EFFICACY AND TOLERABILITY OF CONVERSION FROM CYCLOSPORINE TO AZATHIOPRINE AFTER KIDNEY-TRANSPLANTATION - A REVIEW OF THE EVIDENCE

After the introduction of cyclosporin as an immunosuppressive drug for organ transplantation at the beginning of the 1980s, concern arose ab out adverse effects of this new drug. Nephrotoxicity, fear of progress ive loss of renal function with long term use of cyclosporin, a higher incidence of lymphomas in the first studies with cyclosporin and the high costs of the new drug led to the modification of immunosuppressiv e regimens so that cyclosporin was replaced by azathioprine several mo nths after renal transplantation. Short and long term follow-up of ele ctive conversion studies demonstrated equal patient and graft survival in the azathioprine (conversion) and cyclosporin (control) groups. Sh ortly after conversion. renal function improved considerably and a dec rease was found in the number of patients with hypertension and gout. Conversion also resulted in a substantial reduction in the costs of im munosuppressive drugs. In most studies a higher incidence of acute rej ection was found after conversion. These rejection episodes were gener ally reversible and at long term followup did not result in a higher i ncidence of chronic rejection or graft loss. Elective conversion from cyclosporin to azathioprine after kidney transplantation can be done s afely and has beneficial effects on renal function and cardiovascular risk factors. Conversion should also be considered fur patients with p rolonged non-function of the graft, in cyclosporin-treated patients wi th substantial renal or neurological toxicity persisting after cyclosp orin dosage reduction, and in patients who cannot afford the high cost s of cyclosporin therapy.