Oseltamivir Mercury Pharmaceuticals Limited (Oseltamivir Phosphate)

Oseltamivir phosphate is an antiviral medication that acts on influenza viruses.

• Treatment of influenza A and B: Reduces symptom duration and may lessen complications in confirmed cases.
• Post‑exposure prophylaxis of influenza: Prevents illness when administered shortly after exposure to the virus.
• Seasonal influenza control: Used in public‑health programs to limit spread during outbreaks.

• Oseltamivir phosphate is a pro‑drug that is rapidly converted in the liver to its active metabolite, oseltamivir carboxylate. The active form binds to the neuraminidase enzyme on the surface of influenza A and B viruses, blocking the enzymatic cleavage of sialic acid residues and thereby preventing release of newly formed viral particles from infected cells.

Oseltamivir is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Vomiting: occasional episodes, often transient.
• Headache: mild headache reported by some patients.
• Diarrhea: loose stools, usually self‑limiting.
• Abdominal pain: mild discomfort in the stomach area.

Serious or Rare Side Effects

• Severe allergic reaction: rash, itching, swelling, or difficulty breathing.
• Neuropsychiatric events: unusual behavior, delirium, or hallucinations, reported mainly in pediatric cases.
• Liver enzyme elevation: occasional increase in hepatic transaminases.
• Renal impairment worsening: accumulation of active drug in patients with kidney dysfunction.
• Stevens‑Johnson syndrome: rare severe skin reaction.

Oseltamivir should be used with caution in specific populations and conditions.

• Renal function: dose adjustment may be required for patients with reduced kidney function.
• Pregnancy: safety not established; weigh potential benefits against risks.
• Breastfeeding: unknown safety; consider infant exposure through milk.
• Age considerations: pediatric dosing differs from adult dosing; follow prescriber guidance.
• Drug interactions: review concomitant medications for potential interactions.
• Store below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Oseltamivir may interact with other medicines, requiring monitoring.

Major Interactions (Avoid)

• Probenecid: may increase oseltamivir plasma levels, raising toxicity risk.

Moderate Interactions (Monitor Closely)

• Antiviral combination therapy: concurrent use with other neuraminidase inhibitors can affect efficacy.
• Live attenuated influenza vaccine (LAIV) administration: timing should be coordinated.
• Warfarin: potential alteration of INR .
• Zanamivir: overlapping antiviral activity may require dose adjustment.
• Acid‑reductant S