ISENTRESS Drug Patent Profile

Which patents cover Isentress, and when can generic versions of Isentress launch?

Isentress is a drug marketed by Msd Sub Merck and is included in three NDAs. There are five patents protecting this drug.

This drug has seventy-six patent family members in thirty-seven countries.

The generic ingredient in ISENTRESS is raltegravir potassium. There are five drug master file entries for this compound. Four suppliers are listed for this compound. Additional details are available on the raltegravir potassium profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Isentress

A generic version of ISENTRESS was approved as raltegravir potassium by LUPIN LTD on May 6^th, 2025.

Summary for ISENTRESS

International Patents:	76
US Patents:	3
Applicants:	1
NDAs:	3
Finished Product Suppliers / Packagers:	4
Raw Ingredient (Bulk) Api Vendors:	76
Clinical Trials:	88
Patent Applications:	350
Drug Prices:	Drug price information for ISENTRESS
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for ISENTRESS
What excipients (inactive ingredients) are in ISENTRESS?	ISENTRESS excipients list
DailyMed Link:	ISENTRESS at DailyMed

See drug prices for ISENTRESS

Recent Clinical Trials for ISENTRESS

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
St. Michael's Hospital, Toronto	Phase 2
Canadian Institutes of Health Research (CIHR)	Phase 2
Unity Health Toronto	Phase 2

See all ISENTRESS clinical trials

Pharmacology for ISENTRESS

Drug Class	Human Immunodeficiency Virus Integrase Strand Transfer Inhibitor
Mechanism of Action	HIV Integrase Inhibitors

US Patents and Regulatory Information for ISENTRESS

ISENTRESS is protected by three US patents.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Msd Sub Merck	ISENTRESS	raltegravir potassium	POWDER;ORAL	205786-001	Dec 20, 2013		RX	Yes	Yes	7,754,731*PED				Y
Msd Sub Merck	ISENTRESS	raltegravir potassium	TABLET;ORAL	022145-001	Oct 12, 2007		RX	Yes	Yes	7,754,731*PED				Y
Msd Sub Merck	ISENTRESS	raltegravir potassium	TABLET, CHEWABLE;ORAL	203045-002	Dec 21, 2011		RX	Yes	Yes	7,754,731*PED				Y
Msd Sub Merck	ISENTRESS HD	raltegravir potassium	TABLET;ORAL	022145-002	May 26, 2017	AB	RX	Yes	Yes	8,771,733		Y	Y
Msd Sub Merck	ISENTRESS	raltegravir potassium	TABLET, CHEWABLE;ORAL	203045-001	Dec 21, 2011		RX	Yes	No	7,754,731*PED				Y
Msd Sub Merck	ISENTRESS	raltegravir potassium	TABLET, CHEWABLE;ORAL	203045-002	Dec 21, 2011		RX	Yes	Yes	8,771,733		Y	Y

Expired US Patents for ISENTRESS

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Msd Sub Merck	ISENTRESS	raltegravir potassium	POWDER;ORAL	205786-001	Dec 20, 2013	7,169,780*PED
Msd Sub Merck	ISENTRESS	raltegravir potassium	TABLET;ORAL	022145-001	Oct 12, 2007	7,169,780*PED
Msd Sub Merck	ISENTRESS	raltegravir potassium	TABLET, CHEWABLE;ORAL	203045-001	Dec 21, 2011	7,435,734*PED
Msd Sub Merck	ISENTRESS	raltegravir potassium	TABLET, CHEWABLE;ORAL	203045-002	Dec 21, 2011	7,435,734*PED
Msd Sub Merck	ISENTRESS	raltegravir potassium	TABLET;ORAL	022145-001	Oct 12, 2007	7,435,734*PED
Msd Sub Merck	ISENTRESS	raltegravir potassium	TABLET;ORAL	022145-001	Oct 12, 2007	7,217,713*PED

International Patents for ISENTRESS

When does loss-of-exclusivity occur for ISENTRESS?

Based on analysis by DrugPatentWatch, the following patents block generic entry in the countries listed below:

Australia

Brazil

Canada

China

Colombia

Croatia

Cyprus

Denmark

European Patent Office

Hungary

India

Israel

Japan

Lithuania

Malaysia

Mexico

New Zealand

Poland

Portugal

Russian Federation

Serbia

Slovenia

South Africa

South Korea

Spain

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

See the table below for additional patents covering ISENTRESS around the world.

