Background: Diltiazem and cyclosporin A (CsA) share a similar metabolism and degradation via the hepatic cytochrome p 450 subfamily 3A4. Co-administration of diltiazem with CsA may lead to CsA dosage reduction, blood pressure control and renal protection.
Objectives: To study the four year outcome of kidney transplant recipients who received diltiazem administration with CsA. This was compared to the outcomes of patients who received CsA without diltiazem and were matched for blood pressure control and other baseline characteristics.
Material and Method: Forty eight patients were included in the diltiazem group and seventy patients in the non-diltiazem group. CsA monitoring was done by using trough level (monoclonal fluorescent polarization immunoassay).
Results: The results showed that both groups has similar 4-year graft survival (92 and 95 %) with a similar mean final serum creatinine (1.3 mg/dl). Mean dose of CsA during the first month was 30 % lower in the diltiazem than non-diltiazem group. At one year, CsA dose was 11% lower in the diltiazem than non-diltiazem group. However, the diltiazem group was associated with significantly higher probability to have chronic allograft nephropathy than the non-diltiazem group (31% VS 19%) (RR 2.93; p = 0.03; Multivariate Cox regression).
Conclusion: Co administration of diltiazem with trough level adjusted CsA is associated with benefits in terms of CsA dose reduction and good graft survival and function. However, there appeared to be no protective effect of diltiazem on the progression to chronic allograft nephropathy.

Keywords: Cyclosporine, Diltiazem, Kidney transplantation, Chronic allograft nephropathy