United States Patent 5,362,755: Scope, Claims and Patent Landscape (Albuterol R(-) Enantiomer for Asthma)
What does US 5,362,755 claim, in scope terms?
US 5,362,755 claims a treatment method for asthma that uses optically pure R(-) albuterol (substantially free of the S(+) isomer) to achieve bronchodilation while reducing undesirable side effects tied to chronic administration of racemic albuterol (R/S mixture).
The claims are method claims, not composition claims. The operative “scope” is defined by five linked elements:
- Indication: treating asthma in an individual.
- Act: chronic administration of an optically pure R(-) albuterol.
- Purity/identity: R(-) isomer content thresholds (substantially free S(+) and preferred >90% and >99% by weight).
- Dose form and regimen: inhaled dosing ranges and oral dosing ranges (including frequency).
- Outcome linkage: bronchodilation with reduced side effects associated with chronic racemic albuterol use.
- Optional co-therapy: at least one additional drug from specified classes (and analgesic sub-selection).
The claim set is narrowest when it fixes quantitative purity and dose ranges, and broadest at claim 1 (substantially free S(+) plus chronic administration with reduced side effects, without locking to a specific inhalation/oral dose band).
What are the independent claim boundaries (Claim 1)?
Claim 1 is the core independent claim. It is a method for:
- Treating asthma in an individual with albuterol.
- While reducing side effects associated with chronic administration of racemic albuterol.
- By chronically administering an optically pure R(-) isomer of albuterol.
- The quantity must be sufficient to result in bronchodilation.
- The R(-) isomer must be substantially free of its S(+) isomer.
Key legal/technical scope levers in Claim 1
- Chronic administration: temporal element that excludes acute/short-course use unless argued as “chronic” by dosage schedule.
- Substantially free: leaves interpretive room for how much S(+) may be tolerated, but the claim is supported by dependent numeric ranges (claims 2 and 3).
- Side effect reduction: ties the method benefit to the enantiomeric substitution relative to racemate. This element can constrain infringement because the method must be practiced in a way that aims for reduced side effects as compared with chronic racemic use.
- Bronchodilation: functional requirement; does not limit to a specific assay but generally requires a clinically meaningful bronchodilator response.
How much does the purity threshold narrow infringement risk (Claims 2 and 3)?
Claim 2 narrows to:
- R(-) > 90% by weight of total albuterol.
Claim 3 further narrows to:
- R(-) > 99% by weight of total albuterol.
Practical interpretation for landscape mapping
For freedom-to-operate analysis, these numeric thresholds create a ladder:
- A product/process that supplies R(-) albuterol with S(+) impurity above tolerances could still potentially fall under claim 1 depending on what “substantially free” means, but will be less likely to meet claim 2 and especially claim 3.
- Products formulated to >90% or >99% R(-) land in higher-risk zones.
What dosing ranges define the method (Claims 4 and 5)?
Claim 4: inhalation dosing range
- 30 mcg to 90 mcg of the R(-) isomer per dose, by inhalation.
Claim 5: oral dosing range and schedule
- 1 mg to 8 mg, two to four times daily (oral administration).
Scope effects
- Claims 4 and 5 are independent narrowing filters: a party practicing only inhaled dosing outside the band, or oral dosing outside the band/frequency, may avoid those dependent claims (though claim 1 could still be asserted depending on whether the practice fits “sufficient quantity” and “chronic administration” with reduced side effects).
- These ranges are specific enough to be used directly in product strategy (dose selection, formulation targets, labeling regimen).
How broad is the combination therapy extension (Claims 6 and 7)?
Claim 6 extends claim 1 by requiring:
- Chronic administration of optically pure R(-) albuterol sufficient for bronchodilation and reduced side effects, and
- at least one additional drug selected from:
- bronchodilators
- antihistamines
- analgesics
Claim 7 narrows analgesic selection to:
- aspirin, acetaminophen, or ibuprofen.
Practical scope mapping
Claim 6 is structurally broad because it covers at least one co-administered drug from three broad classes. It does not limit the exact bronchodilator or antihistamine. It narrows only for analgesics by naming three members.
From an infringement standpoint, the combination clause can capture standard asthma polytherapy patterns, but only where the enantiomeric R(-) albuterol is administered as claimed and the regimen is practiced as a chronic method.
What is the overall claim chart coverage of US 5,362,755?
Below is a compact mapping of scope elements to each claim:
| Claim |
Treatment target |
Enantiomer requirement |
Purity numeric threshold |
Administration mode |
Dose / schedule limits |
Co-therapy |
| 1 |
Asthma |
Optically pure R(-) |
Substantially free of S(+) |
Any (implied by bronchodilation; no modality fixed) |
Quantity sufficient (no numeric dose) |
No |
| 2 |
Asthma |
R(-) |
>90% by weight |
Any |
Quantity sufficient |
No |
| 3 |
Asthma |
R(-) |
>99% by weight |
Any |
Quantity sufficient |
No |
| 4 |
Asthma |
R(-) |
Not specified beyond claim 1 |
Inhalation |
30 to 90 mcg per dose |
No |
| 5 |
Asthma |
R(-) |
Not specified beyond claim 1 |
Oral |
1 to 8 mg, 2 to 4 times daily |
No |
| 6 |
Asthma |
R(-) |
Incorporates claim 1 scope |
Any |
Incorporates claim 1, plus combination |
Yes: bronchodilator OR antihistamine OR analgesic |
| 7 |
Asthma |
R(-) |
Incorporates claim 6 scope |
Any |
Incorporates claim 6 |
Analgesic must be aspirin/acetaminophen/ibuprofen |
Where does US 5,362,755 sit in the albuterol patent landscape?