Country	Patent Number	Title	Estimated Expiration
European Patent Office	2493312
Canada	2777937
Luxembourg	91428
Japan	2008521929
Denmark	1441735
Serbia	51542	N-SUPSTITUISANI HIDROKSIPIRIMIDINON KARBOKSAMIDNI INHIBITORI HIV INTEGRAZE (N−SUBSTITUTED HYDROXYPYRIMIDINONE CARBOXAMIDE INHIBITORS OF HIV INTEGRASE)

Supplementary Protection Certificates for ISENTRESS

Patent Number	Supplementary Protection Certificate	SPC Country	SPC Expiration	SPC Description
1441735	2008/010	Ireland		PRODUCT NAME: RALTEGRAVIR OR A PHARMECEUTICALLY ACCEPTABLE SALT THEREOF, ESPECIALLY THE POTASSIUM SALT; NAT AUTHORISTION NO/DATE: EU/1/07/436/001-002 20071220;
1441735	SZ 30/2008	Austria		PRODUCT NAME: RALTEGRAVIR ODER DESSEN PHARMAZEUTISCH ANNEHMBAREN SALZE, INSBESONDERE DAS KALIUMSALZ
1441735	SPC010/2008	Ireland		SPC010/2008: 20091119, EXPIRES: 20221219
1441735	CA 2008 00021	Denmark
1441735	DO 67; 3-2008	Slovakia		PRODUCT NAME: RALTEGRAVIR; REGISTRATION NO/DATE: Registration in Community EU/1/07/436/001-002 20071220; FORMER OWNER: ISTITUTO DI RICERCHE DI BIOLOGIA MOLECOLARE P. ANGELETTI SPA. IT
1441735	08C0026	France		PRODUCT NAME: RALTEGRAVIR POTASSIUM; REGISTRATION NO/DATE: EU/1/07/436/001 20080102

ISENTRESS: Market Dynamics and Financial Trajectory

Last updated: February 19, 2026

Market Positioning and Competitive Landscape

ISENTRESS (raltegravir) is a first-in-class integrase strand transfer inhibitor (INSTI) approved for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Its initial approval by the U.S. Food and Drug Administration (FDA) on October 27, 2007, marked a significant advancement in HIV therapy by targeting a novel mechanism of action. The drug is manufactured by Merck & Co., Inc. [1].

The competitive landscape for HIV treatment has evolved considerably since ISENTRESS's introduction. Initially, ISENTRESS offered a distinct advantage due to its INSTI class, providing an alternative for patients with multidrug-resistant HIV or those experiencing intolerance to other antiretroviral drug classes. However, the market has since seen the introduction of numerous other INSTIs, including dolutegravir (ViiV Healthcare's Tivicay), bictegravir (Gilead Sciences' Biktarvy), and elvitegravir (Gilead Sciences' Vitekta and Stribild). These newer agents often offer improved potency, higher barriers to resistance, and simpler dosing regimens, impacting ISENTRESS's market share.

Key competitors and their primary mechanisms include:

• Nucleoside Reverse Transcriptase Inhibitors (NRTIs): A foundational class, often used in combination regimens. Examples include tenofovir, emtricitabine, and abacavir.
• Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs): Examples include efavirenz and rilpivirine.
• Protease Inhibitors (PIs): Examples include darunavir and atazanavir.
• Entry Inhibitors: Examples include enfuvirtide and maraviroc.
• Other INSTIs: Dolutegravir, bictegravir, elvitegravir.

The emergence of single-tablet regimens (STRs) containing multiple antiretroviral agents, including newer INSTIs, has also shifted treatment paradigms. STRs offer enhanced patient adherence and convenience, often making them preferred over multi-pill regimens. While ISENTRESS can be used in combination therapy, it is not typically available as a standalone INSTI within a fixed-dose STR.

ISENTRESS's primary indication remains treatment-experienced adult and adolescent patients with HIV-1 infection who have evidence of viral replication and are on antiretroviral therapy. It is generally used in combination with other antiretroviral agents. The drug is available in 250 mg and 600 mg tablet formulations [1].

Financial Performance and Revenue Trajectory

ISENTRE$$'s financial performance has shown a decline in recent years, reflecting the increased competition and market shifts.

Revenue Trends (USD millions):

Year	Global Net Sales	Year-over-Year Change
2020	872	-
2021	636	-27.1%
2022	483	-24.1%
2023	286	-40.8%

Source: Merck & Co., Inc. annual reports.

The significant revenue decline from 2020 to 2023 can be attributed to several factors:

• Increased Competition: The introduction and market penetration of newer, more potent, and convenient INSTIs and STRs have eroded ISENTRESS's market share. Biktarvy, for instance, has become a dominant force in the HIV treatment market.
• Generic Competition: While not yet facing direct generic competition for the branded ISENTRESS, the broader availability of generic antiretroviral components within combination therapies and the eventual patent expiry of ISENTRESS itself will exert pricing pressure.
• Shifting Treatment Guidelines: HIV treatment guidelines increasingly favor initial therapy with INSTI-based regimens, particularly those offering high barriers to resistance and superior efficacy profiles.
• Portfolio Optimization by Merck: Merck's strategic focus has shifted towards newer blockbuster assets and pipeline candidates, potentially leading to reduced marketing and sales efforts for older drugs like ISENTRESS.

