Variation in Tacrolimus Trough Concentrations in Liver Transplant Patients Undergoing Endoscopic Retrograde...

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.

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.

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.

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.