Selective antibodies to propranolol enantiomers produced from a new conjugate

A selective antibody to (S)-propranolol enantiomer was produced in rabbits by immunization with a new conjugate of N-aminopropylpropranolol-albumin. A hapten was first prepared by condensing (S)-propranolol or the racemate with 3-bromopropylphthalimide followed by hydrazinolysis, and the resulting compound conjugated to serum albumin by means of a glutaraldehyde- or carbodiimide-mediated reaction. Rabbits were immunized, and titres and specificity of antibodies were determined by ELISA. The antibodies obtained were tested with (S)-, (R)-, (R,S)-propranolol, and other structural analogs. Selective (S)-antibodies recognized (S)-propranolol 20 times more avidly than (R)-isomer while an antiserum against (R,S)-propranolol recognized both (S)- and (R)-isomers to about the same degree.