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: 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
VI. 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
VII. 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
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
- Jefferson (2012) Cochrane Database Syst Rev 1: CD008965 [PubMed]
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]
Images: Related links to external sites (from Bing)
Related Studies
oseltamivir (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
OSELTAMIVIR PHOS 30 MG CAPSULE | Generic | $8.15 each |
OSELTAMIVIR PHOS 45 MG CAPSULE | Generic | $8.10 each |
OSELTAMIVIR PHOS 75 MG CAPSULE | Generic | $8.83 each |
tamiflu (on 4/19/2017 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
TAMIFLU 30 MG CAPSULE | Generic | $8.15 each |
TAMIFLU 45 MG CAPSULE | Generic | $8.10 each |
TAMIFLU 6 MG/ML SUSPENSION | $2.30 per ml | |
TAMIFLU 75 MG CAPSULE | Generic | $8.83 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 |
Russian | ЗАНАМИВИР, 4-ГУАНИДИНО-2,4-ДИДЕЗОКСИ-2,3-ДИДЕГИДРО-N-АЦЕТИЛНЕЙРАМИНОВАЯ КИСЛОТА, ZANAMIVIR, 4-GUANIDINO-2,4-DIDEZOKSI-2,3-DIDEGIDRO-N-ATSETILNEIRAMINOVAIA KISLOTA |
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) |
Russian | ТАМИФЛУ, ОЗЕЛТАМИВИР, GS 4071, ТАМИФЛЮ, TAMIFLU, OZELTAMIVIR, TAMIFLIU |
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 |
Ontology: Neuraminidase inhibitor (C1443650)
Concepts | Pharmacologic Substance (T121) |
SnomedCT | 409228005, 409227000 |
English | Sialidase inhibitor, Neuraminidase inhibitor, Neuraminidase inhibitor (product), Neuraminidase inhibitor (substance) |
Spanish | inhibidor de la neuraminidasa (producto), inhibidor de la neuraminidasa (sustancia), inhibidor de la neuraminidasa |
Ontology: peramivir (C1675326)
Definition (NCI) | A cyclopentane derivative with activity against influenza A and B viruses. Peramivir is a neuraminidase inhibitor which prevents normal processing of virus particles such that virus particles are not released from infected cells. |
Concepts | Organic Chemical (T109) , Pharmacologic Substance (T121) |
MSH | C414210 |
English | Peramivir, (1S,2S,3R,4R)-3-((1S)-1-acetylamino-2-ethylbutyl))-4-((aminoiminomethyl)amino-2-hydroxycyclopentanecarboxylic acid, trihydrate, peramivir, PERAMIVIR, 3-(1-acetamido-2-ethyl-butyl)-4-guanidino-2-hydroxy-cyclopentane-1-carboxylic acid |