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Greetings,
Are there any FDA or other guidelines to obtain PK data,for example how
many data points, in the ascending curve or descending curve, how long,
what time intervals etc. Or is it up to the pharmacokineticist to decide
such parameters? Is there any advantage of taking samples before 5 min
after dosing?
Thank you for your response.
Chandrani Gunaratna
Chandrani Gunaratna, Ph.D.
Senior Research Chemist
Bioanalytical Systems
2701 Kent Avenue
West Lafayette, IN 47906
Phone: (765)463-4527
E-Mail: prema.-at-.bioanalytical.com
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Dear Chandrani,
To the best of my knowledge there are no FDA guidelines. Most researchers
select sampling points based on preliminary experiments or past experience;
this approach works well.
One ref. on theoretical solutions to the problem, that you might find useful,
is: Kinetic Drug Analysis (L. Endreyni, Editor) Plenum Press, NY, 1981 pp.
137-167.
A 5 min sample after IV bolus may be of some value because "good" mixing of
the drug with blood (blood volume/cardiac output) can be expected.
Hope this will be helpful to you.
Sri
Sri Melethil, Ph.D.
Professor of Pharmaceutics and Medicine
University of Missouri-KC
School of Pharmacy
Room 203-B, 5005 Rockhilll Road
Kansas City, MO 64110
816-235-1794 (fax: 816-235-5190)
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Dear Chandrani:
Of course this brings up the general question of optimal experimental
design. When ARE the best times to get serum levels and to measure other
responses? This usually depends on what type of structural model we have in
mind, and what specific parameter values we are thinking of. A good
discussion of this was done by D'Argenio, DZ, Optimal Sampling Times for
Pharmacokinetic Experiments, J. Pharmacokin. Biopharm. 9: 739-756, 1981.
There have been many more papers before and since, but this is a good one.
The general idea is to take samples when the serum concentrations are
expected to be most sensitive to any changes in the expected parameter
values in the pharmacokinetic model.
Best regards,
Roger Jelliffe
Roger W. Jelliffe, M.D. Professor of Medicine, USC
USC Lab of Applied Pharmacokinetics
2250 Alcazar St, Los Angeles CA 90033, USA
Phone (323)442-1300, fax (323)442-1302, email= jelliffe.aaa.hsc.usc.edu
Our web site= http://www.usc.edu/hsc/lab_apk
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