International journal of clinical pharmacology, therapy, and toxicology
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Int J Clin Pharmacol Ther Toxicol · Apr 1989
Phenytoin Michaelis-Menten pharmacokinetics in Saudi patients.
The Michaelis-Menten pharmacokinetic parameters Vmax and Km were calculated for 17 epileptic Saudi patients receiving phenytoin. Their ages ranged from 2.5 to 47 years (mean 21 years) and their weight ranged from 9.5 to 80 kg (mean 53 kg). Eight were females and 9 were males. ⋯ There is a significant increase in Vmax with weight (r = 0.816, p less than 0.01). A plot of Km vs age and weight showed a poor correlation (r = 0.302, r = 0.218, respectively) and a large amount of variability. Based on this data, the daily phenytoin doses for children and adults are 7.21 mg.kg-1 and 4.83 mg.kg-1, respectively, in order to achieve and maintain a steady-state phenytoin concentration of 15 mg.l-1.