[Radioimmuno assay of the sulfonylurea AR-DF 26(author's transl)].

A radioimmunological method was developed for 1-cyclohexyl-3-[p-(beta-4,4-dimethyl-7-methoxy-1,3-(2H,4H)-isoquinolinedion-2-yl)phenethyl]-sulfonylurea (AR-DF 26, gliquidone, Glurenorm) estimations in plasma. The antisera were obtained by immunization of rabbits with AR-DF 26-bovine serum albumin (BSA) conjugate. The estimation is based on the competitive displacement in plasma samples of known amounts of labelled AR-DF 26, bound to a specific antibody by unknown amounts of unlabelled AR-DF 26. Concentrations of as low as 1 ng of AR-DF 26 per sample can be measured by this method. The investigations into the specificity of this reaction have shown that the antiserum is extremely specific for AR-DF 26. There is good reproducibility of the results and no differences could be found by variance analysis between different measurements of the same AR-DF 26 concentration. Since more than 70% of the plasma concentration correspond to unchanged AR-DF 26 for a longer period after application, the results of this AR-DF 26-radioimmuno assay is only minimally altered by its metabolites.