Oseltamivir Dosage

Medically reviewed by Drugs.com. Last updated on Sep 15, 2023.

Usual Adult Dose for Influenza

75 mg orally twice a day for 5 days

Comments:

• Therapy should begin within 48 hours of onset of influenza symptoms.

Use: For the treatment of acute, uncomplicated illness due to influenza A and B infection in patients symptomatic for no more than 48 hours

Usual Adult Dose for Influenza Prophylaxis

75 mg orally once a day

Duration of Therapy:

• After close contact with an infected individual: At least 10 days
• During a community outbreak: Up to 6 weeks
• In immunocompromised patients: Up to 12 weeks

Comments:

• Postexposure prophylaxis should begin within 48 hours after close contact with an infected individual; seasonal prophylaxis should begin during a community outbreak.
• Duration of protection lasts as long as dosing is continued.

Use: For the prophylaxis of influenza A and B

Usual Pediatric Dose for Influenza

2 weeks to less than 1 year: 3 mg/kg orally twice a day

1 to 12 years:

• Weight up to 15 kg: 30 mg orally twice a day
• Weight 15.1 to 23 kg: 45 mg orally twice a day
• Weight 23.1 to 40 kg: 60 mg orally twice a day
• Weight at least 40.1 kg: 75 mg orally twice a day

13 years or older: 75 mg orally twice a day

Duration of Therapy: 5 days

Comments:

• Therapy should begin within 48 hours of onset of influenza symptoms.
• For patients younger than 1 year: An appropriate dosing device that can accurately measure and administer small volumes should be provided.

Use: For the treatment of acute, uncomplicated illness due to influenza A and B infection in patients (2 weeks or older) symptomatic for no more than 48 hours

US CDC and American Academy of Pediatrics (AAP) Recommendations:
Preterm infants:

• Postmenstrual age less than 38 weeks: 1 mg/kg orally twice a day
• Postmenstrual age 38 through 40 weeks: 1.5 mg/kg orally twice a day
• Postmenstrual age greater than 40 weeks: 3 mg/kg orally twice a day

Full-term infants 8 months or younger: 3 mg/kg orally twice a day
Infants 9 to 11 months: 3 to 3.5 mg/kg orally twice a day

Children 1 year or older:

• Weight up to 15 kg: 30 mg orally twice a day
• Weight greater than 15 to 23 kg: 45 mg orally twice a day
• Weight greater than 23 to 40 kg: 60 mg orally twice a day
• Weight greater than 40 kg: 75 mg orally twice a day

Duration of therapy: 5 days

Comments:

• A pediatric infectious disease specialist should be consulted for extremely premature infants (postmenstrual age less than 28 weeks).
• A longer duration of therapy may be needed for severely ill patients.
• Current guidelines should be consulted for additional information.

Usual Pediatric Dose for Influenza Prophylaxis

1 to 12 years:

• Weight up to 15 kg: 30 mg orally once a day
• Weight 15.1 to 23 kg: 45 mg orally once a day
• Weight 23.1 to 40 kg: 60 mg orally once a day
• Weight at least 40.1 kg: 75 mg orally once a day

13 years or older: 75 mg orally once a day

Duration of Therapy:

• After close contact with an infected individual: 10 days
• For community outbreak (seasonal/preexposure) prophylaxis: Up to 6 weeks
• In immunocompromised patients: Up to 12 weeks

Comments:

• Postexposure prophylaxis should begin within 48 hours after close contact with an infected individual; seasonal prophylaxis should begin during a community outbreak.
• For patients 13 years or older: This drug should be used for at least 10 days after close contact with an infected individual. The duration of protection lasts as long as dosing is continued.

Use: For the prophylaxis of influenza A and B

US CDC and AAP Recommendations:
Full-term infants younger than 3 months: Not recommended unless situation judged critical.
Full-term infants 3 to 8 months: 3 mg/kg orally once a day
Infants 9 to 11 months: 3 to 3.5 mg/kg orally once a day

Children 1 year or older:

• Weight up to 15 kg: 30 mg orally once a day
• Weight greater than 15 to 23 kg: 45 mg orally once a day
• Weight greater than 23 to 40 kg: 60 mg orally once a day
• Weight greater than 40 kg: 75 mg orally once a day

Duration of therapy: 7 to 10 days (after last exposure)

• As preexposure prophylaxis during community outbreak (per AAP): Up to 6 weeks
• For outbreaks in institutional settings and hospitals (per US CDC): At least 2 weeks, continuing up to 1 week after last known case identified

Comments:

• Current guidelines should be consulted for additional information.

