Synthesis of isotopically labelled compounds at Schering‐Plough, an historical perspective

The use of isotopically labelled compounds at Schering‐Plough (S‐P) has substantially increased over the past 30 years. Since the formation of the S‐P Radiochemistry section in the early 1970s, the group has expanded its role from supplying 14C‐ and 3H‐labelled compounds for ADME studies for compounds in development, to providing 3H‐labelled compounds for drug discovery and also to provide stable isotope‐labelled compounds that are used as LC/MS internal standards. Other isotopes used by the group have included 125I and 35S, which have been used to label both small molecules and proteins.