Pharm
Neuraminidase Inhibitor
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Neuraminidase Inhibitor
, Zanamivir, Relenza, Oseltamivir, Tamiflu, Peramivir, Rapivab
See Also
Influenza
Influenza Vaccine
Baloxavir Marboxil
(
Xofluza
)
Amantadine
Indications
Covers both
Influenza
A and
Influenza
B
Influenza
Influenza
prophylaxis
Contraindications
Zanamivir (Relenza)
Asthma
COPD
Precautions
Influenza
A (H1N1 Strain) was resistant to Tamiflu in 2008 (Relenza was used)
Symptom reduction is minimal (<14-16 hours) compared with those not treated
Best efficacy if started within first 48 hours (although may still initiate later in high risk cases)
Reserve use for those at highest risk of complications (although efficacy is limited even in high risk cases)
Age under 2 years old or age over 65 years old
Pregnancy
Hospitalized patients
Serious comorbidity
Dosing
Oseltamivir (Tamiflu)
Indicated for age 2 weeks and older (reduced from 1 year in U.S. as of 2013)
Suspension may be compounded if not available
Pharmacist can compound or
Parents can mix contents of a Tamiflu capsule ort suspension with thick liquid (and give appropriate fraction of dose)
Examples: Coffee Creamer, Chocolate syrup or similar
Treatment
Infants (approved for 2 weeks old and over)
Dose: 3 mg/kg twice daily for 5 days
Children
Age <1 year: Dose: 3 mg/kg/dose up to 75 mg orally twice daily for 5 days
Weight <15 kg: 30 mg orally twice daily for 5 days
Weight 15 to 23 kg: 45 mg orally twice daily for 5 days
Weight 23 to 40 kg: 60 mg orally twice daily for 5 days
Teens and Adults
Weight >40kg or Adult: 75 mg orally twice daily for 5 days
Renal Dosing
Creatinine Clearance
30-60 ml/min
Dose 30 mg twice daily for 5 days
Creatinine Clearance
10-30 ml/min
Dose 30 mg once daily for 5 days
Dialysis
Dose 30 mg after
Dialysis
Prevention
Not routinely recommended due to medication shortage and resistance risk
However, consider in high risk patients and their contacts (e.g. pregnancy,
Immunocompromised
)
Postexposure Prophylaxis
is very effective in preventing severe disease
(2018) Pediatrics 142(4): e20182367 +PMID:30177511 [PubMed]
Age <3 months: Discuss with specialist
Age 3 months to 1 year: 3 mg/kg daily for 7-10 days
Weight <15 kg: 30 mg orally daily for 7-10 days
Weight 15 to 23 kg: 45 mg orally daily for 7-10 days
Weight 23 to 40 kg: 60 mg orally daily for 7-10 days
Weight >40kg or Adult: 75 mg orally daily for 7-10 days
Advanced renal disease (
Creatinine Clearance
10-30)
75 mg every other day or 30 mg orally daily for 7-10 days
Nursing Home
Treat for at least 2 weeks and for at least 7 days after the last infected case in
Nursing Home
Isolate index patient to room and follow standard droplet precautions
Dosing
Peramivir (Rapivab)
IV antiviral with no better efficacy than Oseltamivir (Tamiflu) except in resistant cases, at 10 times the cost
Indicated in hospitalized
Influenza
patients with <2 days of symptoms, unable to take oral Oseltamivir (Tamiflu)
Dose 600 mg IV as single dose in adults >18 years old (Category C in pregnancy)
Adjust dose for renal
Impairment
Dosing
Zanamivir (Relenza)
Contraindicated in bronchospastic disease
Treatment (age 7 years and older)
Dose: 10 mg (2 inhalations) twice daily for 5 days
Prevention (age 5 years and older)
Dose: 10 mg (1 inhalation daily) for 10 days
Efficacy
Oseltamivir (Tamiflu)
Reduces myalgias, fever and flu-like symptoms by 1 day (if started in first 48 hours)
As of 2014, symptom reduction appears to be as little as <16 hours than if not treated
Does NOT reduce
Influenza
complications (
Pneumonia
, mortality) including in the elderly and chronically ill
However is still recommended for high risk and hospitalized patients when started early
References
Jefferson (2012) Cochrane Database Syst Rev 1: CD008965 [PubMed]
Adverse effects
Nausea
and
Vomiting
(Tamiflu)
Diarrhea
(common with Peramivir)
Bronchospasm (with Relenza only)
Neuropsychiatric effects
Stevens-Johnson Syndrome
(rare)
Resources
CDC
Influenza
Antivirals summary
http://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm
References
(2014) Presc Lett 21(12): 70
(2002) Pediatrics 110(6):1246-52 [PubMed]
Stiver (2003) CMAJ 168(1):49-57 [PubMed]
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