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OSELTAMIVIR PHOSPHATE

Medical Diagnosis and Drugs, Medications
OSELTAMIVIR PHOSPHATE
(o-sel'tam-i-vir)
Tamiflu
Classifications: antiviral agent;
Therapeutic:antiviral
Pregnancy Category: C

Availability

30 mg, 45 mg, 75 mg capsule; 12 mg/mL suspension

Action

Inhibits influenza A and B viral neuraminidase enzyme, preventing the release of newly formed virus from the surface of the infected cells. Inhibits replication of the influenza A and B virus.

Therapeutic Effect

Effectiveness indicated by relief of flu symptoms. Prevents viral spread across the mucous lining of the respiratory tract.

Uses

Treatment of uncomplicated acute influenza in adults symptomatic for no more than 2 d.

Contraindications

Hypersensitivity to oseltamivir; pregnancy (category C); infants <1 y or neonates. Safety in hepatic disease has not been established.

Cautious Use

Renal impairment; lactation. Safety and efficacy in chronic cardiac/respiratory disease are not established.

Route & Dosage

Influenza Treatment
Adult: PO 75 mg b.i.d. x 5 d
Child (1–12 y): PO >40 kg, 75 mg b.i.d. x 5 d 23–40 kg, 60 mg b.i.d. x 5 d 15–22 kg, 45 mg b.i.d. x 5 d <15 kg, 30 mg b.i.d. x 5 d

Influenza Prevention
Adult/Child (>13 y): PO 75 mg qd x 7 d; begin within 2 d of contact with infected person

Renal Impairment
Clcr <30 mL/min: (treatment) 75 mg q.d. (prophylaxis) 75 mg q.o.d. or 30 mg q.d.

Administration

Oral
  • Give with food to decrease the risk of GI upset.
  • Start within 48 h of onset of flu symptoms.
  • Take missed dose as soon as possible unless next dose is due within 2 h.
  • Store at 15°–30° C (59°–86° F); protect from moisture, keep dry.

Adverse Effects (≥1%)

Body as a Whole: Fatigue. CNS: Dizziness, headache, insomnia, vertigo. GI: Nausea, vomiting, diarrhea, abdominal pain. Respiratory: Bronchitis, cough.

Pharmacokinetics

Absorption: Readily absorbed, 75% bioavailable. Distribution: 42% protein bound. Metabolism: Extensively metabolized to active metabolite oseltamivir carboxylate by liver esterases. Elimination: Primarily in urine. Half-Life: 1–2 h; oseltamivir carboxylate 6–10 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor ambulation in frail and older adult patients due to potential for dizziness and vertigo.
  • Monitor children for abnormal behavior such as delirium or self-injury.

Patient & Family Education

  • Contact your physician regarding the use of this drug in children.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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