Last updated: September 7, 2026
Peramivir is a small-molecule intravenous neuraminidase inhibitor marketed in the United States as Rapivab by BioCryst Pharmaceuticals. The drug has a narrow commercial position: it is used mainly when oral or inhaled influenza therapies are unsuitable, particularly in hospital and emergency-care settings. Its single-dose intravenous administration is its principal differentiator, while limited seasonal demand, competition from oseltamivir and baloxavir, and the absence of durable patent protection constrain revenue potential.
BioCryst’s public filings do not report Rapivab revenue as a consistently separate, material financial line item. The company’s recent financial trajectory is driven primarily by Orladeyo for hereditary angioedema, not by peramivir. Peramivir remains a commercial product and a source of seasonal revenue, but it is not a core growth asset.
What is peramivir and how is Rapivab used?
Peramivir is an intravenous antiviral that inhibits influenza A and B neuraminidase, an enzyme required for release of newly formed viral particles. Rapivab is approved by the U.S. Food and Drug Administration for treatment of acute uncomplicated influenza in patients aged six months and older who have been symptomatic for no more than two days.[1]
The adult dose is 600 mg administered intravenously as a single dose. Pediatric dosing is weight-based. The product is administered over approximately 15 to 30 minutes, depending on the formulation and clinical setting.[1]
| Product attribute |
Rapivab peramivir |
| Active ingredient |
Peramivir |
| U.S. brand |
Rapivab |
| U.S. sponsor/commercial company |
BioCryst Pharmaceuticals |
| FDA approval |
October 22, 2014 |
| Route |
Intravenous |
| Standard adult regimen |
600 mg once |
| Approved population |
Patients aged 6 months and older |
| Treatment window |
Symptoms for no more than 2 days |
| Therapeutic class |
Influenza neuraminidase inhibitor |
| Disease category |
Influenza A and B |
| FDA pathway |
New drug application |
| Biosimilar status |
Not applicable; peramivir is a small molecule |
The label is directed to acute uncomplicated influenza. Evidence and regulatory positioning for critically ill or hospitalized patients are more limited than for uncomplicated disease. In practice, intravenous use can make peramivir relevant when a patient cannot swallow, has impaired gastrointestinal absorption, or requires treatment in a supervised care setting.
How large is the peramivir market?
Peramivir occupies a small segment of the influenza antiviral market. The overall market is seasonal and highly dependent on influenza incidence, circulating strains, vaccination rates, prescribing behavior, and hospital utilization.
The principal commercial demand drivers are:
- High influenza activity.
- Hospital and emergency-department use.
- Patients unable to take oral medication.
- Institutional purchasing and government stockpiling.
- Clinician preference for a single supervised intravenous dose.
The principal constraints are:
- Oral oseltamivir is widely available in generic form.
- Baloxavir provides a single-dose oral alternative for eligible patients.
- Zanamivir offers an inhaled option.
- Most uncomplicated influenza cases are treated outside hospitals.
- Antiviral treatment is most effective when started within 48 hours.
- Seasonal demand creates significant revenue volatility.
- Peramivir has limited differentiation outside the intravenous-use niche.
CDC guidance generally places oral oseltamivir at the center of treatment for hospitalized patients and individuals at higher risk of complications. Peramivir remains an alternative in selected patients, but it does not control the treatment standard for the broader influenza market.[2]
How has peramivir revenue developed over time?
Peramivir revenue has been commercially modest relative to BioCryst’s current portfolio. BioCryst’s public reporting shows that the company’s financial trajectory shifted sharply after the launch of Orladeyo, which became the company’s main growth product. Rapivab revenue is seasonal and is not the primary driver of consolidated revenue, operating performance, or valuation.
