Clinical experience of conversion from twice-daily standard-release tacrolimus to once-daily prolonged-release tacrolimus in stable renal transplant recipients

SummaryBackgroundConversion of standard-release tacrolimus to prolonged-release once-daily tacrolimus is often performed in a 1:1 (mg:mg) manner. We sought to determine the safety and efficacy of this conversion strategy in Chinese renal transplant recipients.MethodsIn this single-center study, 16 stable renal transplant recipients were observed for 1 year after a milligram to milligram switch from standard-release to prolonged-release tacrolimus formulation. Trough blood tacrolimus level and graft function were serially monitored.ResultsMean daily dose of tacrolimus was 0.040 ± 0.018 mg/kg before conversion. After conversion, we observed a significant decrease in trough tacrolimus levels, from 4.5 ± 2.2 ng/mL to 3.4 ± 1.1 ng/mL (p = 0.046) at 1 month, and from 4.5 ± 2.2 ng/mL to 3.3 ± 1.1 ng/mL (p = 0.01) at 12 months. After 12 months, 44% of patients (n = 7) experienced a decrease in tacrolimus blood levels of more than 20%. All patients maintained stable graft function otherwise, without acute rejection.ConclusionOur findings confirm that trough tacrolimus blood level can decrease following a 1:1 (mg:mg) conversion from standard-release to prolonged-release tacrolimus formulation in Chinese patients. Close monitoring of the drug levels and clinical condition seems to be warranted after medication switch.背景從標準釋放型 tacrolimus 轉換至一天一次延長釋放型 tacrolimus 通常是按 1:1 (mg:mg) 的比例進行；以下研究以華裔腎臟移植接受者為對象，對此轉換法的功效及安全性作出調查。方法本研究於單一院所進行，參與者為 16 位穩定的腎臟移植接受者，從標準釋放型轉換至延長釋放型 tacrolimus (按 1:1 之 mg:mg 比例) 後接受 1 年的持續追蹤，內容包括 tacrolimus 谷底血液濃度及植入腎臟功能。結果轉換前，tacrolimus 之平均劑量為 0.040 ± 0.018 mg/kg；轉換後，tacrolimus 谷底濃度呈現明顯下降：1 個月時從 4.5 ± 2.2 ng/mL 至 3.4 ± 1.1 ng/mL (p = 0.046)，12 個月時從 4.5 ± 2.2 ng/mL 至 3.3 ± 1.1 ng/mL (p = 0.01)。在經過 12 個月後，44% 的病人 (n = 7) 呈現 >20% 的 tacrolimus 血液濃度降幅。然而，所有病人的植入腎臟均維持穩定的功能，未出現急性排斥現象。結論本研究證實在華裔病人間，從標準釋放型 tacrolimus 按 1:1 (mg:mg) 比例轉換至延長釋放型 tacrolimus 後，tacrolimus 谷底濃度會有所下降，因此理應有需要在轉換後密切監察病人的藥物濃度及臨床狀況。