Oseltamivir excretion

Nohle U, Beau JM, Schauer R (1982) Uptake, metabolism and excretion of orally and intravenously administered, double-labeled A-glycoloylneuraminic acid and single-labeled 2-deoxy-2,3-dehydro-A-acetylneuraminic acid in mouse and rat, Eur J Biochem 126 543-548 Oxford J (2005) Oseltamivir in the management of influenza. Expert Opin Pharmacother 6 2493-2500... 

Excretion - Absorbed oseltamivir is primarily (more than 90%) eliminated by conversion to oseltamivir carboxylate. Plasma concentrations of oseltamivir declined with a half-life of 1 to 3 hours in most subjects after oral administration. Oseltamivir carboxylate is not further metabolized and is eliminated in the urine. Plasma concentrations of oseltamivir carboxylate declined with a half-life of 6 to 10 hours in most subjects. Oseltamivir carboxylate is eliminated entirely (more than 99%) by renal excretion. Renal clearance (18.8 L/h) exceeds glomerular filtration rate (7.5 L/h) indicating that tubular secretion occurs, in addition to glomerular filtration. Less than 20% of an oral dose is eliminated in feces. 

Lactation It is not known whether oseltamivir or oseltamivir carboxylate is excreted in human breast milk. Therefore, use oseltamivir only if the potential benefit for the lactating mother justifies the potential risk to the breast-fed infant. 

Oseltamivir is an orally administered prodrug that is activated in the gut and liver. Dosage is 75 mg twice daily. The half-life of oseltamivir is 6-10 hours, and excretion is primarily in the urine. In addition to treatment of influenza, prophylaxis once daily may be effective in preventing influenza. Potential side effects include nausea and vomiting, which may be decreased by administration with food. 

METHOTREXATE ANTIVIRALS -OSELTAMIVIR Possible t efficacy/toxicity Competition for renal excretion Monitor more closely for signs of immunosuppression. Predicted interaction... 

Oseltamivir (GS4104) is an ester prodrug, whose active metabolite (GS4071) is a potent selective inhibitor of influenza virus neuraminidase, to which it is rapidly hydrolysed by hepatic carboxylesterases. The metabolite is then completely excreted by the kidneys by filtration and secretion. In animals oseltamivir had a wide safety margin, with no evidence of teratogenicity or adverse effects on fertility. Oseltamivir has also been studied in the treatment and prevention of influenza A and B, but published results are sparse. To date it has been well tolerated. Headache was the most frequent complaint and mild to moderate gastrointestinal adverse effects (nausea, diarrhea) have been described (3). 

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