Commercial timeline
| Period |
Commercial development |
Financial implication |
| 2014 |
FDA approves Rapivab |
U.S. commercial launch begins |
| 2015-2019 |
Product establishes a hospital and emergency-care niche |
Revenue tied to influenza seasons |
| 2019 |
U.S. regulatory exclusivity period ends for the original approval |
Generic and alternative-treatment risk increases |
| 2020-2021 |
COVID-19 mitigation sharply suppresses influenza circulation |
Peramivir demand weakened by low influenza activity |
| 2022 onward |
Influenza activity rebounds unevenly |
Seasonal recovery, but no structural growth reset |
| 2021-present |
Orladeyo becomes BioCryst’s principal commercial product |
Rapivab has declining strategic weight in the portfolio |
BioCryst’s annual reports identify Rapivab among commercial products but emphasize Orladeyo as the company’s principal revenue engine. The company’s reported revenue growth in recent years has therefore reflected hereditary-angioedema sales rather than expansion of the peramivir market.[3]
Public filings do not provide a reliable, uninterrupted multi-year Rapivab revenue series that would support a precise standalone compound-level financial model. The most defensible conclusion is that Rapivab generates recurring but relatively small seasonal revenue and has limited influence on BioCryst’s consolidated financial trajectory.
What are the main financial drivers for Rapivab?
Influenza season severity
Rapivab sales can move sharply between seasons. The 2020-2021 influenza seasons were unusually weak because masking, social distancing, school closures, travel restrictions, and other public-health measures reduced influenza transmission. This created a direct negative shock for all influenza antiviral manufacturers.
A return to normal influenza circulation supports volume, but it does not necessarily create sustained growth. The product remains exposed to annual epidemiological variation.
Hospital utilization
Because Rapivab is intravenous, its commercial demand is concentrated in hospitals, emergency departments, infusion settings, and institutional purchasers. That concentration limits prescription volume but supports use cases in which oral administration is impractical.
Generic pricing pressure
The dominant influenza antiviral, oseltamivir, is available from multiple generic suppliers. Peramivir competes against generic pricing but provides a different route of administration. The price premium for intravenous treatment must be justified by clinical convenience, patient condition, or institutional protocols.
Government procurement
Influenza antivirals may be purchased for public-health reserves and emergency preparedness. These contracts can produce periodic volume but are difficult to forecast and are not equivalent to recurring commercial demand.
Portfolio allocation at BioCryst
BioCryst’s commercial resources, investor focus, and operating investments are concentrated on Orladeyo. Rapivab is therefore more likely to be managed as an established, seasonal product than as a platform for major new investment.
What is the FDA regulatory status of Rapivab?
Rapivab holds FDA approval under NDA 206426. The approved use is treatment of acute uncomplicated influenza in patients who have been symptomatic for no more than two days.[1]
The product is not approved as a broad prophylaxis product. It is also not interchangeable with oral antivirals under an automatic pharmacy substitution framework because it is an intravenous formulation with different administration requirements.
The key regulatory limitations are:
- The approved indication is narrow.
- Benefit is greatest when treatment begins early.
- Data are less definitive for severe, late-presenting, or complicated influenza.
- The product requires intravenous administration by trained personnel.
- Renal impairment requires dose adjustment.
These restrictions limit outpatient use and keep peramivir commercially tied to healthcare facilities.
What patents protect peramivir and Rapivab?
Peramivir is an older small molecule whose principal U.S. regulatory and patent barriers have largely elapsed. The original FDA approval date was October 22, 2014. New chemical entity exclusivity generally extends for five years from approval, subject to statutory exceptions, placing the core U.S. exclusivity endpoint in October 2019.[4]
The commercial assessment is more important than any single patent number: Rapivab does not have the type of active biologic, device, or complex formulation estate that can normally delay generic entry for many years after approval.
Core IP categories
| IP category |
Peramivir position |
| Composition of matter |
Older estate; core term largely expired or near expiration |
| New chemical entity exclusivity |
Began at FDA approval in 2014; five-year period generally ended in 2019 |
| Intravenous formulation |
Potentially relevant, but limited by the simplicity of the dosage form |
| Method of use |
Narrow influenza-treatment claims may exist, but practical blocking value is limited |
| Manufacturing process |
May create technical barriers, but generally does not prevent all competing supply |
| Device patents |
Not a principal barrier because Rapivab is administered through standard intravenous equipment |
| Biologic exclusivity |
Not applicable |
| Biosimilar pathway |
Not applicable |
The FDA Orange Book should be used to confirm the current listed-patent position for NDA 206426 before any paragraph IV or launch analysis. A generic sponsor would likely evaluate an ANDA if it can match the reference product’s active ingredient, dosage form, strength, route, and labeling. A 505(b)(2) application could be relevant if the proposed product differs in formulation, dosing, or clinical use.
