Elective cyclosporine withdrawal 1 year after renal transplantation.

Whether the risks of acute rejection after elective cyclosporine (CsA) withdrawal in renal transplantation outweigh the potential benefits is unclear. We examined results for 236 patients who underwent transplantation between January 1986 and June 1991. Patients were treated with prophylactic CsA, prednisone, and azathioprine, and had grafts that functioned at least 1 year. We elected to withdraw CsA after 1 year in 192 patients who were rejection free for 12 months. Thirty-four patients elected to continue CsA. In 1988 a protocol that tapered CsA over 6 weeks was abandoned when eight (29.6%) of the first 27 patients developed acute rejection within 6 months. We then adopted a 12-week CsA taper preceded by 1 month of increased azathioprine (2.5 mg/d as tolerated) and followed by increased prednisone (30 mg/d for 1 week, 20 mg/d for 1 week, 15 mg/day for 6 months, then 15 mg/d on alternate days). With this protocol the incidence of postwithdrawal acute rejection within 6 months was reduced to 9.1% among 165 patients (P < 0.01 v 6-week taper). Actuarial 5-year graft survival (patients living with a functioning graft) was 81.7% for patients left on CsA, 88.9% for patients tapered over 6 weeks, and 81.5% for patients tapered over 12 weeks (P > 0.05). We also examined risk factors for acute rejection after CsA withdrawal using a Cox proportional hazards model and found that the relative risk of acute rejection within 6 months of taper was approximately two times greater for each DR mismatch (P < 0.001). We conclude that CsA withdrawal has not affected renal allograft survival at our center.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunosuppressive properties of calcium channel blockers.

Calcium channel blockers are extensively used for their beneficial effects on the cardiovascular system. Solid organ transplant recipients commonly have cardiovascular disease and are often treated with these agents. Research demonstrates that calcium antagonists may have beneficial effects in this population that are independent of their effects on the cardiovascular system. Indeed, both in vitro and in vivo studies suggested that they may possess immunosuppressive properties. Their actions at the cellular level in both the afferent and efferent arms of the immune system indicate that alone, as well as in combination with cyclosporine, these agents possess immunosuppressive properties that may potentially benefit the transplant population.

Cyclosporine-amiodarone interaction.

OBJECTIVE: To report a possible interaction between cyclosporine (CsA) and amiodarone in a kidney transplant recipient. CASE SUMMARY: A 66-year-old kidney transplant recipient with a history significant for hypertension, moderate mitral valve insufficiency, and decreased left ventricular function developed ventricular tachycardia posttransplant and was eventually treated with amiodarone. Maintenance immunosuppression included prednisone, azathioprine, and CsA. CsA concentrations before amiodarone initiation were stable (range 100-150 ng/mL). After amiodarone initiation, the CsA concentration increased more than twofold. Following CsA dosage reduction, concentrations returned to the desired range. The patient did not experience any toxicity with the increased concentration of CsA. DISCUSSION: The possible mechanisms of an interaction between CsA and amiodarone are reviewed. Reports of this interaction in heart transplant recipients are also reviewed. Changes in protein binding, changes in metabolism, or both may explain the interaction. Both CsA and amiodarone are protein bound and metabolized by the cytochrome P-450 enzyme system. CONCLUSIONS: It is likely that there is an interaction between CsA and amiodarone. The exact mechanism of this interaction has not been fully determined. When CsA is administered concurrently with amiodarone, CsA concentrations should be monitored closely and the CsA dosage should be adjusted as necessary.