Oseltamivir Phosphate ( INN)
Product name: Oseltamivir phosphate
Chemical name: Ethyl(3R,4R,5S)-4-acetamido-5-amino-3-pentan-3-yloxycyclohexene-1-carboxylate phosphate
CAS No.: 204255-11-8
Molecular formula : C16H28N2O4.H3PO4
Assay: 97%min
Product Description
Appearance: White to off-white crystalline powder
Purity(HPLC): 99%min
Melting Point : 201-203degree
Optical Rotation: -34.0- -38.0degree
Moisture: 0.30%max
Heavy metals: 20ppm max
Residue on ignition: 0.1%max
Impurity Ro-1637: 0.03%max
Any other individual impurity: 0.50%max
Total impurities: 1.0%max
| Productivity: | 500kg/month |
Mode of action
Resistance
As with other antivirals, resistance to the agent was expected with widespread use of oseltamivir, though the emergence of resistant viruses was expected to be less frequent than with amantadine or rimantadine. The resistance rate reported during clinical trials up to July 2004 was 0.33% in adults, 4.0% in children, and 1.26% overall. Mutations conferring resistance are single amino acid residue substitutions in the neuraminidase enzyme.
H3N2
Mutant H3N2 influenza A virus isolates resistant to oseltamivir were found in 18% of a group of 50 Japanese children treated with oseltamivir.This rate was similar to another study where resistant isolates of H1N1 influenza virus were found in 16.3% of another cohort of Japanese children. Several explanations were proposed by the authors of the studies for the higher-than-expected resistance rate detected. First, children typically have a longer infection period, giving a longer time for resistance to develop. Second, Kiso et al. claim to have used more rigorous detection techniques than previous studies.
H5N1 avian influenza
High-level resistance has been detected in one girl suffering from H5N1 avian influenza in Vietnam. She was being treated with oseltamivir at time of detection. de Jong et al. (2005) describe resistance development in two more Vietnamese patients suffering from H5N1, and compare their cases with six others. They suggest that the emergence of a resistant strain may be associated with a patient's clinical deterioration. They also note that the recommended dosage of oseltamivir does not always completely suppress viral replication, a situation that could favor the emergence of resistant strains. Moscona (2005) gives a good overview of the resistance issue, and says that personal stockpiles of Tamiflu could lead to under-dosage and thus the emergence of resistant strains of H5N1.
Resistance is of concern in the scenario of an influenza pandemic (Wong and Yuen 2005), and may be more likely to develop in avian influenza than seasonal influenza due to the potentially longer duration of infection by novel viruses. Kiso et al. suggest that "a higher prevalence of resistant viruses should be expected" during a pandemic.
Note: Veterinary use
There have been anecdotal reports of oseltamivir reducing disease severity and hospitalization time in canine parvovirus infection. The drug may limit the ability of the virus to invade the crypt cells of the small intestine and decrease gastrointestinal bacteria colonization and toxin production.
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Article : Swine influenza
Swine influenza (also called H1N1 flu, swine flu, hog flu, and pig flu) is an infection by any one of several types of swine influenza virus. Swine influenza virus (SIV) is any strain of the influenza family of viruses that is endemic in pigs. As of 2009, the known SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H3N1, H3N2, and H2N3.
Swine influenza virus is common throughout pig populations worldwide. Transmission of the virus from pigs to humans is not common and does not always lead to human influenza, often resulting only in the production of antibodies in the blood. If transmission does cause human influenza, it is called zoonotic swine flu. People with regular exposure to pigs are at increased risk of swine flu infection. The meat of an infected animal poses no risk of infection when properly cooked.
During the mid-20th century, identification of influenza subtypes became possible, allowing accurate diagnosis of transmission to humans. Since then, only 50 such transmissions have been confirmed. These strains of swine flu rarely pass from human to human. Symptoms of zoonotic swine flu in humans are similar to those of influenza and of influenza-like illness in general, namely chills, fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort.
Oseltamivir phosphate is an antiviral medication (a drug that kills or inhibits the growth of viruses) used to treat adults and children who have influenza (the flu). It is also used to reduce the chance of catching influenza in someone who has recently been exposed to the virus. Although getting a flu vaccine is probably the best way to prevent someone from catching the flu, anti-influenza drugs, such as oseltamivir phosphate, can be used as a second line of defense for treating or preventing the illness.
Uses
Treatment of influenza
Oseltamivir phosphate is used to treat uncomplicated illness due to influenza infection in adults and children at least one year old, who have had symptoms of the flu for no more than two days. In people who have had flu symptoms for more than two days, oseltamivir phosphate and other drugs in its class are not effective in improving symptoms or shortening the length of illness.
Prevention of influenza
Oseltamivir phosphate is also used to prevent someone from catching the flu if they have been exposed to another person with influenza, or in cases where there has been an outbreak of the flu in the community.
Benefits
Research has shown that using neuraminidase inhibitors, including oseltamivir phosphate, can lead to a reduction in the severity of symptoms and length of illness caused by the flu. The drugs are also about 70% to 90% effective in preventing the flu if used early enough after exposure. TAMIFLU (oseltamivir phosphate) is available as capsules containing 30 mg, 45 mg, or 75 mg oseltamivir for oral use, in the form of oseltamivir phosphate, and as a powder for oral suspension, which when constituted with water as directed contains 12 mg/mL oseltamivir base. In addition to the active ingredient, each capsule contains pregelatinized starch, talc, povidone K 30, croscarmellose sodium, and sodium stearyl fumarate. The 30 mg capsule shell contains gelatin, titanium dioxide, yellow iron oxide, and red iron oxide. The 45 mg capsule shell contains gelatin, titanium dioxide, and black iron oxide. The 75 mg capsule shell contains gelatin, titanium dioxide, yellow iron oxide, black iron oxide, and red iron oxide. Each capsule is printed with blue ink, which includes FD&C Blue No. 2 as the colorant. In addition to the active ingredient, the powder for oral suspension contains sorbitol, monosodium citrate, xanthan gum, titanium dioxide, tutti-frutti flavoring, sodium benzoate, and sacchrin sodium.
Oseltamivir phosphate is a white crystalline solid with the chemical name (3R,4R,5S)-4acetylamino-5-amino-3(1-ethylpropoxy)-1-cyclohexene-1-carboxylic acid, ethyl ester, phosphate (1:1). The chemical formula is C16H28N2O4 (free base). The molecular weight is 312.4 for oseltamivir free base and 410.4 for oseltamivir phosphate salt. The structural formula is as follows:
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tandard Dosage – Treatment of Influenza
Adults and Adolescents
The recommended oral dose of TAMIFLU 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.
Pediatric Patients
TAMIFLU is not indicated for treatment of influenza in pediatric patients younger than 1 year.
The recommended oral dose of TAMIFLU for pediatric patients 1 year and older is shown in Table 5. TAMIFLU for Oral Suspension may also be used by patients who cannot swallow a capsule. For pediatric patients who cannot swallow capsules,
TAMIFLU for Oral Suspension is the preferred formulation. If the for Oral Suspension product is not available, TAMIFLU Capsules may be opened and mixed with sweetened liquids such as regular or sugar-free chocolate syrup.
AMIFLU Capsules
