Zanamivir
General Information
Both injection and diskhaler are Restricted formulary antimicrobials: For details see OUH netFormulary
Adult prescriptions may be authorised as below:
| Flu point of care or Lab result | Action |
| Flu positive | Zanamivir can be commenced without Micro/ID advice |
| Flu negative or pending | Discuss prescriptions with Micro/ID |
| No result available | Discuss prescriptions with Micro/ID |
Standard dose
Diskhaler: 10mg (2x5 mg) inhaled BD for 5 days
Intravenous infusion: 600 mg iv BD for 5 to 10 days
Renal and hepatic impairment
Renal impairment:
Diskhaler - No dose adjustment required
IV: See dosing table below. Renal dosing recommendations are from UKHSA Influenza: treatment and prophylaxis using anti-viral agents
| Creatinine clearance mL/min | zanamivir IV dose |
|
Greater than or equal to 80mL/min OR haemo(dia)filtration greater than 4.7L/hour exchange rate |
Initial dose: 600mg and 12 hours later, maintenance dose: 600mg BD |
|
50 to 79 OR haemo(dia)filtration 3.0 to 4.7L/hour exchange rate |
Initial dose: 600mg and 12 hours later, maintenance dose: 400mg BD |
|
30 to 49 OR haemo(dia)filtration 1.8 to 2.9L/hour exchange rate |
Initial dose: 600mg and 12 hours later, maintenance dose: 250mg BD |
|
15 to 29 OR Haemo(dia)filtration 1 to 1.7L/hour exchange rate |
Initial dose: 600mg and 24 hours later, maintenance dose: 150mg BD |
|
less than 15
|
Initial dose: 600mg and 48 hours later, maintenance dose: 60mg BD |
Note: Dose ranges use creatinine clearance, rather than eGFR.
Hepatic impairment
Diskhaler - No dose adjustment required
IV - No dose adjustment required
Pregnancy and breastfeeding
Discuss with pharmacy.
References
- UKHSA (2025) Guidance on use of antiviral agents for the treatment and prophylaxis of seasonal influenza. Accessed 21/11/25. LINK
- GSK. Relenza 5mg/dose inhalation powder. Summary of Product Characteristics. Last revision of text 18/12/23. Accessed 21/11/25
- GSK UK. Dectova 10mg/mL solution for infusion. Summary of Product Characteristics. Last revision of text 28/2/25. Accessed 21/11/25