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.

Oseltamivir is indicated for prevention of flu (influenza) in adults and adolescents aged 13 years and over who have been in contact with someone diagnosed with flu; treatment of flu (influenza) in adults and in children over one year of age when the influenza virus is circulating in the community

Oseltamivir Phosphate may be taken with or without food. However, when taken with food, tolerability may be enhanced in some patients.

Standard oral dose for the treatment of influenza:

• Adults and Adolescents: The recommended oral dose of Oseltamivir for treatment of influenza in adults and adolescents 13 years and older is 75 mg twice daily for 5 days. Treatment should begin within 2 days of onset of symptoms of influenza.
• Pediatric patients: The safety and efficacy of Oseltamivir for prophylaxis of influenza in pediatric patients younger than 13 years of age have not been established.

Recommended oral dose for the treatment of influenza:

• For prophylaxis of influenza in adults and adolescents 13 years and older following close contact with an infected individual: 75 mg once daily for at least 7 days. Therapy should begin within 2 days of exposure.
• For prophylaxis during a community outbreak of influenza: 75 mg once daily. Safety and efficacy have been demonstrated for up to 6 weeks. The duration of protection lasts for as long as dosing is continued.

Administration

May be taken with or without food. May be taken with meals to reduce GI discomfort. Cap may be opened & mixed with sweetened food products eg chocolate syr, sweetened condensed milk, apple sauce or yogurt. Swallow mixture immediately after preparation.

Oseltamivir is contraindicated in patients with known hypersensitivity to any of the components of the product.

The most frequently reported adverse events are nausea and vomiting. These events generally of mild to moderate degree and usually are occurred on the first 2 days of administration. Additional adverse events occurring in <1% of patients receiving Oseltamivir for treatment include unstable angina, anemia, pseudomembranous colitis, humerus fracture, pneumonia, pyrexia, and peritonsillar abscess.

Overdose Effects

At present there has been no experience of over dose. Single dose of up to 1000 mg of Oseltamivir have been associated with nausea and/or vomiting.

There is no evidence for efficacy of Oseltamivir Phosphate in any illness caused by agents other than influenza viruses Types A and B. Efficacy of Oseltamivir Phosphate in patients who begin treatment after 40 hours of symptoms has not been established.

Use in Special Populations

Hepatic Impairment: The safety and pharmacokinetics in patients with hepatic impairment have not been evaluated.

Renal Impairment: Dose adjustment is recommended for patients with a serum creatinine clearance <30 mL/min.

Geriatric Use: The safety of Oseltamivir Phosphate has been established in clinical studies.

Pediatric Use: The safety and efficacy of Oseltamivir Phosphate in pediatric patients younger than 1 year of age have not been studied. Oseltamivir Phosphate is not indicated for either treatment or prophylaxis of influenza in pediatric patients younger than 1 year of age.

Pregnancy & Lactation

Pregnancy Category C: There are insufficient human data upon which to base an evaluation of risk of Oseltamivir Phosphate to the pregnant woman or developing fetus.

Nursing Mothers: It is not known whether oseltamivir or oseltamivir carboxylate is excreted in human milk. Oseltamivir Phosphate should, therefore, be used only if the potential benefit for the lactating mother justifies the potential risk to the breast-fed infant.