Dosing, Storage & Administering Information | Tamiflu� (oseltamivir phosphate)

Dosing By Weight

Administering Tamiflu

New strength: Announcing a new strength of Tamiflu for Oral Suspension 6 mb/mL.

Tamiflu is indicated in patients 1 year and older for the treatment of uncomplicated influenza caused by virus Types A and B who have been symptomatic for no more than 2 days, and for the prophylaxis of influenza. We have changed the concentration from 12 mg/mL to 6 mg/mL and the dispenser from mg to mL. The new 6 mg/mL Tamiflu for Oral Suspension (NDC 0004-0820-09) coupled with a new oral dispenser in mL will help simplify prescribing and dosing.

The 12 mg/mL concentration is no longer being manufactured.

Quick links

Dosing and administration ›
Commonly asked questions by healthcare professionals ›
Taking Tamiflu with other medications ›
Important Safety Information ›
Storing Tamiflu for Oral Suspension ›

Important Prescribing Information (revised March 2011)

Please prescribe Tamiflu for appropriate patients as follows.

Formulation and concentration or strength:

Oral suspension (6 mg/mL) or capsules (30 mg, 45 mg or 75 mg).
Dose: mL (preferred for oral suspension) or mg (preferred for capsules), based on patient's weight (please refer to the dosing table for more information).

Frequency and duration:

Treatment twice daily for 5 days.
Prophylaxis: once daily, typically for 10 days for postexposure prophylaxis or for up to 6 weeks during community outbreak.

Dosing and administration

Tamiflu may be taken with or without food. However, when taken with food, tolerability may be enhanced in some patients. The recommended oral treatment and prophylaxis dose of Tamiflu for patients 1 year of age and older is shown in the table below.

Dosing and administration table

Patients aged 13 years and older should receive Tamiflu 75 mg regardless of weight.

Please see the Tamiflu full Prescription Information for complete safety information.

Commonly asked questions by healthcare professionals

What has changed with the new Tamiflu (oseltamivir phosphate) for Oral Suspension (OS)?

The concentration of the constituted OS product has changed from 12 mg/mL to 6 mg/mL.
The new oral dispenser is labeled in mL, rather than mg.
Usable bottle volume has changed from 25 mL to 60mL.
The drug product/formulation has not changed.

Why are these changes being made?

The new strength of Tamiflu for Oral Suspension helps to reduce the potential for prescribing and dosing confusion through the following:

Including a new oral dispenser labeled in mL to align with how prescriptions are commonly written.
Lowering the OS concentration can simplify administration for caregivers:
- Previous: 15 mg/mL for pharmacist-compounded and 12 mg/mL for premanufactured OS.
- New: 6 mg/mL harmonizing concentration in emergency compounding instructions to match premanufactured OS.

What if the local pharmacy does not have any Tamiflu for Oral Suspension in stock?

Genentech expects the supply of Tamiflu for Oral Suspension and all other formulations, including the 75-mg capsules for adults and the 30-mg and 45-mg capsules for children, to be ample to meet demands of the 2011-2012 season.

Tamiflu provides the flexibility for healthcare professionals to treat and prevent influenza with alternatives to oral suspension:

Tamiflu 30-mg or 45-mg capsules, depending on the weight of the child.
For patients with difficulty swallowing capsules, contents can be mixed into sweetened liquids, such as chocolate syrup, by a caregiver.

In emergency situations, if commercially manufactured Tamiflu for Oral Suspension is not readily available from wholesalers or Genentech, a liquid suspension can be compounded by a pharmacist using Tamiflu 75-mg capsules. Instructions for dosing and compounding may be found in the Tamiflu Prescribing Information.

Pharmacists: we encourage you to order Tamiflu for Oral Suspension 6 mg/mL and other formulations of the capsules for appropriate stocking of antiviral therapy to meet patient needs.

Taking Tamiflu with other medications¹

Information derived from pharmacology and pharmacokinetic studies of oseltamivir suggests that clinically significant drug interactions are unlikely.

Oseltamivir is extensively converted to oseltamivir carboxylate by esterases, located predominantly in the liver.

Drug interactions involving competition for esterases have not been extensively reported in literature. Low protein binding of oseltamivir and oseltamivir carboxylate suggests that the probability of drug displacement interactions is low.

The concurrent use of Tamiflu and live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the possibility for interference between these products, LAIV should not be given within 2 weeks before or 48 hours after administration of Tamiflu, unless medically indicated. The concern about possible interference arises from the potential for antiviral drugs to inhibit replication of live virus. Trivalent inactivated influenza vaccine can be administered at any time relative to use of Tamiflu.¹

In vitro studies showed no interference with the cytochrome P450 pathway.¹

No pharmacokinetic interactions have been observed when coadministering oseltamivir with amoxicillin, acetaminophen, cimetidine, antacids (magnesium and aluminum hydroxides and calcium carbonates), or warfarin.¹

Storing Tamiflu for Oral Suspension

Refrigeration: stable for 5 weeks (35 days) when stored in a refrigerator at 2° to 8°C (36° to 46°F).
Room temperature: stable for five days when stored at room temperature, 25°C (77°F).

Alternatively, store constituted liquid Tamiflu for up to 10 days at 77°F (25°C). As with all medications, keep out of the reach of children.¹ Discard any unused portion when you are finished with your prescribed dosing of Tamiflu.

Tamiflu can be mixed by a pharmacist extemporaneously when needed.

Important Safety Information

Tamiflu is contraindicated in patients who have had severe allergic reactions such as anaphylaxis or serious skin reactions such as toxic epidermal necrolysis, Stevens-Johnson syndrome, or erythema multiforme to any component of Tamiflu. Cases of these events have been reported in postmarketing experience with Tamiflu. Tamiflu should be stopped and appropriate treatment instituted if an allergic-like reaction occurs or is suspected.

