DELAVIRDINE MESYLATE - Generic Drug Details

What are the generic sources for delavirdine mesylate and what is the scope of patent protection?

Delavirdine mesylate is the generic ingredient in one branded drug marketed by Viiv Hlthcare and is included in one NDA. Additional information is available in the individual branded drug profile pages.

Summary for DELAVIRDINE MESYLATE

US Patents:	0
Tradenames:	1
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	66
Clinical Trials:	18
DailyMed Link:	DELAVIRDINE MESYLATE at DailyMed

Recent Clinical Trials for DELAVIRDINE MESYLATE

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

Sponsor	Phase
Agouron Pharmaceuticals	N/A
Pharmacia and Upjohn	Phase 3
National Institute of Allergy and Infectious Diseases (NIAID)	Phase 2

See all DELAVIRDINE MESYLATE clinical trials

Medical Subject Heading (MeSH) Categories for DELAVIRDINE MESYLATE

Anti-HIV Agents

Reverse Transcriptase Inhibitors

Anatomical Therapeutic Chemical (ATC) Classes for DELAVIRDINE MESYLATE

J05AG	Non-nucleoside reverse transcriptase inhibitors
J05A	DIRECT ACTING ANTIVIRALS
J05	ANTIVIRALS FOR SYSTEMIC USE
J	Antiinfectives for systemic use

US Patents and Regulatory Information for DELAVIRDINE MESYLATE

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Viiv Hlthcare	RESCRIPTOR	delavirdine mesylate	TABLET;ORAL	020705-002	Jul 14, 1999		DISCN	Yes	No
Viiv Hlthcare	RESCRIPTOR	delavirdine mesylate	TABLET;ORAL	020705-001	Apr 4, 1997		DISCN	Yes	No

Expired US Patents for DELAVIRDINE MESYLATE

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Viiv Hlthcare	RESCRIPTOR	delavirdine mesylate	TABLET;ORAL	020705-001	Apr 4, 1997	5,563,142
Viiv Hlthcare	RESCRIPTOR	delavirdine mesylate	TABLET;ORAL	020705-002	Jul 14, 1999	6,177,101
Viiv Hlthcare	RESCRIPTOR	delavirdine mesylate	TABLET;ORAL	020705-002	Jul 14, 1999	5,563,142
Viiv Hlthcare	RESCRIPTOR	delavirdine mesylate	TABLET;ORAL	020705-001	Apr 4, 1997	6,177,101

Delavirdine Mesylate Market Dynamics, Financial Trajectory, Patents, and Generic Entry Risk

Last updated: September 9, 2026

Delavirdine mesylate, marketed as Rescriptor, is a discontinued or commercially inactive first-generation non-nucleoside reverse transcriptase inhibitor used to treat HIV-1 infection. FDA approval came in 1997, but the product lost clinical relevance as newer antiretroviral regimens offered better potency, simpler dosing, fewer drug interactions, and higher barriers to resistance. No meaningful current revenue stream, active exclusivity position, biosimilar exposure, or commercially significant patent barrier remains publicly evident for delavirdine mesylate.

What is the FDA status of delavirdine mesylate?

Delavirdine mesylate received FDA approval on September 4, 1997, under the brand name Rescriptor. The product was approved for use with other antiretroviral agents in adults with HIV-1 infection.

Regulatory item	Delavirdine mesylate
Brand	Rescriptor
Active ingredient	Delavirdine mesylate
Drug class	Non-nucleoside reverse transcriptase inhibitor
FDA approval	September 4, 1997
Original sponsor	The Upjohn Company
Dosage form	100 mg and 200 mg tablets
Primary indication	Combination treatment of HIV-1 infection
Current commercial position	No meaningful active branded market
Biosimilar status	Not applicable
Current clinical role	Obsolete in standard HIV treatment

The FDA label recommended delavirdine in combination with other antiretroviral agents. The approved adult regimen required 400 mg three times daily, which created a substantial adherence disadvantage compared with once-daily or fixed-dose combination therapies that later became standard of care (U.S. Food and Drug Administration [FDA], 2008).

The product also had extensive cytochrome P450-related drug interaction concerns. Delavirdine inhibited CYP3A and was affected by enzyme-inducing or enzyme-inhibiting medicines. These issues narrowed its use in a patient population frequently receiving multiple medicines.

When did delavirdine mesylate lose market exclusivity?

