Zanamivir (Relenza) is another neuraminidase inhibitor effective against influenza strains A and B. We are currently reserving its use for patients with H1N1 that may develop resistance to oseltamivir (Tamiflu) since it has been effective in these situations with past influenza strains.

• Zanamivir is given by inhalation only (powder) and can therefore not be given to ventilated patients
• Treatment dose is 10 mg (two blister packs) BID for 5 days
• Prophylaxis is 10 mg (two blister packs) once daily for 10 days
• Most common adverse effects are respiratory related and include bronchospasm and cough
• Pregnancy category C (same as Tamiflu) and should be used in pregnant patients with suspected/confirmed H1N1 due to the increased risk of morbidity/mortality
  • In fact, zanamivir may be the preferable antiviral for pregnant women because of its limited systemic absorption