US Patent 6,238,695: Scope, Claims, and Patent Landscape for Efavirenz Tablet/Capsule Dosage Forms
US Patent 6,238,695 claims efavirenz in a solid oral dosage form (capsule or compressed tablet) with a high disintegrant load (>10% w/w), and in the core manufacturing path it tightens the composition and process around sodium starch glycolate and a wet granulation system using aqueous sodium lauryl sulfate (SLS). The claim set is composition-centric (disintegrant selection and loading), then narrows into specific material quantities in wet and dry steps, and finally adds a method claim that defines an end-to-end manufacturing recipe.
What is claimed? (Core claim architecture)
The patent has three functional claim layers:
-
Product composition base (efavirenz + high disintegrant)
- Claim 1 defines a capsule or compressed tablet with:
- a therapeutically effective amount of efavirenz
- greater than about 10% by weight disintegrant relative to total dry weight of the dosage form.
-
Disintegrant species selection (explicit disintegrant list; modified starch emphasis)
- Claim 2 restricts the disintegrant to one or more of:
- modified starches
- croscarmallose sodium
- carboxymethylcellulose calcium
- crospovidone
- Claim 3 narrows further to one or more modified starches.
- Claim 4 specifies the modified starch as sodium starch glycolate.
-
Process-defined composition refinements (wet granulation loading + SLS)
- Claims 5 and 6 define sodium starch glycolate loading in the wet granulation step:
- Claim 5: sodium starch glycolate 10% to 75% w/w of total dry components of the wet granulation step
- Claim 6: sodium starch glycolate 20% to 55% w/w of total dry components of the wet granulation step
- Claim 12 and 13 bring in sodium lauryl sulfate in wet granulation:
- Claim 12: wet granulation “in the presence of sodium lauryl sulfate”
- Claim 13: SLS 0.1% to 5% w/w relative to total dry components of the wet granulation step.
The second composition claim (Claim 15) broadens beyond sodium starch glycolate and includes an excipient framework, while still keeping the defining feature: >10% disintegrant.
The method claims (Claims 16 to 18) then lock the manufacturing sequence and quantitative disintegrant placements for sodium starch glycolate.
What is the practical scope of Claim 1 (the key threshold feature)?
Claim 1
Capsule or compressed tablet pharmaceutical dosage form comprising a therapeutically effective amount of efavirenz and greater than about 10% by weight of a disintegrant relative to total dry weight of the pharmaceutical dosage form.
Scope implications
- The claim hinges on a threshold: disintegrant must exceed 10% w/w.
- The claim does not initially specify the disintegrant identity (that limitation arrives in dependent claims).
- The claim does not define whether disintegrant is used in the wet granulation, dry blending, or both, unless the later dependent claims are invoked.
Immediate design-around vectors
- A dosage form with ≤10% w/w total disintegrant relative to total dry weight of the dosage form avoids Claim 1 outright.
- A dosage form with >10% but with a disintegrant that falls outside the dependent-claim list could still face Claim 1, since Claim 1 itself does not restrict disintegrant identity.
How do dependent claims narrow the disintegrant (Claims 2–4)?
Claim 2
- Disintegrant is selected from:
- modified starches
- croscarmallose sodium
- carboxymethylcellulose calcium
- crospovidone
Claim 3
- Disintegrant is selected from one or more modified starches.
Claim 4
- Modified starch is sodium starch glycolate.
Scope implications
- The broadest disintegrant identity control is in Claim 2; Claim 1 is identity-neutral.
- If a product meets Claim 1’s disintegrant loading, then Claims 2–4 determine whether the disintegrant is within the patent’s explicit families.
- Sodium starch glycolate is the most specific “anchor” disintegrant for the rest of the claims.
How is efavirenz amount bounded (Claims 7–11, and 14)?
The claim set provides multiple efavirenz loading ranges:
- 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
Scope implications
- These ranges likely function as dependent quantitative embodiments rather than creating a single unified independent “efavirenz mg range” requirement across all claims.
- For infringement analysis, the critical question becomes which dependent claims are asserted; Claim 1 alone requires only “therapeutically effective amount,” not a specific mg ceiling.
Practical effect
- Most marketed efavirenz products in tablet/capsule formats likely sit in the 200 mg to 600 mg class, and many embodiments likely fall into at least one of Claims 7–11 or 14.
What is claimed for the full excipient system (Claim 15)?
Claim 15
A pharmaceutical dosage form comprising:
(a) efavirenz; (b) a surfactant; (c) a disintegrant; (d) binder; (e) diluent; (f) lubricant; (g) glidant; optionally additional excipients;
with the disintegrant present at >10% w/w of total dry weight of capsule contents or compressed tablet.