Delavirdine’s principal regulatory exclusivity expired many years ago. The five-year new chemical entity exclusivity associated with its 1997 approval would have ended in 2002, subject to any pediatric or other statutory extensions. No current FDA exclusivity period protects the product.

Exclusivity category	Estimated status
New chemical entity exclusivity	Expired, approximately 2002
Orphan-drug exclusivity	No established orphan exclusivity
Pediatric exclusivity	No material current effect
Patent exclusivity	Expired or commercially immaterial
Regulatory exclusivity today	None identified

Delavirdine was approved before the modern antiretroviral market consolidated around high-barrier integrase strand transfer inhibitor regimens. By the time generic competition could have become commercially attractive, the underlying product had already become clinically obsolete.

What patents protected Rescriptor?

The early delavirdine patent estate included Upjohn patent filings covering substituted heterocyclic compounds and related pharmaceutical compositions. A commonly associated patent is U.S. Patent No. 5,290,751, directed to substituted bisheteroaryl piperazine compounds. That patent issued in 1994 and is no longer an active commercial barrier.

Publicly available patent records do not indicate an active, enforceable U.S. patent estate capable of supporting a current branded monopoly for delavirdine mesylate. Any formulation, manufacturing, or method-of-use patents associated with the original development program would also have reached the end of their practical life.

Patent issue	Commercial assessment
Core compound patents	Expired
Tablet formulation patents	No current material barrier identified
Method-of-use patents	Expired or commercially irrelevant
Manufacturing patents	No current barrier to ordinary generic development identified
Patent term extension	No material extension identified
Current patent strength	Very weak

What is the Orange Book status of delavirdine mesylate?

The Orange Book historically included Rescriptor and associated patent information. The product’s historical listings do not create a current market advantage because the relevant patent and exclusivity periods have expired.

A current Orange Book strategy is unlikely to support branded lifecycle management for delavirdine. There is no apparent active listed patent position comparable to the estates supporting newer HIV products such as dolutegravir, bictegravir, or long-acting cabotegravir.

The practical distinction is important: an old Orange Book listing may document the historic approval and patent record, but it does not establish that a sponsor presently controls meaningful market exclusivity.

How did delavirdine’s market position change over time?

Delavirdine entered a competitive HIV market in which treatment choices were expanding rapidly. Its commercial trajectory can be divided into four phases.

Period	Market dynamics	Financial effect
1997-2000	Launch into early combination-therapy market	Initial sales opportunity
2000-2005	Competition from efavirenz, protease inhibitors, and improved regimens	Slower uptake and declining share
2005-2012	Growing use of once-daily and fixed-dose combinations	Accelerated erosion
2012 onward	Near-complete clinical displacement	Minimal or no meaningful commercial revenue

Launch and early adoption

Delavirdine entered the market as an NNRTI during the expansion of combination antiretroviral therapy. The drug benefited from the established clinical importance of combination treatment and from the commercial growth of HIV medicines in the late 1990s.

Its limitations were apparent at launch. The 400 mg three-times-daily dose was burdensome. Resistance could develop rapidly if virologic suppression was incomplete. The product also had a complex interaction profile and lacked the convenience of later fixed-dose combinations.

Competitive displacement

Efavirenz became a stronger NNRTI competitor because of once-daily dosing and broader use in combination regimens. Protease inhibitor combinations also improved, while later products offered greater potency and more durable viral suppression.

The largest competitive shift came from integrase inhibitors. Raltegravir, elvitegravir, dolutegravir, and bictegravir-based regimens displaced older NNRTIs in many treatment guidelines. Modern HIV guidelines generally recommend integrase inhibitor-based initial therapy rather than delavirdine-containing treatment (National Institutes of Health, 2024).

What were the main commercial weaknesses of delavirdine?

Delavirdine had several characteristics that reduced prescribing and limited its revenue potential.

Three-times-daily dosing

The dosing schedule was less convenient than competing once-daily products. HIV treatment depends on sustained adherence, making dosing frequency a material commercial and clinical factor.

Low resistance barrier

Delavirdine had a lower resistance barrier than leading modern agents. A single regimen failure could compromise activity across the NNRTI class, particularly when adherence was inconsistent.

Drug interactions

Delavirdine affected CYP3A metabolism and had clinically important interactions with other medicines. HIV patients often receive therapies for cardiovascular disease, psychiatric disorders, infections, and other comorbidities, making interaction risk commercially consequential.

