Tamiflu, Oseltamivir Phosphate

Oseltamivir, Tamiflu ®, and Antiviral Drugs Used to Treat Influenza: Oseltamivir, known as Tamiflu®, is an antiviral drug produced by Hoffman La Roche Inc. used to treat influenza A and B. The drug is a neuraminidase inhibitor and shares this category with zanamivir, Relenza®, produced by GlaxoSmithKline. Lately the drug, which is not yet produced generically, has been catapulted to drug fame for its potential in treating the H5N1 subtype of Influenza A, bird flu, the next candidate for a pandemic flu.

Indications and Mechanism of Action.: Oseltamivir is used to treat Influenzas A and B administered within 48 hours of the onset of symptoms. It is also used to prevent the spread of the flu to other people. Some resistance to oseltamivir has been found in humans infected with the current strain of H5N1. Neuraminidase inhibitors attack the N component of influenza, neuraminidase, a surface antigen on the influenza A and B viruses that allows newly formed viruses (virons) to be released from host cells to infect healthy cells.

Not a Subtitute for a Flu Shot: Oseltamivir is intended to treat flu, not prevent it. The best prevention of influenza is a vaccine. The seasonal flu shot is a vaccine against three different types of flu, two Influenza A subtypes and one strain of Influenza B. The seasonal flu vaccine will not prevent you from contracting the H5N1 bird flu virus or pandemic influenza.

Use in Children: Oseltamivir can be used in children, but the dose must be adjusted because children metabolize the drug at a different rate than adults.

Contraindications: Caution should be taken for those with decreased kidney funtion, kidney, liver, lung or heart disease, those who are pregnant, or trying to get pregnant, breastfeeding women and anyone with allergies to oseltamivir or other medicines, food dyes, and preservatives.

Oseltamivir in the Treatment of Bird Flu: The Writing Committee of the World Health Organization (WHO) Consultation on Human Influenza (A/H5) recommends that anyone suspected of having been infected with Influenza A H5N1 should be treated with a neuraminidase inhibitor (oseltamivir (Tamiflu®) or zanamivir (Relenza®)). The ideal dose and the length of time the drug should be taken is not yet determined. Both drugs have shown promise in cell culture, but their use in treatment of H5N1 has so far been limited and very recent.

Dosage of Oseltamivir for Bird Flu: The dosage for the treatment of bird flu if caught early is likely to be the same as that indicated for seasonal flu. However, The Writing Committee of the World Health Organization (WHO) Consultation on Human Influenza states that treatment of severe cases with higher doses (150mg for adults) for 7-10 days needs to be studied.