| Item |
Information |
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Drug Groups
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approved |
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Description
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An acetamido cyclohexene that is a structural homolog of sialic acid and inhibits neuraminidase. [PubChem] |
| Indication |
Oseltamivir (Tamiflu) is for the treatment of uncomplicated acute illness due to influenza infection in patients 1 year and older who have been symptomatic for no more than 2 days. It is also used for the prophylaxis of influenza in adult patients and adolescents 13 years and older. |
| Pharmacology |
Oseltamivir is an antiviral drug, a neuraminidase inhibitor used in the treatment and prophylaxis of both influenza A and influenza B. Oseltamivir is a prodrug (usually administered as phosphate), it is hydrolysed hepatically to the active metabolite, the free carboxylate of oseltamivir (GS4071). Like zanamivir, oseltamivir acts as a transition-state analogue inhibitor of influenza neuraminidase. |
| Toxicity |
At present, there has been no experience with overdose. Single doses of up to 1000 mg of oseltamivir have been associated with nausea and/or vomiting. Mean LD (intravenous, mouse) = 100 mg/kg. |
| Affected Organisms |
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| Biotransformation |
Extensively converted to oseltamivir carboxylate by esterases located predominantly in the liver. Neither oseltamivir nor oseltamivir carboxylate is a substrate for, or inhibitor of, cytochrome P450 isoforms. At least 75% of an oral dose reaches the systemic circulation as oseltamivir carboxylate. |
| Absorption |
Readily absorbed from the gastrointestinal tract after oral administration with a bioavailability of 75%. |
| Half Life |
1 to 3 hours in most subjects after oral administration. |
| Protein Binding |
Oseltamivir carboxylate: low (3%), Oseltamivir free base: 42%. |
| Elimination |
Absorbed oseltamivir is primarily (>90%) eliminated by conversion to oseltamivir carboxylate. Oseltamivir carboxylate is not further metabolized and is eliminated in the urine. Oseltamivir carboxylate is eliminated entirely (>99%) by renal excretion. |
| Distribution |
* 23 to 26 L |
| References |
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Chokephaibulkit K, Uiprasertkul M, Puthavathana P, Chearskul P, Auewarakul P, Dowell SF, Vanprapar N: A child with avian influenza A (H5N1) infection. Pediatr Infect Dis J. 2005 Feb;24(2):162-6.
[Pubmed]
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de Jong MD, Tran TT, Truong HK, Vo MH, Smith GJ, Nguyen VC, Bach VC, Phan TQ, Do QH, Guan Y, Peiris JS, Tran TH, Farrar J: Oseltamivir resistance during treatment of influenza A (H5N1) infection. N Engl J Med. 2005 Dec 22;353(25):2667-72.
[Pubmed]
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Kiso M, Mitamura K, Sakai-Tagawa Y, Shiraishi K, Kawakami C, Kimura K, Hayden FG, Sugaya N, Kawaoka Y: Resistant influenza A viruses in children treated with oseltamivir: descriptive study. Lancet. 2004 Aug 28-Sep 3;364(9436):759-65.
[Pubmed]
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Ward P, Small I, Smith J, Suter P, Dutkowski R: Oseltamivir (Tamiflu) and its potential for use in the event of an influenza pandemic. J Antimicrob Chemother. 2005 Feb;55 Suppl 1:i5-i21.
[Pubmed]
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