Scope and Claims Analysis for US Patent 9,433,619 (Hydrocodone Bitartrate Hepatic Impairment Oral Extended-Release)
US Patent 9,433,619 is a US method-of-treatment patent with tightly engineered pharmacokinetic and formulation limitations. The claims target (i) patients with mild or moderate hepatic impairment, (ii) oral hydrocodone bitartrate as the only active ingredient, and (iii) an AUC- and Cmax-bounded release profile for hydrocodone (including specific half-life and dissolution performance metrics). The dependent claims then narrow into a particular two-stage delivery architecture (immediate-release + sustained-release components, and in some claims a multiparticulate bead system with specified polymer coating families and bead ratios).
The practical result for freedom-to-operate (FTO) and licensing strategy is that the estate is unlikely to be captured by a generic “extended-release hydrocodone for hepatic impairment” concept alone. It is instead anchored to exact exposure windows (AUC0-inf bands per 20 mg dose; Cmax ranges), dose loading thresholds (≥20 mg in claims 9-20), and controlled release behavior measured under USP dissolution buffered at defined pH.
Because you provided only the claim text (not the patent’s specification, prosecution history, claim construction record, or priority/application data), the analysis below is confined to what is extractable from the claims themselves.
What does US Patent 9,433,619 claim for treating pain with hydrocodone bitartrate in mild or moderate hepatic impairment?
Core claim structure: method-of-treatment + patient population + drug purity + exposure window + controlled release
The independent claim (Claim 1) is a method claim with the following required elements:
- Patient condition: patient has mild or moderate hepatic impairment.
- Drug and route: administer an oral dosage unit with hydrocodone bitartrate as the only active ingredient.
- Two-component formulation: dosage unit contains a first formulation of hydrocodone bitartrate and a second formulation of hydrocodone bitartrate.
- Release profile bounded by exposure: hydrocodone release yields AUC0-inf windows per 20 mg dose:
- Non-renal/non-hepatic impairment reference: 300 to 500 ng·h/mL
- Mild hepatic impairment: 300 to 570 ng·h/mL
- Moderate hepatic impairment: 300 to 700 ng·h/mL
The claim is therefore not just “extended release.” It is extended-release behavior defined by in vivo exposure outcome, with explicit numerical bounds tied to AUC0-inf.
Key implication for scope
- A product that delivers hydrocodone to hepatic-impairment patients but falls outside the AUC ranges for the specified comparator conditions would not meet Claim 1’s release-profile limitation.
- A product that uses hydrocodone bitartrate with other active ingredients is excluded by “only active ingredient.”
- A product that does not include two hydrocodone bitartrate formulations in one dosage unit (as the claim frames “first” and “second”) is excluded.
How tight are the exposure limits (AUC0-inf and Cmax) and what do they do to claim coverage?
Claim 1: AUC0-inf per 20 mg hydrocodone bitartrate
Claim 1 uses AUC0-inf ranges normalized to 20 mg hydrocodone bitartrate:
| Setting |
AUC0-inf range required (per 20 mg) |
Claim text location |
| Subjects without renal or hepatic impairment |
~300 to ~500 ng·h/mL |
Claim 1 (1) |
| Subjects with mild hepatic impairment |
~300 to ~570 ng·h/mL |
Claim 1 (2) |
| Subjects with moderate hepatic impairment |
~300 to ~700 ng·h/mL |
Claim 1 (3) |
Claim 18: adds Cmax bounded release + extended-release window
Claim 18 is a separate independent claim (method of treating pain in mild/moderate hepatic impairment) that requires both:
- Dissolution-based release behavior (USP apparatus, buffered pH), and
- Exposure constraints:
- AUC0-inf per 20 mg: ~312 to ~500 ng·h/mL
- Cmax per 20 mg: ~17 to ~27 ng/mL
This matters for scope because Claim 18 acts as a second “gate” with both time-dependent release metrics and peak exposure constraints.
Scope effect: numeric outcome limitations narrow design-arounds
For licensing and generic risk, the numeric bounds mean:
- Even if two products are both “extended-release hydrocodone,” exposure and release timing can differ enough to avoid literal infringement.
- But if a defendant’s formulation is measured and found to fall within the exact ranges under the claim’s test framing (including the pH of the dissolution apparatus in Claim 8/18 language), that numerical alignment can be dispositive.
What specific half-life limitations does US 9,433,619 require for hepatic impairment subgroups?
Claim 2-4 require specific plasma half-life values:
| Claim |
Population |
Required hydrocodone half-life |
| Claim 2 |
No hepatic impairment |
about 8 hours |
| Claim 3 |
Mild hepatic impairment |
about 9 hours |
| Claim 4 |
Moderate hepatic impairment |
about 10 hours |
Scope implication
These are additional pharmacokinetic outcome requirements. A formulation that meets AUC bands but yields materially different half-life would not meet the half-life-dependent dependent claims (2-4), though it could still meet Claim 1 if AUC windows are satisfied.
What formulation architecture is protected (immediate + sustained components; bead populations; coatings)?
Claim 5 and 7: two formulations and specific weight split
Claim 5: first formulation = immediate release component; second = sustained release component.
