TheraRadar
Data updated: May 26, 2026

RELENZA (zanamivir)

Neuraminidase Inhibitors Trial Activity: Stable 3 active trials
Infectious Disease Approved 1999-07-26

Relenza is an inhaled antiviral medication used to manage influenza A and B infections in adults and children. It helps patients aged 7 and older who have recently developed flu symptoms, and it is also used to prevent the flu in those aged 5 and older. Because of the risk of breathing complications, this medication is not recommended for people with chronic respiratory conditions like asthma or COPD. It serves as an additional tool for flu management but does not replace the need for an annual flu vaccine.

Source: FDA Label • GSK • Neuraminidase Inhibitor

How RELENZA Works

This medication works by inhibiting neuraminidase, an enzyme essential for the influenza virus. By blocking this protein, the drug interferes with the virus's ability to spread to other cells. This antiviral action helps control the infection or prevents it from taking hold in the first place.

Development Insights

GlaxoSmithKline conducting 6 trials (46%)
10 indications explored (Broad Platform)
influenza (4 trials)
influenza, human (4 trials)
influenza a virus, h1n1 subtype (3 trials)
3
Indications
--
Phase 3 Trials
3
Priority Reviews
26
Years on Market

Details

Status
Prescription
First Approved
1999-07-26
Routes
INHALATION
Dosage Forms
POWDER

Companies

Active Ingredient: ZANAMIVIR

RELENZA Approval History

2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
Original
New Indication
New Form
Label Update
26 FDA actions from 1999 to 2023 · 2 indication expansions
Oct 2023 SUPPL
Label · Labeling
Oct 2021 SUPPL
Label · Labeling
Jun 2018 SUPPL
Label · Labeling

What RELENZA Treats

1 indications

RELENZA is approved for 1 conditions since its original approval in 1999. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Influenza
Source: FDA Label

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Shared indications:
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Clinical Trial Registry

11 trials
Trial Sponsor ID Phase Status Title
NCT05648448 AD ASTRA VIR22003 Ph 2 recruiting A Phase 2 Trial Comparing Antiviral Treatments in Early Symptomatic Influenza
NCT04597437 ZAP-DENGUE NCR203024 Ph 2 recruiting Zanamivir Treatment of Vascular Permeability in Dengue (ZAP-DENGUE)
NCT04867707 NAED results posted 2038203 Ph 2 completed Role of Neuraminidase Activity on Endothelial Dysfunction in Type 2 Diabetes
NCT04494412 200925 Ph 2 recruiting An Intravenous (IV) Zanamivir Pharmacokinetics (PK) Study in Hospitalized Neonates and Infants With Influenza Infection
NCT01231620 ZORO results posted 114373 Ph 3 completed A Study of Intravenous Zanamivir Versus Oral Oseltamivir in Adults and Adolescents Hospitalized With Influenza
NCT00989404 NAI113625 113625 Ph 1 completed Crossover Study to Investigate the Safety, Tolerability, and Pharmacokinetics of Repeat Dose Zanamivir/Placebo Via Devices Administered Twice Daily for 5 Days
NCT02377401 117104 Ph 1 completed Pharmacokinetics of Zanamivir After Single and Repeated Dose Infusion Administration in Healthy Chinese Adults
NCT00784784 Stop-Flu-2 results posted 08-0189-A CRT113936 Ph 3 completed Zanamivir Versus Trivalent Split Virus Influenza Vaccine
NCT01459081 SIM-100 Ph 3 completed Efficacy and Safety of Inhaled Zanamivir in Treatment of Influenza A and B Virus Infections in China
NCT00979667 CCT2009-CS-6 Ph 3 terminated A Clinical Trial Comparing Oseltamivir With Placebo And Zanamivir With Control As First Line Treatment For Human Swine Influenza Infection
NCT00921726 SEA 003 Ph 1 completed Pharmacokinetic Study of Oseltamivir and Intravenous Zanamivir in Healthy Adults
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Active Pipeline

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Ongoing clinical trials by development phase

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Key Completed Trials

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Completed studies with published results, ranked by significance

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Trial Timeline

Full development history with FDA approval milestones

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Understanding FDA Approval Types
Count Type What it means
- ORIG Original approval - drug first enters market
- SUPPL - Efficacy New indication (new disease/condition approved)
- SUPPL - Labeling Label text changes (warnings, dosing updates)
- SUPPL - Manufacturing Production changes (new facility)
- SUPPL - Chemistry Formulation changes (new dosage strength)

Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.

RELENZA FDA Label Details

Indications & Usage

FDA Label (PDF)

RELENZA is indicated for the treatment of Influenza.

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Data Sources

Data sourced from official FDA and NIH databases. Click links to verify on original sources.

How We Calculate These Metrics

Trial Activity Stage

Measures the current development activity pattern based on trial phases, status, and trends. Important: This measures R&D activity, not commercial lifecycle.

Trial statuses: "Active" means recruiting or ongoing. "Completed" means reached planned endpoint. "Terminated" means stopped early—often due to safety, efficacy, or business reasons.

  • Growth: High proportion of early-phase trials (Phase 1/2), active development
  • Expansion: Significant Phase 3 activity, approaching or pursuing approvals
  • Mature: Substantial Phase 4 post-marketing studies
  • Stable: Mixed phase distribution, steady development
  • Declining: Low active trial ratio, reduced R&D investment