Influence of posttransplant time on dose and concentration of tacrolimus in liver transplant patients.

The dosage of tacrolimus (D), the trough blood concentrations (C) and the evolution of the D/C ratio were followed for 1 year after transplantation in so adult patients (38 males and 12 females) undergoing liver allograft. A total of 1489 samples were analysed by the IMx tacrolimus method. The overall median concentration was 11.27 ng/ml. During the 1st month the median of the tacrolimus levels was 8.4 ng/ml, and 73.1% of the analysed samples were within the established therapeutic range. The median oral tacrolimus dose was progressively reduced from 0.12 mg/kg per day during the 1st month to 0.06 mg/kg per day at the end of studied period. A significant negative association was observed between the D/C ratio and the post-transplantation period (r = -0.3892; P < 0.0001). The median D/C ratio ranged from 0.0144 at 1st month to 0.0053 at 1 year. Significant D/C declines were observed after the 1st and 3rd months posttransplant. The decrease in corticosteroid doses and the increase in serum albumin may explain the reduction in clearance with time.