Oseltamivir is a neuraminidase inhibitor indicated for the treatment of uncomplicated acute illness due to influenza infection in patients ≥2 weeks of age who have been symptomatic for ≤2 days, but would using this antiviral agent outside the FDA-approved recommendations benefit patients? A study published in the American Journal of Health-System Pharmacy investigates whether available data suggests any benefit to increasing the window of when treatment can begin, whether extending treatment improves outcomes, or if doubling the standard dose improves survival.
A literature search on the use of oseltamivir outside its approved labeling uncovered six studies evaluating the effects of administering the drug 48 hours after symptom onset, giving the drug at double the standard dose (recommended dose is 75mg twice daily for 5 days), or continuing treatment past five days. Results of these studies showed that doubling the recommended dose of oseltamivir did not produce significant survival benefit. One study, which included ICU patients infected with H1N1 did suggest improved survival in patients who received oseltamivir no later than five days after the onset of symptoms. For outpatients or hospitalized general medicine patients, there appears to be no benefit in initiating oseltamivr treatment >48 hours after symptom onset or doubling the recommended dose.
The authors conclude that little data is available on the effectiveness of oseltamivir treatment beyond the recommended 5-day period. Critically-ill H1N1-infected ICU patients may possibly benefit from receiving extended therapy in some cases.