Low-dose tacrolimus (FK506)-based immunosuppressive protocol in living donor renal transplantation.

In order to avoid the side effects of tacrolimus (FK506), a lowdose FK506-based regimen was started from 1 June 1991. The dose was adjusted to maintain the FK506 whole blood trough level at 15-20 ng/ml for 7 days postoperatively, at 10-15 ng/ml for 2 months, and under 10 ng/ml thereafter. The graft survival rates at 3 years and 5 years were 87.8 and 82.3% (FK506) vs 86.8 and 86.8% [cyclosporine (CyA)]. The incidence of acute rejection within the first 90 days was 31.6% in the FK506 group which was lower than the 57.1% of the CyA group (P = 0.0585). Grades of acute rejection episodes over IIA in the FK506 group were 20%, which was lower than the 37% in the CyA group. The mean oral dosages of FK506 were 0.061 and 0.04 mg/kg per day at 3 and 5 years, respectively. The incidence of new onset diabetes was 27.8% in the FK506 group and 17.1% in the CyA group. However, insulin therapy was withdrawn in all patients of the FK506 group within 5 months. The percentage of patients who required an antihypertensive agent was 28.6% and 40% in the FK506 group and 73.2% and 88% in the CyA group at 1 and 3 years, respectively (P < 0.05). Nephrotoxicity was seen in 20% of the FK506 group and 14.3% of the CyA group. Hypercholesterolemia was less frequent in the FK506 group than the CyA group. The FK506-based regimen described here is a protocol with the potential to reduce its adverse effects. The Whole blood concentration of FK506 should be monitored and blood levels maintained in the range of 5-10 ng/ml after 90 postoperative days for optimal efficacy and minimal toxicity.