Lack of fixed-dose combination participation

Delavirdine did not become part of a widely adopted fixed-dose combination. Fixed-dose products reduced pill burden and strengthened the commercial position of competing manufacturers.

Limited salvage value

As resistance accumulated and newer options became available, delavirdine offered little strategic value for treatment-experienced patients. Its clinical niche narrowed further after integrase inhibitors entered routine use.

What was the financial trajectory of delavirdine mesylate?

No reliable, separately reported public revenue series for delavirdine mesylate has been established in the annual reports of its successive corporate owners. The product was not disclosed as a material standalone revenue contributor in public company reporting.

Its financial trajectory is therefore best assessed through product lifecycle indicators rather than reported product-level sales.

Financial driver	Effect on delavirdine
Initial HIV market expansion	Supported launch revenue
Heavy competition	Limited peak share
Complex dosing	Reduced adherence and prescribing
Generic-era economics	Reduced pricing power
Clinical obsolescence	Eliminated growth potential
Discontinuation or inactive marketing	Reduced revenue to negligible levels

The product did not achieve the scale of leading HIV brands such as Sustiva, Atripla, Truvada, Isentress, Tivicay, or Biktarvy. Its financial value declined as prescribing shifted toward newer agents and as HIV treatment became increasingly concentrated in large combination products.

The lack of standalone revenue disclosure also reflects portfolio accounting. Rescriptor changed corporate ownership and was a minor product relative to the HIV portfolios of Upjohn, Pharmacia, Pfizer, and later ViiV Healthcare-related businesses. Small legacy products are often grouped into “other products” or excluded from individual revenue tables.

Which companies challenged or replaced delavirdine?

No current competitive company appears to be pursuing a major branded challenge to delavirdine. The product was displaced through therapeutic substitution rather than a major patent confrontation.

The principal competitive products included:

Competitor	Competitive advantage
Efavirenz	Once-daily dosing and established early-market use
Rilpivirine	Improved dosing convenience in selected patients
Raltegravir	Integrase inhibition and strong efficacy
Dolutegravir	High resistance barrier and once-daily dosing
Bictegravir	Fixed-dose combination and strong commercial adoption
Long-acting cabotegravir	Injectable administration for selected patients

The competitive landscape shifted from brand-versus-brand substitution to class-level displacement. Delavirdine was not replaced by a single direct generic competitor. It was replaced by more convenient, more potent, and more durable treatment architectures.

Is there biosimilar risk for delavirdine mesylate?

There is no biosimilar risk. Delavirdine mesylate is a small-molecule chemical drug, not a biologic. Any competitive entry would occur through the abbreviated new drug application pathway for generics, not through the biosimilar pathway under the Public Health Service Act.

The relevant commercial risk is generic availability combined with clinical obsolescence. Even if an approved generic product existed, the addressable market would be very small because treatment guidelines no longer favor delavirdine.

What generic entry risks exist for delavirdine?

The legal barrier to generic entry is low. The commercial incentive is also low.

A potential generic manufacturer would face limited patent risk because the core intellectual property has expired. The principal barriers would be:

• Small and declining demand.
• Limited prescriber use.
• Low reimbursement value.
• Manufacturing economics for a low-volume product.
• Potential difficulty securing a stable commercial supply chain.
• Competition from inexpensive and clinically preferred alternatives.

No material current Paragraph IV litigation or settlement agreement involving delavirdine mesylate is identified in the principal public regulatory record. A generic applicant would more likely pursue a conventional abbreviated new drug application with Paragraph III or Paragraph IV certifications depending on the status of any residual listed patents.

What manufacturing and intellectual-property barriers remain?

Manufacturing barriers are limited. Delavirdine is a conventional small-molecule tablet, and its chemical composition is not protected by an active exclusivity regime. The relevant technical work would involve active pharmaceutical ingredient synthesis, salt formation, tablet manufacture, dissolution performance, stability, and bioequivalence.

The main obstacle is economic rather than technical. A sponsor would need to justify development, registration, inventory, and distribution costs against a narrow market with limited demand.

Formulation patents are unlikely to create a meaningful current barrier. The original tablet formulation was not a differentiated delivery system, long-acting injectable, implant, or complex modified-release product. Delavirdine also lacks the device-related and manufacturing complexity that can extend lifecycle protection for newer therapies.

