Oral Tacrolimus Bioavailability Is Increased After Right Split Liver Transplantation

Abstract Objective Tacrolimus (Tac) is mainly metabolized in the liver. The aim of this trial was to analyze Tac bioavailability after partial liver transplantation. Patients and Methods A total of 33 patients after right split liver grafting (n = 8 living related, LRLT; n = 8 cadaver split, CS) or full-size liver transplantation (n = 17, FS) were included in this trial. All of them received Tac perorally with an initial dose of 2 × 5 mg/d. Dose adjustment was performed according to the Tac trough level (T0) with an initial target T0 levels of 12 to 15 ng/mL. Results The time to reach target T0 levels tended to be lower ( P = .05) in the split liver groups (LRLT: 2.8 ± 1.6 days; CS: 2.1 ± 0.9 days; FS: 4.5 ± 3.2 days). In addition, mean Tac dose to maintain the target T0 level was significantly decreased ( P = .01) in the split liver cohorts (LRLT: 5.8 ± 1.1 mg/d; CS: 5.5 ± 2.5 mg/d; FS: 9.8 ± 3.9 mg/d). Only graft weight/standard liver volume ratio ( r = .566, P = .02) and graft weight/body weight ratio ( r = .709, P = .002) showed significant correlations with Tac maintenance doses in the split liver group. Conclusions Peroral Tac bioavailability was significantly higher after partial liver transplantation using the right hepatic lobe compared with full-size transplants. The volume of the split liver graft highly correlated with Tac maintenance therapy and should be used to calculate the most appropriate initial posttransplantation Tac dose.