Determination of felbamate in human serum by high-performance liquid chromatography

A rapid and sensitive high-performance liquid chromatographic method for the analysis of the antiepileptic felbamate in human serum has been developed. Following protein precipitation with acetonitrile containing the internal standard alphenal, the drugs are extracted from serum using dichloromethane. The extraction efficiency averages 98% for felbamate. Chromatography is performed with use of reversed phase octyl (C8) column, monitored at 210 nm. The isocratic mobile phase is acetonitrile:acetate buffer, pH 5.3, flow rate 2.0 ml/min. Felbamate is resolved from other common antiepileptic drugs that may be co-administered. The assay is linear to 200 micrograms/ml in serum. The effect of mobile phase pH changes on the chromatographic characteristics of the antiepileptic drugs and some potential interferents is discussed.