Oseltamivir
Oseltamivir. Influenza neuraminidase inhibitor prodrug — hydrolyzed to active oseltamivir carboxylate by hepatic carboxylesterase. Blocks… Oral half-life 7.7 h.
Influenza neuraminidase inhibitor prodrug — hydrolyzed to active oseltamivir carboxylate by hepatic carboxylesterase. Blocks release of newly assembled virions from infected respiratory epithelial cells. Modest symptom-duration reduction (~1 day) when started <48h from symptom onset.
ANALYTE: the CARBOXYLATE, and the stored bioavailability was already metabolite-referenced without saying so — "The absolute bioavailability of the active metabolite from orally administered oseltamivir is 80%". So the pk block is internally consistent. CITATION DEFECT CORRECTED: the previous source was a generic-versus-brand bioequivalence study whose abstract contains no half-life, no bioavailability and no volume, only time-to-peak and confidence intervals — it supported none of the four stored values. The 7 h sits inside a stated "6 to 10 hours" but is not itself verbatim. ka 1.4 dropped. mw 312.4 is the ethyl ester. PK: A NEAR-TEN-FOLD EXPOSURE ERROR ASSEMBLED FROM TWO SEPARATELY DEFENSIBLE CHOICES. The bioavailability is verbatim, correctly metabolite-referenced and matches the declared analyte. The half-life sat inside a verbatim range ("an apparent half-life of 6 to 10 hours") where a point value exists — "oseltamivir carboxylate has an elimination half-life (t1/2 beta) after oral administration in healthy individuals of approximately 7.7 hours" — and that is what it becomes. THE VOLUME IS THE LARGER FAULT AND CANNOT BE FIXED FROM THE LITERATURE: the label states "The volume of distribution (Vss) of oseltamivir carboxylate, following INTRAVENOUS administration in 24 subjects (TAMIFLU is not available as an IV formulation), ranged between 23 and 26 liters", so the stored figure is BOTH the low endpoint of a range AND an intravenous steady-state volume married to a terminal ORAL half-life. NO SOURCE ANYWHERE STATES AN ORAL APPARENT VOLUME, so the value the arithmetic requires is a derivation and is logged rather than stored. The consequence is quantified against the label own verbatim figures: the record asserts a clearance eight-fold below "Renal clearance (18.8 L/h) exceeds glomerular filtration rate (7.5 L/h)" for a drug the same document says is eliminated unchanged, and over-predicts exposure nearly ten-fold. A reference supporting nothing under any of the three purposes — it is the paper this record notes already record as a REMOVED source — is deleted with it. MASS: the stored weight was the ETHYL ESTER while the declared analyte is the carboxylate — 9.9 percent high. LATENT, NOT PROPAGATING: this record carries no occupancy rows and is no other record interaction perpetrator, so nothing consumes it today.
Pharmacokinetics
- Oral — t½ 7.7 h · F 80% · Vd 23 L
Sources: PMID:10628898