Overview
Oseltamivir is an antiviral medication used for the treatment and prophylaxis of influenza A and B viruses. It works by inhibiting neuraminidase, an enzyme essential for viral replication and spread. Clinical use is recommended within 48 hours of symptom onset for treatment and as directed for prevention during flu season.
Mechanism of Action
Oseltamivir is a prodrug that is converted to its active metabolite, oseltamivir carboxylate, which selectively inhibits influenza neuraminidase enzymes. This inhibition prevents the release of viral particles from infected cells, reducing viral spread in the respiratory tract.
Indications
- Treatment of uncomplicated acute influenza in patients 2 weeks and older who have been symptomatic for no more than 48 hours
- Prophylaxis of influenza in patients 1 year and older following close contact with an infected individual
- Seasonal prophylaxis of influenza when circulating in the community
Common Doses
- 30 mg
- 45 mg
- 75 mg
Dosage
For treatment: 75 mg twice daily for 5 days. For prophylaxis: 75 mg once daily for at least 10 days following contact or up to 6 weeks during community outbreaks. Dosage adjustments required for renal impairment.
Contraindications
- Known serious hypersensitivity to oseltamivir or any component of the product
Side Effects
- Nausea, vomiting, diarrhea, headache
- Bronchitis, abdominal pain, dizziness
- Serious skin reactions, hypersensitivity reactions
- Neuropsychiatric events
Interactions
- No clinically significant drug interactions identified with common medications
- Probenecid may increase plasma concentrations of oseltamivir carboxylate
Counseling Points
- Take with food to reduce gastrointestinal side effects
- Complete full course of treatment even if symptoms improve
- For prophylaxis, continue medication for recommended duration
- Report any skin rash, breathing difficulties, or behavioral changes immediately
- Shake oral suspension well before each use