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Dear All,
I would like to know if it is common practice to centrifuge blood
samples obtained during a pK study for obtaining plasma using a
centrifuge that has the capability of cooling the samples or can this
be done also in centrifuges with out a cooling option?
Thanks in Advance.
Leo
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The following message was posted to: PharmPK
When you centrifuge a sample, your samples may get hot. High
temperature may cause changes to drug you are studying or change the
(equilibrium of drug or metabolite if you are assaying both). If you
think your drug is stable, you don't need to use a centrifuge that
has a cooling option. I think it is safer to cool your samples.
Eyob
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Dear Leo,
Cool conditions are maintained in centrifuges to avoid any stability
issues of analytes from the heat generated in centrifugation. The rpm
and the duration of centrifugation are also important to be
maintained. Especially the cooling conditions are maintained for
protien related samples.
If your analyte of interest in blood sample is quiet stable, then
there is no problem in using the centrifuge without cooling option.
Thanks
regards
Akshanth
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Dear Leo,
I agree with Adane and Akshanth. One thing is to avoid degradation of
drug because of heat generated during centrifugation.
Another thing I feel is that at reduced temperatures, the solubility
of plasma proteins gets reduced in organic (extraction) solvents. So,
It also helps in reducing impurity load in extracted samples. Cooling
conditions are generally maintained for Protein Precipitation samples.
hope this helps.
Regards
Sivacharan.
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Unless specified otherwise, the centrifuge is pre-cooled and
maintained at
4oC for harvesting plasma/serum/tissue extracts.
Ed O'Connor, Ph.D.
Laboratory Director
Matrix BioAnalytical Laboratories
25 Science Park at Yale
New Haven, CT 06511
Web: www.matrixbioanalytical.com
Email: eoconnor.-a-.matrixbioanalytical.com
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The following message was posted to: PharmPK
Dear Leo!
> I would like to know if it is common practice to centrifuge blood
> samples obtained during a pK study for obtaining plasma using a
> centrifuge that has the capability of cooling the samples or can this
> be done also in centrifuges with out a cooling option?
>
It's actually not an option but a necessity.
If you don't use a cooled centrifuge, the whole blood will coagulate
forming an almost solid plug making separation of plasma impossible.
The temparature within a centrifuge without cooling may easily get up to
more than 50 oC... (we tried it once - don't repeat it)
Best regards,
Helmut
--
Ing. Helmut SchA\0x00tz
BEBAC - Consultancy Services for
Bioequivalence and Bioavailability Studies
Neubaugasse 36/11
1070 Vienna, Austria
e-mail helmut.schuetz.aaa.bebac.at
web http://bebac.at
forum http://forum.bebac.at
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The following message was posted to: PharmPK
I was under the impression that anticoagulants (EDTA or heparin) are
added to the blood prior to centrifugation.
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The following message was posted to: PharmPK
Dear Eyob!
> I was under the impression that anticoagulants (EDTA or heparin) are
> added to the blood prior to centrifugation.
>
Sure, but you are likely running into problems by denaturation
of proteins by high temperatures.
Just give it a try: put a sample vial containg whole blood
(+ anticoagulant) in a water-bath at 60 degrees centigrade
for 20 minutes...
Best regards,
Helmut
--
Ing. Helmut Schutz
BEBAC - Consultancy Services for
Bioequivalence and Bioavailability Studies
Neubaugasse 36/11
1070 Vienna, Austria
e-mail helmut.schuetz.-at-.bebac.at
web http://bebac.at
forum http://forum.bebac.at
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