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hello
does anyone know what the half life of creatinine is?
I am trying to look at the pharmacokinetics of a drug in preterm
neonates however i fear that the creatinine concentrations which i am
using as a predictor of their renal function may actually be maternal
creatinine
Does anyone know how long a newborns creatinine concentration is more
reflective of the mothers creatine than the newborns?
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The following message was posted to: PharmPK
Paul,
> I am trying to look at the pharmacokinetics of a drug in preterm
> neonates however i fear that the creatinine concentrations which i am
> using as a predictor of their renal function may actually be maternal
> creatinine
> Does anyone know how long a newborns creatinine concentration is more
> reflective of the mothers creatine than the newborns?
The half-life of creatinine is determined by its clearance (CLcr) and
its volume of distribution (V). In adults the value of V is about 0.5
L/70 kg. My guess is that it will be 0.7 L/kg in neonates (they have
lots of extra water). The Clcr will depend on renal function.
A 3 kg neonate with 'normal for age and size' renal function should
have a CLcr around 0.3 L/h and V around 2 L so creatinine half-life
will be about 5 h.
Maternal creatinine is commonly assumed to have gone within 24 h of
birth which agrees with this prediction.
Nick
--
Nick Holford, Dept Pharmacology & Clinical Pharmacology
University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New
Zealand
email:n.holford.at.auckland.ac.nz tel:+64(9)373-7599x86730 fax:373-7556
http://www.health.auckland.ac.nz/pharmacology/staff/nholford/
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