Development and Validation of Bioanalytical Method for Quantification of Phenytoin in Rat Brain Tissues as per ICH Guidelines

Phenytoin is an antiepileptic drug approved in the USA, Europe and several other countries. Phenytoin is currently used to manage partial onset seizures in humans suffering from epilepsy. A rapid, sensitive, novel and simple UV method was developed and validated according to ICH guidelines for the quantification of phenytoin in rat brain homogenate supernatant. Calibration curves were found to be linear ranging from 0.02-0.1 μg/ml giving regression of r2=0.998, using detection wavelength at 214 nm. Precision, limit of detection and limit of quantitation were calculated. Recovery ranged from 96.38% to 98.55% w/w. The assay was applied successfully to a pre-clinical study of Phenytoin. By applying this method, we were able to determine the brain concentration of phenytoin during at least 1 h after IV administration of 1mg/kg phenytoin. The method proved to be simple, useful and appropriate, for preclinical and experimental research for various biomedical applications.