When did peramivir lose exclusivity?
The principal U.S. regulatory exclusivity period associated with the original approval ended in 2019. Any remaining commercial protection would depend on specific listed patents, pediatric exclusivity, regulatory exclusivity for later indications, or litigation-related stays.
Peramivir does not have the exclusivity profile of a recently approved specialty medicine. The principal barriers to competition are more likely to be:
- Manufacturing validation.
- Sterile injectable production.
- Bioequivalence and product quality requirements.
- Limited market size.
- Seasonal demand volatility.
- Commercial economics for a generic entrant.
A small market can delay generic entry even when legal barriers are weak because the expected return may not justify injectable manufacturing and regulatory costs.
Are there paragraph IV challenges to Rapivab?
A publicly visible, commercially significant paragraph IV challenge has not become a central part of Rapivab’s market history. The absence of a prominent challenge does not establish that no generic filing has ever been made. It indicates that no widely reported litigation campaign has materially reshaped the U.S. market.
For a generic sponsor, the relevant questions are:
- Whether NDA 206426 has active Orange Book patents.
- Whether any listed patent remains enforceable.
- Whether the proposed product can be filed under an ANDA.
- Whether the product must use a 505(b)(2) pathway.
- Whether the market supports sterile injectable manufacturing.
The legal risk is therefore more likely to be a filing and commercial-execution issue than a high-value patent litigation issue.
How does peramivir compare with competing influenza antivirals?
| Drug |
Route |
Dosing profile |
Main advantage |
Main commercial weakness |
| Peramivir |
Intravenous |
Usually one dose |
Useful when oral treatment is unsuitable |
Facility-based administration |
| Oseltamivir |
Oral |
Usually twice daily for five days |
Generic, familiar, broad use |
Multi-day regimen and resistance concerns |
| Baloxavir |
Oral |
Single dose |
Convenient oral administration |
Eligible-population and resistance considerations |
| Zanamivir |
Inhaled |
Repeated administration |
Non-oral option |
Respiratory administration limitations |
Peramivir’s strongest competitive position is not convenience in the general population. Baloxavir is also single-dose and oral. Peramivir’s value is concentrated in patients who need parenteral treatment or cannot reliably take an oral medicine.
Which companies challenge peramivir commercially?
The main competitive threat comes from manufacturers of alternative influenza antivirals rather than from direct peramivir generic manufacturers.
Oseltamivir manufacturers
Generic oseltamivir suppliers exert the greatest pricing pressure because the product is widely available and supported by established treatment guidelines. Roche’s Tamiflu remains the reference brand, but generic competition has substantially broadened supply.
Baloxavir manufacturer
Shionogi developed baloxavir, marketed in the United States as Xofluza by Roche under a collaboration. Baloxavir competes directly on single-dose convenience, although it does not replicate peramivir’s intravenous use case.
Generic injectable entrants
A future generic peramivir supplier could compete on price and institutional contracts. The likely barriers are sterile manufacturing, modest market size, and seasonal inventory risk rather than a dominant patent wall.
What is the licensing and geographic structure for peramivir?
Peramivir has been commercialized through a territory-specific licensing structure involving BioCryst and international partners. Shionogi has commercial rights in Japan and certain other territories, where the product is known as Rapiacta. Green Cross and other regional companies have also been associated with development or commercialization activities outside the United States.[3,5]
The geographic market is therefore fragmented:
- BioCryst is associated with U.S. commercialization.
- Shionogi has held important rights in Japan and selected Asian markets.
- Other regional partners have participated in non-U.S. development or distribution.
- Regulatory approvals, reimbursement, and influenza treatment protocols differ by country.
International revenue is not directly comparable with U.S. Rapivab sales because brand names, license economics, supply arrangements, and reporting practices vary by territory.
What patent litigation or settlement agreements affect Rapivab?
