Pharmacokinetics of phenylethylmalonamide (PEMA) in elderly men

Determination of antiepileptic drugs in biological material

Current analytical methodologies applied to the determination of antiepileptic drugs in biological material are reviewed. The role of chromatographic techniques is emphasized. Special attention is focused on new chemical entities as well as current trends such as high-speed liquid chromatographic techniques, hyphenated techniques and electrochromatography techniques. A review with 542 references.

Simultaneous determination of primidone and its three 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, phenobarbital (PB), p-hydroxyphenobarbital (p-HO-PB) and phenylethylmalonamide (PEMA), in rat urine, was developed. After acid hydrolysis, these compounds were extracted from urine by means of a Bond Elut Certify LRC column with good clean-up. The extracts were chromatographed on a C18 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 (r2>0.99) was observed within the calibration ranges studied: 37.4-299.3 microg/ml for PRM, 26.4-211.2 microg/ml for PB, 12.5-100.2 microg/ml for p-HO-PB and 12.1-97.0 microg/ml for PEMA. Repeatability was in the range 3.1-6.8%. This method constitutes a useful tool for studies on the influence of various parameters on primidone metabolism.

Simultaneous determination of primidone and its active metabolites in rat plasma by high-performance liquid chromatography using a solid-phase extraction technique

Primidone (PRM) and its active metabolites, phenylethylmalonamide (PEMA) and phenobarbital (PB), in rat plasma were simultaneously determined using a solid-phase extraction technique followed by high-performance liquid chromatography (HPLC). Twenty microliters of plasma was applied to a Bond-Elut C-18 cartridge column with 0.1 microgram of acetanilide (internal standard, IS). After the column was washed, PRM, PEMA, PB, and IS were eluted with methanol and injected into the HPLC system. Calibrations for these substances were linear in the range of 0-20 micrograms/mL. The coefficients of variation were 1.5-7.9% and 3.4-9.1% in the within-day and between-day assays, respectively. The recovery rates were 96.8-101.8%. The pharmacokinetics of these substances were examined after oral administration of PRM (50 mg/kg) to rats. The Tmax values for PRM, PEMA, and PB were 1.4, 5.7, and 6.6 h, respectively, and the Cmax values were 18.2, 8.1, and 9.6 micrograms/mL, respectively. This method is useful for pharmacokinetic studies of PRM and its active metabolites.