Azathioprine
was first introduced into clinical practice by Sir Roy Calne, the British
pioneer in transplantation. Following the work done by Sir Peter Medawar in
discovering the immunological basis of rejection of transplanted tissues and
organs, a great deal of research was carried out to discover drugs to suppress this immune reaction. Sir Roy Calne, working as a researcher in the pioneering kidney transplant unit at the Brigham Hospital in Boston (USA), conducted experiments into the use of the drug 6-mercaptopurine as an immunosuppressant for kidney transplants. When azathioprine was
discovered, he then introduced it as a less toxic replacement for
6-mercaptopurine. For many years, dual therapy with azathioprine and steroids
was the standard anti-rejection regime, until ciclosporin was gradually introduced into
clinical practice (also by Sir Roy Calne) from 1978.
Azathioprine
is also used for some conditions caused by an over-active immune system, such
as rheumatoid arthritis and Crohn’s disease.