Tamiflu™ (Oseltamivir) for Healthcare Providers
Tamiflu™ (Oseltamivir) is a prescription drug referred to as a neuraminidase inhibitor.
Neuraminidase inhibitors are a class of antiviral agents that are active against both
Influenza A and B. They are approved by Health Canada for prophylaxis and/or
treatment of influenza in healthy adults and/or children. Currently, two products are
available in Canada – Tamiflu™ and Relenza (Zanamivir). Tamiflu is the recommended
drug of choice for both prophylaxis and treatment in an influenza outbreak.
Prophylactic
Dosage
Oseltamivir (Tamiflu™)
A - No known renal disease
Or if in the presence of renal
Disease and the serum Creatinine
Is less than 150 umol/l
75 mg OD (once daily) for 14 days
or until outbreak is declared over
Zanamivir (Relenza™)
No applicable. Health
Canada has not approved
Zanamivir for use as a
prophylaxis against Influenza A
or B.
B – Known renal disease and a
serum Creatinine greater than 150
umol/l, or if on dialysis
75 mg OD x 5 days, stop for 5 days,
then repeat 5 days on, 5 days off,
then stop; or until outbreak is
declared over
Treatment
Dosage
A – No known renal disease or
A – No known renal disease
serum Creatinine is 150-250 umol/l 2 puffs (10 mg) BID for 5 days
75 mg BID (twice daily) for 5 days
B – Known renal disease and
B – Known to have renal disease,
patient is on dialysis or has a
serum Creatinine is 150-250 umol/l serum creatinine of >250
75 mg OD daily for 5 days
umol/l
If on dialysis and Creatinine is >250
mol/l, and cannot take Zanamivir,
Oseltamivir 75 mg OD for 2 days
2 puffs (10 mg) BID (10 = 2
blisters) for 5 days
Measurement of serum creatinine and estimation of creatinine clearance is not required
for the use of neuraminidase inhibitors. Measurement of serum creatinine is required
only if there is a clinical reason to suspect a new onset of renal impairment.
Recommendations for Use in Institutional Outbreaks of Influenza
Treatment:


If treatment of influenza is started within 48-hours after the first symptoms, there
is a modest reduction in symptom duration, severity and possibly some reduction
in the risk of complications.
Treatment provided more than 48-hours after the onset of illness will not provide
any benefit.
Prophylaxis:

Antiviral prophylaxis should be given to all residents who are not already ill with
influenza regardless of influenza vaccine status and to all unvaccinated staff.

Unvaccinated healthcare workers who choose to take Tamiflu™ are able to work
as soon as they start the medication. However, these workers must be alert to the
signs and symptoms of influenza, particularly in the first 48-hours after starting
the medication.

Employees who receive their flu shot at the onset of the outbreak are considered
unvaccinated for 2 weeks and must take Tamiflu™ for 2 weeks from the date of
vaccination.

Prophylaxis is to continue until the outbreak is declared over. Under normal
circumstances outbreaks are declared over 8 days after the onset of the last case.

If respiratory symptoms develop in a patient on prophylaxis, the dose should be
changed to the therapeutic dose and continued for a total of five days, starting
from the day when the therapeutic dose was first given.

Oseltamivir should only be given to a pregnant or lactating woman if the potential
benefit justifies the potential risk to the fetus or nursing infant.

Gastrointestinal upset has been noted as a side effect, as such, it is recommended
that Tamiflu be given with a snack or at mealtime. GI upset, if it occurs, is
usually associated with the first dose.
Source: Grey Bruce Health Unit, Ontario, Canada