Renal Dose Adjustments

Adults:
Influenza Treatment:

• Mild renal dysfunction (CrCl greater than 60 to 90 mL/min): 75 mg orally twice a day
• Moderate renal dysfunction (CrCl greater than 30 to 60 mL/min: 30 mg orally twice a day
• Severe renal dysfunction (CrCl greater than 10 to 30 mL/min): 30 mg orally once a day
• ESRD and not undergoing dialysis (CrCl up to 10 mL/min): Not recommended.

Duration of therapy: 5 days

Influenza Prophylaxis:

• Mild renal dysfunction (CrCl greater than 60 to 90 mL/min): 75 mg orally once a day
• Moderate renal dysfunction (CrCl greater than 30 to 60 mL/min: 30 mg orally once a day
• Severe renal dysfunction (CrCl greater than 10 to 30 mL/min): 30 mg orally every other day
• ESRD and not undergoing dialysis (CrCl up to 10 mL/min): Not recommended.

Duration of therapy:

• Postexposure prophylaxis: At least 10 days
• For community outbreak (seasonal/preexposure) prophylaxis: Up to 6 weeks
• In immunocompromised patients: Up to 12 weeks

Comments:

• According to some experts: These renal dose adjustments may be useful for pediatric patients who weigh more than 40 kg.

Liver Dose Adjustments

Mild to moderate liver dysfunction: No adjustment recommended.
Severe liver dysfunction: Data not available

Precautions

CONTRAINDICATIONS:
Known serious hypersensitivity to the active component or any of the ingredients

Treatment of influenza: Safety and efficacy have not been established in patients younger than 2 weeks.
Prophylaxis of influenza: Safety and efficacy have not been established in patients younger than 1 year.

Consult WARNINGS section for additional precautions.

Dialysis

Adults:
Influenza Treatment:

• ESRD on hemodialysis (CrCl up to 10 mL/min): 30 mg orally immediately and then 30 mg orally after each hemodialysis cycle

Duration of therapy: Not to exceed 5 days

• ESRD on CAPD (CrCl up to 10 mL/min): 30 mg orally immediately as a single dose

Influenza Prophylaxis:

• ESRD on hemodialysis (CrCl up to 10 mL/min): 30 mg orally immediately and then 30 mg orally after alternate hemodialysis cycles
• ESRD on CAPD (CrCl 10 mL/min or less): 30 mg orally immediately and then 30 mg orally once a week

Duration of therapy:

• Postexposure prophylaxis: At least 10 days
• For community outbreak (seasonal/preexposure) prophylaxis: Up to 6 weeks
• In immunocompromised patients: Up to 12 weeks

Comments:

• For ESRD patients on CAPD: Data derived from studies in CAPD patients.

Other Comments

Administration advice:

• Start therapy within 48 hours of onset of influenza symptoms; start postexposure prophylaxis within 48 hours after close contact with an infected individual; start seasonal prophylaxis during a community outbreak.
• May administer with or without food; administration with food may improve tolerability.
• The oral suspension is preferred for patients unable to swallow capsules; use an oral dosing device that measures the appropriate volume in mL.
• If the commercial oral suspension is not available, the capsules can be used to prepare an extemporaneous suspension or mixture.
• Shake the oral suspension (commercial or emergency preparation) well before each use; discard unused portions after the completion of therapy.
• Consult the manufacturer product information regarding missed doses.

Storage requirements:

• Capsules and powder for oral suspension: Store at 25C (77F); excursions permitted to 15C to 30C (59F to 86F).
• Constituted oral suspension: Store under refrigeration for up to 17 days at 2C to 8 C (36F to 46F); do not freeze. Alternatively, store for up to 10 days at 25C (77F); excursions permitted to 15C to 30C (59F to 86F).
• Emergency preparation of oral suspension from 75 mg capsules: Stable for 35 days when stored refrigerated (2C to 8 C [36F to 46F]) or 5 days when stored at room temperature (25C [77F]).

