United States Patent 7,820,660: Scope, Claim Strategy, and Patent Landscape
What is claimed in US 7,820,660?
US 7,820,660 claims a combination product: a specific HIV reverse transcriptase (RT) inhibitor plus a large set of defined dihydropyrimidine-carboxamide compounds (including many stereochemical and substituent variants), with additional dependent narrowing to a single compound and a single RT inhibitor.
Claim 1 (core scope)
Claim 1 is written as:
- (i) a compound selected from a long enumerated list (multiple chemical “scaffold” variants and substituent classes), and
- (ii) a reverse transcriptase inhibitor selected from:
- efavirenz
- emtricitabine
- lamivudine
- tenofovir disoproxil fumarate
- zidovudine
- plus pharmaceutically acceptable salts of the dihydropyrimidine-carboxamide compound.
This is a two-component selection claim: liability attaches when both selections are present in the combination, even if the RT inhibitor is one of several listed choices and even if the dihydropyrimidine is one of many listed alternatives.
Claim 2 (narrowing within claim 1)
Claim 2 narrows the dihydropyrimidine selection to a single member of the enumerated set:
- N-(4-fluorobenzyl)-5-hydroxy-1-methyl-2-(1-methyl-1-{[(5-methyl-1,3,4-oxadiazol-2-yl)carbonyl]amino}ethyl)-6-oxo-1,6-dihydropyrimidine-4-carboxamide
- or its pharmaceutically acceptable salt.
The RT inhibitor remains within the set of claim 1 in the text you provided (claim 2 only narrows the compound, not the RT inhibitor).
Claim 3 (narrowing within claim 2)
Claim 3 narrows the RT inhibitor to a single listed option:
So claim 3 covers the specific pairing:
- the single dihydropyrimidine compound of claim 2 + lamivudine.
How broad is the chemical scope in claim 1?
Claim 1 uses a strategy common in combination patents: it enumerates many alternative “active” compounds under a single selection umbrella, while keeping the RT inhibitor side limited to a small canonical list.
Size and structure of the covered dihydropyrimidine set
From the claim text provided, the dihydropyrimidine-carboxamide selection set includes:
- N-benzyl variants (multiple benzyl rings and substitutions, including fluoro, ethoxy, dimethoxy, chloro-methyl, trifluoromethyl, and other substituted benzyls)
- substituted phenyl linkers at the 2-position (including p-tolyl, phenyl substitutions)
- amine-containing substituents on the pendant aromatic/sidechain region:
- dimethylamino, diethylamino, (dimethylamino)(phenyl)methyl
- piperazine derivatives (including methylpiperazine and ethylpiperazine)
- pyrrolidine and piperidine substituted variants
- morpholine derivatives and morpholine-alkyl motifs
- carbonyl-linked heterocycles and amide-like pendant groups:
- pyridinylcarbonyl, pyrimidinylcarbonyl, pyrazinylcarbonyl
- imidazole-containing and oxadiazole-containing carbonyl motifs
- stereochemical variants (multiple chiral centers indicated as (2S,4R), (2R,4S), etc.)
- ring-expanded/alternative cyclic motifs at the 2-position:
- indolyl, tetrahydroquinolinyl, isoquinolinyl variants
- thiazolidinyl, imidazothiazole-carboxamide structures
What this means for infringement risk
- If a product uses lamivudine, tenofovir disoproxil fumarate, emtricitabine, zidovudine, or efavirenz with any enumerated dihydropyrimidine compound, that product falls within claim 1.
- The breadth is mostly controlled by the enumeration of the dihydropyrimidine list, not by generic Markush language.
- Because claim 1 is a “selection” claim, it is easier for an accused product to match because it only needs to satisfy the exact RT inhibitor list and one exact dihydropyrimidine member.
Where the scope tightens: claims 2 and 3
Claim 2: one specific dihydropyrimidine
Claim 2 pins down a single member distinguished by:
- N-(4-fluorobenzyl)
- 5-hydroxy-1-methyl-6-oxo-1,6-dihydropyrimidine-4-carboxamide
- a side chain containing an oxadiazole carbonyl:
- [(5-methyl-1,3,4-oxadiazol-2-yl)carbonyl]
- and a 1-methyl-substituted amino-ethyl linkage
This makes claim 2 narrower than claim 1 by collapsing the dihydropyrimidine selection set to one compound.
Claim 3: one RT inhibitor
Claim 3 further limits the RT inhibitor to:
Together, claim 2 and claim 3 map to a single combination: the claim-2 compound with lamivudine.
Patent landscape implications (based on claim structure)
A full landscape requires bibliographic and citation data for US 7,820,660, its priority lineage, assignee, prosecution history, and whether it sits within a family covering the dihydropyrimidine scaffold and the RT inhibitor pairing. That information is not present in your input.
What can be concluded from the claim architecture you provided is narrower but still actionable:
Landscape node 1: Combination patents targeting standard-of-care RT inhibitors
Claim 1 lists five RT inhibitors that are historically and commercially central to HIV therapy. A claim like this tends to create:
- blocking coverage around fixed pairings of a novel (or less-standard) second active with a mainstream RT inhibitor set.
- multiple points of leverage across generic entry timelines for the RT component, because the RT inhibitors in the set are widely used and often supported by multiple regulatory submissions.
