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I need to know does anyone have a reference that clearly states what the
ratios of ka/k would be for a drug exhibiting 1-compartment first order
absorption kinetics to be considered an immediate release formulation.
The values for these ratios should be consistent with the half-life of
absorption being less than Tau(dosing interval) when the formulation is
given in a multiple dosing regimen.
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Dear Dr. Jackson:
I would say taht a ka/k ratio between 5-10 would be satisfactory.
I am not clear about your question reg: consistency with half-life of
absorption being < than Tau. In most practical cases Tau can be selected
to be > the time needed for absorption.
Sri
Srikumaran Melethil, Ph.D.
Professor of Pharmaceutics and Medicine
School of Pharmacy (Room 203-B)
University of Missouri-Kansas City
5005 Rockhill Road
Kansas City, MO 64110
Phone: 816-235-1794: Fax:816-235-5190
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One of our papers entitled:
M.L. Kaltenbach, S.H. Curry, and H. Derendorf. Extent of drug
absorption at the time of peak plasma concentration in an open
one-compartment body model with first order absorption.
J. Pharm. Sci. 79 (5) (1990) 462.
may help you in determining the ka/k ratio needed for a drug exhibiting
1-compartment first order absorption kinetics to be considered an immediate
release formulation.
I can also remember that Dr. Macheras publishe an extension to this work for
drugs exhibiting 2 compartments characteristics in the same journal a few
years later.
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Matthieu L. Kaltenbach, PharmD, PhD
Laboratoire de Pharmacocinetique
UFR de Pharmacie
Universite de Reims Champagne Ardenne
51 rue Cognacq-Jay
F-51100 Reims, FRANCE
Tel: (33) 03 2605-3726
Fax: (33) 03 2605-3552
E-mail: matthieu.kaltenbach.-at-.univ-reims.fr
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