oseltamivir

Absorption: Rapidly absorbed from the GI tract; 75% reaches systemic circulation as the active drug.

Distribution: Well distributed to tissues.

Metabolism/Excretion: Rapidly metabolized by the liver to oseltamivir carboxylate, the active drug. >99% excreted unchanged in urine.

Half-Life: Oseltamivir carboxylate: 6–10 hr.

Time/Action Profile ⬆ ⬇

(plasma concentrations)

ROUTE	ONSET	PEAK	DURATION
PO	unknown	unknown	12 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
End-stage renal disease and not receiving dialysis.

Use Cautiously in:

Renal impairment (↓ dose if CCr ≤60 mL/min);
Hereditary fructose intolerance (75 mg of oral suspension contains 2 g of sorbitol);
OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk;
Lactation: Use during breastfeeding only if potential maternal benefit justifies potential risk to infant;
Pedi: Children <2 wk (safety and effectiveness not established for treatment); children <1 yr (safety and effectiveness not established for prevention). Oral suspension contains sodium benzoate; avoid use in neonates.

Adv. Reactions/Side Effects ⬆ ⬇

Derm: ERYTHEMA MULTIFORME, STEVENS-JOHNSON SYNDROME (SJS), TOXIC EPIDERMAL NECROLYSIS (TEN)

GI: nausea, vomiting

Neuro: abnormal behavior, agitation, confusion, delirium, hallucinations, insomnia, nightmares, SEIZURES, vertigo

Resp: bronchitis

Interactions ⬆ ⬇

Drug-drug:

May ↓ therapeutic effect of influenza virus vaccine; avoid use 2 days prior to and 2 wk after vaccine administration.

Route/Dosage ⬆ ⬇

Treatment of Influenza

PO (Adults and Children ≥13 yr): 75 mg twice daily for 5 days.
PO (Children 1–12 yr and >40 kg): 75 mg twice daily for 5 days.
PO (Children 1–12 yr and 23.1–40 kg): 60 mg twice daily for 5 days.
PO (Children 1–12 yr and 15.1–23 kg): 45 mg twice daily for 5 days.
PO (Children 1–12 yr and ≤15 kg): 30 mg twice daily for 5 days.
PO (Infants 2 wk–<1 yr): 3 mg/kg/dose twice daily for 5 days.

Renal Impairment

PO (Adults ): CCr 30–60 mL/min: 30 mg twice daily for 5 days; CCr 10–30 mL/min: 30 mg once daily for 5 days; CCr ≥10 mL/min and on hemodialysis: 30 mg after each hemodialysis session (not to exceed 5 days); CCr ≥10 mL/min and on peritoneal dialysis: 30-mg single dose immediately after a dialysis exchange; CCr <10 mL/min and not on dialysis: Not recommended.

Influenza Prevention

PO (Adults and Children ≥13 yr): 75 mg once daily for ≥10 days.
PO (Children 1–12 yr and >40 kg): 75 mg once daily for 10 days.
PO (Children 1–12 yr and 23.1–40 kg): 60 mg once daily for 10 days.
PO (Children 1–12 yr and 15.1–23 kg): 45 mg once daily for 10 days.
PO (Children 1–12 yr and ≤15 kg): 30 mg once daily for 10 days.

Renal Impairment

PO (Adults ): CCr 30–60 mL/min: 30 mg once daily for ≥10 days; CCr 10–30 mL/min: 30 mg every other day for ≥10 days; CCr ≥10 mL/min and on hemodialysis: 30 mg after alternate hemodialysis sessions (treatment duration ≥10 days); CCr ≥10 mL/min and on peritoneal dialysis: 30 mg once weekly immediately after a dialysis exchange (treatment duration ≥10 days); CCr <10 mL/min and not on dialysis: Not recommended.

Availability ⬆ ⬇

(Generic available)

Capsules: 30 mg; 45 mg; 75 mg
Oral suspension tutti-frutti flavor: 6 mg/mL

Assessment ⬆ ⬇

Monitor progression of influenza symptoms. Additional supportive treatment may be indicated.
Monitor for signs of hypersensitivity reaction including anaphylaxis and serious skin reactions (TEN, SJS, erythema multiforme). If symptoms occur, discontinue oseltamivir and treat as indicated.

Implementation ⬆ ⬇

Begin therapy as soon as possible from the 1st sign of flu symptoms, within 2 days of exposure.
PO: May be administered with food or milk to minimize GI irritation.
Use correct oral dosing device for measuring oral solution. Dosing errors have occurred due to oseltamivir dosing in mg and solution in mL. Make sure units of measure on prescription instructions match dosing device provided with the drug.
- If oral suspension is not available, capsules may be opened and mixed with flavored foods (regular or sugar-free chocolate syrup, corn syrup, caramel topping, light brown sugar dissolved in water). If correct dose and oral suspension are not available, pharmacist may compound emergency supply of oral suspension from 75 mg capsules.

Patient/Family Teaching ⬆ ⬇

Explain purpose and side effects of medication. Advise patient to read Patient Information before starting therapy.
Instruct patient to take oseltamivir as soon as influenza symptoms appear and to continue to take it as directed for the full course of therapy, even if feeling better. Take missed doses as soon as remembered unless within 2 hr of next dose. Do not double doses.
Caution patient that oseltamivir should not be shared with anyone, even if they have the same symptoms.
Advise patient that oseltamivir is not a substitute for an influenza vaccine. Patients should receive annual influenza vaccine according to immunization guidelines.
Advise patients to report behavioral changes (hallucinations, delirium, abnormal behavior) to health care provider immediately.
Advise patient to notify health care provider of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care provider before taking other medications.
Rep: Advise women of reproductive potential to notify health care provider if pregnancy is planned or suspected or if breastfeeding.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