Oseltamivir phosphate
[CAS# 204255-11-8]

Identification

• Classification: API >> Antibiotics >> Other antibiotics
• Name: Oseltamivir phosphate
• Synonyms: Tamiflu; Ethyl (3R,4R,5S)-4-acetamido-5-amino-3-pentan-3-yloxycyclohexene-1-carboxylate phosphate
• Molecular Formula: C₁₆H₂₈N₂O₄.H₃PO₄
• Molecular Weight: 410.40
• CAS Registry Number: 204255-11-8
• EC Number: 641-362-5
• SMILES: CCC(CC)O[C@@H]1C=C(C[C@@H]([C@H]1NC(=O)C)N)C(=O)OCC.OP(=O)(O)O

Properties

• Solubility: 2 mg/mL (DMSO), <1 mg/mL (water) (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302+H312+H332-H302-H312-H315-H317-H319-H332-H335-H412
• Safety Statements: P261-P264-P264+P265-P270-P271-P272-P273-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P317-P319-P321-P330-P332+P317-P333+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Skin sensitization	Skin Sens.	1	H317
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	4	H302

Discovery and Applications

Oseltamivir phosphate is an antiviral medication widely used for the treatment and prevention of influenza. It belongs to the class of neuraminidase inhibitors, which work by blocking the action of the neuraminidase enzyme on the surface of the influenza virus. This enzyme is essential for the release of new viral particles from infected host cells. By inhibiting this enzyme, oseltamivir prevents the spread of the virus within the body, reducing the severity and duration of symptoms.

The compound was first developed by the pharmaceutical company Gilead Sciences in the 1990s and was later marketed under the brand name Tamiflu. Its discovery was part of the global effort to combat influenza, a disease that remains a significant public health concern due to its high mutation rate and the frequent emergence of new strains. Oseltamivir phosphate was approved for medical use in several countries in the early 2000s and has since become one of the most commonly prescribed medications for influenza.

The chemical structure of oseltamivir phosphate consists of a bicyclic structure with a central nitrogen atom and several functional groups, including an ester group. It is administered orally as a prodrug, meaning that it is converted into its active form, oseltamivir carboxylate, in the body. The carboxylate form of the drug is responsible for inhibiting the neuraminidase enzyme.

Oseltamivir phosphate has been shown to be effective against various strains of the influenza virus, including seasonal strains and some strains with pandemic potential, such as H1N1. The drug is typically used to treat influenza in both adults and children, and it can also be prescribed as a prophylactic measure for individuals who have been exposed to the virus but have not yet developed symptoms. It is most effective when taken within 48 hours of the onset of symptoms, although it may still offer benefits when administered later.

In addition to its antiviral activity, oseltamivir phosphate has been investigated for its potential use in the treatment of other viral infections, such as avian influenza (H5N1) and the novel coronavirus (COVID-19). While its use for COVID-19 is not as established as for influenza, some studies have suggested that oseltamivir may offer modest benefits in treating this viral infection, particularly in combination with other antiviral therapies.

The compound is generally well tolerated, but like all medications, it may cause side effects. Common side effects include nausea, vomiting, and abdominal discomfort. In rare cases, more serious adverse effects such as psychiatric disturbances and allergic reactions have been reported, particularly in children. Despite these risks, oseltamivir phosphate remains a critical tool in the management of influenza, particularly during seasonal outbreaks and pandemics.

Oseltamivir phosphate’s role in public health extends beyond individual treatment. It is considered an important component of stockpiles for pandemic preparedness, as the rapid spread of influenza and other viral diseases can pose a global health threat. The drug’s ability to reduce the duration and severity of illness makes it a vital tool in mitigating the impact of influenza outbreaks, especially in vulnerable populations such as the elderly, young children, and individuals with underlying health conditions.

In conclusion, oseltamivir phosphate has played a key role in the fight against influenza since its development and approval in the early 2000s. Its mechanism of action as a neuraminidase inhibitor and its effectiveness against various strains of the influenza virus have made it an essential medication in the treatment and prevention of flu. As new viral threats continue to emerge, oseltamivir phosphate remains an important part of the antiviral arsenal, contributing to public health efforts worldwide.

References

2024. The Clinical Effectiveness and Tolerability of Oseltamivir in Unvaccinated Pediatric Influenza Patients during Two Influenza Seasons after the COVID-19 Pandemic: The Impact of Comorbidities on Hospitalization for Influenza in Children. Viruses, 16(10).
DOI: 10.3390/v16101576

1998. Identification of GS 4104 as an Orally Bioavailable Prodrug of the Influenza Virus Neuraminidase Inhibitor GS 4071. Antimicrobial Agents and Chemotherapy, 42(3).
DOI: 10.1128/aac.42.3.647

1998. Oral Administration of a Prodrug of the Influenza Virus Neuraminidase Inhibitor GS 4071 Protects Mice and Ferrets against Influenza Infection. Antimicrobial Agents and Chemotherapy, 42(3).
DOI: 10.1128/aac.42.3.640