Dear all,

I have trouble modeling some rat PK data obtained after intravenous 
dosing. I have dense data for two different doses, given either as bolus, 
half-hour or 3-hour infusion. We know that the compound has a large 
binding affinity to intracellular structures and therefore has a high 
volume of distribution (~100L/kg in rats). However, what we observed in 
the mentioned study is that the AUC after bolus dosing is ~3 times higher 
than after infusions (no difference between 0.5 and 3 h), and this was 
observed for both dose groups (effect a bit less pronounced for high dose, 
but still there). Noncompartmental analysis indicates that this is due to 
lower clearance and not a change in Vss. At the moment I have no idea what 
kind of model would capture an observation like this. Has anybody ever 
observed something like this, and even better, have some ideas on model 
coding? Any ideas would be welcome! 

Best regards
Nele
_________________________________________

Bayer Schering Pharma AG
Development Pharmacokinetics
Berlin, S109, 03, 306A
Phone: +49 30 468-15146 
Fax: +49 30 468-11527
E-mail: [EMAIL PROTECTED]
Web: http://www.bayerscheringpharma.de

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Ulrich Köstlin, Kemal Malik, Bernd Metzner, Gunnar Riemann
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