Development and validation of an HPLC-UV detection assay for the determination of rufinamide in human plasma and saliva

The development of a simple and rapid high-performance liquid chromatography (HPLC) method for the determination of the new antiepileptic drug rufinamide (RFN) in human plasma and saliva is reported. Samples (250 mu l) are alkalinized with ammonium hydroxide (pH 9.25) and extracted with dichloromethane using metoclopramide as internal standard. Separation is achieved with a Spherisorb silica column (250 x 4.6 mm i.d., 5 mu m) at 30 A degrees C using as mobile phase a solution of methanol/dichloromethane/n-hexane 10/25/65 (vol/vol/vol) mixed with 6 ml ammonium hydroxide. The instrument used was a Shimadzu LC-10Av chromatograph and flow rate was 1.5 ml min(-1), with a LaChrom L-7400 UV detector set at 230 nm. Calibration curves are linear [r (2) = 0.998 A +/- 0.002 for plasma (n = 10) and r (2) = 0.999 A +/- 0.001 for saliva (n = 9)] over the range of 0.25-20.0 mu g ml(-1), with a limit of quantification at 0.25 mu g ml(-1). Precision and accuracy are within current acceptability standards. The assay is suitable for pharmacokinetic studies in humans and for therapeutic drug monitoring.