Adult: 75 mg bid for 5 days. Initiate w/in 2 days of onset of symptoms. Child: 0-1 mth 2 mg/kg; >1-3 mth 2.5 mg/kg; >3-12 mth 3 mg/kg. >1 yr ≤15 kg: 30 mg; >15-23 kg: 45 mg; >23-40 kg: 60 mg; >40 kg: 75 mg. All doses to be given bid for 5 days. Initiate w/in 2 days of onset of symptoms.
Oral Prophylaxis of influenza A and B
Adult: 75 mg once daily for at least 10 days. Initiate w/in 2 days of exposure. For community outbreak: May continue dosing for up to 6 wk. Child: 0-1 mth 2 mg/kg; >1-3 mth 2.5 mg/kg; >3-12 mth 3 mg/kg. >1 yr ≤15 kg: 30 mg; >15-23 kg: 45 mg; >23-40 kg: 60 mg; >40 kg: 75 mg. All doses to be given once daily for 10 days. Initiate w/in 2 days of exposure. For community outbreak: May continue dosing for up to 6 wk.
Renal Impairment
Prophylaxis of influenza A and B: Haemodialysis patient: 30 mg after every 2nd dialysis session. Peritoneal dialysis patient: 30 mg once wkly.
CrCl (mL/min)
Dosage
≤10
Not recommended.
>10-30
30 mg every 2nd day.
>30-60
30 mg once daily.
Influenza A and B: Haemodialysis patient: 30 mg after each dialysis session. Peritoneal dialysis patient: 30 mg as a single dose.
CrCl (mL/min)
Dosage
≤10
Not recommended.
>10-30
30 mg once daily.
>30-60
30 mg bid.
Administration
May be taken with or without food. May be taken w/ meals to reduce GI discomfort. Cap may be opened & mixed w/ sweetened food products eg chocolate syr, sweetened condensed milk, apple sauce or yogurt. Swallow mixt immediately after preparation.
Reconstitution
Reconstitute w/ 55 mL of water to a final concentration of 6 mg/mL susp.
Contraindications
Hypersensitivity to oseltamivir.
Special Precautions
Patient w/ resp disease, chronic cardiac disease. Renal and severe hepatic impairment. Immunocompromised patient. Childn. Pregnancy and lactation.
Adverse Reactions
Nausea, vomiting, abdominal pain, insomnia, bronchitis, vertigo, diarrhoea, cough, dizziness, headache, fatigue, unstable angina, anaemia, arrhythmias, GI bleeding, haemorrhagic or pseudomembranous colitis, pneumonia, pyrexia, peritonsillar abscess, aches and pains, upper resp infections, dyspepsia, rhinorrhoea. In childn: Vomiting and other GI disturbances, bronchitis, asthma, conjunctivitis, dermatitis, ear disorders, otitis media, epistaxis, lymphadenopathy, sinusitis, pneumonia. Potentially Fatal: Anaphylaxis and skin rashes (e.g. Stevens-Johnson syndrome, erythema multiforme, epidermal necrolysis; neuropsychiatric events (e.g. delirium, hallucinations, abnormal behaviour). Rarely, fulminant hepatitis or hepatic failure.
Monitor closely for signs and symptoms of behavioural changes.
Drug Interactions
May potentially inhibit replication of influenza virus in live/attenuated influenza virus vaccine.
Action
Description: Oseltamivir is a prodrug of oseltamivir carboxylate. Oseltamivir carboxylate inhibits neuraminidase (sialidase), a viral surface enzyme which is responsible for the replication and infectivity of influenza virus A and B, thereby preventing the release of viruses from infected cells. Pharmacokinetics: Absorption: Readily absorbed from the GI tract. Bioavailability: 75% (as carboxylate). Time to peak plasma concentration: W/in 3-4 hr (as carboxylate). Distribution: Distributed throughout the body, including the upper and lower resp tract. Volume of distribution: 23-26 L (as carboxylate). Plasma protein binding: Approx 3% (as carboxylate); 42% (as parent drug). Metabolism: Extensively metabolised to oseltamivir carboxylate by hepatic esterases. Excretion: Via urine (>90% as carboxylate); faeces. Elimination half-life: 1-3 hr (as parent drug); 6-10 hr (as carboxylate).
Chemical Structure
Oseltamivir Source: National Center for Biotechnology Information. PubChem Database. Oseltamivir, CID=65028, https://pubchem.ncbi.nlm.nih.gov/compound/Oseltamivir (accessed on Jan. 22, 2020)
Storage
Store at 25°C. Reconstituted susp: Store between 2-8°C for up to 17 days or at 25°C for up to 10 days. Do not freeze.
J05AH02 - oseltamivir ; Belongs to the class of neuraminidase inhibitors. Used in the systemic treatment of viral infections.
References
Anon. Oseltamivir. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 29/10/2015.Buckingham R (ed). Oseltamivir Phosphate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 29/10/2015.Joint Formulary Committee. Oseltamivir. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 29/10/2015.McEvoy GK, Snow EK, Miller J et al (eds). Oseltamivir Phosphate. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 29/10/2015.Tamiflu Information. U.S. FDA. http://www.fda.gov/. Accessed 29/10/2015.Tamiflu Powder for Suspension; Capsule (Genentech, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 29/10/2015.
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