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Oseltamivir

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Oseltamivir, Tamiflu, Neuraminidase Inhibitor

  • See Also
  1. Zanamivir
  2. Peramivir
  3. Baloxavir Marboxil
  4. Influenza
  5. Influenza Vaccine
  6. Amantadine
  • Indications
  • Neuraminidase Inhibitor
  1. Neuraminidase Inhibitors covers both Influenza A and Influenza B
  2. Influenza
  3. Influenza prophylaxis
  • Precautions
  1. Influenza A (H1N1 Strain) was resistant to Oseltamivir in 2008 (Zanamivir was used)
  2. Symptom reduction is minimal (<14 to 16 hours) compared with those not treated
  3. Best efficacy if started within first 48 hours (although may still initiate later in high risk cases)
  4. Reserve use for those at highest risk of complications (although efficacy is limited even in high risk cases)
    1. Age under 2 years old or age over 65 years old
    2. Pregnancy
    3. Hospitalized patients
    4. Serious comorbidity
  • Dosing
  1. Indicated for age 2 weeks and older (reduced from 1 year in U.S. as of 2013)
  2. Suspension may be compounded if not available
    1. Pharmacist can compound or
    2. Parents can mix contents of a Tamiflu capsule ort suspension with thick liquid (and give appropriate fraction of dose)
      1. Examples: Coffee Creamer, Chocolate syrup or similar
  3. Influenza Treatment
    1. Infants (approved for 2 weeks old and over)
      1. Dose: 3 mg/kg twice daily for 5 days
    2. Children
      1. Age <1 year: Dose: 3 mg/kg/dose up to 75 mg orally twice daily for 5 days
      2. Weight <15 kg: 30 mg orally twice daily for 5 days
      3. Weight 15 to 23 kg: 45 mg orally twice daily for 5 days
      4. Weight 23 to 40 kg: 60 mg orally twice daily for 5 days
    3. Teens and Adults
      1. Weight >40kg or Adult: 75 mg orally twice daily for 5 days
    4. Renal Dosing
      1. Creatinine Clearance 30 to 60 ml/min
        1. Dose 30 mg twice daily for 5 days
      2. Creatinine Clearance 10 to 30 ml/min
        1. Dose 30 mg once daily for 5 days
      3. Hemodialysis
        1. Dose 30 mg after Dialysis
  4. Influenza Prophylaxis
    1. Not routinely recommended due to medication shortage and resistance risk
      1. However, consider in high risk patients and their contacts (e.g. pregnancy, Immunocompromised)
      2. Postexposure Prophylaxis is very effective in preventing severe disease
        1. (2018) Pediatrics 142(4): e20182367 +PMID:30177511 [PubMed]
    2. Weight <15 kg (and age>=1 year): 30 mg orally daily for 7 to 10 days
    3. Weight 15 to 23 kg: 45 mg orally daily for 7 to 10 days
    4. Weight 23 to 40 kg: 60 mg orally daily for 7 to 10 days
    5. Weight >40kg or Adult: 75 mg orally daily for 7 to 10 days
    6. Advanced renal disease (Creatinine Clearance 10 to 30 ml/min)
      1. 75 mg every other day or 30 mg orally daily for 7-10 days
    7. Nursing Home
      1. Treat for at least 2 weeks and for at least 7 days after the last infected case in Nursing Home
      2. Isolate index patient to room and follow standard droplet precautions
  • Efficacy
  • Oseltamivir (Tamiflu)
  1. Reduces myalgias, fever and flu-like symptoms by 1 day (if started in first 48 hours)
    1. As of 2014, symptom reduction appears to be as little as <16 hours than if not treated
  2. Does NOT reduce Influenza complications (Pneumonia, mortality) including in the elderly and chronically ill
    1. However is still recommended for high risk and hospitalized patients when started early
  3. References
    1. Jefferson (2012) Cochrane Database Syst Rev 1: CD008965 [PubMed]
  • Adverse effects
  1. Nausea and Vomiting
  2. Neuropsychiatric effects (e.g. Delirium)
  3. Stevens-Johnson Syndrome (rare)
  • Safety
  1. Considered safe in Pregnancy (and recommended by CDC)
  2. Safe in Lactation
  • Drug Interactions
  1. Warfarin
    1. Monitor INR
  • Resources
  1. Oseltamivir (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=d306e22c-0cb8-46cb-9a40-8194a2bc9e85
  2. CDC Influenza Antivirals summary
    1. http://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm
  • References
  1. (2014) Presc Lett 21(12): 70
  2. (2013) Med Lett Drugs Ther 11(127): 19-30 [PubMed]
  3. (2002) Pediatrics 110(6):1246-52 [PubMed]
  4. Stiver (2003) CMAJ 168(1):49-57 [PubMed]