Claim 7 specifies a weight ratio:
- Immediate release component: 15% to 25% by weight of total hydrocodone
- Sustained release component: 75% to 85% by weight
Scope implication
A formulation that uses different proportions (e.g., 10/90 or 30/70) misses Claim 7’s dependent limitation.
Claim 8: USP dissolution release behavior at pH 6 (percent in first hour; percent by hour 12)
Claim 8 requires:
- Release 10% to 30% in first hour
- Release >60% during first 12 hours
- Measured in USP dissolution apparatus buffered at pH 6
Scope implication
This ties infringement to a measurable in vitro release curve. If a product’s dissolution method or buffer pH materially differs from the claim’s stated conditions, design-around leverage increases.
What does the multiparticulate extended-release sub-portfolio (Claims 9-20) add beyond Claim 1?
Claim 9: extended release with ≥20 mg hydrocodone bitartrate
Claim 9 (independent) requires:
- mild/moderate hepatic impairment patient
- oral dosage unit
- hydrocodone bitartrate only
- at least 20 mg
- extended release formulation
Claims 10-13: multiparticulate modified release in capsule; multiple bead populations
- Claim 10: multiparticulate modified release composition
- Claim 11: capsule containing that composition
- Claim 12: bead populations:
- bead population 1 (immediate): 15-25% of total hydrocodone
- bead population 2 (sustained): 75-85% of total hydrocodone
- Claim 13: a third bead population distinct from the first two
Claims 14-16: specific polymer coating families and inert cores
Claim 14 requires the coating of the sustained bead population includes one or more polymers selected from a long list including:
- cellulose acetate phthalate (CAPh)
- cellulose acetate trimaletate
- hydroxypropyl methylcellulose phthalate (HPMCP)
- polyvinyl acetate phthalate
- ammonio methacrylate copolymers
- polyacrylic acid; polyacrylate and methacrylate copolymers
- polyvinyl acetaldiethylamino acetate
- hydroxypropyl methylcellulose acetate succinate
- shellac
Claim 15 further narrows:
- polymer coating comprises ammonio methacrylate copolymers
Claim 16 adds:
- first and second beads comprise sugar spheres as inert core
Scope implication
Claims 9-16 add a product-structure burden:
- “extended release” alone is broader than “multiparticulate bead system with sugar sphere cores and specified polymer coatings.”
- Therefore, the strongest coverage is likely in contexts where products use polymer-coated multiparticulates in capsules with the explicit bead fractionation.
What dosage strengths are explicitly captured?
Claims 17 and 20: explicit dose contents
- Claim 17: dosage unit contains 20 mg, 30 mg, 40 mg, or 50 mg hydrocodone bitartrate
- Claim 20: same dosage-unit content list (in Claim 19/20 chain)
Scope implication
The “at least 20 mg” language in Claim 9 may allow broader dose coverage, but Claims 17 and 20 capture explicit discrete strengths. Products outside those strengths could still avoid the narrow dependents while potentially still implicating Claim 9 if they are ≥20 mg.
Which parts of the claim set are likely easiest to design around?
Design-around opportunities derived from explicit limitations
- AUC and Cmax windows: if formulation changes shift exposure outside the numeric ranges for hepatic impairment groups, Claim 1/18 can be avoided.
- Two hydrocodone bitartrate formulations: if the design does not present “first” and “second” formulations as claimed (or uses a different internal architecture), coverage can narrow.
- Weight split (15-25% / 75-85%): changing bead/unit ratios can miss dependents like Claim 7/12.
- USP dissolution pH: altering dissolution conditions or engineering a different dissolution curve (especially first-hour and >60% by hour 12 at buffered pH 6 or pH 6.8 as stated) can reduce risk.
- Polymer family constraints: if a sustained bead coating omits the polymer family required in Claim 14/15, those dependents are avoided.
What is hardest to design around
- The combination of patient population + drug purity + oral dosing unit + extended release architecture with measured release/exposure outcomes creates a multi-constraint infringement surface. Even a single mismatched limitation can defeat a particular claim, but if a product is engineered to match exposure windows and release behavior, it can land in multiple claim lanes simultaneously.
How strong is the patent estate based on claim drafting (literal coverage vs. “similar effect” coverage)?
Claim language indicates high literalness
The claims are anchored to:
- numerical pharmacokinetic bounds (AUC0-inf, Cmax, half-life),
- numerical dissolution release thresholds and buffer pH,
- specific composition constraints (only hydrocodone bitartrate; bead weight fractions),
- specific material lists (coating polymer families),
- specific structural architecture (multiparticulate beads; sugar spheres; multiple bead populations).
This style typically produces:
- high clarity for infringement comparisons where testing replicates the claim’s test framing, and
- greater design-around potential where developers can shift exposure/release curves outside the bounded ranges or use different polymer systems.
Patent landscape and enforceability impacts for US 9,433,619 (what the claim set implies for litigation risk)
Risk drivers for an ANDA/505(b)(2) with extended-release hydrocodone bitartrate
Because the claim is a method of treating pain in hepatic impairment patients, infringement analysis usually turns on:
- whether the accused product is prescribed/administered in the claimed patient category, and
- whether the product’s release/exposure performance matches the claimed AUC/Cmax/half-life and dissolution thresholds.
