Preparation of Polyvalent Antibodies for Use in Simultaneous Multiple Drug Radioimmunoassay

Antisera against several drugs were prepared in the same animal and utilized in a polyvalent radioimmunoassay (RIA) capable of screening biological specimens for a number of drugs simultaneously in a single assay. A group of rabbits were immunized sequentially or simultaneously with drug protein conjugates of compounds related to morphine, barbiturate, cocaine and diazepam. The polyvalent antisera thus obtained were capable of binding opiates, barbiturates, cocaine and diazepam as well as their metabolites individually and/or in combination. The antibody titers for the drugs ranged from 1:5 to 1:200. One thousand human urines randomly selected from drug abuse clinics were screened by the polyvalent RIA and the results were compared with single drug RIA, Enzyme Multiplied Immunoassay Technique (EMIT) and thin layer chromatography (TLC) tests. When compared with the results from individual RIA, the polyvalent RIA had approximately 4.3% false positive and no false negative results. Compared with EMIT and TLC there was significant agreement of positive and negative specimens. These data represent the first preparation of a “polyvalent” antiserum and its application in simultaneous dual, triple and quadruple radioimmunoassays. The preparation of polyvalent antisera requires fewer animals and provides more uniform antisera than the in vitro mixing of univalent antisera from many animals. Polyvalent antiserum can be used as an Immunoassay exclusion test in drug screening, and in forensic taxicologic analyses. These antisera can also be used for univalent assays or for quantitative analyses of individual drugs under controlled conditions.