United States RE46365 patent landscape: scope, claim coverage, and exclusivity risk for opioid side-effect prevention compounds
RE46365 is a U.S. reissue patent. Based on the claim text provided, its scope is directed to (i) a broad genus of compounds defined by a formula (I) with extensive substituent permutations at R1-R5 (and a secondary ring-defined substructure), and (ii) downstream pharmaceutical compositions and treatment uses centered on opioid receptor antagonistic activity and prevention of emesis/vomiting/constipation and mitigation of opioid-induced side effects (with morphine/oxycodone called out in dependent claims). The practical risk for generic or follow-on entrants is driven less by the exact skeleton described in claim 1 and more by (a) how tightly the genus is actually supported in the specification (enablement/breadth), (b) whether key preferred embodiments map to known marketed/non-marketed agents, and (c) whether the reissue broadened or narrowed the original claims in ways that affect intervening rights and obviousness/novelty.
Because no bibliographic record (application number, original patent number, assignee, filing date, reissue history, specification disclosures, or prosecution/litigation record) is included, the patent landscape below is limited to claim-scope and typical exclusivity risk pathways implied by the claims themselves. No parties, related patents, or Orange Book/Biologics data can be added without a RE46365 record.
What is US patent RE46365 and what do its claims cover?
Short answer: RE46365 claims a compound genus of formula (I) and includes method/composition claims for opioid receptor antagonistic activity and prevention/alleviation of opioid-induced side effects, specifically emesis, vomiting, and constipation, including when the triggering opioid is morphine or oxycodone.
Claim 1: the core genus of “compound of formula (I)”
Claim 1 recites:
Scope effect: Claim 1 is drafted to capture a very large set of structural variants that share the same overall scaffold and substitution positions, with broad “optionally substituted” language. That makes RE46365 an umbrella claim if the specification provides adequate disclosure of the breadth.
Claims 2-4: narrower R3 and “preferred” R1/R2/R5 combinations
- Claim 2: limits R3 to hydroxy (or salt).
- Claim 3: limits R3 to optionally substituted amino (or salt).
- Claim 4: adds a more specific substitution pattern:
- R1 is hydrogen or lower alkyl
- R2 is optionally substituted lower alkyl, optionally substituted phenyl, optionally substituted cycloalkyl, or optionally substituted heterocyclic group
- R5 is cyclopropylmethyl (or salt)
Claims 5-11: composition claims and opioid side-effect indications
- Claim 5: pharmaceutical composition containing compound of claims 1-4 (or salt).
- Claim 6: composition for opioid receptor antagonistic activity.
- Claim 7-9: compositions/agents for treating/preventing:
- emesis, vomiting, and/or constipation
- Claim 10: the opioid agonist referenced in the side-effect mitigation is morphine or oxycodone (or salts).
- Claim 11: analgesic composition with an opioid agonist plus an effective amount of the RE46365 compound to alleviate/prevent opioid-induced side effects.
Claims 12-13: explicit formula (I) embodiments with R1-R5 fixed
These are “example-like” claim embodiments that carve out defined preferred structures:
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Claim 12: specifies:
- R1 = hydrogen
- R3 = hydroxyl
- R4 = hydrogen
- R5 = cyclopropylmethyl
- R2 is selected from defined lower alkyl/alkoxycarbonyl/heterocyclic options, and specific aryl/heteroaryl patterns.
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Claim 13: specifies:
- R1 = hydrogen
- R3 = hydroxyl
- R4 = hydrogen
- R5 = cyclopropylmethyl
- R2 includes lower alkyl substituted with lower alkoxy or substituted heteroaryl/aryl patterns and cycloalkyl carbonyl options.
Claims 12-13 function as “anchor” embodiments that can be easier to map to real chemical entities than claim 1’s abstract genus.
Claims 14-15 and 20-30: additional compound claims (text is truncated)
The provided text shows placeholder claim language (“wherein the compound is or a pharmaceutically acceptable salt thereof”) and a later claim 20 and onwards that appear to define yet another compound/formula (not reproduced in the prompt). Because the chemical formula for claim 20 is not shown, the exact identity of those later embodiments cannot be determined from the provided excerpt.
Still, claims 14-19 and 16-19 mirror the same use structure: analgesic/opioid side-effect mitigation compositions built around “a compound having opioid receptor agonistic activity” plus an effective amount of the RE46365 compound.
Claims 23-25 and tablet/formulation claims (29-30)
- Claim 23: specifies p-toluenesulfonic acid salt as a salt form.
- Claims 29-30: specify tablet dosage form for the relevant compositions.
Scope effect: Salt and dosage-form claims can block entry even if a competitor designs around the free base by selecting a specific salt or standard oral format.
How broad are RE46365’s compound claims (formula I) and where are the claim boundaries?
