Back to the Top
The following message was posted to: PharmPK
Dear All,
I have a query regarding pharmacokinetic modelling. What is biphasic
elimination and how is it calculated?
What is it's importance in Serum and tissue pharmacokinetic studies?
Regards
Anasuya Patel
Wockhardt Research Centre
Aurangabad
[Do you mean multi-compartment pharmacokinetics? Alpha/beta phases?
http://www.boomer.org/c/p4/c19/c1901.html
db]
Back to the Top
hi
The biphasic elimination refers to the excretion of the drug with
simulteneous distribution of drug in the tissues. The plasma
concentration-time curve after Cmax shows two different orders of
release. it is calculated from the slope of elimination curve (two
different slopes). it is important in studying the tissue distribution
of the drug in tissues.
i think this will help.
with regards
Sachin Ramrao Patil
M.Pharm. scholar,
Dept. of Pharmaceutical Technology (Formulations),
NIPER, SAS Nagar,
Mohali, Punjab-160062,
INDIA.
sachin_prits.-a-.yahoo.co.in
Back to the Top
The following message was posted to: PharmPK
Dear Patel,
Many drugs follow a biphasic elimination curve -- first a steep slope
then a shallow slope.
STEEP (initial) part of curve ------> initial distribution of the drug
in the body.
SHALLOW part of curve ------> ultimate renal excretion of drug, which
is dependent on the release of the drug from tissue compartments into
the blood.
Refer to this website for detail.
http://www.geocities.com/doctor_uae/pharm1.htm
Regards,
Santosh Tata
Back to the Top
Dear Patel,
In a typical bi-phasic concentration-time curve, the rate of decline
of concentrations over time is larger in the earlier time-points,
shifting to a slower rate at later times. Although the first part is
normally referred to as the "distribution" phase, it is important to
remember that the distribution of the drug from plasma to the tissues
is not a separate process (in time) from its elimination. In other
words, during the early phase, the drug leaves the plasma by two
processes: distribution to the tissues and elimination by the
eliminating organs. So what one sees in the first part of the
concentration-time curve is the sum of distribution and elimination of
the substance. When the drug has been distributed throughout the body
and the flow from plasma to tissue is equal to the flow from the
tissues back to the plasma, elimination becomes the only process
resulting in concentration decline. That's why the concentration-time
curve declines with a slower rate.
Toufigh
Toufigh Gordi, Ph.D.
Associate Director, Pharmacokinetics
Depomed, Inc
1360 O'Brien Drive, Menlo Park, CA 94025
tgordi.-a-.Depomedinc.com
http://www.depomedinc.com
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 "Biphasic elimination" as the subject | Support PharmPK by using the |
Copyright 1995-2011 David W. A. Bourne (david@boomer.org)