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To ,
The members of PK-PD group.
My student is working on the project "Pharmacokinetic Evaluation of new
NSAIDs in comparison with Ibuprofen.In this context,we wanted to clarify
the following.
1.What is the therapeutic range of Ibuprofen?
2.The t1/2 of Ibuprofen is reported to be 1-2 hrs.When we conducted
animal PK studies in rats,we got the t1/2 of 4 hrs.What could be the
reason.Can any one explain ..
Thanks in advance.
regards,
Dr.Shobha
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[A few replies - db]
From: "PERSIANI Stefano"Date: Thu, 17 Jan
2002 09:20:39 +0100
To: david.-at-.boomer.org
Subject: R: PharmPK PK of NSAIDS
The following message was posted to: PharmPK
Difference in the sensitivity of the bioanalytical methods used in the
two study might explain the different t1/2 calculated. Less sensitive
bioanalytical methods usually underestimate the t1/2, especially if the
elimination phase is biphasic.
Another explanation might be the formulation used in the two studies.
For instance if in one study the drug was given in solid form and in the
other study was given as a solution, the dissolution time of the former
might have affected the calculation of the t1/2 (absorption rate limited
elimination i.e. flip-flop effect).
Another explanation might be the doses used, if you used high doses and
kinetics are not linear i.e. dose-dependency of one of these parameters:
CL, k, or Vd, you will obtain different t1/2 values.
I hope this help.
Stefano
Stefano Persiani, PhD
Manager, Pharmacokinetics and Phase I
Rotta Research Laboratorium, S.p.A.
Via Valosa di Sopra, 7-9
20052 Monza (MI)
ITALY
e-mail stefano.persiani.aaa.rotta.com
---
From: "Koteshwara"
Date: Thu, 17 Jan 2002 14:00:34 +0530
To: david.at.boomer.org
Subject: Re: PharmPK PK of NSAIDS
The following message was posted to: PharmPK
Dear Dr. Shoba,
Perhaps the following link might help u about Ibuprofen half life
difference [[PDF] Catechol O -Methyltransferase: Glucuronidation of
Inhibitors ... File Format: PDF/Adobe Acrobat - View as HTML ... may
explain part of its approximately seven times faster elimination
half-life in
vivo . Both compounds, especially entacapone, were excellent substrates
of ...
ethesis.helsinki.fi/julkaisut/mat/farma/vk/lautala/catechol.pdf ]
Or download the file shown in link here
http://ethesis.helsinki.fi/julkaisut/mat/farma/vk/lautala/catechol.pdf
with regards,
koteshwara
Mysore
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From: "Sharp, Dale"Date: Thu, 17 Jan 2002
08:04:11 -0500
To: david.aaa.boomer.org
Subject: RE: PharmPK PK of NSAIDS
The following message was posted to: PharmPK
If I recall correctly, this is due to extensive secretion of the
ibuprofen glucuronide in the bile, followed by enterohepatic
recirculation. This process is more significant in the rat than in other
species. This is true of all the propionic acid NSAIDS.
[No gall bladder no hump but would still influence the 'terminal slope'
- db]
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The following message was posted to: PharmPK
Ibuprofen is short acting NSAID and so has little side effects as
compared to NSAIDS having longer half life.
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