IV. 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
V. 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
- Creatinine Clearance 30-60 ml/min
- Infants (approved for 2 weeks old and over)
- 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
- 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
- Not routinely recommended due to medication shortage and resistance risk
VI. 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
VII. 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
VIII. 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
IX. Adverse effects
- Nausea and Vomiting (Tamiflu)
- Diarrhea (common with Peramivir)
- Bronchospasm (with Relenza only)
- Neuropsychiatric effects
- Stevens-Johnson Syndrome (rare)
X. Resources
- CDC Influenza Antivirals summary
XI. 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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Related Studies
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 |