Which medications in the drug class Antivirals, Influenza are used in the treatment of Influenza?

Updated: Apr 23, 2019
  • Author: Hien H Nguyen, MD, MS; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Antivirals, Influenza

The antiviral drugs indicated for the treatment and chemoprophylaxis of influenza are the neuraminidase inhibitors (ie, oseltamivir and zanamivir) and the cap-dependent endonuclease inhibitor, baloxavir marboxil (treatment only). Neuraminidase inhibitors act directly on the viral proteins, decreasing the virulence of infection. Baloxavir marboxil inhibits cap-dependent endonuclease, which leads to inhibition of viral replication. Adamantanes (amantadine and rimantadine) were used in the past, but resistance against these agents has become widespread, and they are no longer recommended.

Oseltamivir (Tamiflu)

Oseltamivir inhibits neuraminidase, an enzyme that breaks the bond between newly produced virions and the host cell membrane. Specifically, neuraminidase—a glycoprotein located on the surface of the influenza virus—cleaves the attachment between hemagglutinin on the viral surface and the sialic acid receptor on the host cell membrane, thereby facilitating the release of the virion from the cell. Inhibition of neuraminidase thus decreases viral spread.

Oseltamivir is effective for the treatment of influenza A or B. It must be administered within 48 hours of symptom onset. The sooner it is taken after symptom onset, the better the effect. Oseltamivir reduces the length of illness by an average of 1.5 days. (In a subgroup of high-risk patients, illness was reduced by 2.5 days.) It also reduces the severity of symptoms. This agent is available as capsules (75, 45, and 30 mg) and as an oral suspension.

Oseltamivir resistance emerged in the United States during the 2008-2009 influenza season. Accordingly, zanamivir is now recommended as the initial choice for antiviral prophylaxis or treatment when influenza A infection or exposure is suspected.

A second-line alternative is to use a combination of oseltamivir and rimantadine rather than oseltamivir alone. Local influenza surveillance data and laboratory testing can assist the physician regarding antiviral agent choice.

The efficacy of oseltamivir against avian influenza is not well established.

Zanamivir (Relenza Diskhaler)

Zanamivir is an inhibitor of neuraminidase, an enzyme that breaks the bond between newly produced virions and the host cell membrane. Specifically, neuraminidase—a glycoprotein located on the surface of the influenza virus—cleaves the attachment between hemagglutinin on the viral surface and the sialic acid receptor on the host cell membrane, thereby facilitating the release of the virion from the cell. Inhibition of neuraminidase thus decreases viral spread.

This agent is effective against both influenza A and B; its efficacy against avian influenza is not well established. Severe and even fatal bronchospasm has been reported during treatment with zanamivir; consequently, this agent is not recommended for treatment or prophylaxis of influenza in individuals with underlying airway diseases (eg, asthma and chronic obstructive pulmonary disease).

Zanamivir is inhaled through a Diskhaler oral inhalation device. Circular foil disks that contain 5-mg blisters of drug are inserted into the supplied inhalation device.

Peramivir (Rapivab)

Peramivir elicits antiviral activity by inhibiting influenza virus neuraminidase, an enzyme that releases viral particles from the plasma membrane of infected cells. It is indicated for the treatment of acute uncomplicated influenza in adults who have been symptomatic for no more than 2 days. It is administered as a single 600 mg IV dose infused over 15-30 minutes.

Baloxavir marboxil (Xofluza)

Baloxavir marboxil is a prodrug that is metabolized to baloxavir. It inhibits cap-dependent endonuclease, an enzyme specific to influenza, resulting in inhibition of viral replication. It is indicated as a single, oral, weight-based dose for treatment of acute uncomplicated influenza in adults and adolescents aged 12 years or older who have been symptomatic for less than 48 hours.


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