Oseltamivir


Generic Medicine Info
Indications and Dosage
Oral
Prophylaxis of influenza A and B
Adult: Postexposure prophylaxis after close contact with an infected individual: 75 mg once daily for 10 days. Initiate prophylaxis within 2 days of exposure. For community outbreak: 75 mg once daily for up to 6 weeks (or up to 12 weeks in immunocompromised patients).
Child: Postexposure prophylaxis after close contact with an infected individual or during community outbreak: 1-12 years weighing ≤15 kg: 30 mg once daily; >15-23 kg: 45 mg once daily; >23-40 kg: 60 mg once daily; >40 kg: 75 mg once daily; ≥13 years Same as adult dose. Recommended duration for postexposure prophylaxis: 10 days. Initiate prophylaxis within 2 days of exposure. Recommended duration for community outbreak: Up to 6 weeks; up to 12 weeks (immunocompromised patients). Dosage and treatment duration recommendations may vary among individual products and between countries (refer to specific product or local official guidelines).

Oral
Influenza A and B
Adult: 75 mg bid for 5 days (or for 10 days in immunocompromised patients). Initiate treatment within 2 days of the onset of symptoms.
Child: <1 year 3 mg/kg bid (dosing recommendation is not intended for premature infants, such as patients with post-conceptual age of <36 weeks); 1-12 years weighing ≤15 kg: 30 mg bid; >15-23 kg: 45 mg bid; >23-40 kg: 60 mg bid; >40 kg: 75 mg bid; ≥13 years Same as adult dose. Treatment duration: 5 days; 10 days (immunocompromised patients). Initiate treatment within 2 days of the onset of symptoms. Dosage recommendations may vary among individual products and between countries (refer to specific product or local official guidelines).
Renal Impairment
Influenza A and B:
Haemodialysis patients: 30 mg after each haemodialysis 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.
Dosage recommendations may vary among individual products and between countries (refer to specific product or local official guidelines).

Prophylaxis of influenza A and B:
Haemodialysis patients: 30 mg after every 2nd haemodialysis session. Peritoneal dialysis patients: 30 mg once weekly.
CrCl (mL/min) Dosage
≤10 Not recommended.
>10-30 30 mg every 2nd day.
>30-60 30 mg once daily.
Dosage recommendations may vary among individual products and between countries (refer to specific product or local official guidelines).
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
Powder for oral susp: Reconstitute with 55 mL of water to make a final concentration of 6 mg/mL. Shake well until suspended.
Contraindications
Hypersensitivity.
Special Precautions
Patient with chronic cardiac and/or respiratory disease; any severe or unstable medical condition that may require hospitalisation. Immunocompromised patients. Not to be used as a substitute for annual influenza vaccination. Concomitant use with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated; avoid administration of LAIV within 2 weeks before or 48 hours after the administration of oseltamivir. Renal and severe hepatic impairment. Children. Pregnancy and lactation.
Adverse Reactions
Significant: Gastrointestinal effects (e.g. nausea, vomiting). Rarely, anaphylaxis, toxic epidermal necrolysis, Stevens-Johnson Syndrome, erythema multiforme, angioneurotic oedema, gastrointestinal bleeding, haemorrhagic colitis.
Cardiac disorders: Arrhythmia.
Ear and labyrinth disorders: Vertigo; earache and otitis media (particularly in children).
Eye disorders: Conjunctivitis (particularly in children).
Gastrointestinal disorders: Abdominal pain, dyspepsia.
General disorders and administration site conditions: Pain, fatigue, pyrexia.
Infections and infestations: Herpes simplex.
Investigations: Elevated liver enzymes.
Musculoskeletal and connective tissue disorders: Pain in limb.
Nervous system disorders: Dizziness, headache, insomnia, altered level of consciousness, convulsion.
Respiratory, thoracic and mediastinal disorders: Cough, sore throat, rhinorrhoea, bronchitis, nasopharyngitis, sinusitis, URTI; nasal congestion (particularly in children).
Skin and subcutaneous tissue disorders: Eczema, dermatitis, rash, urticaria.
Potentially Fatal: Rarely, neuropsychiatric effects, including confusion, delirium, hallucination, or self-injury (particularly in children and adolescents); fulminant hepatitis, and hepatic failure.
Monitoring Parameters
Consider repeat real-time reverse transcription polymerase chain reaction (rRT-PCR) or viral culture to determine ongoing viral replication in critically ill patients. Closely monitor for signs of unusual behavioural changes including confusion, delirium, hallucination, or attempts at self-injury.
Drug Interactions
Oseltamivir may potentially inhibit the replication of live vaccine virus which may reduce the efficacy of intranasal LAIV. May result in approx 2-fold increased systemic exposure to oseltamivir carboxylate with probenecid. May compete for renal tubular secretion when given with co-excreted agents with narrow therapeutic index (e.g. chlorpropamide, methotrexate, phenylbutazone).
Action
Description:
Mechanism of Action: Oseltamivir is a prodrug of oseltamivir carboxylate (active metabolite). Oseltamivir carboxylate selectively inhibits the influenza virus neuraminidase, an enzyme essential for viral entry and release of recently formed virus particles from infected cells, and spreading the infectious viruses in the body. The inhibition of viral neuraminidase reduces the replication of influenza A and B viruses.
Pharmacokinetics:
Absorption: Readily and well absorbed from the gastrointestinal tract. Bioavailability: Approx 75% (oseltamivir carboxylate). Time to peak plasma concentration: Within 3-4 hours (oseltamivir carboxylate).
Distribution: Distributed throughout the body, including the upper and lower respiratory tract. Crosses the placenta and enters breast milk. Plasma protein binding: Approx 3% (oseltamivir carboxylate); 42% (oseltamivir).
Metabolism: Extensively metabolised predominantly by hepatic esterases into oseltamivir carboxylate (active metabolite).
Excretion: Mainly via urine (>90% as oseltamivir carboxylate); faeces (<20%). Elimination half-life: 1-3 hours (oseltamivir); 6-10 hours (oseltamivir carboxylate).
Chemical Structure

