The association between trough blood concentration and systemic exposure of tacrolimus: Comparison between once-daily (Advagraf®) and twice-daily (Prograf®) formulation in de novo kidney transplant recipients

Available data of early conversion from twice-daily tacrolimus (TAC-BID) to once-daily tacrolimus (TAC-OD) in de novo kidney transplant (KT) recipients are limited. We conducted a prospective study of early conversion to TAC-OD in de novo KT recipients. Eligible patients were enrolled to receive TAC-BID (Prograf (R)) and then converted to TAC-OD (Advagraf (R)) by 1:1 ratio, approximately 14 days after KT (range 9-22). Blood samples were investigated for pharmacokinetic parameters before and 7-14 days after the conversion. Fifteen patients were included and provided AUC(0-24) of 202.9 +/- 44.4 ng h/mL for TAC-BID (pre-conversion) and 193.0 +/- 63.4 ng h/mL for TAC-OD (post-conversion) (p = 0.41). Mean trough blood concentration (C-min) of TAC-BID and TAC-OD was 6.4 +/- 1.4 ng/mL and 4.9 +/- 1.6 ng/mL (p = 0.01). Correlation coefficient (r) between C(mi)n and AUC(0-24) of TAC-BID and TAC-OD were 0.620 and 0.875. Additional analysis found that patients with a drop of C-min > 30% had a significant lower AUC(0-24) after conversion. Renal function remains stable. We conclude that early conversion to TAC-OD is safe and well tolerated with an indifferent systemic exposure. However, patients with a drop of C-min > 30% after conversion to TAC-OD will require additional dose adjustment. (C) 2019 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.