- uncomplicated influenza noted within 48 hours of illness onset
- bacterial coinfection
- high risk for complications ie. residents of nursing homes and chronic care facilities, adults with chronic medical conditions such as pulmonary disease, cardiovascular disease, active malignancy, chronic renal insufficiency, chronic liver disease, DM, hemoglobinopathies, immunosupression
- two classess of antiviral drugs available: neuramindase inhibitors (zanamivir and oseltamivir) and adamantanes (amantadine and rimantadine)
- influenza comes in several flavors: influenza A including subtypes H1N1 and H3N2; and influenza B
- traditionally, as in just last year, the neuraminidase inhibitors were active against both influenza A and B; and the adamantanes were active against influenza A, although there were high rates of resistance particularly among H3N2
- this year, while influenza activity has been relatively low, there is a 98% rate of resistance to oseltamivir (Tamiflu) among H1N1. Fortunately though, the the H1N1 viruses tested to date have been susceptible to zanamivir, amantadine and rimantadine.
- in light of these susceptibility results, the CDC's most recent, hot off the press, influenza treatment guidelines for this year are (click to enlarge):
- Of note, Zanamivir is an inhaled powder and is contraindicated in those at risk of bronchospasm ie asthma or COPD patientsSources
Interim Antiviral Guidance for 2008-2009. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/professionals/antivirals/index.htm
Zachary, K. MD. "Antiviral drugs for the treatment of influenza in adults." Up to Date. 2009 6 Jan