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I am going to plan a series of in vitro stability studies in rat plasma
for prodrugs.
Anyone knows where I could buy pooled rat plasma in Europe and at which
prices?
As I am interested in plasma esterase activity remaining constant, can
I use freezed plasma or should I use fresh one? And if I can use the
freezed, which is the temperature of storage to mantain the enzymatic
activity?? -70°C or even -20°C is enough??
Thanks a lot for help!
Federica
federica.vacondio.aaa.unipr.it
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Hello Federica,
It is not advisable to performin vitro stability in plasma kept
frozen, whether it is -20 or -70 degC. To simulate in vivo conditions,
stability should be performed infreshly collected and pooled
ratplasma, incubated at 37 deg C.
Good luck,
Vijay V. Upreti.
Department of Pharmaceutical Sciences. School of Pharmacy, University
of Maryland. Baltimore. MD 21201. USA
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Dear Federica
There are different types os stability studies which ushould perform.
You have to perform Freeze thaw stability where u take out the frozen
samples thaw them at room temperature and then compare it with freshly
spiked plasma samples. You have to perform at least 3 cycles of this
freeze thaw stability. You have to perform in injector as well as bench
top stability. all these have to be performed at room temperature.
Rgards
Tausif Ahmed
Ph.D. student,
Dept. of Pharmaceutical Medicine
Ranbaxy CPU, Majeedia hospital,
Hamdard University, New DeLhi
India
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Dear Sir
I need to know about plasma stability.
Regularity authority says that keep the processed study sapmle of
plasma for about 5 yrs at -70*C.
But for eg:
The Std Spiked sample as well as the study samples are for instance
stable at -70*C for 6 months in that case why need to keep samples for
5 years?Or is it required to keep or discard the samples.
Many says that sample will be stable at -70*C as at this temp no enzyme
activity is seen so the plasma sample will remain stable than why to
do stability studies?
I want ot know Why 5 years samples has to be stored?
Thanks in advance
Jyoti Idnani
NCER-PK
Lupin research park,pune
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Plasma Stability wrt PK studies:
Our laboratory has also struggled with this concept. You need to prove
stability of your samples for the period you intend to store them.
Should the sample not be stable for 5 years, why keep them for 5 years?
We have adopted the policy of retaining duplicate samples for 2 years,
having shown stability for that time. After that, we discard them.
Other feedback I have had is that other companies discard their samples
following release and acceptance of the study report.
Also, regulatory guidelines tend to be vague. Retention of tissue
samples may mean histology slides or biopsies and not PK samples,
bearing in mind that not all clinical studies are pharmacokinetic. These
tissue specimens are preserved much more easily and for longer periods
of time.
Regards,
Jennifer Norman
Quality Assurance
Division of Pharmacology
University of Cape Town
Tel. +27 (0)21 406 6498
Fax. +27 (0)21 448 1989
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Dear Jennifer
As you had adopted the policy of retaining duplicate samples for 2
years,having shown stability for that time. After that, you discard
them.But all the samples are not stable for 2 years right.
By your statement that "stability of your samples for the period you
intend to store them".By this it is very clear that if your sample is
stable for 3 months than store it for three months only that what you
mean?
I just wanted to clearify my doubt.
Thanks in advance
jyoti idnani.
NCER-Pk
Lupin research park.
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Dear Jyoti,
I would differ in the storage of plasma samples as:
If the analysis of the samples are completed and a report for the same
has been made, the storage of samples beyond the period of validated
long term stability cannot be defended to regulatory authorities.
The regulatory authorities ask for the archival of enough nos of drug
samples used in the study only for the reason so that the studies can
be repeated if any doubt.
You may store and use these samples in preclinical studies as a tool
for the identification of metabolites which serve as a template to
guide you for further method development studies.
Awaiting responses from the group to share their veiws
Thanks,
Naveen Sharma
Sr Scientist -PK
Aurobindo Pharma Ltd.
Hyderabad, India.
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Dear Jyoti,
I think you have hit the nail on the head. The reason why you will store
the samples is to reassay them upon request from the regulatory
authority and/or sponsor - Am I right? And if you try and reassay them
if you know they have not been stable at the most appropriate storage
temperature, you will get a result that doesn't mean anything.
As long as you have data to show that the samples are not stable for
that period (not data that shows that they are stable for 3 months with
no further testing) - I don't think there should be a problem.
Jennifer
Jennifer Norman
Quality Assurance
Division of Pharmacology
University of Cape Town
Tel. +27 (0)21 406 6498
Fax. +27 (0)21 448 1989
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The following message was posted to: PharmPK
Dear jyothi,
I do agree with naveen and Jennifer regarding plasma stability.
It is the common criteria as so many of our friends mentioned earlier
that u have to carry all types stability studies relevant to BA/BE
studies and then u have to store the duplicate plasma or serum samples
till u get the approval of the report u submitted to any regulatory
agency. Once if u get one approval u need not to keep the samples for
second agency if any. In case if u are completing study and report and
then applying for the same after a long period then there is no point of
keeping your plasma samples in storage as u can show the logs for every
samples stored and utilized during the period of study and analysis to
regulatory agency whenever they audit . But one has to keep the drug
samples of the same batch for the sake of regulatory audits minimum of 2
years up to the expiry dates.
In case of preclinical discovery, u can keep biological samples
containing drugs can be stored till then u knows the stability of drug.
Idea is to carry the samples for distribution and metabolism purpose. In
practice we do not preserve for longer periods as we can perform the
studies whenever it is required.
KANTHI KIRAN
Sr. Res. Scientist-PK
Glenmark Pharmaceuticals Ltd.
Mumbai-India
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