United States Patent 6,555,133 (Efavirenz + High-Disintegrant Wet-Granulation Capsules/Tablets): Claim Scope, Allowed Boundaries, and US Patent Estate
US Patent 6,555,133 covers method-of-treatment claims for HIV infection using efavirenz in capsule or compressed tablet dosage forms, with a core limitation tying efficacy to disintegration behavior via (i) disintegrant content >10% by dry weight and, in dependent claims, (ii) specific disintegrants (notably sodium starch glycolate) and (iii) wet granulation ranges and (iv) optional sodium lauryl sulfate (SLS) during manufacture.
What does US 6,555,133 claim cover for efavirenz capsules and compressed tablets?
Core independent claim (claim 1):
A method for treating HIV by administering a patient a capsule or compressed tablet pharmaceutical dosage form comprising:
- a therapeutically effective amount of efavirenz, and
- greater than about 10% by weight disintegrant relative to total dry weight of the pharmaceutical dosage form.
Claim 15 expands the formulation architecture (via method of administering a dosage form defined by excipient categories):
A dosage form with:
- (a) therapeutically effective amount of efavirenz
- (b) surfactant
- (c) disintegrant
- (d) binder
- (e) diluent
- (f) glidant
- (g) optional additional excipients
with at least one disintegrant from the enumerated group and present >10% by weight of total dry weight.
Immediate scope takeaway: the patent is not a “new efavirenz molecule” claim. It is an oral solid formulation performance-driven claim, protected through method-of-use language tied to dose form composition (capsule/tablet) and disintegrant loading threshold.
Claim 1 boundary conditions that matter in freedom-to-operate (FTO)
- Dosage form must be “capsule or compressed tablet.” Powder for suspension, film-coated tablets, orally disintegrating tablets with different architectures, or non-compressed forms sit outside the literal claim language unless they still qualify as “compressed tablet” or “capsule.”
- Disintegrant threshold is categorical: “greater than about 10% by weight” of total dry weight.
- Literal risk increases as the formulation approaches higher disintegrant loading (for example 12–20%).
- Designs near exactly 10% risk a claim construction fight around “about,” but the threshold is still a litigation focal point because it is explicit.
“Method for treating HIV” and how it’s used legally
The “treating infection by HIV” phrasing typically converts a formulation into a method-of-use claim: if the accused product is administered for HIV treatment, the method is met when the dosage form matches the formulation limitations.
Which disintegrants are explicitly protected, and what does that mean for design-around?
Dependent claim 2: disintegrant selected from:
- modified starches
- croscarmellose sodium
- carboxymethylcellulose calcium
- crospovidone
Dependent claim 3: disintegrant is one or more modified starches.
Dependent claim 4: modified starch is sodium starch glycolate (SSG).
Dependent claim 15: repeats the enumerated disintegrant list and threshold >10% by dry weight.
Practical claim scope: enumerated disintegrants are both inclusion and limitation
- The patent explicitly anchors “disintegrant” to a specific list (or to “modified starches” where narrowed further).
- If a competitor uses a disintegrant not in the enumerated group and keeps disintegrant content >10% by weight, the literal disintegrant identity limitation is a key defense against literal infringement of the dependent claims, and a potential narrowing argument against claim 1 if “disintegrant” is argued as constrained by the specification’s examples (depending on claim construction).
- If the competitor uses SSG, the design space is sharply limited because claim 4 is direct: sodium starch glycolate as the modified starch.
How much disintegrant is required, and where are the manufacturing ranges captured?
Quantitative threshold in claim 1:
- Disintegrant is > about 10% by weight relative to total dry weight of the dosage form.
Wet granulation-specific ranges in claims 5 and 6:
- Claim 5: in wet granulation step containing efavirenz and one or more modified starches, modified starch is present in 10% to 75% by weight relative to total dry weight of wet granulation step components.
- Claim 6: narrower manufacturing range: modified starch is present in wet granulation step in 20% to 55% by weight.
Scope implications for formulation strategy
- Claim 1 does not require a manufacturing step. It only requires the end dosage form composition.
- Claims 5 and 6 add process architecture and internal ratios “relative to wet granulation step dry components,” not the final dosage form. That matters for infringement because:
- An accused product could meet claim 1 without necessarily matching claims 5–6, if it is made by different process routes (for example dry blending or direct compression) while still ending with >10% disintegrant in final composition.
- Conversely, a competitor that meets wet granulation internal ratios but ends with ≤10% disintegrant in final composition may avoid claim 1.
What does the sodium lauryl sulfate wet-granulation dependent coverage add?
Claim 12: wet granulation step uses modified starches (claim 3/4 context) in a wet granulation process.
Claim 12 adds SLS: wet granulation is carried out in the presence of sodium lauryl sulfate.
Claim 13 quantifies SLS: SLS present at about 0.1% to about 5% by weight relative to total dry weight of components of the wet granulation step.
Why this is strategically relevant
- This is a manufacturing limitation.
- If an accused product uses efavirenz + high disintegrant loading but uses a different wetting/surfactant system, the SLS-dependent claims may be avoidable while claim 1 could remain at risk.
What efavirenz dosage ranges are stated in the claims, and do they constrain infringement?
Claims 7–11 and 14 add efavirenz amount ranges (dosage-form content), all tied back to claim 1.
- Claim 7: 5 to 1000 mg
- Claim 8: 5 to 500 mg
- Claim 9: 500 to 1000 mg
- Claim 10: 25 to 350 mg
- Claim 11: 50 to 200 mg
- Claim 14: 5 to 800 mg
Claim construction and overlap
These ranges overlap heavily. In practice, they do not carve out large safe harbors because typical commercial efavirenz tablet strengths fall within the covered mg windows. The key constraint remains the >10% disintegrant limitation and the disintegrant identity list.
