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Hi all,
I need some clarification, ie
a comination of drug say product A and Product B
Product A tmax is 1 hr and Thalf is 2 hrs.
Product B tmax is 6-12 hr and T half is 30-50 hrs
how to fix the time points for the withdrwal of blood sample.
kindly give me the answer.
devisha.
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The following message was posted to: PharmPK
Hi Devisha
> Product A tmax is 1 hr and Thalf is 2 hrs.
> Product B tmax is 6-12 hr and T half is 30-50 hrs
> how to fix the time points for the withdrwal of blood sample.
It depends what you want to know.
If you are doing a model based analysis then you could consider
estimating
the sampling times that optimize your ability to estimate the
parameters for
the model for each drug simultaneously. You could even weight the
sampling
times so that you could put more experimental effort for one of the
products
over the other.
This can be done in a population modelling setting using available
software
such as POPT
http://www.uq.edu.au/pharmacy/sduffull/POPT.htm
However if it is for a NCA then usual guidances would seem appropriate.
Steve
Stephen Duffull
School of Pharmacy, University of Queensland, Brisbane 4072, Australia
Tel +61 7 3365 8808, Fax +61 7 3365 1688, Email:
sduffull.aaa.pharmacy.uq.edu.au
www http://www.uq.edu.au/pharmacy/index.html?page=31309
Design: http://www.uq.edu.au/pharmacy/sduffull/POPT.htm
MCMC: http://www.uq.edu.au/pharmacy/sduffull/MCMC_eg.htm
University Provider Number: 00025B
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The following message was posted to: PharmPK
Hi devisha,
You want to do combination drugs. Also both are vary in their Tmax and
T1/2.
Generally we have to take time points upto 3 half lives. for this it is
sufficient upto 6 hr for drug A and 90 hours for drug B.
But selection of these points is critical because of both are having
vast
differnce in their Tmax and T1/2
And also while selecting time points we have to consider safety of
subjects. Because of it should be approved by IRB.
For this reason according to my Knowledge I am suggesting the points.
0.00, 0.33, 0.66, 1.00, 1.33, 1.66, 2.00, 2.50, 3.00, 3.50, 4.50, 5.00,
5.50, 6.00, 7.00, 8.00,9.00, 10.00, 12.00, 16.00, 24.00,36.00, 48.00,
72.00, 96.00, 120.00.
using this time points both the drugs may be estimated.
hope this helps you,
with regards,
Srinivasa Reddy.E
Research Analyst,
Bioserve Clinical Research
Hyderabad
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The following message was posted to: PharmPK
Hi devisha,
You want to do combination drugs. Also both are vary in their Tmax and
T1/2.
Generally we have to take time points upto 3 half lives. for this it is
sufficient upto 6 hr for drug A and 90 hours for drug B.
But selection of these points is critical because of both are having
vast
differnce in their Tmax and T1/2
And also while selecting time points we have to consider safety of
subjects. Because of it should be approved by IRB.
For this reason according to my Knowledge I am suggesting the points.
0.00, 0.33, 0.66, 1.00, 1.33, 1.66, 2.00, 2.50, 3.00, 3.50, 4.50, 5.00,
5.50, 6.00, 7.00, 8.00,9.00, 10.00, 12.00, 16.00, 24.00,36.00, 48.00,
72.00, 96.00, 120.00.
using this time points both the drugs may be estimated.
hope this helps you,
with regards,
Srinivasa Reddy.E
Research Analyst,
Bioserve Clinical Research
Hyderabad
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The following message was posted to: PharmPK
Dear Devishah
According to text book "Parameters for Compartment-free
Pharmacokinetics", the time points can be as follows:
The sampling period should be continued at least 3 to 5 times (X) the
t1/2 terminal following tmax
Total number of time poins should ideally be 15, but 12 can also be
taken.
The first 4 - 5 time points are selected before tmax (inclusive)
The second 4-5 time points between tmax an t1/2 (inclusive of t1/2)
The last 4-5 points between t1/2 and 5Xt1/2
There should be a higher density of points around Tmax value. The
last sampling point will depend upon the LOQ of the analytical method.
In the cases stated, it is better to have a pilot study with a
limited number of animals and check the ratio of AUC0-t/AUC0-inf.The
ratio higher than 80% sampling will indicates appropriate number of
samples
Hoping it will be of some help.
Nadeem Irfan Bukhari
Lecturer Pharmaceutical Technology,
International Medical University,
Bukit Jalil 57000, Kuala Lumpur, Malaysia
nadeemirfan_bukhari.-a-.imu.edu.my
Web: http://www.imu.edum.my
Tel: +60 3 8656 7228, Ext. 1186; Fax: 86567229
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The following message was posted to: PharmPK
Dear Devishah
According to text book "Parameters for Compartment-free
Pharmacokinetics", the time points can be as follows:
The sampling period should be continued at least 3 to 5 times (X) the
t1/2 terminal following tmax
Total number of time poins should ideally be 15, but 12 can also be
taken.
The first 4 - 5 time points are selected before tmax (inclusive)
The second 4-5 time points between tmax an t1/2 (inclusive of t1/2)
The last 4-5 points between t1/2 and 5Xt1/2
There should be a higher density of points around Tmax value. The
last sampling point will depend upon the LOQ of the analytical method.
In the cases stated, it is better to have a pilot study with a
limited number of animals and check the ratio of AUC0-t/AUC0-inf.The
ratio higher than 80% sampling will indicates appropriate number of
samples
Hoping it will be of some help.
Nadeem Irfan Bukhari
Lecturer Pharmaceutical Technology,
International Medical University,
Bukit Jalil 57000, Kuala Lumpur, Malaysia
nadeemirfan_bukhari.aaa.imu.edu.my
Web: http://www.imu.edum.my
Tel: +60 3 8656 7228, Ext. 1186; Fax: 86567229
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The following message was posted to: PharmPK
Try this time interval in hours 0.5,1,2,4,6,7,8,10,12
s.o.o
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