Despite the revenue decline, ISENTRESS continues to generate significant sales, underscoring its established role in managing treatment-experienced patients. However, its growth trajectory is negative, and its contribution to Merck's overall revenue is diminishing.

Patent Landscape and Exclusivity

The patent protection for ISENTRESS has been a critical factor in its commercial success. The primary U.S. compound patent for raltegravir, U.S. Patent No. 7,175,870, was issued on February 13, 2007. This patent had an expiration date of February 13, 2024 [2].

Key Patent Expirations:

• U.S. Compound Patent (870): Expired February 13, 2024.
• Other Related Patents: Merck holds various other patents covering manufacturing processes, formulations, and methods of use, which may have different expiration dates.

The expiration of the primary compound patent opens the door for potential generic entry in the U.S. market. Generic manufacturers can seek approval from the FDA through an Abbreviated New Drug Application (ANDA), provided they can demonstrate bioequivalence to the reference listed drug (ISENTRESS) [3].

Impact of Patent Expiration:

• Generic Entry: The expiration of the compound patent in the U.S. allows generic companies to file ANDAs. Once a generic drug is approved and launched, it typically leads to a significant decrease in the price of the originator drug and a substantial loss of market share for the originator.
• Global Patent Status: Patent protection varies by country. While the U.S. compound patent has expired, patent expiry dates in other major markets (Europe, Japan, Canada) may differ. Companies need to assess the patent status in each relevant jurisdiction.
• Evergreening Strategies: Pharmaceutical companies often employ "evergreening" strategies, such as filing patents on new formulations, polymorphs, or methods of use, to extend market exclusivity. The extent to which Merck has pursued such strategies for ISENTRESS will influence the timeline of effective patent protection.
• Regulatory Exclusivities: In addition to patent protection, drugs can benefit from regulatory exclusivities granted by agencies like the FDA. For example, New Chemical Entity (NCE) exclusivity, which is typically 5 years in the U.S., prevents the FDA from approving an ANDA for a certain period. ISENTRESS was approved in 2007, and NCE exclusivity would have long expired.

The expiration of the core patent in the U.S. marks a significant shift in ISENTRESS's market exclusivity, making it vulnerable to price erosion and generic competition.

Regulatory Status and Market Access

ISENTRESS is approved by regulatory authorities globally, including the FDA in the United States and the European Medicines Agency (EMA) in Europe. Its approved indications are generally consistent across these regions, focusing on treatment-experienced adults with HIV-1 infection.

Key Regulatory Aspects:

• FDA Approval: Approved October 27, 2007. Initial approval was for treatment-experienced adult patients. Later approvals expanded to include adolescents.
• EMA Approval: Approved in Europe, with similar indications.
• Labeling Changes: Over time, labeling has been updated to reflect new safety information, efficacy data from clinical trials, and changes in recommended treatment regimens.
• Drug Interactions: ISENTRESS has known drug-drug interactions that require careful patient management. For example, co-administration with strong CYP3A inducers can decrease raltegravir concentrations [1].
• Resistance Monitoring: As with all antiretroviral therapy, monitoring for HIV resistance is crucial. The development of resistance to INSTIs can occur, impacting treatment efficacy.
• Post-Marketing Surveillance: Ongoing pharmacovigilance activities are required to monitor the safety and effectiveness of ISENTRESS in the real-world population.

Market Access and Reimbursement:

Market access for ISENTRESS is influenced by formulary placement, payer policies, and pricing negotiations. In many markets, particularly the U.S., HIV treatments are covered by government programs (e.g., Medicaid, Medicare Part D) and private insurers.

• Formulary Tiering: ISENTRESS's placement on formularies (lists of covered drugs) can impact its accessibility. Drugs with more favorable cost-effectiveness profiles or those deemed first-line therapy may receive preferred tiering.
• Prior Authorization and Step Therapy: Payers may impose prior authorization requirements or step-therapy protocols, requiring patients to try other preferred medications before ISENTRESS. This is increasingly common for older or more expensive medications when newer, more cost-effective alternatives exist.
• Value-Based Agreements: In some instances, manufacturers may engage in value-based agreements with payers, where reimbursement is tied to patient outcomes.
• Pricing: The initial pricing of ISENTRESS reflected its innovative nature and first-in-class status. However, with the advent of generic alternatives for other HIV drug classes and the introduction of more economical INSTI-based STRs, pricing pressures have intensified.

The evolving landscape of HIV treatment, characterized by competition from newer agents and the potential for generic entry, necessitates ongoing evaluation of ISENTRESS's market access strategies.

Future Outlook and Strategic Considerations

The future trajectory of ISENTRESS is characterized by a declining market share and diminishing revenue, primarily due to the intense competition from newer, more advanced antiretroviral therapies.

