Niridazole as an immunosuppressive agent.

The immunosuppressive properties of niridazole, an antihelminthic drug, have been investigated in rats. When given orally at a dosage of 50 mg/kg it extended the median survival of cardiac allografts from 7 to 20 days. The immunosuppressive effect was not increased by giving either azathioprine or prednisolone concurrently, but when all three drugs were combined the immunosuppression was profound, and only 2 of 8 grafts were rejected. Drug combinations incorporating niridazole at a lower dosage or for a shorter period were less effective, and azathioprine and prednisolone on their own or together prolonged graft survival only marginally in this model.