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: 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

VI. 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

VII. 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]

VIII. Adverse effects

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

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Cost: Medications

tamiflu (on 7/1/2016 at Medicaid.Gov Survey of pharmacy drug pricing)
TAMIFLU 30 MG CAPSULE $12.65 each
TAMIFLU 45 MG CAPSULE $12.79 each
TAMIFLU 75 MG CAPSULE $13.88 each

Ontology: Zanamivir (C0216660)

Definition (NCI) A sialic acid-analogue neuraminidase inhibitor with antiviral activity. Administered into the respiratory tract by aerosol inhalation, zanamivir selectively binds to and inhibits influenza A and B virus neuraminidase-mediated cleavage of sialic acid residues in host cell membrane-bound glycoprotein receptors for influenza viruses, preventing the release of progeny viruses from host cell surfaces and, so, further viral replication.
Definition (NCI_NCI-GLOSS) A drug used to prevent and to treat influenza virus infections. It blocks the release of the virus from infected cells. It is a type of antiviral agent.
Definition (MSH) A guanido-neuraminic acid that is used to inhibit NEURAMINIDASE.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D053243
SnomedCT 116100000, 387010007
LNC LP101309-5, MTHU047708
English 4-Guanidino-2,4-dideoxy-2,3-dehydro-N-acetylneuraminic Acid, 5-Acetamido-2,6-anhydro-3,4,5-trideoxy-4-guanidino-D-glycero-D-galacto-non-2-enonic Acid, GANA, Zanamivir, 5-acetylamino-4-guanidino-6-(1,2,3-trihydroxypropyl)-5,6-dihydro-4H-pyran-2-carboxylic acid, Acid, 4-Guanidino-2-Deoxy-2,3-Didehydro-N-Acetylneuraminic, 2,3-Didehydro-2,4-Dideoxy-4-Guanidino-N-Acetyl-D-Neuraminic Acid, 2,3-Didehydro-2,4-Dideoxy-4-Guanidinyl-N-Acetylneuraminic Acid, 4 Guanidino 2 Deoxy 2,3 Didehydro N Acetylneuraminic Acid, 4 Guanidino Neu5Ac2en, 4-Guanidino-2,4-Dideoxy-2,3-Didehydro-N-Acetylneuraminic Acid, 4-Guanidino-2-Deoxy-2,3-Didehydro-N-Acetylneuraminic Acid, 5-Acetylamino-2,6-Anhydro-4-Guanidino-3,4,5-Trideoxy-D-Galacto-Non-Enoic Acid, 4-Guanidino-Neu5Ac2en, zanamivir, zanamivir (medication), ZANAMIVIR, Zanamivir [Chemical/Ingredient], Zanamivir (product), Zanamivir (substance)
Portuguese Zanamivir
Spanish Zanamivir, zanamivir (producto), zanamivir (sustancia), zanamivir
Italian Zanamivir
German 2,3-Didehydro-2,4-Dideoxy-4-Guanidino-N-Acetyl-D-Neuraminsäure, 4-Guanidino-2,4-Dideoxy-2,3-Didehydro-N-Acetylneuraminsäure, 4-Guanidino-2-Deoxy-2,3-Didehydro-N-Acetylneuraminsäure, 4-Guanidino-Neu5Ac2en, Zanamivir, 2,3-Didehydro-2,4-Dideoxy-4-Guanidinyl-N-Acetylneuraminsäure
French Zanamivir, Acide 5-acétamido-2,6-anhydro-4-guanidino-3,4,5-tridésoxy-D-glycéro-D-galacto-non-2-énonique, Acide N-acétyl-2,3-déhydro-2,4-didésoxy-4-guanidino-neuraminique
Finnish Tsanamiviiri
Czech zanamivir
Japanese ザナミビル
Swedish Zanamivir
Polish Zanamiwir

Ontology: Oseltamivir (C0874161)

Definition (NCI) A synthetic derivative prodrug of ethyl ester with antiviral activity. Osetamivir blocks neuraminidases on the surfaces of influenza viruses, interfering with host cell release of complete viral particles.
Definition (MSH) An acetamido cyclohexene that is a structural homolog of SIALIC ACID and inhibits NEURAMINIDASE.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D053139
SnomedCT 386142008, 412261005
LNC LP101308-7, MTHU036068
English ethyl (3R,4R,5S)-4-acetamido-5-amino-3-pentan-3-yloxy-cyclohexene-1-carboxylate, Oseltamivir [Chemical/Ingredient], OSELTAMIVIR, oseltamivir, Oseltamivir, Oseltamivir (product), Oseltamivir (substance)
Portuguese Oseltamivir
Spanish Oseltamivir, oseltamivir (producto), oseltamivir, oseltamivir (sustancia)
Italian Oseltamivir
German Oseltamivir
Finnish Oseltamiviiri
Czech oseltamivir
Japanese オセルタミビル
Swedish Oseltamivir
French Oséltamivir
Polish Oseltamiwir

Ontology: Relenza (C0876148)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D053243
English Relenza, Biota Brand of Zanamivir, Glaxo Wellcome Brand of Zanamivir, GlaxoSmithKline Brand of Zanamivir, Zanamivir Biota Brand, Zanamivir GlaxoSmithKline Brand, relenza
German Relenza
Czech Relenza

Ontology: Tamiflu (C0876173)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D053139
English Tamiflu, oseltamivir phosphate (Tamiflu), tamiflu
French Tamiflu
German Tamiflu
Italian Tamiflu
Czech Tamiflu