George Hitchings

Hitchings' rational drug design approach at Burroughs Wellcome produced several landmark medications, including 6-mercaptopurine for leukemia, azathioprine for organ transplant rejection, allopurinol for gout, and trimethoprim for bacterial infections. These drugs were designed by targeting specific enzymes involved in nucleic acid synthesis rather than being discovered by trial and error. Azathioprine made kidney transplantation viable in the 1960s.

Hitchings shared the 1988 Nobel Prize in Physiology or Medicine with his longtime collaborator Gertrude Elion and the Scottish pharmacologist Sir James Black. Elion and Hitchings worked together at Burroughs Wellcome for decades, while Black was honored separately for developing beta-blockers like propranolol and the histamine H2 receptor antagonist cimetidine.

Rational drug design involves designing molecules to specifically target known biochemical differences between pathogenic cells (like cancer cells or bacteria) and healthy cells, rather than screening thousands of random compounds. Hitchings and Elion focused on purine and pyrimidine metabolism, designing analogs that selectively blocked DNA synthesis in rapidly dividing cells while sparing normal tissue.

Azathioprine, developed by Hitchings and Elion, suppresses the immune system by inhibiting purine synthesis in proliferating T and B lymphocytes. When combined with corticosteroids in the 1960s, it became the standard immunosuppressive regimen that made kidney transplantation widely survivable. It remained a cornerstone of transplant therapy until cyclosporine was introduced in the early 1980s.