How does delavirdine compare with modern HIV drugs?

Attribute	Delavirdine	Modern integrase-based therapy
Dosing	Three times daily	Often once daily
Resistance barrier	Low to moderate	Generally higher
Drug interactions	Significant CYP3A concerns	Product-dependent, often more manageable
Fixed-dose combinations	No major commercial platform	Extensive use
Current guideline role	Generally obsolete	Preferred or recommended
Patent value	Expired	Often active
Revenue outlook	Negligible	Material for leading products
Generic threat	Legally possible but commercially limited	Often delayed by active patents

Delavirdine’s remaining value is primarily historical. It does not offer a credible platform for a new branded lifecycle strategy unless a sponsor identifies an unusual niche indication, which is not supported by current HIV treatment practice.

What is the outlook for delavirdine mesylate revenue?

The forward revenue outlook is negligible. Any residual sales would likely come from legacy inventory, exceptional access, isolated international markets, or patients maintained on older therapy when alternatives are unsuitable.

A relaunch would face substantial barriers:

1. No meaningful patent protection.
2. No regulatory exclusivity.
3. Weak guideline support.
4. Strong competition from low-cost generic and branded antiretroviral options.
5. Poor dosing convenience.
6. Limited prescriber familiarity and demand.
7. No established fixed-dose combination franchise.

The product has no credible path to material revenue growth under the current HIV treatment paradigm.

Key Takeaways

• Delavirdine mesylate was FDA-approved in 1997 as Rescriptor for combination treatment of HIV-1 infection.
• Its five-year new chemical entity exclusivity expired approximately in 2002.
• Core compound and formulation protection are expired or commercially immaterial.
• The drug’s three-times-daily dosing, drug interactions, and low resistance barrier weakened adoption.
• Efavirenz, protease inhibitors, integrase inhibitors, and fixed-dose combinations displaced delavirdine.
• No biosimilar pathway applies because delavirdine is a small-molecule drug.
• Generic entry is legally feasible but commercially unattractive.
• No material current Paragraph IV litigation or settlement activity is identified.
• Standalone revenue was not materially disclosed by the product’s corporate owners.
• Future revenue potential is negligible.

FAQs About Delavirdine Mesylate Market and Patent Risk

Is Rescriptor still commercially available in the United States?

Rescriptor is not a meaningful active product in the U.S. commercial market. Its historical FDA approval does not indicate current broad availability or routine use.

Did delavirdine mesylate have pediatric exclusivity?

No current pediatric exclusivity affects delavirdine mesylate. Any historical regulatory exclusivity has expired.

Can a generic company still launch delavirdine tablets?

A generic company could pursue approval if it satisfies FDA abbreviated new drug application requirements. The practical obstacle is limited market demand rather than patent protection.

Was delavirdine included in a major HIV fixed-dose combination?

No major commercially successful fixed-dose combination established delavirdine as a platform product. This limited its ability to compete with combination regimens containing efavirenz, rilpivirine, dolutegravir, or bictegravir.

Is delavirdine a potential licensing or acquisition asset?

Its licensing value is low. The product has no apparent active exclusivity, lacks guideline support, and has negligible expected revenue. Any transaction would be more likely to involve legacy regulatory rights or market access in a narrow jurisdiction than a growth-oriented HIV asset.

References

1. National Institutes of Health. (2024). Guidelines for the use of antiretroviral agents in adults and adolescents with HIV. ClinicalInfo.HIV.gov. https://clinicalinfo.hiv.gov/en/guidelines

2. U.S. Food and Drug Administration. (1997). Rescriptor approval information and prescribing information. Drugs@FDA. https://www.accessdata.fda.gov/scripts/cder/daf/

3. U.S. Food and Drug Administration. (2008). Rescriptor (delavirdine mesylate) tablets prescribing information. DailyMed. https://dailymed.nlm.nih.gov/dailymed/

4. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book-data-files

5. U.S. Patent No. 5,290,751. (1994). Substituted bisheteroaryl piperazine compounds. United States Patent and Trademark Office. https://patents.google.com/patent/US5290751

6. U.S. Patent and Trademark Office. (2024). Patent term adjustment and patent term information. https://www.uspto.gov/patents/laws/patent-term-adjustment-patent-term-extension-prioritization-examination-accelerated-examination