BENEFITS OF A CLINICAL PHARMACOKINETIC SERVICE IN OPTIMIZING PHENYTOIN USE IN THE WESTERN CAPE

Objectives. To study the benefits of a clinical pharmacokinetic servic e in optimising phenytoin use in the Western Cape. Design;Assessment o f the response to treatment was based on the number of seizures during the 3 months before entering the study (first baseline period), 3 mon ths after entering the study (second baseline period) and 3 months bef ore the termination of the study (test period).. Patients kept a seizu re diary throughout the study. The Michaelis-Menten model was used to calculate doses and predict steady-state serum concentrations. Setting .Nine epilepsy clinics. Subjects.One hundred and ninety-five (113 blac k and 82 coloured) compliant people with epilepsy receiving generic ph enytoin monotherapy. Outcome measures. Reduction in seizure frequency and adverse effects. Results. A reduction in seizure frequency (64.8% compared with ere-optimisation) was experienced by 64.9% of patients. Mean seizure frequency was reduced from 3.39 to 1.18 per month. Reduct ions in seizure frequency of 100% and more than 50% were reported by 3 9.2% and 58.7% of patients, respectively. Adverse effects of phenytoin were reduced from 20.5% at the first visit to 3.2% at the last visit. Conclusion. The clinical pharmacokinetic dosing service for phenytoin applied in this study contributed significantly to the success of epi lepsy management.