[Study of an anti-serum against phenytoin with two organometallic tracers].

In order to develop a new immunoassay procedure based on the use of organometallic labels, an antiserum is raised against antiepileptic drug: diphenyl-hydantoin (phenytoin). Immunization was performed in rabbits with phenytoin coupled to bovine-serum albumin. The evaluation of the specificity and the affinity constants of the antiserum is studied by radioimmunoassay against different antiepileptic drugs and metallotracers (phenytoin labelled with organometallic fragments derived respectively from cobaltocene and ferrocene). The results of this study indicate that metallotracers cross-react slightly with phenytoin (cross reaction percent about 11 for the two compounds). The affinity constants of the antiserum for phenytoin and for metallohaptens derived from cobaltocene and from ferrocene are respectively 0.03 nM-1, 0.05 nM-1 and 0.06 nM-1.