Anticonvulsant drugs determined by EMIT in spiked brain samples: a correlation with HPLC values

Phenobarbital (PB), diphenylhydantoin (PHT) and carbamazepine (CBZ) levels were determined in spiked rat brain homogenates by means of the EMIT assay, and these were compared with results obtained by high-pressure liquid chromatography (HPLC). The extraction procedure of the three drugs was identical for both methods, with minor modifications for EMIT (no addition of internal standard; reconstitution with the buffer used in routine plasma level analysis). Correlation coefficients between the data obtained by EMIT and HPLC were extremely good (PB, 0.90-0.98; PHT, 0.92-0.98; CBZ, 0.93-0.99). The results indicate that the EMIT system can detect PB, PHT, and CBZ in brain tissue with good accuracy, although HPLC remains the most accurate and proven method available for research purposes.