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Dear All,
Do any one have a idea that PK parameters will alter in case of
insulin when it is being studied at following conditions
1. Fast Vs fed
2.Diurnal Vs nocturnal
3.Male Vs female.
Your answers with references will be a great help for our project.
Thanking you
Yours sincerely
Subramanian
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Dear Subramanian,
Which species are you looking at? I am currently working on the
pharmacokinetics of insulin in rat after subcutaneous administration.
I haven't noticed any significant variation between fasted and fed
rats for human insulin.
There is difference in the rate of absorption between the day and
night, obviously the rate being higher during the night.
I have no idea about the pharmacokinetics between male/female rats.
My apologies for not being able to provide a reference as I am still
working on this project, hope this helps, Jagannath
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Hi Ganesh, I am not very clear about rats but in humans, insulin
secretion follows a circadian rhythm (Amer J Physio, End and Met, vol
271, 1996). In humans the peak is between noon and 6 p.m. However as
rats are nocturnal animals I would probably expect them to follow an
opposite pattern with insulin secretion reaching a peak around 12
a.m. Regarding gender differences, it seems that if any gender
difference exists regarding the PK of insulin it is a minor
difference. However there might be gender differences at different
levels (e.g. transport of glucose in certain tissues) which needs
studies to be conducted at the cellular and/or molecular level to
appropriately address your question. Just a thought.
Indranil Bhattacharya
DMPK
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The following message was posted to: PharmPK
Dear Jagannath
I was curious about why you see greater absorption of insulin from
subcutaneous injection during the night as compared to day?
Is this particular to insulin or particular to the administration
route? are
rats nocturnal?
Thanks!
-Rachel
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The following message was posted to: PharmPK
Thanks for your interest Rachel. The greater absorption rate of insulin
during the night is probably because rats are nocturnal. We have also
found this in case of another protein drug darbepoetin alfa (DA). I am
presenting my work on DA at AAPS 2006, in San Antonio, TX, USA.
The activity increases the blood circulation and lymphatic uptake at the
injection site thus increasing the rate of absorption, cheers,
Jagannath Kota
PhD Student
Victorian College of Pharmacy
Monash University
Parkville
381 Royal Parade
VICTORIA 3052
AUSTRALIA
Work: +61 03 9903 9525
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