Free phenytoin? Despite the kinetics, the concentration-effect and
concentration-toxicity relationship for phenytoin, although better than that
for carbamazepine, valproate etc is not as well defined as you may think.
Measuring free rather than total phenytoin does not improve this.
I once reduced the phenytoin dose slightly in an asymptomatic patient
because of a total and free phenytoin concentration in the roof (total
50mg/L). The next time I saw him was in status epilepticus in ICU.
Next, you'll be recommending that lamotrigine levels are measured!
Dr. Eric S. Kilpatrick
Consultant in Chemical Pathology
Hull Royal Infirmary
Anlaby Rd
Hull HU3 2JZ
Tel: 01482-674312/674814
Fax: 01482-674310
----- Original Message -----
From: Greg Watts <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, March 22, 2000 6:24 AM
Subject: RE: Free phenytoin
> Bruce,
> Could it be that the membrane is slowly leaking protein with phenytoin
> attached. More as the centrifuging increases?
>
>
> Greg Watts
> Senior Biochemist
> Sydney Adventist Hospital
> ____________________________________________________________________
>
> -----Original Message-----
> From: Bruce Campbell [mailto:[log in to unmask]]
> Sent: Wednesday, March 22, 2000 12:24 PM
> To: 'John Whitfield'; [log in to unmask]
> Subject: RE: Free phenytoin
>
>
> Discussion on this topic has generated some heat but not much light that I
> can see. Why is the free phenytoin measured by this technique apparently
> incorrect and how are the other contributer's observations of increasing
> apparent free concentration with increasing centrifugation explained?
>
>
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>
>
>
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