How broad is claim 15 compared with claim 1?
Claim 15 is broader on formulation categories but still constrained by disintegrant identity and loading threshold.
It defines the dosage form composition functionally and categorically:
- efavirenz
- surfactant
- disintegrant
- binder
- diluent
- glidant
- optional additional excipients
And then narrows with:
- disintegrant is from the enumerated group, and
- disintegrant is present at >10% by weight of total dry weight.
Risk note
Claim 15 is an “excipient class” claim that can capture many conventional solid formulations because binder/diluent/glidant categories are standard. The discriminant is still the disintegrant: identity list + >10% loading.
How does the claim set map to likely infringement theories?
Likely plaintiff theory (literal infringement)
- Accused product is a capsule or compressed tablet containing efavirenz.
- The product’s final dry composition includes at least one disintegrant from the enumerated group (or modified starch category) at >10% by weight.
- Administration is for HIV treatment (method-of-use step satisfied by intended use and labeling).
Likely defenses
- Disintegrant identity mismatch (using disintegrants outside the enumerated group).
- Disintegrant loading mismatch (formulation at or below 10% “about”).
- Dosage form mismatch (not a “capsule or compressed tablet”).
- Process mismatch (SLS and wet granulation limits only matter for dependent claims 12–13; they are not part of claim 1).
What does the patent likely target in the competitive landscape of efavirenz oral solids?
From the claim set, the patent targets a formulation approach:
- keep efavirenz in a conventional oral solid,
- use high levels of disintegrant, especially modified starch/SSG,
- use wet granulation with defined internal disintegrant ratios,
- optionally include SLS as wetting/surfactant.
This aligns with technical goals that are directly tied to patentability in many efavirenz solid dose programs: rapid disintegration and robust manufacturability under compression/capsule fill conditions.
How strong is the patent estate for 6,555,133 based on claim focus?
Strength indicators from the claims themselves
- The independent method claim 1 is not limited to a particular wet granulation process, which increases its reach: it can read on multiple manufacturing routes so long as the final product composition matches.
- The quantitative disintegrant threshold (>10% by weight) is clear and litigation-friendly.
- The disintegrant identity list is enumerated, which gives defendants a straightforward way to argue non-infringement, but it also gives plaintiffs a straightforward path if the accused product uses croscarmellose sodium, crospovidone, calcium carboxymethylcellulose, or sodium starch glycolate.
Weakness indicators
- The “capsule or compressed tablet” and disintegrant identity list provide design-around paths.
- The “about 10%” feature can create dispute over measurement and tolerances, but the threshold remains hard-coded.
Where are the key non-infringement design-around levers?
- Lower disintegrant loading to ≤ about 10% (final dosage dry weight basis).
- Use a disintegrant outside the enumerated list (and outside “modified starches” if the claim construction ties “modified starches” to specific modified starch families).
- Change the dosage form to avoid “capsule or compressed tablet” characterization.
- For dependent claims 12–13, remove SLS from the wet granulation step and change surfactant/wetting systems.
How does this patent compare with typical efavirenz generic formulation patterns?
Most generic efavirenz products must meet dissolution and bioequivalence requirements but can differ substantially in excipient strategy. The claim set suggests that the patent’s differentiation is not efavirenz itself but a specific excipient configuration, especially disintegrant-heavy formulations.
Therefore the biggest generic entry risk factor under this patent is whether the generic uses high disintegrant loading above 10% by dry weight with one of the enumerated disintegrants. If not, the infringement exposure drops sharply.
Key takeaways
- US 6,555,133 is a formulation-driven method-of-use patent: HIV treatment by administering efavirenz in capsule or compressed tablet form with >10% by weight disintegrant (dry basis).
- Disintegrant identity is a major fence: enumerated options include modified starches (including SSG), croscarmellose sodium, carboxymethylcellulose calcium, and crospovidone.
- Wet granulation and SLS are captured only in dependent claims, with explicit internal modified starch ranges (10–75% and 20–55% in the wet granulation step) and SLS 0.1–5% in wet granulation dry components.
- Efavirenz dosage ranges are broad and overlapping, so they are less likely to be a practical design-around lever than disintegrant identity and >10% loading.
- The most direct design-arounds are disintegrant loading at or below ~10%, disintegrant identity outside the enumerated group, or dosage form change.
FAQs
1) What is the single highest-risk formulation parameter under US 6,555,133?
Disintegrant loading: the product must have > about 10% by weight disintegrant relative to total dry weight.
2) Does US 6,555,133 require wet granulation to infringe claim 1?
No. Claim 1 does not include a manufacturing-step limitation. Wet granulation appears in dependent claims 5–6 and SLS in dependent claim 12–13.
3) If a generic uses sodium lauryl sulfate but keeps disintegrant at 9%, is it covered by claim 1?
Claim 1’s >10% disintegrant threshold would not be met on the dry weight basis, so the core limitation would fail.
4) If a product uses sodium starch glycolate (SSG) at 12% by dry weight, does it automatically fall under the dependent claims?
It would meet disintegrant identity (SSG) and threshold; dependent claims 4 and 15 align on those points, while dependent claims tied to wet granulation and SLS depend on the manufacturing facts.
5) Can a formulation using crospovidone avoid claim 2 but still meet claim 1?
Claim 2 is an additional limitation (disintegrant selected from the list). Since crospovidone is in that list, it would not avoid claim 2 if claim 2 is asserted; avoiding depends on disintegrant identity or the >10% threshold.
