レーザーイムノケミカルシステム(i-PiT)による血中薬物濃度測定法の検討

抄録

The determination of drug concentration in the serum by laser immunochemical system (i-PiT) is a method based on the inhibition of immunoprecipitation by hapten (drug) when the antibodies can react with both hapten and polyhapten. We studied the i-PiT method using formalin to stop the antigen-antibody reaction after a regular reaction period, because of the fact that when the antibody is treated with formalin the reactivity is completely lost. At first, we investigated the formalin concentration in assay solution to inhibit the reaction completely and immediately after the addition of formalin. Consequently, we recognized that the reaction was inhibited almost completely at 35×14^-1% of formalin, and more completely at 50×14^-1%. Thus, commercial formalin as an inhibiting reagent was added into the assay solution to contain about 50×14^-1% of formalin, the precision and accuracy of i-PiT method using formalin were studied in phenobarbital (PB) and phenytoin (PHT) assay. Hourly change, expressed as coefficient of variation, was less than 7.1%, and daily change for five days was less than 6.3% in PB and PHT assay. Mean recovery was 102.1% in PB assay, and 102.7% in PHT assay. The patients'serum specimens were analyzed, and the values correlated well to those determined by EMIT method. The coefficient correlation was 0.989 (n=37) for PB, and 0.980 (n=29) for PHT. In view of good precision and accuracy, i-PiT method using formalin was recognized as a useful method for the determination of PB and PHT in the serum.