title: A comparison of the OPUS and TDx analysers for antiepileptic drug monitoring.
abstract: Therapeutic drug monitoring of a variety of antiepileptic drugs is used routinely as a guide to individualising the drug treatment of patients with epilepsy. Thin dry film multilayer immunoassays (OPUS) for carbamazepine, phenytoin, phenobarbitone, and valproic acid were evaluated and compared with fluorescence polarisation immunoassay (TDx), using commercially available control material and patient sera. For the OPUS, the within-batch coefficient of variation (CV) for the different drugs in the control material varied between 3.9% (phenobarbitone) and 8.1% (valproic acid). The between-batch CVs varied between 5.3% (valproic acid) and 18.3% (carbamazepine). The comparative between-batch CVs for the TDx varied between 2.0% (phenytoin) and 7.0% (valproic acid). Analysis of 209 patient samples containing carbamazepine, phenytoin, phenobarbitone, or valproic acid demonstrated significant correlation between the two analytical methods, with correlation coefficients of 0.9336, 0.9560, 0.9448, and 0.9618, with slopes of the regression lines of 0.9042, 0.8663, 1.1368, and 1.1244, respectively. It is concluded that both the TDx and OPUS instruments exhibit comparable performance for the analysis of carbamazepine, phenobarbitone, phenytoin, and valproic acid in patient samples. Moreover, the OPUS instrument, with its facilities of random assay access and statim analysis, may be useful in an outpatient setting in which a major consideration would be a rapid turnaround of patient assay results.
authors.affiliation: University Department of Clinical Neurology, National Hospital for Neurology and Neurosurgery, London, England.
authors.forename: M T
authors.initials: MT
authors.lastname: O'Connell
authors.forename: N
authors.initials: N
authors.lastname: Ratnaraj
authors.forename: A A
authors.initials: AA
authors.lastname: Elyas
authors.forename: M H
authors.initials: MH
authors.lastname: Doheny
authors.forename: S
authors.initials: S
authors.lastname: Darsot
authors.forename: P N
authors.initials: PN
authors.lastname: Patsalos
mesh_terms: D000927:Anticonvulsants / Q000032:analysis* / Q000627:therapeutic use; D002220:Carbamazepine / Q000032:analysis / Q000627:therapeutic use; D016903:Drug Monitoring; D004827:Epilepsy / Q000188:drug therapy*; D005260:Female; D016231:Fluorescence Polarization Immunoassay; D006801:Humans; D007118:Immunoassay; D008297:Male; D010634:Phenobarbital / Q000032:analysis / Q000627:therapeutic use; D010672:Phenytoin / Q000032:analysis / Q000627:therapeutic use; D012044:Regression Analysis; D015203:Reproducibility of Results; D014635:Valproic Acid / Q000032:analysis / Q000627:therapeutic use
chemical_list: D000927:Anticonvulsants; D002220:Carbamazepine; D014635:Valproic Acid; D010672:Phenytoin; D010634:Phenobarbital