Automated and routine liquid chromatographic analysis of antiepileptic drugs

We describe an optimized automated liquid chromatographic method for simultaneous measurement of primidone, phenobarbitone, phenytoin, carbamazepine and clonazepam. A Waters Tri-Module automation system is used and it provides direct read-out of results after chromatography. A one-step extraction with ethyl acetate is used to extract the drugs from 100 microL serum samples. We use an isocratic mobile phase and monitor the column effluent at 210 nm. Drug levels as low as 5 mumol/L can be detected. The within-run CV's range from 1.4 to 2.7%, and the between-run CV's range from 5.2 to 6.1%. Analytical recovery is in the range from 94-108%. The method compares favourably with the enzyme multiple immunoassay technique for routine antiepileptic drugs monitoring, in accuracy, efficiency and cost-effectiveness.