Radioimmunoassay of Triazolam

Abstract

Two radioimmunoassay (RIA) assay methods (I, II) were developed for triazolam (T), a sedative-hypnotic, in human serum and plasma. The parameters of equilibration time, serum blank, antibody specificity, extraction efficiency and drug-binding to glass were studied. Of the various triazolam analogs tested for cross reactivity, only the hydroxy metabolites intefered significantly. At the levels normally found in plasma or serum, a background blank was encountered from constituents such as fatty acids, lysolecithin, lecithin and cholesterol. Serum or plasma samples could be analyzed with (I) by constructing standard curves in which blank serum from the same subject was used. An alternate method (II) was found which simultaneously extracted and precipitated the interferences. Both methods could be employed for analysis of plasma or serum samples. However, II detects T metabolite less efficiently than I. The within day and between day coefficients of variation for method I were found to be 5.7% and 3.9%, respectively, at the 8 ng/ml level. Method I is suitable for measuring large numbers of samples where blank subject serum can be obtained and where detection of T metabolites in addition to T would not present a problem.