Bulk OEM Reagents (Reagent 1/ Reagent 2) for automated chemistry analyzers. Phenytoin is an anticonvulsant used in the treatment of tonic-clonic (Grand Mal) and focal seizures. Therapeutic drug monitoring by determining Phenytoin concentration in serum or plasma is often required. A narrow therapeutic index necessitates an accurate and reliable means for the measurement of phenytoin concentration in human body fluid such as serum, plasma and urine. Due to the low therapeutic index, the increasing number of phenytoin intoxications, and the large number of potential patients worldwide; a high throughput detection method with high sensitivity and specificity is used. Phenytoin Assay provides a convenient and efficient method to monitor this drug concentration in serum or plasma.