SIMULTANEOUS DETERMINATION OF PRIMIDONE AND ITS 3 MAJOR METABOLITES IN RAT URINE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY USING SOLID-PHASE EXTRACTION

A new high-performance liquid chromatographic method for simultaneous determination of primidone (PRM) and of its three major metabolites, p henobarbital (PB), p-hydroxyphenobarbital (p-HO-PB) and phenylethylmal onamide (PEMA), in rat urine, was developed. After acid hydrolysis, th ese compounds were extracted from urine by means of a Bond Elut Certif y LRC column with good clean-up. The extracts were chromatographed on a C-18 reversed-phase column using isocratic elution at 40 degrees C, with UV detection at 227 nm. The Limit of detection was 0.5 mg/ml for the four compounds. Good linearity (r(2) > 0.99) was observed within t he calibration ranges studied: 37.4-299.3 mu g/ml for PRM, 26.4-211.2 mu g/ml for PB, 22.5-100.2 mu g/ml for p-HO-PB and 12.1-97.0 mu g/ml f or PEMA. Repeatability was in the range 3.1-6.8%. This method constitu tes a useful tool for studies on the influence of various parameters o n primidone metabolism. (C) 1998 Elsevier Science B.V. All rights rese rved.