Original Article: PDF OnlyEvaluation of the Cloned Enzyme Donor Immunoassay for Measurement of Phenytoin and Phenobarbital in Serumvan der Weide, Jan; Luiting, Hendrik-Jan; Veefkind, Adriaan H.*Author Information Department of Clinical Chemistry, Psychiatric Hospital Veldwijk, Ermelo; and Department of Clinical Chemistry, *Psychiatric Centre Zon en Schild, Amersfoort, The Netherlands Therapeutic Drug Monitoring: August 1993 - Volume 15 - Issue 4 - p 344-348 Buy Abstract We report the evaluation of the cloned enzyme donor immunoassay (CEDIA) for the estimation of phenytoin and phenobarbital in serum. The assays were performed with a Hitachi 911 analyzer. Intra-assay coefficients 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 to 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 phenytoin and 93% at 14 mg/L and 101% at 40 mg/L phenobarbital. The detection limit was 1.2 mg/L for phenytoin and 0.6 mg/L for phenobarbital. Results of this assay correlated well with those of a conventional high-performance liquid chromatography (HPLC) method: r = 0.99 for phenytoin (n = 47) and r = 0.98 for phenobarbital (n = 48). The CEDIA was easy to handle and especially suitable for short turn-around time application. © Lippincott-Raven Publishers.