Blood Level Determin a t ions and Pharmacokinetic Stud ies of Anticonvulsants i n Ethiopian Epileptics
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Date
1987-06
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Addis Ababa Universty
Abstract
A gas chromatographic method was employed to monitor
plasma levels of phenytoin and phenobarbital in 101 Ethiopian
epileptic patients who were on chronic drug treatment and
kinetics and plasma level-response relationship was studied.
40% of the patients were on single drug treatment while the
remaining were taking both phenytoin and phenobarbital . A
very low correlation between dose and plasma level was observed
and there was high variation among individuals. Although 86%
of the patients were receiving 300 mg of phenytoin per day ,
some patients showed plasma levels as low as 5|ig / ml
others as high as 60 pg/ ml .
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About 70% of patients were seizure-free at the range
of 10-20 pg /ml phenytoin levels. However the best range for
maximum seizure control in this study was 20-30 p g / ml. At
lower levels, that is below 10 pg /ml , and at higher levels
above 30 jug/ml , the seizures were poorly controlled. The
therapeutic range of phenobarbital for optimum control of
seizure was found to be comparable with that of phenytoin
( 20-30 pg /ml ).
The kinetics of phepytoin is best described by Michaelis-
Menten kinetics. The most important parameters K and V m max
were estimated and found to be 6.5 mg /lt and 6.9 mg /kg / d
respectively. The maximum metabolic capacity, vmax » for
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Keywords
Anticonvulsants in Ethiopian Epileptics