1.
Doxercalciferol is required by claim 1.

Range-limited by claim 1.

Polysorbate 20 range is 0.05% to 5% w/w.
BHT range is 20 to 2000 ppm.
Ethanol is 0 to 30% w/w (optional).

Range-limited by dependent claims.

Ethanol: claim 2 (0–10%), claim 3 (1–3%).
Polysorbate/BHT/ethanol: claim 4 locks in 0.5–2.5%, BHT 20 ppm, ethanol 2.5%.
Doxercalciferol potency: claim 5 (2–10 μg/mL).
Claim 6 combines the full set: potency + polysorbate range + BHT fixed + ethanol fixed + indication language.

Enforcement consequence.

Claim 1 supports broad coverage across product variants as long as excipient identities and ranges remain.
Claims 4–6 provide “pinpoint infringement” targets for formulations that track a common commercial embodiment.

What is the likely patent-exclusivity coverage role of US 7,148,211 in generic or biosimilar-like risk for doxercalciferol injectables?

Doxercalciferol is a small molecule drug, so the competitive risk profile is primarily generic (ANDA) rather than biosimilar. The patent landscape most often affects generic entry through:

composition patent coverage requiring Paragraph IV analysis against formulation patents;
potential settlement leverage if the generic’s formulation is within the numeric ranges.

For this specific patent, the strongest “entry barrier” effect is when an applicant’s proposed formulation uses:

polysorbate 20 in the 0.05% to 5% window, and
BHT in the 20–2000 ppm window, and
ethanol anywhere within 0–30% w/w (or matches 1–3% / 2.5% embodiment for dependent claims).

Because claim 4/6 include fixed values (BHT 20 ppm and ethanol 2.5% w/w), the practical litigation risk increases if a generic is trying to mirror an existing reference formulation that uses that exact excipient profile.

How do the claim boundaries map to common formulation parameters used in practice?

Even without product-specific data, the claim set indicates typical formulation engineering assumptions:

Polysorbate 20 is the solubilizer at sub-percent to a few percent w/w (typical range 0.5–2.5%).
BHT is used at low tens of ppm up to the low-thousands of ppm.
Ethanol is used as a co-solvent at low single-digit levels, with a broader permissive range in claim 1.

This combination pattern matters because applicants often adjust excipient levels to match stability and solubility, and those adjustments can still land inside claim 1. Dependent claim fixed values create especially sensitive infringement triggers.

What litigation-relevant “claim construction pressure points” exist for US 7,148,211?

Without quoting file history, the claim text itself creates predictable interpretive pressure points:

“about” range interpretation

Polysorbate 20 (0.05–5% w/w “about”)
BHT (20–2000 ppm “about”)
Ethanol (0–30% “about”)
Doxercalciferol (2–10 μg/mL “about” in claim 5 as stated numerically)

“About” can expand effective boundaries beyond literal endpoints, raising risk for design-arounds that sit near range edges.

“lipophilic drug which is doxercalciferol”

A competitor must use doxercalciferol. If they use another vitamin D analog, they are outside the required drug identity.

“non-ionic solubilizer which is polysorbate 20”

Even if a formulation uses another surfactant, the claim requires polysorbate 20. In litigation, presence of polysorbate 20 likely becomes a central factual issue.

“lipophilic antioxidant which is butylated hydroxytoluene (BHT)”

Similarly, the antioxidant identity is anchored to BHT.

What competitor product outcomes follow if their formulation matches claim 1 but not claim 4 or 6?

If a product is within claim 1 but outside claim 4/6:

Claim 1 exposure remains.
Dependent-claim “preferred embodiment” claims may not apply, but they are not required for infringement of the independent claim.

If a product is outside claim 1 because it misses either polysorbate 20 identity, BHT identity, or ranges:

The product may avoid all asserted claim coverage, subject to whether a separate formulation patent covers the substitute design.

Key takeaways

US 7,148,211 claims a doxercalciferol parenteral formulation anchored on polysorbate 20 (0.05–5% w/w), BHT (20–2000 ppm), and an aqueous vehicle, with ethanol optional (0–30% w/w).
Dependent claims create a “preferred” numeric fingerprint: 0.5–2.5% polysorbate 20, 20 ppm BHT, 2.5% ethanol, with 2–10 μg/mL doxercalciferol, tied to secondary hyperparathyroidism.
For design-around, the most robust levers are excipient identity changes (swap out polysorbate 20 or BHT). Range tweaks alone may not avoid claim 1.
Enforcement leverage is highest when an accused product mirrors the tight excipient values in claim 4/6, even if claim 1 is broader.

FAQs

1) Does claim 1 require ethanol to be present?

No. Claim 1 defines ethanol as an optional agent with a range of 0 to about 30% w/w, so absence can still fit claim 1.

2) What is the exact ethanol concentration in the narrowest dependent claims?

Claim 4 and claim 6 require 2.5% w/w ethanol.

3) If a product uses BHT at 25 ppm instead of 20 ppm, does it avoid claim 4 and 6?

It would not match the fixed 20 ppm requirement in claims 4 and 6, but it may still fall within claim 1 if BHT remains within 20 to 2000 ppm (subject to claim construction of “about”).

4) Can a formulation avoid claim 5 while still infringing claim 1?

Yes. Claim 5 is a doxercalciferol potency range (2–10 μg/mL). Claim 1 does not impose a doxercalciferol potency range.

5) What single excipient change would most directly reduce infringement risk?

Replacing polysorbate 20 or replacing BHT with a different solubilizer/antioxidant identity is the most direct way to fall outside the claim language across independent and dependent claims.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2003267131	⤷ Start Trial
Brazil	0314354	⤷ Start Trial
Canada	2498331	⤷ Start Trial
China	100349573	⤷ Start Trial
China	1684691	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,148,211

Summary for Patent: 7,148,211