Treatment of Influenza: Oseltamivir is used to treat uncomplicated acute influenza infection in patients over 1 year old who have shown symptoms for no more than 2 days.

Prevention of Influenza: Oseltamivir can be used to prevent influenza in adults and adolescents aged 13 years and older.

Oseltamivir is a prodrug in the form of an ethyl ester, which needs to be converted into its active form, Oseltamivir carboxylate, through ester hydrolysis. It works by inhibiting the neuraminidase enzyme of the influenza virus, which may prevent the virus from multiplying and being released from infected cells.

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

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.

Prophylaxis of Influenza: The safety and efficacy of Oseltamivir for prophylaxis of influenza in pediatric patients younger than 13 years of age have not been established. The recommended oral dose of Oseltamivir for prophylaxis of influenza in adults and adolescents 13 years and older following close contact with an infected individual is 75 mg once daily for at least 7 days. Therapy should begin within 2 days of exposure. The recommended dose for prophylaxis during a community outbreak of influenza is 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.

Based on pharmacology and pharmacokinetic studies, Oseltamivir is unlikely to have clinically significant interactions with other drugs. Taking Oseltamivir together with amoxicillin does not affect the blood levels of either medication.

This medicine should not be used in patients who have a known allergy or hypersensitivity to any of its ingredients.

The most commonly reported side effects of Oseltamivir are nausea and vomiting. These are usually mild to moderate and often occur during the first 2 days of treatment. Other less common side effects, seen in less than 1% of patients, may include unstable angina, anemia, pseudomembranous colitis, fracture of the humerus, pneumonia, fever, and peritonsillar abscess.

Pregnancy (Category C): There is not enough information from human studies to determine the safety of Oseltamivir Phosphate for pregnant women or the developing fetus.

Nursing Mothers: It is not known whether Oseltamivir or its active form, Oseltamivir carboxylate, passes into human breast milk. Therefore, Oseltamivir Phosphate should only be used during breastfeeding if the potential benefit to the mother outweighs any possible risk to the baby.

General: Oseltamivir Phosphate is effective only against influenza viruses Types A and B. Its benefit in illnesses caused by other agents has not been proven. Starting treatment more than 40 hours after symptom onset may reduce its effectiveness.

Hepatic Impairment: The safety and how the body processes Oseltamivir in patients with liver problems has not been studied.

Renal Impairment: Dose adjustment is recommended for patients whose serum creatinine clearance is less than 30 mL/min.

Use in Special Populations:

• Geriatric Use: Oseltamivir Phosphate has been shown to be safe in older adults in clinical studies.
• Pediatric Use: Safety and effectiveness in children under 1 year have not been established. Oseltamivir Phosphate is not recommended for treatment or prevention of influenza in this age group.

There is currently no extensive experience with Oseltamivir overdose. However, a single dose of up to 1000 mg has been reported to cause nausea and/or vomiting.

Respiratory viral infections (Influenza)

Store Oseltamivir at 25°C. For reconstituted suspension: keep in the refrigerator at 2–8°C for up to 17 days, or at room temperature (25°C) for up to 10 days. Do not freeze.