Back to the Top
The following message was posted to: PharmPK
Dear colleagues,
I plan to determine the level of some antihelminthic
drugs in the milk of lactating women. Do I have to
make any on-site sample clean-up, before storing
samples. Can I just take the samples, cool them, then
send them for -50 C freezing, till the time of assay?
Is milk a special matrix that needs a prelimimnary
extraction before storage?
I'll be grateful to have your response.
Ahmed M. Abdel-tawab; MD; PhD
Associate Professor,
Department of Pharmacology,
Faculty of Medicine, Ain Shams University,
Cairo, Egypt
Back to the Top
The following message was posted to: PharmPK
Dear Ahmed,
I've determined levels of antidepressant drugs in breast milk. We just
stored them by putting the fresh milk into a -20 C freezer and had no
problems. Nothing needs to be done to the milk before storage unless the
compounds you are investigating have, for some reason of their own, a
problem with stability. This is not to say that measuring drugs in milk
is a simple task. Differences in drug levels between fore-milk and
hind-milk have been reported. Also, milk is a difficult matrix to
extract from. It does not pass easily through an SPE column and getting
a clean extraction with a good recovery can be difficult.
Dr Seetal Dodd
Research Fellow
Department of Pharmaceutics,
Victorian College of Pharmacy, Monash University
381 Royal Parade, Parkville, Victoria 3052
Australia.
Tel: +61 3 9903 9053
Fax: +61 3 9903 9583
Back to the Top
The following message was posted to: PharmPK
If your compound has no obvious instability properties then you just need to
run some storage stability and freeze thaw stability studies. If you are
concerned about the physical nature of the matrix why not just dilute the
milk with water prior to freezing
Dave
RCC Ltd
Back to the Top
[Hello members of PharmPK - our campus mail server was 'upgraded'
over the weekend (before classes started??) and as a result many/most
of the PharmPK email addresses bounced and were made inactive on the
list. I finally realized what had happened yesterday and this morning
set all addresses to be active. Thus, a few of you (about 10 as
messages and about 15 as digests - the list currently has over 2000
addresses) have received this and the following messages. I'm sorry
this might be your third or fourth copy. I will use my small mail
server to send out the message posted this week over the next couple
of days.
Some have you may have set your address inactive while on
holiday/vacation etc. Unfortunately I wasn't able to determine which
these were so all addresses are now active. Let me know if inactive
is more appropriate. Also, I regularly get a few bad address messages
when I send out a PharmPK message. From time to time I unsubscribe
these addresses. If you receive an unsubscribe message it is probably
because a temporary email system glitch made it lok like your email
address was 'bad' and I have subscribed you. I'm sorry if this is by
mistake. It is had to tell the difference sometime. Either
resubscribe or tell and I'll re subscribe you.
Thank you for your patience and now the first of the message that may
have bounced ;-) - db]
The following message was posted to: PharmPK
Dear colleagues,
I plan to determine the level of some antihelminthic
drugs in the milk of lactating women. Do I have to
make any on-site sample clean-up, before storing
samples. Can I just take the samples, cool them, then
send them for -50 C freezing, till the time of assay?
Is milk a special matrix that needs a prelimimnary
extraction before storage?
I'll be grateful to have your response.
Ahmed M. Abdel-tawab; MD; PhD
Associate Professor,
Department of Pharmacology,
Faculty of Medicine, Ain Shams University,
Cairo, Egypt
Back to the Top
[A couple of replies - looks like that 'first' message got out to
some PharmPK members at least - db]
From: Seetal Dodd
Date: Mon, 20 Aug 2001 11:24:41 +1100
To: david.-at-.boomer.org
Subject: Re: PharmPK Milk samples!!
Status: R
The following message was posted to: PharmPK
Dear Ahmed,
I've determined levels of antidepressant drugs in breast milk. We just
stored them by putting the fresh milk into a -20 C freezer and had no
problems. Nothing needs to be done to the milk before storage unless the
compounds you are investigating have, for some reason of their own, a
problem with stability. This is not to say that measuring drugs in milk
is a simple task. Differences in drug levels between fore-milk and
hind-milk have been reported. Also, milk is a difficult matrix to
extract from. It does not pass easily through an SPE column and getting
a clean extraction with a good recovery can be difficult.
--
Dr Seetal Dodd
Research Fellow
Department of Pharmaceutics,
Victorian College of Pharmacy, Monash University
381 Royal Parade, Parkville, Victoria 3052
Australia.
Tel: +61 3 9903 9053
Fax: +61 3 9903 9583
---
From: "Dave Vowles"
Date: Mon, 20 Aug 2001 09:49:42 +0100
To: david.aaa.boomer.org
Subject: Re: PharmPK Milk samples!!
Status: R
The following message was posted to: PharmPK
If your compound has no obvious instability properties then you just need to
run some storage stability and freeze thaw stability studies. If you are
concerned about the physical nature of the matrix why not just dilute the
milk with water prior to freezing
Dave
RCC Ltd
Back to the Top
The following message was posted to: PharmPK
Dear Ahmed,
I have analyzed an anthelmintic compound in cow milk and faced some
problems initially. Here are some hints to minimize them.
1. Make sure you do not freeze the whole milk sample and then pipet
the required volume for analysis after thawing the frozen milk
sample. Upon free-thaw, milk phases tend to separate and you will
have problems in pipeting the required volume. Even if you vortex-mix
the thawed samples, homogeneity is lost and depending on the
partitioning of the compound into milk protein and milk fat, you will
either over or underestimate the drug. If the assay method is already
developed, pipet the required volume (for analysis) into a fresh
tube/vial and then freeze it.
2. Although milk looks "White" and clean, it has lots of protein and
fat. You may want to do a protein precipitation (with at least 2
portions of acetonitrile) step before extraction.
3. Analyze as soon as possible.
Hope this helps.
Raj
Nelamangala V. Nagaraja
S110/T5-1, Pre-Clinical DMPK
DuPont Pharmaceuticals
Ph: 302-366-6342 (W)
302-738-3529 (H)
PharmPK Discussion List Archive Index page
Copyright 1995-2010 David W. A. Bourne (david@boomer.org)