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Introducing Xofluza1
FDA-approved October 2018 as a prescription medication used to treat the flu in patients 12 years of age and older who have had flu symptoms for no more than 48 hours.
Drug class: Anti-viral (specific to Influenza A and B)
Manufacture: Genentech
Formulations: 20mg tablet and 40mg tablet
Administration:
| Patient Body Weight (kg) | Dose |
| 40-79kg | 40mg in a single dose |
| >79kg | 80mg in a single dose |
Novel Mechanism of Action
Baloxavir marboxil is a prodrug converted into Baloxavir, the active form that inhibits the endonuclease activity of the polymerase acidic (PA) protein.
polymerase acidic (PA) protein, an influenza virus-specific enzyme in the viral RNA polymerase complex required for viral gene transcription, resulting in inhibition of influenza virus replication
5
PK
Absorption
Tmax: 40mins
Food: decreases 36% in AUC and 48% in Cmax
Distribution
Vd: 1180 L
Metabolism
Substrate of UGT1A3 and CYP3A4
Elimination
1/2 Life: 79 hours
Counseling and special populations
Medication Counseling
Do not take with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids or oral supplements (eg, calcium, iron, magnesium, selenium, or zinc)
Consult patient to notify healthcare professional of treatment with this drug before receiving a live attenuated influenza vaccine
Side effects: Diarrhea, Nausea, Headache, Bronchitis, Nasopharyngitis
Pregnancy and Lactation
Currently no data
Animal models showed no adverse effects at 5x maximum recommended human dose (MRHD) in mice and 2 abortions out of 19 pregnancies at 7x MRHD in rabbits.
Clinical Study3,1
Two randomized, double-blind, controlled trials-outpatient care with acute uncomplicated influenza
In the phase 3 trial, the intention-to-treat infected population included 1064 patients
| Medication | Dose | Time to relieve Symptoms |
| Xofluza | Weight based Dosing, single dose | 53.7 hours |
| Placebo | -- | 80.2 hours |
| Tamiflu | 75mg twice a day x 5 days | Similar to Xofluza |
Efficacy Study3
Xofluza vs Placebo
1 day vs 4 days (P<0.001)
Xofluza vs Tamiflu
1 day vs 3 days (P<0.001)
Measuring detectable viral loads in the blood, flu
symptoms tend to last an extra day or two.
Less Side effects3,1
Reported Any Side effect
Xofluza 20.7%
Placebo 24.6%
Tamiflu 24.8%
10
Price4,5
Xofluza
Retail costs: ~150$ for a single dose
Manufacture coupon: 30-90$
Depending on your insurance
Compared to Tamiflu for 10 doses
Retail cost: ~125$
Good Rx Coupon: ~48$
Refrences
1. FDA full prescribing information: XOFLUZATM (baloxavir marboxil). Genentech, Inc. 2018
2. Ng K. E. (2019). Xofluza (Baloxavir Marboxil) for the Treatment Of Acute Uncomplicated Influenza. P & T : a peer-reviewed journal for formulary management, 44(1), 9–11.
3. Hayden F.G. (2018) Baloxavir Marboxil for Uncomplicated Influenza in Adults and Adolescents. N Engl J Med. 2018 Sep 6. 379(10):913-923