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Neuraminidase Inhibitor

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Neuraminidase Inhibitor, Zanamivir, Relenza, Oseltamivir, Tamiflu

  1. Influenza
  2. Influenza prophylaxis
  • Contraindications
  • Zanamivir (Relenza)
  • 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
  • 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
  • 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 capsules with chocolate syrup or similar thick liquid (and give appropriate fraction of dose)
  3. Treatment
    1. Infants (approved for 2 weeks old and over)
      1. Dose: 3 mg/kg twice daily for 5 days
    2. Children
      1. Dose: 2 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 (not routinely recommended due to medication shortage and resistance risk)
    1. Weight <15 kg: 30 mg orally daily for 10 days
    2. Weight 15 to 23 kg: 45 mg orally daily for 10 days
    3. Weight 23 to 40 kg: 60 mg orally daily for 10 days
    4. Weight >40kg or Adult: 75 mg orally daily for 10 days
    5. Advanced renal disease (Creatinine Clearance 10-30)
      1. 75 mg every other day or 30 mg orally daily for 10 days
    6. 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
  3. Jefferson (2012) Cochrane Database Syst Rev 1: CD008965 [PubMed]
  • Adverse effects
  1. Nausea and Vomiting (Tamiflu)
  2. Bronchospasm (with Relenza only)
  3. Neuropsychiatric effects
  4. Stevens-Johnson Syndrome (rare)