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The following message was posted to: PharmPK
Dear all,
I am doing a pharmacokinetic study using rat as my
model animal. I have to collect samples from singgle
rat by jugular vien cathertization. My plasma
processing volumes are very small (0.1-0.2 ml). Can
anybody tell me what is the maximum amount of blood
that I can withdraw from a single rat (250 g with
approx 8-10 ml blood volume) by this process within a
period of 24 hours. It will be kind enough if i am
provided with any refernce in this regard so that i
can support my study.
Regards
Nitin Mehrotra
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The following message was posted to: PharmPK
Dear Nitin
we used to take as much as 10 samples around 0.5 mL
in 8 hours, replacing with saline. Our rats weight
around 300-320 g.
A pair of references with the procedure described (and
the curves)
Ruíz A., Bermejo M.V., Merino V., Sánchez G., Freixas
J., Garrigues T.M Pharmacokinetics and bioavailability
of flumequine in rat
Eur. J. Biopharm Pharmacokin,48 : 253- 258(1999).
2. Sánchez-Castaño G., Ruiz-García A., Bañón N.,
Bermejo M., Merino V., Freixas J., Garrigues T.M.,
Plá-Delfina J.M."Intrinsic absolute bioavailability
predictions in rats, based on in situ absorption rate
constants and or in vitro partition coefficients:
6-fluoroquinolones"Journal of Pharmaceutical Sciences
89(11): 1395-1403 (2000)
Marival
www.uv.es/~mbermejo/absorption.htm
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Nitin,
There are established guidelines from the IACUC that address this
issue. Copies are available from the USDA.
Regards,
Garry Boswell
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That sampling rate is too aggressive and alters
hemodynamics. Saline does not stay within the vascular space
and is not a valid way of maintaining circulating volume. A
single sample of blood as large as 0.5 ml will cause an acute
hemodynamic circulatory change and will make your kinetic
data of questionable validity in an animal of the size you
described.
D. Sitar, University of Manitoba
Daniel S. Sitar, PhD
Professor and Head
Department of Pharmacology and Therapeutics
sitar.at.ms.UManitoba.ca
Tel: 204-789-3532 FAX: 204-789-3932
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The following message was posted to: PharmPK
Hi Nitin,
We did one study recently using 12 animals with 6 hrs sampling from
each rat. To avoid hemodynamic changes, instead of using just saline,
we resuspended blood cells in saline (Blood sample was collected in 50
u/mL Heparin). It was injected just before the next sampling.
But, we think our drug does not enter RBCs or may be if it does... it
is minimal.
I hope it helps.
Pravin.
Pravin Jadhav
Ph.D. Student
Drug Metabolism Research Group
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The following message was posted to: PharmPK
I agree with you in that the sampling is kind of
agressive...
but the decrease in haematocrit that we have observed
at the end of our experiments never was higher than
15% and the pK parameters obtained with this model
were almost the same than when we use more animals and
splits sampling times among them to make an "average
animal" with the data from several rats...so we are
more than confident about the validity of our results.
Marival
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The following message was posted to: PharmPK
Garry:
Could you tell me the website to find the guidance?
Thanks!
Lily
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Lily,
The IACUC site is www.IACUC.org. I am looking for the specific
guidance but my Vivarium manager has been out of the office. I'll send
that info soon.
Garry
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The following message was posted to: PharmPK
You can find recommended maximal blood sample volumes of several animal
species at: J. Applied Toxicology, 21, 2001, 15-23.
Ofer
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The following message was posted to: PharmPK
You can find recommended maximal blood sample volumes of several animal
species at: J. Applied Toxicology, 21, 2001, 15-23.
Ofer
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