First Tacrolimus Dose Trough Level is Better Than CYP3A5 Genotyping in Tacrolimus Dose Prediction

Tacrolimus dose highly varies among Asian kidney transplant recipients. This can be explained by variety of CYP3A5 expression. CYP3A5 genotyping is highly recommended for patients receiving tacrolimus. Here, we assessed the tacrolimus dose prediction by comparing CYP3A5 expression and tacrolimus dosage using tacrolimus concentration after single dose administration prior to kidney transplantation. Plasma tacrolimus trough level was measured at 12 hours after first dose of 0.1 mg/kg of tacrolimus (TacC12), orally administered in 51 new kidney transplant recipients. Patients with CYP3A5 inhibitor/inducer co-medications were excluded. Genotyping for CYP3A5 expression were carried out by RT-PCR. The dosages of tacrolimus at post-operative day 7 and dosage which provided stable therapeutic levels in post-operative month 1 to 3 (C0 5-8 ng/mL) were recorded. The genotyping, TacC12, and target tacrolimus dosage have good correlations.