Oseltamavir PFOS

Oseltamivir is an antiviral medication used to treat and prevent influenza (flu) caused by influenza A and B viruses.

What does “PFOS” mean?

In medication labeling, PFOS usually refers to Oseltamivir Phosphate — the phosphate salt form of oseltamivir.

It improves the drug’s stability and absorption in the body.

⚠️ It is not related to the chemical pollutant PFOS (perfluorooctanesulfonic acid). In this context, it simply indicates the pharmaceutical salt form.

How it works

Oseltamivir is a neuraminidase inhibitor.

It blocks the influenza virus enzyme neuraminidase, which prevents the virus from spreading to healthy cells.

Best results occur when started:

Within 48 hours of flu symptom onset. 

Common Uses

✔ Treatment of flu symptoms

✔ Prevention after exposure (e.g., family member with flu)

✔ Used in adults and children (dose depends on age/weight)

Typical Adult Dose

Treatment: 75 mg twice daily for 5 days

Prevention: 75 mg once daily for 7–10 days

Always follow a doctor’s prescription.

Possible Side Effects

Most common:

Nausea

Vomiting

Headache

Rare but serious:

Allergic reactions

Confusion or unusual behavior (mostly reported in children)

Important Notes

It does not cure the flu instantly.

It does not replace flu vaccination.

It is ineffective against common cold viruses.

Basic Information as per USP

  • Molecular formula (free base): C₁₆H₂₈N₂O₄

  • Molecular formula (phosphate salt – PFOS form marketed): C₁₆H₂₈N₂O₄ · H₃PO₄

  • Molecular weight (free base): 312.4 g/mol

  • Drug class: Neuraminidase inhibitor (antiviral)

Key Structural Features

  • Cyclohexene ring core

  • Ethyl ester group

  • Primary amine (–NH₂)

  • Secondary amine

  • Ether linkage

  • Acetamido group

The marketed form is oseltamivir phosphate, which is the phosphate salt of the active oseltamivir base.

Oseltamavir PFOS in usp 

Oseltamivir phosphate in United States Pharmacopeia (USP)

In the USP–NF, the official monograph name is:

Oseltamivir Phosphate

It is listed as the phosphate salt of oseltamivir (not “PFOS” — the correct abbreviation in pharmacopeial context is simply oseltamivir phosphate).


📌 USP Monograph Key Information

Official Name: Oseltamivir Phosphate

Category: Antiviral agent

Dosage forms covered:

Capsules

Powder for Oral Suspension

🧪 USP Description (Summary)

Chemical name:

Ethyl (3R,4R,5S)-4-acetamido-5-amino-3-(1-ethylpropoxy)-1-cyclohexene-1-carboxylate phosphate

Molecular formula:

C₁₆H₂₈N₂O₄ · H₃PO₄

Molecular weight:

410.40 g/mol

Structure: Oseltamivir base + phosphoric acid (1:1 salt)

🔬 USP Identification Tests Typically Include

Infrared (IR) spectroscopy

HPLC retention time comparison with USP Reference Standard

Phosphate identification test

📊 USP Assay Method (General)

Technique: HPLC

Acceptance criteria: Typically 98.0% – 102.0% (on anhydrous basis)

Impurities controlled per USP related substances test

📦 USP Reference Standard

USP provides:

Oseltamivir Phosphate RS

Used for:

Assay

Related substances

System suitability testing

Full USP monograph assay conditions (mobile phase, column, wavelength)

Impurity limits

Dissolution specifications for capsules

Comparison with Ph. Eur. or BP