Potential litigation focal points derived from the claim set
- Exposure testing design: mapping AUC0-inf and Cmax to the “per 20 mg” normalization and verifying whether clinical study conditions align with the claim’s framing.
- PK stratification: verifying mild vs moderate hepatic impairment cohort performance.
- Dissolution method alignment: confirming USP apparatus and buffer pH match the claim’s specified conditions (pH 6 in Claim 8; pH 6.8 in Claim 18).
- Formulation mapping: demonstrating bead populations, weight fractions, and polymer coating presence from the Claim 12-16 dependents.
Claim-by-claim scope map (what each claim adds)
| Claim |
Add-on element (beyond method + hepatic impairment + oral hydrocodone bitartrate only) |
Scope effect |
| 1 |
AUC0-inf bands for non-hepatic, mild hepatic, moderate hepatic; two formulations; defined AUC ranges per 20 mg |
Core coverage; outcome-bounded |
| 2 |
half-life about 8 hours in no hepatic impairment |
Narrows to PK outcome |
| 3 |
half-life about 9 hours in mild hepatic impairment |
Narrows to PK outcome |
| 4 |
half-life about 10 hours in moderate hepatic impairment |
Narrows to PK outcome |
| 5 |
first formulation IR component; second sustained release component |
Locks delivery-stage architecture |
| 6 |
IR comprises first particle population; sustained comprises second particle population |
Tightens microarchitecture |
| 7 |
IR 15-25 wt% and sustained 75-85 wt% |
Tightens composition split |
| 8 |
dissolution: 10-30% in first hour; >60% by 12 hours at USP pH 6 |
In vitro release constraint |
| 9 |
extended release formulation; at least 20 mg |
Independent extended-release/dose floor |
| 10 |
multiparticulate modified release composition |
Architecture constraint |
| 11 |
capsule containing multiparticulate composition |
Dosage form constraint |
| 12 |
bead populations with 15-25% and 75-85% hydrocodone wt fractions |
Tightens bead distribution |
| 13 |
third bead population distinct |
Further narrows multiparticulate design |
| 14 |
sustained bead coating includes specified polymer family list |
Material constraint |
| 15 |
polymer coating comprises ammonio methacrylate copolymers |
Narrow polymer subcategory |
| 16 |
sugar spheres as inert cores |
Core material constraint |
| 17 |
dosage strengths include 20/30/40/50 mg |
Discrete strength capture |
| 18 |
dissolution at pH 6.8 plus AUC0-inf and Cmax ranges per 20 mg |
High-constraint independent claim |
| 19 |
dosage unit has at least 20 mg hydrocodone bitartrate |
Reinforces dose floor |
| 20 |
dosage strength in 20/30/40/50 mg |
Strength dependent |
Key Takeaways
- US 9,433,619 is a method-of-treatment patent covering oral hydrocodone bitartrate only administered to mild or moderate hepatic impairment patients with release-defined pharmacokinetics.
- The claims are numerically bounded: AUC0-inf ranges in Claim 1; AUC0-inf and Cmax ranges plus dissolution requirements in Claim 18; half-life bands in Claims 2-4; and USP dissolution release thresholds at specified buffer pH in Claims 8 and 18.
- A substantial portion of the estate narrows coverage to a specific two-stage IR + sustained architecture with defined hydrocodone weight fractions and, in Claims 9-16, to a multiparticulate bead system with polymer coating families (including ammonio methacrylate copolymers) and sugar sphere inert cores.
- For FTO and litigation analysis, the claim set favors testable, formulation-specific comparisons. Exposure and dissolution performance are likely to dominate infringement and validity disputes.
FAQs
Which claim elements are most decisive for infringement of US 9,433,619?
Claim 1 and Claim 18 are most decisive because they require specific AUC0-inf (and in Claim 18, Cmax) outcome windows tied to dosing per 20 mg, plus (in Claim 18) USP dissolution release criteria at specified buffered pH.
Does US 9,433,619 cover combination products with additional active ingredients?
No. The claims require hydrocodone bitartrate as the only active ingredient in the oral dosage unit.
What design changes most likely avoid the multiparticulate dependents?
Changing the sustained bead polymer coating away from the listed families (or away from ammonio methacrylate copolymers for Claim 15), changing inert core away from sugar spheres (Claim 16), or altering the bead population architecture (Claim 13’s third distinct population).
How do the USP dissolution pH settings affect non-infringement strategy?
Claim 8 references USP dissolution apparatus buffered at pH 6, while Claim 18 references buffered at pH 6.8. Different release behavior under those specified conditions can be used to argue the required in vitro thresholds are not met.
Can a product that meets one PK window still avoid infringement if it misses another?
Yes. The estate contains multiple claim lanes with different numeric gates. Meeting AUC bands in Claim 1 does not automatically meet Claim 18’s combined AUC0-inf + Cmax and dissolution constraints, and vice versa.
References
- US Patent 9,433,619, “Method of treating pain in patients having hepatic impairment,” claim set provided in prompt.
