Clonazepam serum levels in epileptic patients determined simply and rapidly by high-performance liquid chromatography using a solid-phase extraction column.

We studied the use of high-performance liquid chromatography (HPLC), using a solid phase extraction column (Bond Elut cartridge column), for the simple, rapid and sensitive determination of serum clonazepam levels in epileptic patients. Extracted aliquots were analyzed by HPLC, using a reverse phase ODS column (mu-Bondapak C18). The analytical mean recovery of clonazepam added to the blank serum averaged 99.9%. The detection limit was as high as approximately 2 ng/ml in the serum. The reproducibilities were 2.3-8.6 CV % in the within-day assay and 6.5 CV % in the between-day assay, indicating that the analysis method was effective in the determination of clonazepam serum levels. Accordingly, we suggest that the present method, using a solid phase extraction column, may be useful for the routine monitoring of clonazepam serum levels in epileptic patients.