II. Indications: Covers both Influenza A and Influenza B

  1. Influenza
  2. Influenza prophylaxis

III. Contraindications: Zanamivir (Relenza)

IV. Precautions

  1. Influenza A (H1N1 Strain) was resistant to Tamiflu in 2008 (Relenza was used)
  2. Symptom reduction is minimal (<14-16 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

V. Dosing: Oseltamivir (Tamiflu)

  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. 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 30-60 ml/min
        1. Dose 30 mg twice daily for 5 days
      2. Creatinine Clearance 10-30 ml/min
        1. Dose 30 mg once daily for 5 days
      3. Dialysis
        1. Dose 30 mg after Dialysis
  4. Prevention
    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. Age <3 months: Discuss with specialist
    3. Age 3 months to 1 year: 3 mg/kg daily for 7-10 days
    4. Weight <15 kg: 30 mg orally daily for 7-10 days
    5. Weight 15 to 23 kg: 45 mg orally daily for 7-10 days
    6. Weight 23 to 40 kg: 60 mg orally daily for 7-10 days
    7. Weight >40kg or Adult: 75 mg orally daily for 7-10 days
    8. Advanced renal disease (Creatinine Clearance 10-30)
      1. 75 mg every other day or 30 mg orally daily for 7-10 days
    9. 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

VI. Dosing: Peramivir (Rapivab)

  1. IV antiviral with no better efficacy than Oseltamivir (Tamiflu) except in resistant cases, at 10 times the cost
  2. Indicated in hospitalized Influenza patients with <2 days of symptoms, unable to take oral Oseltamivir (Tamiflu)
  3. Dose 600 mg IV as single dose in adults >18 years old (Category C in pregnancy)
    1. Adjust dose for renal Impairment

VII. Dosing: Zanamivir (Relenza)

  1. Contraindicated in bronchospastic disease
  2. Treatment (age 7 years and older)
    1. Dose: 10 mg (2 inhalations) twice daily for 5 days
  3. Prevention (age 5 years and older)
    1. Dose: 10 mg (1 inhalation daily) for 10 days

VIII. 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]

IX. Adverse effects

  1. Nausea and Vomiting (Tamiflu)
  2. Diarrhea (common with Peramivir)
  3. Bronchospasm (with Relenza only)
  4. Neuropsychiatric effects
  5. Stevens-Johnson Syndrome (rare)

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Related Studies

Cost: Medications

oseltamivir (on 12/28/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
OSELTAMIVIR 6 MG/ML SUSPENSION Generic $0.38 per ml
OSELTAMIVIR PHOS 30 MG CAPSULE Generic $1.27 each
OSELTAMIVIR PHOS 45 MG CAPSULE Generic $1.44 each
OSELTAMIVIR PHOS 75 MG CAPSULE Generic $1.49 each
tamiflu (on 2/23/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
TAMIFLU 6 MG/ML SUSPENSION Generic $0.38 per ml
TAMIFLU 75 MG CAPSULE Generic $1.49 each