Back to the Top
Hi all,
a collegue has send me an excel sheet with some plasma values, and now
he wants to know the AUC steady state.
The AUC calculation, no problem with that, but how do I calculate the
steady state?
One way of thinking was with the aid of multiple t-test, to find where
we couldn't find difference between the different measuring points,
and take this as steady state, but I'm not sure that this is the right
way.
As I'm not home in the pharmacokinetic world, I was hoping someone
with some more experience can shed some light on this (altough for me)
dark material.
Kind Regards
Ace
PS: here are some example data:
Sample Time conc
1 12 0.62
1 36 0.88
1 60 0.92
1 84 0.88
1 108 0.85
1 132 0.22
2 12 1.22
2 36 1.30
2 60 1.00
2 84 1.33
2 108 1.43
2 132 0.29
[How often was the dose given? Was it the same dose and dosing
interval throughout? A number of data points during a dosing interval
at steady state (after 5 elimination half-lives) would be useful
(essential) - db]
Back to the Top
The following message was posted to: PharmPK
Check
http://www.boomer.org/c/p3/c26/c2603.html
AUC during one dosing interval at steady state is the same as the AUC
from zero to infinity after one single dose.
Back to the Top
The following message was posted to: PharmPK
Hi Ace,
To calculate AUC steady state you can use WinNonlin 5.2 software. This
software has option of steady state calculations. For more details
please see WinNonlin user or Example guide
With best regards
Ravi
Back to the Top
The following message was posted to: PharmPK Hi,
Well, it can be too expensive to afford WinNonlin,
just for a set of data. I think that you can use any
spreadsheet program, such as OpenOffice- calc
(freeware, www.openoffice.org). If you have MS-Excel,
it will do a pretty job, too. The method is called
"trapezoidal method." However, the data set seems
not so perfect.
Regards,
Yung-jin
Back to the Top
Hi
By looking the time points and conc, which you have given as sample
data. there are things which are not clear to me.
You should have given the units for each column, dosing schedule and
probably half life also
These are my thoughts on this data
The time points which you have provided has difference of a unit of
24. Whether you have provided the predose concentrations in once in a
day dosing scenario. if it is so there are no significant differences
in the concentrations except the last one. then i would have said that
the molecule has reached a steady state.
You can look for helmort contrast values to analyse the predose conc.
to evaluate the steady state. I am not expert in statistics, i came to
know about this recently when i was going through a Multiple Ascending
Dose trial report
If you have the half life values, then time=5 half lifes is sufficient
to reach a steady state in case of linear kinetics.
If those are the nth day profile, as others said use WiNonlin or
spreadsheet to calculate the AUC by trapezoidal method
Comments are welcome
Back to the Top
Step 1 Plot a graph of Plasma concentration versus time in hours
Time should be on the horizontal axis and concentration on the
vertical axis
Step 2 Based on on your timing points divide the curve into a series
of trapeziums
Step three estimate the area of each trapezium independently
Step four Sum up the total area of all the trapeziums
The total sum is your AUC value .Unit should be micro gram per ml per
hour.
For pharmacokinetic parameters like steady state concentration
maximum plasma concentration ,Biological half life etc. Check in the
appropriate reference pharmacokinetic text book depending on how your
drug will be administered.For instance if you are dealing with
eryrhromycine delayed release tablets try single compartment model
oral drug administration.
s.o.o
Want to post a follow-up message on this topic?
If this link does not work with your browser send a follow-up message to PharmPK@boomer.org with "AUC steady state calculation" as the subject | Support PharmPK by using the |
Copyright 1995-2011 David W. A. Bourne (david@boomer.org)