Design of a New Predictive Equation for the Induction Dose of Tacrolimus in Immediate Renal Transplantation.

INTRODUCTION: Kidney transplantation is the treatment of choice for end-stage chronic kidney failure. It requires pharmacological immunosuppressive therapy to prevent graft rejection while minimizing adverse effects. Tacrolimus (TAC) is one of the most widely used agents in this setting. The aim of this study was to determine the proportion of patients achieving optimal TAC concentrations with a 0.10 mg/kg/12 h regimen, identify factors influencing this outcome, and develop a predictive model to optimize dosing. METHODS: This retrospective observational study included kidney transplant recipients treated at Hospital General Universitario de Elche between January 2019 and January 2024. RESULTS: Ninety-three patients were analyzed, including 56 men and 37 women. Demographic, clinical, and pharmacotherapeutic data were collected. Regression analysis showed TAC levels were associated with weight, body mass index, hematocrit, total proteins, and glutamate-pyruvate transaminase (GPT). Only 30% (26 patients) achieved optimal TAC concentrations with the current dosing formula during the initial pharmacokinetic monitoring. However, this study developed a new predictive formula that could theoretically enable better initial dosing adjustments in up to 76% (71) patients. CONCLUSION: The current TAC dosing framework can be improved and adapted to the specific patient population being treated. In this regard, although the number of patients is low and additional internal and external validations are needed, the new formula developed in this study not only improves the accuracy of prediction results but is also flexible and adaptable enough for use in other clinical settings. Graphical Abstract available for this article.