Products
Zanamivir is commercially available as a dischaler for powder inhalation (Relenza). It has been approved in many countries since 1999. Zanamivir is far less well known than oseltamivir (Tamiflu), probably mainly because of its more complicated administration.
Structure and properties
Zanamivir (C12H20N4O7, Mr = 332.3 g/mol) exists as a white powder. It has a low oral bioavailability of only 2%, unlike oseltamivir, and is therefore administered by inhalation rather than perorally.
Effects
Zanamivir (ATC J05AH01) has antiviral properties against influenza viruses. It reduces the duration and severity of illness. The effects are due to inhibition of viral neuraminidase and thus replication of the virus. Neuraminidase is central on the surface of influenza viruses for the release of newly formed viruses from infected cells and thus for the further spread of infectious viruses in the organism. Note also the following descriptive animation: Tamiflu animation.
Indications
For the prevention and treatment of influenza (influenza A and B).
Dosage
According to the SmPC. The drug should be used as soon as possible, preferably within 36 hours after the onset of symptoms. The drug is inhaled with a dischaler (see there). Inhalation is performed therapeutically twice daily for 5 days.
Contraindications
- Hypersensitivity
For complete precautions, see the drug label.
Interactions
Drug-drug interactions are considered unlikely. Other inhaled medications should be used before zanamivir.
Adverse Effects
The most common potential adverse effects include nasal symptoms; headache; indigestion; sore throat; malaise; fatigue; loss of appetite; muscle pain; fever; ear, nose, and throat infections; bronchitis; and cough. However, in our view, these side effects could also be related to influenza illness.
