Pharmacotherapy Newsletter

Volume 1, Issue 23, 06/22/2009

Question

Is oseltamivir (Tamiflu®) effective if administered greater than 48 hours after the onset of flu-like symptoms caused by swine-origin influenza A (H1N1) viral infection?

Answer

As the swine-origin influenza type A (H1N1) virus spreads across the globe, more patients will qualify for treatment with the neuraminidase inhibitor, oseltamivir (Tamiflu®). For information on how oseltamivir works to prevent and treat the current H1N1 virus, please refer to the Pharmacotherapy Newsletter from May 4, 2009.¹  The Centers for Disease Control and Prevention (CDC) currently recommends that clinicians initiate oseltamivir therapy within 48 hours of symptom onset.²  However, many patients are not able or simply do not present to their health care provider within this window of time.  How effective is oseltamivir in patients who have been experiencing flu-like symptoms for greater than 48 hours?