Variation in Tacrolimus Trough Concentrations in Liver Transplant Patients Undergoing Endoscopic Retrograde Cholangiopancreatography: A Retrospective, Observational Study.

Objective: High variabilities in tacrolimus (TAC) exposure are still problems that confuse physicians. TAC trough levels (TAC C _min ) fluctuated considerably after endoscopic retrograde cholangiopancreatography (ERCP) treatment in several liver transplant (LT) patients. We aimed to investigate the variation regularity of TAC C _min post-ERCP and related factors.
Methods: This study was a retrospective, observational study conducted at the First Affiliated Hospital of Zhejiang University in China. From October 2017 to January 2019, 26 LT patients that received ERCP were included (73 TAC C _min measures). The absolute difference and the variation extent in TAC C _min pre- and post-ERCP were analyzed. Patients were divided into mild and obvious variation groups, and the differences were compared.
Results: The TAC C _min in LT patients significantly increased in the first three days post-ERCP ( p <0.05) and increased by more than 20% in 18 out of 26 (69.2%) patients. The mean extent of variation in TAC C _min was 45.1% (95% confidence interval [CI]: 28.3-81.3%) and 31.4% (95% CI: 9.7-53.1%) on days 1 and 3 post-ERCP, respectively. The increasing TAC C _min gradually returned to baseline within a week ( p >0.05). The daily TAC dose and total bile acid (TBA) level were significantly higher ( p <0.05) in patients with obvious variation in TAC C _min . The differences in other demographics, clinical characteristics, variation in laboratory data, and serum amylase levels between the two groups were not significant.
Conclusion: The TAC C _min significantly increased in LT patients during the first three days after ERCP, and the level returned to baseline within a week. The daily TAC dose and TBA levels may be related to this increase. Frequent drug concentration monitoring should be executed in the early phase post-ERCP, especially in patients with related factors.
(Copyright © 2020 Wang, Wang, Ma, Duan, Wang, Huang, Zhang and Liang.)