There have been postmarketing reports of delirium and abnormal behavior leading to injury, and in some cases resulting in fatal outcomes, in patients with influenza who were receiving Tamiflu. These events were reported primarily among pediatric patients and often had an abrupt onset and rapid resolution. The contribution of Tamiflu to these events has not been established. Patients with influenza should be closely monitored for signs of abnormal behavior. If neuropsychiatric symptoms occur, the risks and benefits of continuing treatment should be evaluated for each patient.

Serious bacterial infections may begin with influenza-like symptoms or may co-exist with or occur as complications during the course of influenza. Tamiflu has not been shown to prevent such complications.

Efficacy in subjects with chronic cardiac and/or respiratory disease or in immunocompromised patients has not been established. No information is available regarding treatment of influenza in patients at imminent risk of requiring hospitalization.

The concurrent use of Tamiflu with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for interference between these products, LAIV should not be administered within 2 weeks before or 48 hours after administration of Tamiflu, unless medically indicated.

Adverse events that occurred more frequently in patients treated with Tamiflu than in patients taking placebo and occurred in ≥2% of patients were (Tamiflu %, placebo %):

Treatment in adults - nausea (10%, 6%), vomiting (9%, 3%), bronchitis (2%, 2%)
Treatment in pediatrics - vomiting (15%, 9%), abdominal pain (5%, 4%), epistaxis (3%, 3%), ear disorder (2%, 1%)
Prophylaxis of adults - headache (18%, 18%), nausea (7%, 3%), diarrhea (3%, 2%), vomiting (2%, 1%), abdominal pain (2%, 1%)
Prophylaxis of pediatrics - vomiting (10%, 2%), abdominal pain (3%, 0%), nausea (4%, 1%)

Please see the Tamiflu full Prescription Information for complete safety information.

Did you know?

In a clinical study, Tamiflu prophylaxis reduced postexposure flu transmission in children aged 1-12 years by 82%.²³

Learn more ›

Indications

TAMIFLU is indicated for the treatment of uncomplicated influenza caused by viruses types A and B in patients 1 year and older who have been symptomatic for no more than 2 days.

TAMIFLU is also indicated for the prophylaxis of influenza in patients 1 year and older.

Efficacy of TAMIFLU in patients who begin treatment after 48 hours of symptoms has not been established.

TAMIFLU is not a substitute for early and annual vaccination as recommended by the Centers for Disease Control’s Advisory Committee on Immunization Practices (ACIP).

There is no evidence for efficacy of TAMIFLU in any illness caused by agents other than influenza viruses Types A and B.

Influenza viruses change over time. Emergence of resistance mutations could decrease drug effectiveness. Other factors (for example, changes in viral virulence) might also diminish clinical benefits of antiviral drugs. Prescribers should consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use Tamiflu.

Important Safety Information¹

TAMIFLU is contraindicated in patients who have had severe allergic reactions such as anaphylaxis or serious skin reactions such as toxic epidermal necrolysis, Stevens-Johnson syndrome, or erythema multiforme to any component of TAMIFLU.

In postmarketing experience, rare cases of anaphylaxis and serious skin reactions, including toxic epidermal necrolysis, Stevens-Johnson syndrome and erythema multiforme, have been reported with TAMIFLU. Tamiflu should be stopped and appropriate treatment instituted if an allergic-like reaction occurs or is suspected.

Influenza can be associated with a variety of neurologic and behavioral symptoms, which can include events such as hallucinations, delirium and abnormal behavior, in some cases resulting in fatal outcomes. These events may occur in the setting of encephalitis or encephalopathy but can occur without obvious severe disease. There have been postmarketing reports (mostly from Japan) of delirium and abnormal behavior leading to injury, and in some cases resulting in fatal outcomes, in patients with influenza who were receiving TAMIFLU. Because these events were reported voluntarily during clinical practice, estimates of frequency cannot be made but they appear to be uncommon based on TAMIFLU usage data. These events were reported primarily among pediatric patients and often had an abrupt onset and rapid resolution. The contribution of TAMIFLU to these events has not been established. Patients with influenza should be closely monitored for signs of abnormal behavior. If neuropsychiatric symptoms occur, the risks and benefits of continuing treatment should be evaluated for each patient.

Serious bacterial infections may begin with influenza-like symptoms or may co-exist with or occur as complications during the course of influenza. TAMIFLU has not been shown to prevent such complications.

Treatment efficacy in subjects with chronic cardiac and/or respiratory disease has not been established. No difference in the incidence of complications was observed between the treatment and placebo groups in this population. No information is available regarding treatment of influenza in patients at imminent risk of requiring hospitalization.

Efficacy of TAMIFLU has not been established in immunocompromised patients.

The concurrent use of TAMIFLU with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for interference between these products, LAIV should not be administered within 2 weeks before or 48 hours after administration of TAMIFLU, unless medically indicated.

Adverse events that occurred more frequently in patients treated with TAMIFLU than in patients taking placebo and occurred in ≥2% of patients were (TAMIFLU %, placebo %):

Treatment in adults - nausea (10%, 6%), vomiting (9%, 3%), bronchitis (2%, 2%)
Treatment in pediatrics - vomiting (15%, 9%), abdominal pain (5%, 4%), epistaxis (3%, 3%), ear disorder (2%, 1%)
Prophylaxis of adults - headache (18%, 18%), nausea (7%, 3%), diarrhea (3%, 2%), vomiting (2%, 1%), abdominal pain (2%, 1%)
Prophylaxis of pediatrics - vomiting (10%, 2%), abdominal pain (3%, 0%), nausea (4%, 1%)

Please see the TAMIFLU full Prescription Information for complete safety information.

Dosing & Storage