US 5,362,755 fits a well-known pattern in enantiomer drug strategy: using stereochemical separation to differentiate efficacy and tolerability relative to racemate, then claiming the method of treating disease with the single enantiomer under chronic conditions.
In market terms, this claim set tends to land in a mid-to-high risk zone for:
- Labeling/regimen that explicitly uses R(-) albuterol for asthma and implies side-effect reduction versus racemic therapy.
- Formulations that target high enantiomeric purity (especially >90% and >99% R(-)).
- Dose selections within the stated inhaled and oral bands.
- Polytherapy instructions that pair R(-) albuterol with drugs in the covered classes.
What does the claim language imply about “enantiomeric switching” versus “new molecular entity”?
The claims do not require discovery of a new chemical structure beyond the stereoisomer. The novelty is framed around:
- Using the R(-) enantiomer in chronic asthma treatment, and
- reducing undesirable side effects linked to chronic racemic administration.
That combination typically strengthens the patent’s ability to reach method practice even if racemate is widely known, because infringement focuses on how the method is conducted (which enantiomer, purity, chronic schedule, and dose range).
How should companies map US 5,362,755 to product decisions (freedom-to-operate levers)?
The actionable levers embedded in the claims are:
Enantiomer purity (highest leverage)
- Products aiming for >99% R(-) are closest to claims 2 and 3.
- Products with lower R(-) purity may still be argued to satisfy “substantially free” under claim 1, but they reduce the probability of meeting the numeric dependents.
Dose band by route (high leverage for dependent-claim exposure)
- Inhaled: 30 to 90 mcg per dose is a direct target in claim 4.
- Oral: 1 to 8 mg, 2 to 4 times daily is a direct target in claim 5.
Regimen duration (method framing)
- The claims require chronic administration. Short-course bronchodilator use may reduce risk if the practice is not plausibly “chronic.”
Product labeling and combination regimens (medium-to-high leverage)
- Claim 6 can be triggered by combination with commonly used asthma co-therapies if those fall within the broad classes.
- Claim 7 adds specific risk if an analgesic such as aspirin, acetaminophen, or ibuprofen is co-administered as part of the method practice.
What is the likely claim strength profile based on the language structure?
- Claim 1 is broad in modality and dose specificity, but still anchored by:
- asthma indication
- chronic administration
- optically pure R(-)
- substantially free of S(+)
- bronchodilation plus reduced side effects
- Claims 2 and 3 are narrower due to purity thresholds and provide clear numeric infringement hooks.
- Claims 4 and 5 are narrowest because they add specific dose ranges and schedules.
- Claims 6 and 7 are narrower than claim 1 but extend reach into multi-drug regimens, which can capture real-world clinical practice.
Key Takeaways
- US 5,362,755 covers method treatment of asthma with chronic R(-) albuterol where the R(-) is optically pure and substantially free of S(+), to achieve bronchodilation with reduced side effects versus chronic racemic albuterol.
- Purity thresholds drive risk granularity: >90% R(-) (claim 2) and >99% R(-) (claim 3).
- Dose and route further define dependent-claim exposure: inhaled 30 to 90 mcg per dose (claim 4) and oral 1 to 8 mg, 2 to 4 times daily (claim 5).
- Combination therapy expands coverage to co-administration of a drug from bronchodilators, antihistamines, or analgesics (claim 6), with analgesic narrowing to aspirin, acetaminophen, or ibuprofen (claim 7).
FAQs
1) Does US 5,362,755 claim an albuterol composition or a treatment method?
It claims a method of treating asthma, defined by chronic administration of optically pure R(-) albuterol with functional outcomes and side-effect reduction language.
2) What enantiomer purity levels are explicitly claimed?
The dependents explicitly claim R(-) >90% by weight (claim 2) and R(-) >99% by weight (claim 3). Claim 1 requires R(-) that is substantially free of S(+).
3) Are specific inhaled and oral dosing regimens required?
Dependent claims do: 30 to 90 mcg per dose inhaled (claim 4) and 1 to 8 mg orally, two to four times daily (claim 5).
4) Can the patent cover combination therapy?
Yes. Claim 6 requires chronic R(-) albuterol administration plus at least one additional drug from bronchodilators, antihistamines, or analgesics, and claim 7 specifies analgesic choices.
5) What is the main differentiator versus racemic albuterol in the claims?
The method requires reduced undesirable side effects during chronic asthma treatment relative to chronic racemic albuterol use, achieved by administering optically pure R(-) albuterol.
References
- United States Patent No. 5,362,755.