Landscape node 2: Heavy enumeration reduces design-around by substitution
Many combination patents use broad Markush language to allow coverage across families. Here the dihydropyrimidine portion is enumerated with many specific structures. Enumeration can:
- make scope “hard-edged” (only listed members are covered),
- but still provide wide coverage if the enumerated set is large and covers typical medicinal chemistry variation patterns.
Landscape node 3: Dependent claims can be used for fallback positions
Even if a challenger attacks claim 1 (e.g., by arguing the product uses a non-enumerated dihydropyrimidine), claims 2 and 3 provide:
- a defined fallback for a particular oxadiazole-containing member,
- and a further defined fallback for lamivudine.
This is consistent with claim strategy designed to preserve enforceability across partial mismatches.
Practical scope map (what products are covered)
Covered RT inhibitors (claim 1)
The following RT inhibitors are explicitly included:
| RT inhibitor |
Included in claim 1 |
Present in claim 3? |
| Efavirenz |
Yes |
No |
| Emtricitabine |
Yes |
No |
| Lamivudine |
Yes |
Yes |
| Tenofovir disoproxil fumarate |
Yes |
No |
| Zidovudine |
Yes |
No |
Covered dihydropyrimidines
Because claim 1 enumerates many dihydropyrimidines, the practical test for claim 1 is:
1) Is the RT inhibitor one of the 5 listed?
2) Does the dihydropyrimidine active match one of the enumerated compounds exactly (or a pharmaceutically acceptable salt of such a compound)?
Key combination pins (claims 2 and 3)
| Claim |
dihydropyrimidine active |
RT inhibitor |
| 2 |
N-(4-fluorobenzyl)-5-hydroxy-1-methyl-2-(1-methyl-1-{[(5-methyl-1,3,4-oxadiazol-2-yl)carbonyl]amino}ethyl)-6-oxo-1,6-dihydropyrimidine-4-carboxamide (or salt) |
Any from claim 1 |
| 3 |
Same as claim 2 |
Lamivudine |
Claim interpretation issues that affect enforcement (from the text provided)
“Combination which comprises” is not limited to a two-drug regimen
The phrasing “A combination which comprises” is open-ended. If the claim language is interpreted in the standard way, a product that includes additional actives besides the two listed components still can satisfy the claim as long as the claimed components are present.
Salts are included only for the dihydropyrimidine portion
The text you provided explicitly adds:
- “and pharmaceutically acceptable salts thereof” for the dihydropyrimidine compounds.
The claim also includes tenofovir disoproxil fumarate as an RT inhibitor variant, which already is a salt/form. But based on what you provided, the explicit “salts thereof” linkage attaches to the dihydropyrimidine selection rather than to the RT inhibitor selection.
What to do with this in R&D and competitive intelligence
For formulators or product teams
- Map the exact small-molecule identity of the dihydropyrimidine component against the claim enumeration. The claim set is large, but enforcement turns on exact identity (or salt identity) rather than broad “similarity.”
- If targeting lamivudine specifically, prioritize analyzing whether the dihydropyrimidine compound is the exact oxadiazole carbonyl member of claim 2, because claim 3 is explicit.
For design-around teams
- Generic substitution around the RT inhibitor is constrained by the fact that claim 1 already lists multiple mainstream RT inhibitors. A design-around that keeps the same dihydropyrimidine but switches RT inhibitors could fall outside claim 1 only if it uses an RT inhibitor not in the set. Conversely, switching the dihydropyrimidine to a structure not enumerated is a potential design-around, but requires careful structure-by-structure matching.
For investors and business planners
- Treat US 7,820,660 as a combination lever that can complicate development of products pairing a dihydropyrimidine analog in the enumerated set with any of the listed RT inhibitors.
- The presence of dependent fallback claims (2 and 3) indicates the patent is structured to survive partial validity or partial infringement disputes targeting claim 1.
Key Takeaways
- Claim 1 covers a two-component combination: an enumerated dihydropyrimidine-carboxamide plus one of five enumerated reverse transcriptase inhibitors (efavirenz, emtricitabine, lamivudine, tenofovir disoproxil fumarate, zidovudine).
- Claim 2 narrows the dihydropyrimidine side to one specific oxadiazole carbonyl member.
- Claim 3 narrows the RT inhibitor side to lamivudine, creating a specific enforceable pairing.
- The scope is broad on the RT side and wide on the dihydropyrimidine side due to extensive enumeration; risk hinges on exact match to a listed dihydropyrimidine member (or its pharmaceutically acceptable salt) and use of a listed RT inhibitor.
FAQs
1) Does US 7,820,660 cover triple-drug HIV regimens?
Yes in principle, because the claim uses “A combination which comprises,” which is open-ended and does not by itself require only the two listed components.
2) What is the single most constrained product covered by the dependent claims?
The combination in claim 3: the specific claim 2 oxadiazole-containing dihydropyrimidine with lamivudine.
3) If a product uses efavirenz instead of lamivudine, is it outside the patent?
No, efavirenz is listed in claim 1, so it can still fall within claim 1 if the dihydropyrimidine compound matches the enumerated set.
4) Are pharmaceutically acceptable salts covered?
Yes for the dihydropyrimidine compound selection (“and pharmaceutically acceptable salts thereof”) as stated in claim 1 text you provided.
5) Is the dihydropyrimidine scope defined generically or by enumeration?
It is defined by enumeration in claim 1, with many specifically named compounds.
References
- United States Patent 7,820,660, claim 1-3 text as provided by user.
