EVALUATION OF THE CLONED ENZYME DONOR IMMUNOASSAY FOR MEASUREMENT OF PHENYTOIN AND PHENOBARBITAL IN SERUM

We report the evaluation of the cloned enzyme donor immunoassay (CEDIA ) for the estimation of phenytoin and phenobarbital in serum. The assa ys were performed with a Hitachi 911 analyzer. Intra-assay coefficient s of variation were from 1.5 to 4.4% for phenytoin and 1.6 to 5.5% for phenobarbital. Interassay coefficients of variation ranged from 1.8 t o 5.3% for phenytoin and 2.9 to 4.8% for phenobarbital. Linearity was satisfactory, with a recovery of 103% at 11 mg/L and 110% at 22 mg/L p henytoin and 93% at 14 mg/L and 101 % at 40 mg/L phenobarbital. The de tection limit was 1.2 mg/L for phenytoin and 0.6 mg/L for phenobarbita l. Results of this assay correlated well with those of a conventional high-performance liquid chromatography (HPLC) method: r = 0.99 for phe nytoin (n = 47) and r = 0.98 for phenobarbital (n = 48). The CEDIA was easy to handle and especially suitable for short turn-around time app lication.