Oseltamivir
An oral neuraminidase inhibitor used to treat influenza A and B early in the illness and to prevent it after exposure.
Drug card
- How it works
- Blocking influenza neuraminidase, so new virus particles cannot leave cells
- Used for
- Treating influenza A and B
- Preventing influenza after exposure
- Known for
- Nausea and vomiting
- Its name
- -vir means an antiviral; -amivir means an influenza neuraminidase inhibitor
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does oseltamivir work?
An ethyl ester prodrug that liver esterases convert to oseltamivir carboxylate, which blocks influenza A and B neuraminidase so new virus particles are not released from infected cells. It helps most when started within 48 hours of symptoms. Resistance can arise through neuraminidase mutations.
Uses
What is oseltamivir used for?
- Treating influenza A and B
- Preventing influenza after exposure
Side effects
Side effects of oseltamivir
- Nausea and vomitingKnown for
- Headache
- Delirium, hallucinations and abnormal behaviorSerious
- Severe skin reactions: SJS, TENSerious
- Anaphylaxis and facial swellingSerious
- Hepatitis and abnormal liver testsSerious
- SeizuresSerious
- Gut bleeding and hemorrhagic colitisSerious
- Irregular heart rhythmSerious
- Worse blood sugar control in diabetes
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Start as soon as possible: benefit is greatest within 48 hours of symptoms, though CDC still advises it for hospitalized patients after that.
- Lower the dose in kidney impairment; not advised in end-stage kidney disease without dialysis.
- Avoid the live nasal flu vaccine from 2 weeks before to 48 hours after treatment.
- Watch for abnormal behavior early in the illness, especially in children.
Good to know: CDC names oral oseltamivir the preferred influenza antiviral in pregnancy and for patients in hospital.
Remember it
A way to remember it
Neuraminidase is the exit door: lock it and the flu cannot get out.
New influenza particles need neuraminidase to leave the cell that made them. Oseltamivir and zanamivir block it, so the virus stays trapped and spreads less, which is why starting within 48 hours matters.
Written for biofideX
Its name
-vir means antiviral
Sub-stems name the target: -ciclovir, -amivir, -fovir, -tegravir, -navir, -buvir, -virine (NNRTIs). Lamivudine and zidovudine are antivirals without it.
-amivir means influenza neuraminidase inhibitor
Oseltamivir, zanamivir and peramivir block influenza neuraminidase, so new virus particles can't leave infected cells.
- Every drug name stem
Its class
Neuraminidase inhibitors
Influenza A and B viruses need their surface enzyme neuraminidase to be released from the cell that made them. Neuraminidase inhibitors block this enzyme, so complete virus particles are not set free to infect more cells. They help most when begun in the first 48 hours of symptoms, and they can also prevent infection after exposure.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Oseltamivir phosphate for oral suspension: label (DailyMed)
- Oseltamivir (NCI Thesaurus)
- Influenza Antiviral Medications: Summary for Clinicians (CDC)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Antivirals
Oseltamivir is one of 10 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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