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The following message was posted to: PharmPK
Hi All,
I was calculating AUC all and AUC inf value but I am getting AUC inf
smaller than AUC all. Is this possible? If so can you please let me
know under what situations?
Can anybody let me know is there is any difference in AUC calculations
when considering single and multiple dose?
Thanks,
Chandra
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Dear Chandra,
Yes, it is possible. Although unusual.
AUCall is calculated up to the last time point. In case of a BQL value
at the last measured timepoint (treated as zero conc.), AUC will be
extrapolated including the area under the curve between AUClast and the
last timepoint.
If this extrapolation is greater than the log-linear extrapolation done
for AUCinf, then AUCall>AUCinf
I would never report it, I would definitely recommend to use AUClast
(calculated up to the last quantifiable conc.)
Regards
Stefano
Stefano Zamuner, PhD
Clinical Pharmacokinetics/Modeling and Simulation
Psychiatry
Verona
Tel. +39-045-8219519
Fax +39-045-8218191
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The following message was posted to: PharmPK
Dear Chandra,
I think the AUC inf should be at least a very small fraction greater
than the AUC 0-t. Logically AUC inf is AUC 0-t + (Clast/Kel), so you are
adding a fraction to the AUC 0-t.
Check if you have taken the negative value of the Kel, where you are
actually subtracting from AUC 0-t rather than adding the fraction. As
you calculated the Kel from the slope which is a negative value, there
are chances of accidentally taking a negative value for Kel. I am sure
you know this but in any case where we complete leave it to MS Excel!!
Hope this helps,
Jagannath
PhD Student
Victorian College of Pharmacy
Monash University
Parkville
381 Royal Parade
VICTORIA 3052
AUSTRALIA
Work: +61 03 9903 9525
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The following message was posted to: PharmPK
Dear Chandra,
I am sorry for my previous mail. I haven't realised until Stefano
pointed it out.
Jagannath
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The following message was posted to: PharmPK
Dear Stefano,
I apologize, however I suspect I have not really understood: you say
that
<< AUCall is calculated up to the last time point. In case of a BQL
value
at the last measured timepoint (treated as zero conc.), AUC will be
extrapolated including the area under the curve between AUClast and the
last timepoint.
If this extrapolation is greater than the log-linear extrapolation done
for AUCinf, then AUCall>AUCinf>>
Can you provide us a numerical example?
I believe that by numerical exemplification I can easily understand...
I apologize again, thank you very much in advance
Best regards
Stefano Porzio
Inpharzam Ricerche SA
Zambongroup
Taverne
Switzerland
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The following message was posted to: PharmPK
Hi Chandra!
I think that 'AUCall' is Pharsight's 'invention' ;-)
Suggestion: never use it; if your software calculates it, simply ignore
it...
have a look at: http://www.boomer.org/pkin/pk/AUCinf.jpg
Best regards,
Helmut
--
Helmut Sch=FCtz
BEBAC
Consultancy Services for Bioequivalence and Bioavailability Studies
Neubaugasse 36/11
1070 Vienna/Austria
tel/fax +43 1 2311746
http://BEBAC.at
Bioequivalence/Bioavailability Forum at http://forum.bebac.at
http://www.goldmark.org/netrants/no-word/attach.html
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AUCall is AUClast plus the area of the triangle assuming that the next
time point after Clast is zero
Try this.
0.25 228.7
0.5 262.8
1 314.3
2 309.2
4 215.3
6 160.5
8 118.8
12 5.4
24 0
Stefano
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)