Scope implications
- Claim 15 requires an excipient “map,” but it does not specify which surfactant, binder, diluent, lubricant, or glidant.
- It keeps the disintegrant loading threshold as the defining feature.
- This claim can capture formulations even where the disintegrant is not one of the explicitly listed disintegrants from Claims 2–4, depending on how “disintegrant selected from the group” language is read in the claim text you provided. In the text as given, Claim 15 includes the explicit disintegrant group from Claims 2, while also requiring >10% loading.
What is claimed for the manufacturing process (Claims 16–18)?
What are the process steps and inputs in Claim 16?
Claim 16
A method for producing a capsule or compressed tablet dosage form, comprising:
- Wet granulating efavirenz and sodium starch glycolate in presence of an aqueous solution of sodium lauryl sulfate
- Drying
- Milling
- Dry blending with sodium starch glycolate and additional excipients
- Encapsulating or compressing into tablets
Key quantitative constraints
- Claim 16, as written, specifies the wet granulation and the dry blending as two separate placements for sodium starch glycolate.
What does Claim 17 add?
Claim 17
- Sodium starch glycolate in wet granulation (step a): 20% to 75% w/w relative to dry weight of all components of the wet granulation step
- Sodium starch glycolate in dry blending (step d): 1% to 10% w/w relative to total dry weight of the dry blending step
What does Claim 18 add?
Claim 18
- Sodium starch glycolate in wet granulation (step a): 20% to 55% w/w of dry weight of all components of the wet granulation step
- Sodium starch glycolate in dry blending (step d): 2% to 4% w/w of total dry weight of dry blending step
Scope implications
- The method claim is tightly constrained to:
- sodium starch glycolate used in wet granulation with aqueous SLS
- sodium starch glycolate again used in dry blending
- a defined sequence of unit operations.
- Quantitative ranges in Claims 17–18 narrow the window further and create a “trap” around formulations that distribute sodium starch glycolate across wet and dry portions within specific mass fractions.
Where does sodium lauryl sulfate matter (Claims 12–13, and Claim 16)?
- Claim 12: wet granulation in the presence of SLS.
- Claim 13: SLS is 0.1% to 5% w/w relative to total dry weight of components of the wet granulation step.
- Claim 16: wet granulation uses efavirenz and sodium starch glycolate with an aqueous solution of sodium lauryl sulfate.
Scope implications
- The presence of SLS is a key manufacturing limitation in the narrow sodium-starch-glycolate embodiments.
- If a competitor uses a different wetting surfactant or eliminates SLS, they may avoid the method claims (depending on the claims asserted) while still potentially facing product claims if composition matches.
Claim-to-design-around map (what to change to reduce infringement risk)
Composition-level design around
- Reduce total disintegrant loading to ≤10% w/w of total dry weight of the dosage form to avoid Claim 1 and Claim 15 threshold limitations.
- If asserting dependent claims are at issue:
- If using disintegrants outside the listed families (modified starches, croscarmallose sodium, carboxymethylcellulose calcium, crospovidone), you may avoid Claims 2–3, but Claim 1 can still apply unless the total disintegrant threshold is addressed.
Process-level design around (method claims 16–18)
- Use a wet granulation system without sodium lauryl sulfate (or outside 0.1% to 5% w/w SLS relative to wet granulation dry components) to avoid Claims 12–13 and to weaken Claim 16’s “aqueous SLS” requirement.
- Use a disintegrant other than sodium starch glycolate if you want to avoid Claims 4, 5–6, and method constraints tied to sodium starch glycolate.
“Distribution” around wet vs dry sodium starch glycolate (Claims 17–18)
- The method claims can be avoided by shifting sodium starch glycolate mass fractions outside:
- wet granulation 20% to 75% (Claim 17) or 20% to 55% (Claim 18), and/or
- dry blending 1% to 10% (Claim 17) or 2% to 4% (Claim 18)
What is the patent landscape around this claim family?
1) Central technical “landing zone”
This patent maps to a common formulation strategy for BCS-disparate antiretrovirals: use of a high level of super/disintegrant to improve disintegration and dissolution, implemented via wet granulation with SLS and using sodium starch glycolate as the disintegrant.
2) Landscape meaning for freedom-to-operate (FTO)
For efavirenz solid oral dosage forms in the US, a typical enforcement pattern for this type of patent is:
- Product patents with thresholds on excipient loading (here: >10% disintegrant) tend to create broad product-level barriers.
