Radioimmunoassay of nicergoline in biological material

A method for radioimmunoassay of nicergoline (Sermion) in plasma and urine is described. The antiserum was produced in rabbits by administration of an immunogen obtained by coupling bovine serum albumin to the nicergoline molecule at the indole nitrogen. The resulting antibodies reacted well with nicergoline and the 1-demethyl derivative and did not cross-react with the principal metabolites of these substrates nor with rye ergot derivatives in particular dihydroergotamine, methysergide and bromocriptine. The tracer was nicergoline labelled with iodine-125. The assay was sensitive because concentrations as low as 125 X 10-12 mol/l nicergoline could be directly determined in plasma and urine without prior extraction. The marked specificity and high sensitivity allowed easy determination of plasma and urine levels of this drug following administration in man.