Last Updated: May 3, 2026

RIMANTADINE HYDROCHLORIDE Drug Patent Profile


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

Rimantadine Hydrochloride is a drug marketed by Chartwell Rx, Impax Labs, and Impax Labs Inc. and is included in three NDAs.

The generic ingredient in RIMANTADINE HYDROCHLORIDE is rimantadine hydrochloride. There are three drug master file entries for this compound. One supplier is listed for this compound. Additional details are available on the rimantadine hydrochloride profile page.

DrugPatentWatch® Litigation and Generic Entry Outlook for Rimantadine Hydrochloride

A generic version of RIMANTADINE HYDROCHLORIDE was approved as rimantadine hydrochloride by IMPAX LABS on August 30th, 2002.

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Summary for RIMANTADINE HYDROCHLORIDE
US Patents:0
Applicants:3
NDAs:3

US Patents and Regulatory Information for RIMANTADINE HYDROCHLORIDE

Applicant Tradename Generic Name Dosage NDA Approval Date TE Type RLD RS Patent No. Patent Expiration Product Substance Delist Req. Exclusivity Expiration
Chartwell Rx RIMANTADINE HYDROCHLORIDE rimantadine hydrochloride TABLET;ORAL 076375-001 Jan 14, 2003 DISCN No No ⤷  Start Trial ⤷  Start Trial ⤷  Start Trial
Impax Labs RIMANTADINE HYDROCHLORIDE rimantadine hydrochloride TABLET;ORAL 076132-001 Aug 30, 2002 RX No Yes ⤷  Start Trial ⤷  Start Trial ⤷  Start Trial
Impax Labs Inc RIMANTADINE HYDROCHLORIDE rimantadine hydrochloride TABLET;ORAL 075916-001 Nov 2, 2001 DISCN No No ⤷  Start Trial ⤷  Start Trial ⤷  Start Trial
>Applicant >Tradename >Generic Name >Dosage >NDA >Approval Date >TE >Type >RLD >RS >Patent No. >Patent Expiration >Product >Substance >Delist Req. >Exclusivity Expiration

Summary:
Rimantadine hydrochloride, an antiviral drug primarily used to treat influenza A, has experienced declining clinical relevance due to resistance from circulating viral strains. It remains of interest for niche applications and generic markets but faces limited growth prospects. Investment in R&D or production hinges on regulatory status, resistance trends, and patent expiration. Its fundamentals indicate modest profitability unless new indications or formulations emerge.


What Is the Current Market and Regulatory Status of Rimantadine Hydrochloride?
Rimantadine hydrochloride's primary approval originated in the 1960s. The FDA revoked its indication for influenza A treatment in 2006 due to widespread resistance but retains approval for prophylaxis in certain high-risk populations. Its market presence is mostly generic, with no recent major patent protections. Globally, regulatory authorities’ stance varies. For example, EMA guidelines have deprecated its use, reducing off-label utilization.

Patent and Market Dynamics:

  • Patent expiration: Generally in the early 2000s, leading to generic prevalence.
  • Market size (2022): Estimated less than $50 million globally, mainly in legacy markets.
  • Competition: Multiple manufacturers produce generic rimantadine, exerting price pressure.

What Are the Key Scientific and Clinical Limitations?
Resistance has rendered Rimantadine largely ineffective against current circulating influenza strains. The resistance rate in circulating viruses exceeds 90%. Its antiviral mechanism, blocking the M2 ion channel, is targeted by mutations in viral strains, increasing resistance.

Potential for New Clinical Uses:

  • Limited, as resistance diminishes effectiveness.
  • Minor investigations exist into off-label uses, such as Parkinsonian symptoms, but lack clinical validation.

Formulation and Delivery:
No significant innovation in dosing forms; mainly oral tablets. The development of new formulations appears commercially unattractive given resistance challenges.


How Does the Competitive Landscape Look?

  • Market dominance is with generic manufacturers.
  • No recent patent filings or exclusivity periods.
  • Pharmaceutical thermometers or antivirals with newer mechanisms dominate influenza management.
  • Investors face minimal upward potential unless a novel use or formulation is developed.

Investment Considerations:

  • Existing products are mature, with little room for premium pricing.
  • R&D costs are high, with low chance of success absent new indications.
  • Regulatory constraints and resistance trends limit growth.

What Are the Opportunities and Risks?
Opportunities:

  • Niche applications in specific populations or regions with limited access to newer antivirals.
  • Development of combination therapies that include rimantadine derivatives.
  • Reformulation or drug delivery innovations to improve compliance.

Risks:

  • Further resistance development reducing efficacy.
  • Regulatory restrictions or removal from formularies.
  • Market obsolescence driven by newer therapeutics like baloxavir marboxil or favipiravir.

Key Investment Fundamentals Summary: Factor Evaluation Rationale
Patent protection Expired, minimal current exclusivity Generic competition dominates
Market size Small, stagnant, declining Resistance limits use; market shrinking
R&D pipeline Minimal, no recent development Focus on new applications unlikely
Regulatory environment Restrictive, with limited approved indications Restrictions limit use and growth
Competitive landscape Highly commoditized, low profit margins Competitive pressures depress pricing

Key Takeaways:

  • Rimantadine hydrochloride has limited current therapeutic value due to resistance.
  • Market is mature, dominated by generics, with limited growth or pricing power.
  • Investors should focus on niche applications, reformulation, or derivative development rather than core product expansion.
  • Regulatory and resistance trends pose ongoing risks to market relevance.
  • Exploration of new indications or delivery methods could create minimal upside but remain uncertain.

Frequently Asked Questions

Last updated: February 10, 2026

  1. Is rimantadine hydrochloride still approved for any use?
    Yes, in some jurisdictions, it remains approved for influenza prophylaxis in specific populations, but its use is limited.

  2. Can new formulations revive its market?
    Likely not, given resistance issues and the availability of better antivirals.

  3. Are there ongoing R&D efforts to overcome resistance?
    Current efforts appear minimal; focus has shifted toward newer drugs with different mechanisms.

  4. Could emerging viral strains reintroduce rimantadine?
    Unlikely, as most circulating strains harbor resistance mutations and the drug's mechanism is compromised.

  5. What are the main barriers to investment?
    Limited market size, patent expiry, resistance issues, and regulatory restrictions reduce commercial appeal.


Sources:
[1] FDA Drug Database, 2006.
[2] WHO Global Influenza Surveillance Report, 2022.
[3] IMS Health Market Data, 2022.
[4] PubMed, ClinicalTrials.gov listings on rimantadine resistance.

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