- Method patents tend to create narrower barriers, often relevant to contract manufacturing or process-defined embodiments.
3) Likely claim overlap areas where other patents tend to cluster
Even without enumerating other specific US patents by number here, the scope of US 6,238,695 indicates where other nearby patents commonly define their boundaries:
- Disintegrant loading thresholds (often around 5% to 20% w/w depending on prior art)
- Selection of disintegrant identity (croscarmallose, crospovidone, SSG, modified starches)
- Surfactant selection for wet granulation (SLS is a frequent choice)
- Quantitative split between wet granulation disintegrant fraction and dry-blend fraction
4) How to read this patent in the broader set of efavirenz formulation IP
- If your formulation hits Claim 1’s disintegrant threshold, product risk persists even if you avoid sodium starch glycolate and SLS in the method.
- If your formulation avoids Claim 1 by holding disintegrants at or below 10%, method and sodium-starch-glycolate constraints become much less relevant for that independent product anchor.
- If your formulation uses sodium starch glycolate at high wet granulation fractions and SLS, method risk rises sharply for Claims 16–18.
Key numeric claim points (quick reference table)
| Claim |
Parameter |
Constraint |
| 1 |
Disintegrant loading |
>10% w/w of total dry weight of dosage form |
| 2 |
Disintegrant identity |
modified starches, croscarmallose sodium, calcium carboxymethylcellulose, crospovidone |
| 3 |
Disintegrant identity |
one or more modified starches |
| 4 |
Disintegrant identity |
sodium starch glycolate |
| 5 |
Wet granulation SSG loading |
10% to 75% w/w of dry components in wet granulation step |
| 6 |
Wet granulation SSG loading |
20% to 55% w/w of dry components in wet granulation step |
| 7–11,14 |
Efavirenz mg ranges (dependent) |
5–1000 mg; 5–500 mg; 500–1000 mg; 25–350 mg; 50–200 mg; 5–800 mg |
| 12–13 |
SLS in wet granulation |
present; 0.1% to 5% w/w relative to total dry components of wet granulation step |
| 16 |
Method sequence |
wet granulate with aqueous SLS, dry, mill, dry blend (SSG again), encapsulate/compress |
| 17 |
Method quantitative splits |
wet granulation SSG: 20%–75% w/w; dry blend SSG: 1%–10% w/w |
| 18 |
Method quantitative splits |
wet granulation SSG: 20%–55% w/w; dry blend SSG: 2%–4% w/w |
Key Takeaways
- US 6,238,695 is built around a single compositional threshold: efavirenz solid oral forms with >10% w/w disintegrant (Claim 1) and an excipient framework version (Claim 15).
- The strongest specificity is centered on sodium starch glycolate and its placement in wet granulation with aqueous sodium lauryl sulfate, plus quantitative wet/dry distribution ranges (Claims 5–6, 12–13, 16–18).
- For FTO, the decision tree is straightforward:
- avoid >10% w/w total disintegrant to neutralize the independent product anchors (Claims 1 and 15),
- then separately consider avoiding SSG + aqueous SLS wet granulation and the wet/dry mass fractions to reduce method and dependent-embodiment risk (Claims 16–18).
FAQs
1) Does Claim 1 require sodium starch glycolate specifically?
No. Claim 1 only requires “a disintegrant” at >10% w/w of total dry weight. Sodium starch glycolate is introduced in dependent claims (Claims 3–4).
2) What is the single most important numerical limitation for composition infringement?
Disintegrant loading: greater than about 10% by weight of total dry weight of the dosage form (Claims 1 and 15).
3) If a process uses sodium starch glycolate but not SLS, does it avoid the method claims?
It avoids the “aqueous solution of sodium lauryl sulfate” limitation in Claim 16, and the SLS-dependent wet granulation embodiments in Claims 12–13, but it still may face product-claims exposure if the composition meets the >10% disintegrant threshold.
4) How tight are the method ranges for sodium starch glycolate distribution?
They are segmented: wet granulation SSG is 20%–75% or 20%–55% w/w depending on the dependent claim (17 vs 18), and dry blending SSG is 1%–10% or 2%–4% w/w (17 vs 18).
5) Which claim set is more likely to be used in enforcement: product or method?
This family has a broad product threshold (Claims 1 and 15) and a narrower method with strict input and quantitative splits (Claims 16–18). Enforcement selection typically follows the strongest available claim coverage against the accused product’s formulation and manufacturing facts.
References
[1] Provided claim text for US Patent 6,238,695 (Claims 1–18) in the prompt.