Chemical Structure Image
Oseltamivir

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 65028, Oseltamivir. https://pubchem.ncbi.nlm.nih.gov/compound/Oseltamivir. Accessed Oct. 26, 2023.

Storage
Cap/powder for oral susp: Store between 15-30°C. Reconstituted oral susp: Store between 2-8°C for up to 17 days or below 25°C for up to 10 days. Do not freeze.
MIMS Class
Antivirals
ATC Classification
J05AH02 - oseltamivir ; Belongs to the class of neuraminidase inhibitors. Used in the systemic treatment of viral infections.
References
Anon. Oseltamivir. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 12/07/2023.

Anon. Oseltamivir. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 12/07/2023.

Buckingham R (ed). Oseltamivir Phosphate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 12/07/2023.

Fluhalt for Oral Suspension 60 mg/5 mL (Ranbaxy [Malaysia] Sdn. Bhd.) . National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia.  https://www.npra.gov.my. Accessed 12/07/2023.

Joint Formulary Committee. Oseltamivir. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 12/07/2023.

Oseltamivir 75 mg Hard Capsules (Accord-UK Ltd). MHRA. https://products.mhra.gov.uk. Accessed 18/09/2023.

Roche Products (New Zealand) Limited. Tamiflu 75 mg, 45 mg and 30 mg Capsules and 6 mg/mL Powder for Oral Solution data sheet 21 January 2021. Medsafe. http://www.medsafe.govt.nz. Accessed 12/07/2023.

Tamiflu 6 mg/mL Powder for Oral Suspension (Roche Products Limited). MHRA. https://products.mhra.gov.uk. Accessed 12/07/2023.

Tamiflu Capsule and Powder for Suspension (Genentech, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 12/07/2023.

Tamiflu Capsules 75 mg (Roche [Malaysia] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 12/07/2023.

Disclaimer: This information is independently developed by MIMS based on Oseltamivir from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2024 MIMS. All rights reserved. Powered by MIMS.com
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