Rapivab has not developed a high-profile patent litigation record comparable with major oncology, immunology, or specialty-pharmacy products. No widely reported settlement has established a major delayed generic-entry date for peramivir in the United States.
The practical legal review should focus on:
- Current Orange Book listings for NDA 206426.
- Any ANDA certifications filed against those listings.
- Patent-term adjustment or extension records.
- Pediatric exclusivity.
- Manufacturing and formulation claims.
- Regulatory exclusivity for any later-approved indication.
Because peramivir is a small molecule with a relatively simple intravenous dosage form, manufacturing know-how and sterile injectable controls may be more relevant to supply continuity than complex formulation patents.
What is the financial outlook for peramivir?
The base-case outlook is stable to declining in strategic importance, with revenue fluctuating around influenza seasons rather than showing a strong secular growth trend.
Base case
Rapivab remains available in the United States and generates recurring seasonal sales. BioCryst retains a modest commercial contribution, while Orladeyo drives corporate growth.
Upside case
A severe influenza season, increased hospital use, government procurement, or expanded acceptance of intravenous treatment could lift sales temporarily. This would likely be episodic rather than permanent.
Downside case
Generic entry, institutional price reductions, broader adoption of baloxavir, continued preference for oseltamivir, or weak influenza seasons could reduce sales. A generic launch would be particularly disruptive if multiple suppliers enter simultaneously.
The investment conclusion is direct: peramivir is a mature, low-growth antiviral asset with useful niche demand but limited ability to alter BioCryst’s overall earnings trajectory. Its value lies in recurring commercial availability, licensing cash flow, and established regulatory status, not in a large protected-market opportunity.
Key Takeaways
- Peramivir is marketed in the United States as Rapivab by BioCryst Pharmaceuticals.
- FDA approval occurred on October 22, 2014, for acute uncomplicated influenza in patients aged six months and older.
- The standard adult regimen is a single 600 mg intravenous dose.
- The drug’s commercial niche is patients who cannot use or reliably absorb oral therapy.
- Oseltamivir and baloxavir are the principal competitive alternatives.
- The original five-year U.S. new chemical entity exclusivity period generally ended in 2019.
- Rapivab does not have a biologic or biosimilar exclusivity framework.
- No major publicly reported paragraph IV litigation campaign has defined the U.S. market.
- BioCryst’s recent financial growth is driven primarily by Orladeyo, not peramivir.
- Rapivab revenue is seasonal, relatively modest, and sensitive to influenza incidence.
- Generic risk is constrained by market size and sterile manufacturing economics but is not principally dependent on a strong remaining patent estate.
- The long-term outlook is recurring niche revenue with limited structural growth.
FAQs About Peramivir Market and Financial Outlook
Is peramivir still commercially available in the United States?
Yes. Rapivab remains an FDA-approved intravenous influenza treatment marketed by BioCryst Pharmaceuticals.
Is peramivir more effective than oseltamivir?
Available evidence does not establish broad superiority. Peramivir’s principal advantage is intravenous administration, not a generally superior efficacy profile.
Can a generic company file an ANDA for peramivir injection?
Potentially. Eligibility depends on pharmaceutical equivalence, bioequivalence, labeling, manufacturing controls, and the status of any Orange Book-listed patents or exclusivities.
Does peramivir have biosimilar competition?
No. Peramivir is a chemically synthesized small molecule, so competition would involve generic or 505(b)(2) products rather than biosimilars.
What would most increase peramivir sales?
A severe influenza season combined with higher hospital utilization, greater use in patients unable to take oral antivirals, or government stockpiling would have the greatest near-term impact.
References
- U.S. Food and Drug Administration. (2014). Rapivab (peramivir injection) prescribing information. https://www.accessdata.fda.gov
- Centers for Disease Control and Prevention. (2024). Influenza antiviral medications: Summary for clinicians. https://www.cdc.gov/flu
- BioCryst Pharmaceuticals, Inc. (2024). Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934. U.S. Securities and Exchange Commission. https://www.sec.gov
- U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob
- Shionogi & Co., Ltd. (2024). Annual report and corporate information. https://www.shionogi.com
