Such success has only been made possible by the development and evolution of immunosuppressive drugs - drugs that dampen down the body's immune system. Although the first immonosuppressant, the corticosteroid cortisone, was introduced in 1951, it was hindered by a lack of efficacy and side effects. Consequently it was not until 1959 when azathioprine became available that transplantation really became a realistic option. Azathioprine was more effective and better tolerated, and it is still in use today.
Azathioprine works by inhibiting cell division.
However, it has relatively wide- ranging effects and this can mean that transplant patients immunosuppressed with this drug may be at risk of skin malignancies. In addition, when given at the same time as certain other drugs, including the gout treatment allopurinol, azathioprine can produce dangerous side effects, affecting the white blood cells and bone marrow. Consequently if you are taking this drug you must make sure you tell your doctor who will probably reduce the amount of azathioprine you are taking. By the time azathioprine was introduced, other corticosteroids had long been identified as immunosuppressive agents and were found to be better than cortisone. This meant that the gold standard in the evolving field of transplantation became the combination of azathioprine and prednisolone.