Immunochemical studies of opioids: Specificities of antibodies against codeine and hydromorphone

Abstract

Two new immunogenic opioid-protein conjugates were prepared. Codeine-6-hemisuccinate was synthesized from the reaction of codeine with succinic anhydride and hydromorphone-6-carboxymethyloxime was synthesized from the reaction of hydromorphone with α-aminoxyacetic acid. Both opioids were attached covalently to bovine serum albumin using the mixed anhydride procedure and employed as immunogens in rabbits. Antibody measured by the ammonium sulfate method showed increases in titer and avidity following subsequent immunizations. The specificities of both antisera were studied by competitively inhibiting the binding of labeled opioid to antibody by the prior addition of increasing concentrations of various unlabeled opioids. The ranges of immunoreactivity of both antisera were different and corresponded closely to the structures of the respective immunizing haptens. These observations suggest that antibodies prepared against codeine, hydromorphone, and morphine may be used in combination for qualitative as well as quantitative determinations of opioids in biologic fluids.