How Gilead Made a Stable HIV Pill Combining Two Medicines
This patent describes a stable, single-pill combination of two HIV drugs, tenofovir disoproxil fumarate and emtricitabine, designed to prevent them from breaking down when stored together.
Original patent title: “Compositions and methods for combination antiviral therapy”
This patent describes a stable, single-pill combination of two HIV drugs, tenofovir disoproxil fumarate and emtricitabine, designed to prevent them from breaking down when stored together. Granted to Gilead Sciences Inc in 2013 with 30 claims and 19 forward citations.
Key facts
Coverage
What does this patent actually cover?
The patent claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more → a specific pharmaceutical recipe that combines 300 mg of tenofovir disoproxil fumarate and 200 mg of emtricitabine into one oral pill. Because these two chemicals are chemically incompatible and tend to degrade when mixed, the patent specifies a precise blend of binders, disintegrants, and lubricants—such as pregelatinized starch and magnesium stearate—to stabilize the mixture. This ensures the pill remains effective for at least six months, even under high-heat and high-humidity conditions, by preventing the active ingredients from breaking down into inactive or harmful components.
The gap
What does this patent NOT cover?
- Does not cover the individual chemical structures of tenofovir disoproxil fumarate or emtricitabine themselves.
- Does not cover combinations of these drugs with other active ingredients not specified in the claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →.
- Does not cover dosage forms that do not meet the specific stability requirement of less than 10% degradation over 6 months at 40 degrees Celsius.
- Does not cover liquid or injectable versions of these drugs.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The innovation lies in solving the chemical incompatibility between the two drugs, which otherwise react to degrade each other. By selecting specific excipients that act as a buffer, the inventors created a stable solid-state environment that prevents this degradation.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Truvada
Why it matters
The bigger picture
This patent is the foundation for Truvada, a landmark medication in HIV treatment and prevention. By combining two drugs into one pill, Gilead significantly improved patient compliance, as taking one pill daily is far easier than managing multiple separate medications. This innovation helped transform HIV from a fatal diagnosis into a manageable chronic condition.
Filed
August 20, 2008
Granted
November 26, 2013
Market context
Who's building on this
Companies in this space
Gilead Sciences continues to build on this foundation with subsequent combination therapies for HIV, such as Descovy. Other pharmaceutical companies have also developed generic versions of this combination following the expiration of certain patent protections.
Market impact
This patent enabled the creation of a 'fixed-dose combination' market for HIV, which became the standard of care. It simplified treatment regimens, increased adherence, and eventually enabled the use of these drugs for PrEP (pre-exposure prophylaxis), which has been a major factor in global HIV prevention efforts.
Claim 1 — Plain English
What this patent covers
The patent claims a specific pharmaceutical recipe that combines 300 mg of tenofovir disoproxil fumarate and 200 mg of emtricitabine into one oral pill. Because these two chemicals are chemically incompatible and tend to degrade when mixed, the patent specifies a precise blend of binders, disintegrants, and lubricants—such as pregelatinized starch and magnesium stearate—to stabilize the mixture. This ensures the pill remains effective for at least six months, even under high-heat and high-humidity conditions, by preventing the active ingredients from breaking down into inactive or harmful components.
The clever bit
The innovation lies in solving the chemical incompatibility between the two drugs, which otherwise react to degrade each other. By selecting specific excipients that act as a buffer, the inventors created a stable solid-state environment that prevents this degradation.
What it does not cover
- Does not cover the individual chemical structures of tenofovir disoproxil fumarate or emtricitabine themselves.
- Does not cover combinations of these drugs with other active ingredients not specified in the claims.
- Does not cover dosage forms that do not meet the specific stability requirement of less than 10% degradation over 6 months at 40 degrees Celsius.
- Does not cover liquid or injectable versions of these drugs.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Moderate
Citation count
26/40
Moderately cited
Claim breadth
20/20
Very broad protection
Recency
5/20
Granted 10–20 years ago
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$176K – $562K
Midpoint $351K · 2.2 yr remaining · industry ×3.0
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
30 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Oliyai, R., Dahl, T. C., & Menning, M. M. (2013). How Gilead Made a Stable HIV Pill Combining Two Medicines (U.S. Patent No. 8,592,397). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/8592397/truvada-tdf-ftc-for-prep
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Gilead Made a Stable HIV Pill Combining Two Medicines cover?
This patent describes a stable, single-pill combination of two HIV drugs, tenofovir disoproxil fumarate and emtricitabine, designed to prevent them from breaking down when stored together.
Who owns patent US 8592397?
Gilead Sciences Inc owns this patent, granted in 2013.
When does this patent expire?
This patent is expected to expire on November 26, 2033, when the invention enters the public domain.
What is patent US 8592397 cited by?
This patent has been cited by 19 later patents that build on its ideas.
What problem does this patent solve?
This patent is the foundation for Truvada, a landmark medication in HIV treatment and prevention. By combining two drugs into one pill, Gilead significantly improved patient compliance, as taking one pill daily is far easier than managing multiple separate medications. This innovation helped transform HIV from a fatal diagnosis into a manageable chronic condition.
What does this patent NOT cover?
Does not cover the individual chemical structures of tenofovir disoproxil fumarate or emtricitabine themselves.
Same assignee
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