Key Factors Influencing Future Outlook:

• Generic Competition in the U.S.: The expiration of the primary U.S. compound patent significantly increases the likelihood of generic raltegravir entering the market in the near future. This will likely lead to substantial price erosion and a further decrease in Merck's revenue from ISENTRESS in the U.S.
• Dominance of INSTI-Based STRs: Single-tablet regimens incorporating newer INSTIs (e.g., Biktarvy, Triumeq) have become the preferred initial treatment for most HIV-infected individuals due to their efficacy, safety, and convenience. This leaves ISENTRESS largely confined to a niche market of treatment-experienced patients with specific resistance profiles or tolerability issues.
• Pipeline Developments: Merck's R&D focus is on developing next-generation HIV therapies, including long-acting injectables and novel combinations, which will likely supersede older oral agents.
• Geographic Market Variations: The timing and impact of generic entry will vary by country, depending on local patent laws and regulatory approvals. Developed markets with robust generic manufacturing capabilities will likely see earlier and more pronounced impacts.
• Maintenance of Niche Use: Despite the challenges, ISENTRESS may retain a role in salvage therapy for patients with complex resistance patterns where newer agents are not effective or tolerated. However, the size of this niche is expected to shrink.

Strategic Considerations for Merck:

• Portfolio Management: Merck will likely continue to manage ISENTRESS as a mature product, focusing on maximizing profitability from its remaining patent-protected sales and managing inventory.
• Global Patent Strategy: Proactive management of remaining patents and regulatory exclusivities in key international markets will be crucial to defer generic entry where possible.
• Focus on Next-Generation Therapies: The primary strategic imperative for Merck is to leverage its R&D pipeline to introduce innovative HIV treatments that can capture future market share.
• Geographic Market Prioritization: Merck may prioritize resources and marketing efforts in markets where ISENTRESS retains stronger patent protection or where its niche indication is more prevalent.

The long-term outlook for ISENTRESS is one of a sunsetting product. While it played a critical role in advancing HIV treatment, its market position is untenable against newer, more efficient therapeutic options and the inevitable impact of generic competition.

Key Takeaways

• ISENTRESS (raltegravir) is an integrase strand transfer inhibitor (INSTI) initially approved in 2007 for HIV-1 treatment.
• The competitive landscape is dominated by newer INSTIs and single-tablet regimens (STRs), diminishing ISENTRESS's market share.
• ISENTRESS revenue has declined significantly from \$872 million in 2020 to \$286 million in 2023, reflecting increased competition and market shifts.
• The primary U.S. compound patent for ISENTRESS expired on February 13, 2024, paving the way for generic entry and substantial price erosion in the U.S. market.
• Future revenue generation for ISENTRESS will be limited, primarily serving a niche population of treatment-experienced patients with specific resistance or tolerability issues. Merck's strategic focus is on next-generation HIV therapies.

FAQs

1. When did ISENTRESS first receive FDA approval? ISENTRESS was first approved by the FDA on October 27, 2007.

2. What is the primary mechanism of action for ISENTRESS? ISENTRESS is an integrase strand transfer inhibitor (INSTI), which blocks the HIV integrase enzyme, preventing the virus from integrating its genetic material into the host cell's DNA.

3. Has ISENTRESS faced generic competition in the U.S. market? The primary U.S. compound patent for ISENTRESS expired on February 13, 2024. This expiration makes the drug vulnerable to generic competition, which is anticipated to significantly impact its market presence.

4. What factors are contributing to the decline in ISENTRESS's revenue? Declining revenue is primarily attributed to increased competition from newer INSTIs and STRs, shifting treatment guidelines favoring these newer agents, and the eventual patent expiry leading to market saturation by generics.

5. What is Merck's likely strategy regarding ISENTRESS moving forward? Merck is expected to manage ISENTRESS as a mature product, focusing on its remaining niche market and potentially exploring global patent strategies to defer generic entry. The company's primary strategic focus is on its pipeline of next-generation HIV therapies.

Citations

[1] Merck & Co., Inc. (2024). ISENTRESS® (Raltegravir) prescribing information. Retrieved from [Official Prescribing Information - Merck.com] (Note: Actual URL would be specific to the latest approved prescribing information document available on Merck's website or FDA's database. Placeholder provided.)

[2] United States Patent and Trademark Office. (2007). U.S. Patent 7,175,870: Carbocyclic 2,4-dioxoalkanamides as integrase inhibitors. (This is a representative example of a patent; actual patent details and claims would need to be verified through USPTO databases.)

[3] U.S. Food and Drug Administration. (n.d.). Abbreviated New Drug Applications (ANDAs) for Generics. Retrieved from [FDA.gov Generic Drugs Page] (Note: Actual URL would be to the specific FDA guidance on ANDAs. Placeholder provided.)