Xofluza™: A New Antiviral Treatment for Influenza

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By Sandhya Vijapurapu

The onset of coughs and sniffles heard, almost like clockwork, throughout classrooms, offices, and hospitals every autumn can signify only one thing: the arrival of flu season. The flu, caused by the influenza virus, is an annual, contagious respiratory illness that affects millions of people and results in symptoms such as a cough, sore throat, muscle/body aches, fatigue, and fever. According to the Centers for Disease Control and Prevention (CDC), the 2017-2018 flu season was particularly severe, with 185 pediatric deaths, 80,000 adult deaths, and 710,000 hospitalizations.1 

Influenza vaccination is recommended to prevent influenza in most patients aged 6 months and older. Due to the unpredictable nature of the virus, the effectiveness of the vaccine can vary each year. For the most recent flu season, the vaccine was estimated to be approximately 40% effective against both influenza A and B viruses.1 Despite variation in effectiveness, the vaccine still represents the best method to prevent flu and reduce the need for physician visits and hospitalizations. Thankfully, in the unfortunate circumstance that someone develops the flu, antiviral therapy can be utilized to shorten the severity and duration of illness, and to lessen the occurrence of serious complications. Antiviral drugs currently on the market include Tamiflu®, Relenza®, and Rapivab®. 

Xofluza™ is a new influenza treatment that was approved by the Food and Drug Administration (FDA) on October 24, 2018 for individuals 12 years and older who have experienced acute, uncomplicated flu symptoms for less than 48 hours. The approval of Xofluza™ represents the first new antiviral flu treatment in almost 20 years. Xofluza™ works by inhibiting polymerase acidic endonuclease, an enzyme crucial for viral replication; this essentially slows the proliferation of the virus by blocking its ability to reproduce. 2 Studies have shown its effectiveness against a broad range of influenza virus types, including other antiviral treatment-resistant strains and avian strains. It is taken as a single oral dose and its safety and efficacy have been tested by two randomized, phase III multicenter, double-blind, placebo-controlled trials known cumulatively as CAPSTONE-1. About 1,832 individuals were included in these trials and were assigned to receive either Xofluza™, a placebo, or a different antiviral flu treatment, each within 48 hours of experiencing symptoms (as this is the optimal window to mitigate the extent of the illness).2 The study showed that Xofluza™ was much quicker in alleviating symptoms compared to the placebo (54 hours for symptom relief for Xofluza™ vs 80 hours for placebo), but had no significant difference from the alternate antiviral treatment given.3 Adverse reactions experienced included diarrhea and bronchitis in 3% and 2% of the population, respectively.4

The addition of Xofluza™ to the already existing multitude of antiviral treatments is notable for a few reasons. Not only is its mechanism of novel, it has an advantage as a single-dose, well-tolerated treatment. As a new therapy, it may continue to undergo further studies to expand use in pediatric populations, post-exposure prophylaxis, and hospitalized patients with the influenza.2 

As the phrase popularized by Game of Thrones aptly states: Winter is coming. Prevention with an annual vaccine is of utmost importance; however, in the case symptoms do arise, Xofluza™ is now available as a new option in the treatment of influenza, among other existing therapies. To learn more, or if you are experiencing symptoms of influenza, contact your pharmacist or physician for more information. 


  1. Influenza (Flu). (2018, November 02). Retrieved from https://www.cdc.gov/flu/about/season/flu-season-2017-2018.htm 
  2. Roche announces FDA approval of Xofluza (baloxavir marboxil) for influenza. (2018, October 24). Retrieved from https://www.roche.com/media/releases/med-cor-2018-10-24.htm 
  3. Introducing XOFLUZA. (2018). Retrieved from https://www.xofluza.com/patient/about-xofluza.html 
  4. Xofluza™ (baloxavir marboxil). (2018). Retrieved from https://www.gene.com/medical-professionals/medicines/xofluza 

This article was written by Sandhya Vijapurapu, a second-year pharmacy student at Duquesne University School of Pharmacy, and reviewed by her faculty advisor, Dr. Jordan Covvey. Sandhya is a student research assistant in the lab of Dr. Rehana Leak, which studies Lewy pathology of Parkinson’s disease, and also holds a leadership position as the committee chair for Generation Rx of APhA-ASP. After graduation, Sandhya would like to pursue a residency and work as a clinical pharmacist. 

Dr. Covvey is an Assistant Professor in Pharmacy Administration at the Duquesne University School of Pharmacy. She earned her Doctor of Pharmacy from the University of Kentucky in 2010, and then completed residency training at Virginia Commonwealth University Health System in 2011. She subsequently passed her board certification in pharmacotherapy (BCPS) and was selected as a recipient of a Fulbright grant to complete a Doctor of Philosophy at the University of Strathclyde Institute of Pharmacy and Biomedical Sciences in Scotland. She currently teaches in the public and global health curriculum for pharmacy students at Duquesne, and her research area is in the health outcomes and the utilization of healthcare data, such as electronic medical records, for quality improvement in clinical care. 

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