Reconstitution/preparation techniques:

• The manufacturer product information should be consulted for preparation of the oral suspension; it should be constituted by the pharmacist prior to dispensing to the patient.
• When the oral suspension is unavailable from wholesalers/manufacturer: The capsules may be opened and mixed with sweetened liquids such as chocolate syrup (regular or sugar-free), corn syrup, caramel topping, or light brown sugar (dissolved in water).
• During emergency situations AND when the age-appropriate capsule strengths (to mix with sweetened liquids) and the oral suspension are not available: A pharmacist may prepare an emergency supply of oral suspension from the 75 mg capsules.

Emergency Preparation of Oral Suspension from 75 mg Capsules:

• The following directions are for use only during emergency situations AND when US FDA-approved, commercially manufactured oral suspension is not available from wholesalers/manufacturer.
• The following steps for emergency preparation will provide enough drug for 1 patient's treatment for 5 days or prophylaxis for 10 days:

STEP 1: Determine the dose of oseltamivir for the patient then determine the total volume of oral suspension necessary to be prepared; if the dose is between listed doses, use the greater listed dose to determine total volume of prepared oral suspension.

• Dose of 15 mg or less: 37.5 mL total volume
• Dose of 30 mg: 75 mL total volume
• Dose of 45 mg: 100 mL total volume
• Dose of 60 mg: 125 mL total volume
• Dose of 75 mg: 150 mL total volume

Step 2: Determine the number of 75 mg capsules (includes overage to ensure delivery of all doses), amount of water, and amount of vehicle (with only 1 of the following: Cherry Syrup [Humco(R)], Ora-Sweet[R] SF [sugar-free][Paddock Laboratories], or simple syrup) necessary to prepare the total volume of prepared oral suspension (6 mg/mL) for a complete treatment or prophylaxis course.

• Total volume of 37.5 mL: 3 capsules (225 mg oseltamivir) plus 2.5 mL water plus 34.5 mL vehicle
• Total volume of 75 mL: 6 capsules (450 mg oseltamivir) plus 5 mL water plus 69 mL vehicle
• Total volume of 100 mL: 8 capsules (600 mg oseltamivir) plus 7 mL water plus 91 mL vehicle
• Total volume of 125 mL: 10 capsules (750 mg oseltamivir) plus 8 mL water plus 115 mL vehicle
• Total volume of 150 mL: 12 capsules (900 mg oseltamivir) plus 10 mL water plus 137 mL vehicle

STEP 3: Follow the procedure below for preparing the 75 mg capsules to produce the oral suspension (6 mg/mL).
(a) Place the specified amount of water into a polyethyleneterephthalate (PET) or glass bottle; constitution in other bottle types not recommended (no stability data).
(b) Carefully separate the capsule body and cap and place the contents of the number of 75 mg capsules needed into the PET or glass bottle.
(c) Gently swirl the suspension to ensure adequate wetting of the oseltamivir powder for at least 2 minutes.
(d) Slowly add the specified amount of vehicle to the bottle.
(e) Use a child-resistant cap to close the bottle and shake well for 30 seconds to completely dissolve the active drug and to ensure homogeneous distribution of the dissolved drug in the resulting suspension; the active drug (oseltamivir phosphate) is soluble in the specified vehicles but some of the inert ingredients are insoluble, causing the suspension.

General:

• This drug is not a substitute for annual, early influenza vaccination as recommended by the US CDC Advisory Committee on Immunization Practices.
• As influenza viruses change over time, resistant or more virulent mutations may emerge and decrease the efficacy of antiviral drugs; available influenza drug susceptibility patterns and treatment effects should be considered when deciding whether to use this drug.
• The sorbitol content in one 75 mg dose of the oral suspension is 2 g, which exceeds the daily maximum limit for patients with hereditary fructose intolerance.

Monitoring:

• Psychiatric: For signs of abnormal behavior in oseltamivir-treated patients with influenza

Patient advice:

• Read the US FDA-approved patient labeling (Patient Information and Instructions for Use).
• Stop this drug and seek immediate medical attention if allergic-like reaction occurs/is suspected.
• Contact physician if signs of abnormal behavior develop while using this drug.

Frequently asked questions

• Does Tamiflu (oseltamivir) work on COVID-19?
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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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