Antiviral medicines for pandemic influenza

This European Medicines Agency (EMA) is responsible for reviewing data on antiviral medicines submitted for authorisation in the European Union (EU) via the centralised procedure.

Page updated on 4 December:
- to include information on Cap-dependent endonuclease (CEN) inhibitors
- to revise outdated content throughout the page

Antiviral medicines play a crucial role in the management of an influenza pandemic. At the onset of a pandemic, they are immediately available to treat infected patients and to prevent exposed contacts from develop the infection. In contrast, vaccines may not be accessible in the early stages of a pandemic.

The appropriate use of antivirals for the treatment and prevention of influenza should be determined on a case-by-case basis and take the following into consideration:

• official recommendations;
• variability of epidemiology;
• impact of the disease in different geographical areas and patient populations.

There are currently three classes of antiviral medicines approved in the European Union (EU):

• Neuraminidase inhibitors (NAIs);
• Cap-dependent endonuclease (CEN) inhibitors;
• M2 inhibitors (adamantanes).

For more information, see:

• Pandemic influenza

Neuraminidase inhibitors (NAIs)

Neuraminidase inhibitors (NAIs) block the activity of influenza neuraminidase, an enzyme involved in the release of viral particles from infected cells. By blocking this release, NAIs prevent the virus from spreading within the respiratory tract.

Three NAIs are currently centrally authorised via EMA for use in all EU Member States:

• Tamiflu (oseltamivir)
• Ebilfumin (oseltamivir)
• Dectova (zanamivir, delivered via an intravenous drip)

In addition:

• Relenza (zanamivir, delivered via inhalation) is authorised at national level in all EU Member States.

Cap-dependent endonuclease (CEN) inhibitor

Cap-dependent endonuclease (CEN) inhibitors block the activity of CEN, an enzyme the influenza virus uses to copy itself. By inhibiting it, the virus is unable to continue replicating.

The only CEN inhibitor currently centrally authorised for use in all EU Member States is:

• Xofluza (baloxavir marboxil)

Matrix-2 (M2) inhibitors (adamantanes)

Matrix-2 (M2) inhibitors block a viral ion channel (M2 protein) and prevent the virus from infecting cells. These medicines are authorised at national level in the EU.

The M2 inhibitors still nationally authorised in some EU Member States include:

• amantadine;
• rimantadine.

Adamantanes are not active against influenza B strains and there is widespread resistance among influenza A strains. For this reason, M2 inhibitors are no longer recommended for the treatment of seasonal influenza virus infections in clinical treatment guidelines.