According to the Centers for Disease Control and Prevention (CDC), antiviral medications are sometimes used to treat swine flu in people who are very sick, people who are at high risk for serious swine flu-related complications and close contacts of these people. As of February 2010, the FDA has only approved two drugs, Tamiflu and Relenza, for the treatment of swine flu. Two other FDA-approved flu drugs, Amantidine and Rimantidine are ineffective against swine flu.
Neuraminidase Inhibitors: Tamiflu and Relenza
Both of the FDA-approved drugs for swine flu are classified as neuraminidase inhibitors. According to a 2009 article in the British Medical Journal, neuraminidase inhibitors work by blocking the exit of the influenza virus from the host cells, effectively stopping replication. Unfortunately, because both drugs work the same way, resistance to one usually means resistance to both. The CDC has stated that neuraminidase inhibitors "can make you feel better and shorten the time you are sick by 1 or 2 days." Reviews such as the one in the British Medical Journal have called into question neuraminidase inhibitors' ability to reduce the risk of complications from influenza.
Tamiflu
According to the manufacturer's prescribing information, Tamiflu (oseltamivir phosphate) is available as 30, 45 and 75 mg capsules and a 12 mg/mL oral suspension suitable for children and people who are unable to swallow the capsule. In adults, the standard dose is 75 mg twice daily for five days in people with swine flu and 75 mg once daily for 10 days for the prevention of swine flu. People with kidney problems should follow a decreased dosing schedule. In children, dosing is weight based and ranges from 30 to 75 mg once or twice daily.
According to MedlinePlus, the FDA granted emergency approval for the use of Tamiflu in the treatment and prevention of swine flu in children under 1 year. (For seasonal flu, Tamiflu is approved only in people over the age of 1.) In clinical studies, the most common side effects of Tamiflu were nausea (10 percent) and vomiting (9 percent). Both were decreased by taking the medication with food.
Relenza
According to the manufacturer's prescibing information, Relenza (zanamivir inhalation) is dispensed as a 5 mg blister, called a"Rotadisk," for oral inhalation. The standard dose for the treatment of swine flu is 10 mg (two Rotadisks) twice daily for five days. The standard dose for prophylaxis of swine flu is 10 mg (two Rotadisks) once daily for 10 days (household settings) or 28 days (community settings). The Rotadisks contain powder which is inhaled through the mouth using an included plastic inhaler called a "Diskhaler." Relenza is approved for the treatment of swine flu in adults and children older than 7 and for swine flu prophylaxis in adults and children older than 5.
Relenza contains lactose, a component of milk, and it is contraindicated in people with milk allergies. Relenza has also been associated with serious, sometimes fatal cases of bronchospasm, so it should not be taken by people with a history of underlying lung disease. In clinical studies, the most common side effects of Relenza, reported by about 1.5 percent of patients, included inflammation of the sinuses, dizziness, fever and/or chills and joint pain.
References
- CDC: 2009 H1N1 and Seasonal Flu: What You Should Know About Flu Antiviral Drugs
- "British Medical Journal;" Neuraminidase Inhibitors for Preventing and Treating Influenza in Healthy Adults: Systematic Review and Metaanalysis; T. Jefferson, M. Jones, P. Doshi, and C. Del Mar; 2009
- Tamiflu: Tamiflu Prescribing Information
