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Baloxavir marboxyl (Xofluza)

[Photo of baloxavir marboxyl (Xofluza)]

Photo source: Fierce Pharma

KEY POINTS

  • Baloxavir marboxyl (Xofluza) is a polymerase acidic endonuclease inhibitor that is active against the influenza virus
    •  Interferes with viral RNA polymerase complex that is necessary for viral gene transcription, which inhibits influenza virus replication
    • Has activity versus influenza A and influenza B
    • Viral resistance has been found due to amino acid substitutions in the polymerase acidic protein
      • As seasonal flu strains in circulation may vary, beware this may impact the utility of baloxavir marboxyl
  • FDA-approved on October 24th of 2018 for treatment of uncomplicated influenza in patients 12 years or greater who have been symptomatic for no more than 48 hours
    • Expanded in October 2019 to include patients who are:
      • otherwise healthy, or
      • at high risk of developing influenza-related complications
  • Available oral only
    • Body weight 40kg – 80kg: 40mg x1
    • Body weight > 80kg: 80mg x1
    • Avoid co-administration with cations (e.g., calcium, iron, magnesium, zinc)
    • No dose-adjustment listed for renal or hepatic impairment, but it has not been studied in severe renal or hepatic impairment
  • May impact effectiveness of live attenuated influenza vaccines
  • The most common side effects reported are: diarrhea, bronchitis, nasopharyngitis, headache, and nausea
  • The ISMP August 2019 Acute Care Medication Alert Newsletter listed concerning post-market adverse event data, including 382 reports of which all but 14 had a serious or fatal outcome. They noted 50 cases of anaphylactic shock, 7 of which were fatal and all were reported by a healthcare professional.
  • Anticipated to cost $150 per course (regardless of dose)

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