Short answer: The compound claim is broad at the genus level (R1-R2/R3/R4/R5), but practical boundaries arise from (1) the fixed scaffold of formula (I), (2) constrained elements like R4 being only H/lower alkyl and R5 limited to a narrow class including cyclopropylmethyl, and (3) dependent claims that lock in functionally important features (R3 hydroxy/amino; specific R2/R5 patterns).
Key “breadth drivers” in claim 1
- Optionally substituted language without a numerical cap on substitution.
- Heterocycle formation: R1 and R2 can jointly form a heterocycle with the nitrogen they are attached to.
- R3 includes multiple functional classes (hydroxy, amino, thiols/thioethers, carbamoyl, acyl/acyloxy, heteroaryls).
- Second motif for R3 (ring A and ring B heterocycles with a broken-line bond option).
Key “narrowing levers”
- R4 is only hydrogen or lower alkyl, which excludes many functionalizable substituents at that position.
- R5 is limited to hydrogen, lower alkyl, cycloalkyl lower alkyl, or lower alkenyl; and the most litigable preferred form is cyclopropylmethyl in claims 4/12/13.
- Functional claims are tied to opioid receptor antagonistic activity and specific indications (emesis/vomiting/constipation), which can limit practical infringement to compounds with the claimed activity and compositions that are used/marketed for those purposes.
Which opioid side-effect indications are claimed under RE46365?
Short answer: RE46365’s composition/use claims are aimed at preventing or treating opioid-induced emesis, vomiting, and constipation, and mitigating side effects of opioid receptor agonists, with morphine and oxycodone expressly identified.
Indication matrix by claim cluster
| Claim(s) |
Target action |
Condition/endpoint |
Opioid context |
| 6 |
opioid receptor antagonistic activity |
activity classification |
not tied to a specific opioid in the claim text |
| 7-9 |
treating/preventing side effects |
emesis, vomiting, constipation |
side effect induced by administering opioid receptor agonistic activity compound (claim 8-9 framing) |
| 10 |
same as above |
emesis/vomiting/constipation |
opioid agonist is morphine or oxycodone |
| 11 |
analgesic combo |
alleviate/prevent side effects induced by administering opioid agonist |
analgesic composition includes opioid agonist + RE46365 compound |
Infringement posture: Competitors marketing an opioid + anti-emetic/anti-constipation adjunct may face exposure if their adjunct compound falls within the RE46365 genus and if labeling/indication corresponds to these claim limitations.
What formulations and salt forms are protected by RE46365?
Short answer: RE46365 covers pharmaceutical compositions broadly, includes at least one specific salt (p-toluenesulfonic acid), and includes tablet dosage-form compositions for the covered compounds.
Protected formulation hooks in the provided claims
- Pharmaceutical composition: claims 5, 24-25.
- Salt: claim 23 specifies p-toluenesulfonic acid salt.
- Dosage form (tablet):
- claim 29: composition of claim 25 in tablet form
- claim 30: composition of claim 27 in tablet form
Practical effect: A design-around that uses a different counterion may still be captured under generic “pharmaceutically acceptable salts” language in claim 1 and dependent clauses; but the specific p-toluenesulfonate is a dedicated target that can become a fallback for enforcement.
What compounds are closest to the likely “in-scope” subset of RE46365?
Short answer: The closest-to-marketable subset is defined by the “preferred” recitations: R1 = H, R3 = hydroxyl, R4 = H, and R5 = cyclopropylmethyl, with R2 constrained to selected lower alkyl/aryl/heterocyclic and carbonyl-substituted variants in claims 12-13.
Claim 12/13 “anchor” pattern
- Common fixed positions: R1=H; R3=OH; R4=H; R5=cyclopropylmethyl
- Variable scope: R2 substituent type is where most diversity sits
Litigation relevance: If infringement focuses on a competitor’s specific chemical, the infringement analysis will likely map that entity to claims 12 or 13 first, then to claim 1’s broader genus if necessary. The “cyclopropylmethyl” constraint is a high-signal anchor for claim construction.
How strong is the patent estate for RE46365 based on claim structure alone?
Short answer: The estate strength (from claim structure) is high for composition/use enforcement but mixed for broad compound-genus certainty. The genus breadth increases infringement coverage if the scaffold is well-supported; it also increases invalidity risk if the specification does not enable the full range of substituents.
Strength indicators from the claim text
- Multiple dependent claims lock in key functional features (hydroxyl/amino at R3; cyclopropylmethyl at R5).
- Dedicated use claims for opioid receptor antagonism and specific clinical endpoints.
- Salt and tablet form claims offer multiple enforcement angles.
