Medications and Drugs

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Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: oseltamivir

BRAND NAME: Tamiflu

DRUG CLASS AND MECHANISM: Oseltamivir is an oral medication used for treating and preventing the "flu." It is similar to zanamivir (Relenza). Oseltamivir suppresses and decreases the spread of influenza A and B viruses, the viruses responsible for the flu. It does this by blocking the action of neuraminidase, an enzyme produced by the viruses that enables the viruses to spread from infected cells to healthy cells. By preventing the spread of virus from cell to cell, the symptoms and duration of influenza infection are reduced. On average, oseltamivir reduces the duration of symptoms by one and a half days if treatment is started within forty-eight hours of the beginning of symptoms. The FDA approved oseltamivir in October 1999.

GENERIC AVAILABLE: No

PRESCRIPTION: Yes

PREPARATIONS: Capsules: 30, 45, and 75 mg. Suspension: 12 mg/ml

STORAGE: Oseltamivir should be stored at room temperature, 15-30 C (59-86 F).

PRESCRIBED FOR: Oseltamivir is used for the treatment of uncomplicated infections with the influenza viruses, including H1N1, in adults and children (one year and older) within two days of the beginning of symptoms. It also is approved for emergency use in children less than 1 year old. Oseltamivir can be used for preventing the flu in healthy individuals, but it is not a substitute for flu vaccine.

DOSING: Oseltamivir is administered orally.

• The recommended dose for treating adults is 75 mg twice daily for five days.
• Children are treated with 30-75 mg twice daily depending on body weight.

For the best results, treatment should begin within 2 days of symptom onset. The recommended dose for preventing flu after close contact with an infected individual is 75 mg daily for 10 days.

DRUG INTERACTIONS: Oseltamivir potentially may interfere with the action of the live attenuated flu vaccine that is given by injection because oseltamivir prevents viral replication. Therefore, live attenuated flu vaccine should not be administered within two weeks before or 48 hours after administration of oseltamivir.

PREGNANCY: The Centers for Disease Control (CDC) recommends use of oseltamivir for treating flu in pregnant women.

NURSING MOTHERS: The CDC recommends that women with flu who have recently given birth may be treated with oseltamivir. Oseltamivir is approved for use in children one year old and older, and available evidence suggests that the risk of adverse events is low when oseltamivir is used in children less than 1 year old.

SIDE EFFECTS: The most frequent side effects of oseltamivir are nausea, vomiting, diarrhea, bronchitis, abdominal pain, headache and dizziness. Administering oseltamivir after meals helps reduce nausea. Other reported adverse events include allergic reactions, skin reactions, seizures, behavioral disturbances, and aggravation of diabetes.

REFERENCES:

Tamiflu Prescribing Information, 2008. Roche Laboratories.

CDC. "Updated Interim Recommendations for the Use of Antiviral Medications in the Treatment and Prevention of Influenza for the 2009-2010 Season."