Baloxavir marboxil

Aka: Baloxavir marboxil, Xofluza

1. Indications
   1. Influenza
      1. Alternative to Oseltamivir (Tamiflu)
2. Mechanism
   1. Cap-dependent endonuclease inhibitor
   2. Some RNA Viruses (including Influenza) replicate via cap snatching
      1. Virus extracts first 15-20 of host RNA residues which is used as 5' cap on virus RNA
      2. Virus RNA polymerase has endonuclease functionality used in cap snatching
3. Dosing
   1. One single oral dose for over age 12 years
      1. Weight 88 to 176 lb (40 to 80 kg): 40 mg (two 20 mg tablets)
      2. Weight >176 lb (>80 kg): 80 mg (two 40 mg tablets)
   2. Costs $155 in 2019 (contrast with $50-75 for Tamiflu)
4. Efficacy
   1. May shorten Influenza symptoms by up to 1 day if started within 48 hours
   2. No evidence for benefit in high risk patients (under age 2, over age 65, pregnancy)
   3. Appears effective for Influenza Prophlaxis (but not FDA approved for prophylaxis as of 2020)
      1. Single dose after household exposure may prevent up to 1 case in 9 contacts
      2. Ikematsu (2020) N Engl J Med 383:309-20 [PubMed]
5. Adverse Effects (in 1-3% of patients)
   1. Diarrhea
   2. Nausea
   3. Bronchitis
   4. Headache
6. Drug Interactions
   1. Agents that decrease absorption (e.g. Calcium including dairy products, aluminum, Magnesium or iron salts)
7. References
   1. (2020) Presc Lett 27(10): 55-6
   2. (2018) Presc Lett 25(12): 67
   3. Erlich (2019) Am Fam Physician 100(12): 776-7 [PubMed]