title: Determination of phenytoin in plasma: a comparison of procedures using a new radioimmunoassay, gas chromatography, and enzyme immunoassay.
abstract: A new commercially available radioimmunoassay (RIA) procedure for the anticonvulsant drug phenytoin has been assessed and compared with a gas-liquid chromatographic (GLC) and an enzyme immunoassay (EMIT) procedure. One hundred and thirty-four plasma samples containing phenytoin were analyzed by the three methods and the results were found to be essentially independent of the procedure used and so would indicate similar clinical interpretation. The correlation coefficients were: RIA/GLC = 0.988; EMIT/RIA = 0.978; EMIT/GLC = 0.981. The cross reactivity of 33 drugs and related compounds was tested in the RIA and EMIT procedures and only a few very closely related substances showed significant cross reactivity. In addition, the three methods were compared with respect to the technical difficulties involved as well as time and cost for the assay of single and multiple samples.
mesh_terms: D002849:Chromatography, Gas / Q000379:methods; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D010672:Phenytoin / Q000097:blood*; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D010672:Phenytoin