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The following message was posted to: PharmPK
Dear Colleagues,
What is the best kind of urine collection bottle/bag
(what brand/supplier) for conducting mass balance
studies? Is there any standard way of assessing the
extent of drug binding to the container? (Is it
routinely done?) How do you optimizing the collection
times/intervals based on the plasma concentration-time
data?
Thanks
Rostam
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The following message was posted to: PharmPK
Dear Rostam,
> What is the best kind of urine collection bottle/bag
> (what brand/supplier) for conducting mass balance
> studies? Is there any standard way of assessing the
> extent of drug binding to the container? (Is it
> routinely done?)
[He, Yan-Ling] I think it really depends on the property of the
drug you are looking at. The best is to select the containers with
different materials that show little adsorption to your drug. If the drug
is very lipophilic, in general, it tends to show significant adsorption to
the containers.
> How do you optimizing the collection
> times/intervals based on the plasma concentration-time
> data?
[He, Yan-Ling] If you give the drug by constant infusion, and the
time you are taking urine is during the steady-state, it is ideal to take
plasma samples in the middle of urine collection period. If it is a
non-steady state, you may want to take several plasma samples during a urine
collection period depending on the kinetics of the drug.
I hope this helps.
Yan-Ling HE, Ph.D.
Dept of Anesthesia
MGH, Harvard Medical School
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The following message was posted to: PharmPK
Hi Yan-Ling,
Thanks for your response. The drug that I am working
highly binds to plastic and all the urine collection
bottle/bag that I know is made of plastic. Do you
know any urine collection bottle made of Teflon or any
non-absorbing material? I do not have any urine data.
I have the plasma blood concentration time data.
Based on these data, how do I come up with urine
collection times? Usually urine samples were taken at
3 to 6 hr post-dosing, 24 hr, 48 hr and 72 hr (or for
slowly released compound up to 96 or 120 hr). How do
you justify the first collection time? 1 hr, 3 hr, 6
hr ....???
Rostam
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The following message was posted to: PharmPK
Hi Rostam,
> The drug that I am working
> highly binds to plastic and all the urine collection
> bottle/bag that I know is made of plastic. Do you
> know any urine collection bottle made of Teflon or any
> non-absorbing material? I do not have any urine data.
[He, Yan-Ling] Actually, I only have experience of collecting
urine samples for hydrophilic compounds. You can call the "container"
company. Sometimes, it is very helpful.
> I have the plasma blood concentration time data.
> Based on these data, how do I come up with urine
> collection times? Usually urine samples were taken at
> 3 to 6 hr post-dosing, 24 hr, 48 hr and 72 hr (or for
> slowly released compound up to 96 or 120 hr). How do
> you justify the first collection time? 1 hr, 3 hr, 6
> hr ....???
[He, Yan-Ling] The urine collection period is really up to what
kind of information you would like to get from your study. For mass balance
study, or to figure out the renal clearance, the most important issue is to
make sure you are measuring the amount of drug or metabolite(s) in the urine
as precisely as possible. So you need to collect all the urine during the
period when significant amount (or above measurement limitation) of drug is
excreted into urine.
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