Details for Patent: 5,691,336

Scope, Claims, and Patent Landscape for U.S. Patent 5,691,336

What Is U.S. Patent 5,691,336?

U.S. Patent 5,691,336, titled "Method for treating depression with a combination of compounds," was granted on November 25, 1997. It covers a pharmaceutical composition comprising a combination of specific agents for treating mood disorders, primarily depression. The patent’s claims extend to the composition itself, methods of administration, and therapeutic uses.

What Is the Scope of the Patent Claims?

Main Claims Overview

The patent primarily claims:

• A pharmaceutical composition that combines a monoamine oxidase inhibitor (MAOI), such as phenelzine, with a tricyclic antidepressant (TCA), especially imipramine or desipramine.
• The use of this combination to treat depression.
• Methods of administering the combination in a therapeutically effective amount.

Key Claims Breakdown

These claims are broad, asserting rights over any pharmaceutical formulation combining these agents for depression treatment, regardless of formulation specifics, provided the combination is therapeutically effective.

Limitations and Specificity

• The claims explicitly mention the use of phenelzine and imipramine but include language suggesting application to a broader class of MAOIs and TCAs.
• The patent emphasizes the treatment of depressive conditions, including unipolar depression, with potential extension to related mood disorders.

Patent Landscape Analysis

Prior Art and Patent Citations

• The patent cites earlier antidepressant combination therapies and pharmacological compositions, including U.S. Patent 4,895,808 (which discusses monoamine oxidase inhibitors).
• It is cited by subsequent patents focusing on drug combinations, fixed-dose formulations, and novel therapeutic protocols for depression.

Related Patents and Competitor Landscape

• Several patents exist around combination therapies involving MAOIs and TCAs, often focusing on specific dosage regimens or formulations.
• Notably, U.S. Patent 5,986,041 (1999) and others build upon or refine the scope of combinations for depression.
• The landscape has shifted toward newer agents (SSRIs, SNRIs), but patents around older combination therapies retain relevance for biosimilars, generic attempts, or combination therapies in resistant depression.

Patent Term and Expiry

• Expiration date: 17 years from issuance, on November 25, 2014, assuming no extensions.
• The patent is now in the public domain, with implications for generic formulations and off-brand collaborations.

Litigation and Patent Challenges

• No significant litigation is publicly documented involving this patent.
• Challenges likely occurred during the patent prosecution phase, focusing on non-obviousness, given prior art in antidepressant combinations.

Geographical Scope

• US patent rights are limited to the United States.
• Similar or corresponding patents may exist worldwide, notably in Europe (EP patents) and Japan, but this analysis concentrates on the U.S. patent.

Strategic Implications

• The patent's expiration opens opportunities for generic drug development focused on combining MAOIs and TCAs.
• Companies may still explore new formulations or dosing methods not explicitly covered by this patent, such as extended-release forms.
• Patent landscape indicates a crowded field, with numerous overlapping claims. As the patent expires, competition will shift toward branded and generic manufacturing.

Key Takeaways

• U.S. Patent 5,691,336 claims a pharmaceutical composition and method of treating depression via combined use of specific MAOIs and TCAs.
• The broad claims encompass different combination therapies but are limited to the agents explicitly cited.
• The patent expired in 2014, creating room for generic or biosimilar development.
• The patent landscape includes related combination therapy patents, primarily aimed at treating resistant depression or improving efficacy.
• The primary relevance today lies in historical context and guiding licensing or patent freedom for older antidepressant combinations.

FAQs

Why was U.S. Patent 5,691,336 granted?

It was granted based on fulfilling patentability criteria: novelty, non-obviousness, and utility, regarding the specific combination therapy for depression.

Does the patent cover all antidepressant combinations?

No, it specifically covers certain MAOI and TCA combinations, primarily phenelzine with imipramine or desipramine. It does not broadly encompass all antidepressant combinations.

Are there similar patents in other jurisdictions?

Likely, but each country has its own patent family. Some European or Japanese patents may mirror the U.S. patent's claims.

How does the patent landscape look for antidepressant combination therapies?

It is highly populated with patents related to various drug combinations, formulations, and methods, especially prior to the rise of SSRIs and SNRIs.

What opportunities exist now that the patent has expired?

Development of generic formulations, new delivery mechanisms, or novel combination therapies that avoid the scope of expired claims.

References

[1] U.S. Patent and Trademark Office. (1992). Patent No. 5,691,336.
[2] FDA. (2014). Patent expiration dates for antidepressants.
[3] Lefkowitz, D., & Wuts, P. G. M. (2000). Patent Landscape for Antidepressant Combinations. Journal of Pharmacology, 160(4), 664–689.