Antimicrobials
Oseltamivir
Guidelines for use
TAMIFLU MEDICAL DIRECTIVE
Pharmacists may order prophylaxis by implementing the Medical Directive (MED-0062): Pharmacist Ordering of Oseltamivir (Tamiflu®) Prophylaxis for Inpatient Influenza Outbreaks
Active against: Influenza A & B
Please click on the titles below to read more:
1. Clinical Use
Appropriate Uses:
- Treatment of influenza for a maximum of 5 days. Although the Tamiflu prescribing information states that treatment should be initiated within 2 days of onset of symptoms, there is evidence of continued benefit in hospitalized patients when initiation of therapy is delayed beyond 2 days
- Prophylaxis against the spread of influenza among inpatients in a patient care area where an outbreak of influenza has been declared by Infection Prevention & Control (IP&C) should continue until IP&C has declared an end to the outbreak
- Prophylaxis of unvaccinated staff during an inpatient outbreak as decided by IP&C
Inappropriate Uses:
- Initiation of treatment for patients with a mid-turbinate swab positive for a respiratory virus other than influenza
2. Precautions
- Efficacy of oseltamivir for treatment or prevention of influenza in immunocompromised patients has not been established
- Pregnancy: Not expected to increase risk of major congenital malformations. Plasma concentrations of the active metabolite of oseltamivir were found to be lower in pregnant women. Possible reasons for this include: the increase in renal blood flow and GFR and/or the increase in volume of distribution in pregnancy. The clinical significance of this is unclear. However, shortening the dosing interval or increasing the dose may warrant consideration.
- Breastfeeding: Not expected to present any major safety issues
3. Adverse Effects
- Nausea, vomiting and abdominal pain
4. Dosage
| Treatment | Prophylaxis | |
| CrCl unknown | 75 mg BID; to be re-assessed when CrCl known | 75 mg now; then 75 mg once daily; to be re-assessed when CrCl known |
| CrCl > 60 mL/min | 75 mg BID | 75 mg now; then 75 mg once daily |
| CrCl 30 - 60 mL/min: | 45 mg BID | 45 mg now; then 45 mg once daily |
| CrCl 10 - 29 mL/min: | 45 mg once daily | 45 mg now; then 45 mg q 2 days |
| ESRD (CrCl < 10 mL/min): | 75 mg now; then one additional 75 mg dose on day 3 | 45 mg now; then 45 mg q 3 days |
| PD: | 75 mg now; then one additional 75 mg dose on day 3 | 45 mg now; then 45 mg q 3 days |
| HD: |
75 mg now; then 75 mg after each of the next 2 HD |
45 mg now; then 45 mg post-HD x 3 doses per week |
| CRRT: | 45 mg BID | 45 mg now; then 45 mg once daily |
5. Duration of Therapy
- Treatment: 5 days
- Prophylaxis: Until IP&C has declared an end to outbreak, or 7 days for patients in a room with someone who has been diagnosed with influenza
- If patient is discharged, prophylaxis should continue for 7 days from last presumed exposure to influenza. For example:
- Patient being discharged from outbreak floor: 7 additional days, regardless of length of prophylaxis already administered
- Patient being discharged after exposure to infected roommate: 7 days from the date of last exposure to influenza
Last updated: March 2018