Weakness indicators from the claim text
- Extensive “optionally substituted” combinations plus a second ring-defined motif in R3 can raise questions on enablement and written description if the specification only provides a narrow set of examples.
What does RE46365 likely block for generics or follow-on entrants?
Short answer: It blocks entry of (i) the covered compound(s) and their pharmaceutically acceptable salts and (ii) combo products using an opioid agonist paired with a RE46365-covered opioid receptor antagonist adjunct for emesis/vomiting/constipation mitigation, including tablet formulations, provided the competitor’s product meets the claim limitations.
Generic entry risk pathways (conceptual)
- Chemical substitution not working: If competitor’s API falls within formula (I) or the anchored claims 12/13, generic manufacturers face infringement exposure.
- Salt switching not working: If competitor uses p-toluenesulfonate or is still within “pharmaceutically acceptable salt” scope for claim 1, they remain exposed.
- Indication/labeling not working: If competitor’s product is marketed for the same opioid side-effect mitigation, composition/use claims can be asserted even if pure API is harder to map.
How do you analyze potential “Paragraph IV”-style challenges against RE46365 using the claim map?
Short answer: A challenger’s analysis would typically focus on three claim-limitation axes: compound structural mapping (formula (I) and R3/R5 anchors), formulation/salt mapping (tablet and p-toluenesulfonate), and use/labeling mapping (emesis/vomiting/constipation mitigation with morphine/oxycodone context).
Claim-limitation axes for challenge design
- Axis A: Compound mapping
- Does the candidate compound meet R1-R5 constraints?
- Is R3 hydroxy or amino (claims 2-4, 12-13)?
- Is R5 cyclopropylmethyl (claims 4, 12-13)?
- Axis B: Salt/form mapping
- Is p-toluenesulfonate used (claim 23) or would the specific salt still be considered “pharmaceutically acceptable” under claim 1?
- Axis C: Use mapping
- Is the intended therapeutic use emesis/vomiting/constipation prevention in opioid-treated patients (claims 7-11)?
- Is morphine or oxycodone expressly in the labeling (claim 10), or is the use implied by the clinical regimen.
RE46365 claim scope vs. common design-around strategies: what is likely to work?
Short answer: The most plausible design-arounds are not in generic “different formulation” changes but in changing the molecule so that it fails key anchor limitations (especially the R3 hydroxy/amino and R5 cyclopropylmethyl positions in dependent claims) or in avoiding claimed use/labeling. Salt changes may not be enough due to broad “pharmaceutically acceptable salts” coverage.
Most vulnerable design choices
- Keeping the same scaffold and only varying R2 broadly, while retaining R3 hydroxy and R5 cyclopropylmethyl, risks falling into claims 12-13 (and then claim 1).
- Selling a tablet combination for opioid-induced constipation/emesis with labeling aligned to claims 7-11 risks use/composition infringement.
Key Takeaways
- RE46365 is a formula (I) genus patent with extensive substituent coverage across R1-R5, supported by dependent claims that tighten to a high-signal subset: R3 = hydroxyl and R5 = cyclopropylmethyl (claims 4, 12, 13).
- The enforceable downstream scope is substantial: pharmaceutical compositions and opioid receptor antagonistic activity claims directed to preventing/treating emesis, vomiting, and constipation, including when the opioid agonist is morphine or oxycodone (claims 7-11).
- Salt and dosage-form hooks matter: p-toluenesulfonic acid salt and tablet formulations are explicitly claimed (claims 23, 29-30).
- For generic/follow-on risk assessment, the infringement map concentrates on three axes: structural mapping to formula (I), retention (or not) of anchor positions (especially R3 and R5), and alignment of product indication/labeling to the claimed opioid side-effect endpoints.
FAQs
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Does RE46365 cover opioid receptor agonists or only antagonistic adjuncts?
Based on the claim text, RE46365 covers compounds and compositions with opioid receptor antagonistic activity and their use to mitigate side effects induced by administering an opioid receptor agonistic compound.
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What claim elements most strongly drive infringement of a competitor product?
Matching the formula (I) substituents, especially the dependent-claim anchors (R3 = hydroxy or amino, and R5 = cyclopropylmethyl), plus product labeling/use for emesis/vomiting/constipation mitigation.
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Can a different salt avoid infringement under RE46365?
A generic counterion change may not avoid claim coverage because claim 1 includes pharmaceutically acceptable salts; however, p-toluenesulfonate is separately claimed, making it a specific risk point.
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Are tablet formulations of the protected compositions covered?
Yes. The provided claims include tablet form coverage (claims 29-30).
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How is morphine/oxycodone treatment implicated in RE46365?
Claim 10 identifies the opioid agonist context as morphine or oxycodone for the side-effect mitigation composition.
References
- RE46365 (U.S. reissue patent). Provided claim text in the prompt.
