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効能
抗ウイルス薬, ノイラミニダーゼ阻害薬
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使用
Oseltamivir is an orally active inhibitor of influenza virus neuraminidase; converted in vivo to the active acid metabolite. An antiviral drug. It is a COVID19-related research product.
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定義
ChEBI: A cyclohexenecarboxylate ester that is the ethyl ester of oseltamivir acid. An antiviral prodrug (it is hydrolysed to the active free carboxylic acid in the liver), it is used to slow the spread of influenza.
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適応症
Oseltamivir phosphate (Tamiflu) is the ethyl ester prodrug
of oseltamivir carboxylate, an analogue of neuraminic
(sialic) acid that is a reversible competitive
antagonist of influenza A and B neuraminidase.Influenza virus resistant to oseltamivir has not been
found in naturally acquired isolates but has been isolated
from influenza patients who have undergone
treatment with this drug.These resistant strains contain
mutations in the active site of neuraminidase and are
generally less virulent and infective than nonresistant
virus. In vitro passage of influenza virus in the presence
of oseltamivir carboxylate can produce mutations in
hemagglutinin that decrease the overall dependence of
viral replication on neuraminidase; however, the clinical
relevance of this resistance mechanism is unknown.
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抗菌性
Oseltamivir is active against influenza A and B, but no other
virus.
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獲得抵抗性
Mutations in the neuraminidase (H274Y) have been
detected in treated patients with seasonal H1N1 infection.
Cross-resistance with zanamivir has been described in
vitro.
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応用例（製薬）
A selective neuraminidase inhibitor, formulated as the phosphate
salt of the ethyl ester for oral administration.
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薬物動態学
Oral absorption: c. 75%
Cmax 75 mg oral: 0.35–0.55 mg/L after 4 h
Plasma half-life: 7–9 h
Plasma protein binding: Not known
The ethyl ester prodrug is hydrolyzed by hepatic esterases
to release the active compound, oseltamivir carboxylate.
Drug is excreted in the urine as the carboxylate
derivative.
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臨床応用
Oseltamivir is approved for the treatment of uncomplicated
acute influenza in patients aged 1 year and older.
It decreases the duration of illness by 1 to 1.5 days when
treatment is initiated within 48 hours of the onset of symptoms. Oseltamivir is also indicated for the prophylaxis
of influenza in individuals aged 13 and older. It reduces
infection rates to approximately 10 to 25% of that
found in untreated populations; however, it is not intended
to substitute for the early vaccination recommended
by the CDC. Oseltamivir can be used as postexposure
prophylaxis in household contacts of infected
patients, with infection rates of treated patients around
10% of placebo control levels.
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副作用
The most frequently reported adverse effects of oseltamivir
are nausea and vomiting.These events are usually
mild to moderate, occur during the first 1 to 2 days of
treatment, and can be lessened by taking the drug with
food. Bronchitis, insomnia, and vertigo may also occur.
Oseltamivir may not be indicated for use in certain
individuals. Its efficacy in patients with chronic cardiac
or respiratory disease has not been established. In clinical
trials, no difference in the incidence of complications
was seen between treatment and control groups.
The efficacy of oseltamivir has not been demonstrated
in immunocompromised patients, patients who begin
treatment after 40 hours of symptoms, or patients given
repeated prophylactic courses of therapy. Dosage adjustment
is recommended for individuals with renal insufficiency;
the drug’s safety in patients with hepatic insufficiency
is unknown.
