Correlação dos níveis de tacrolimus com a formulação da dose: implicações para a toxicidade e rejeição do enxerto renal em uma coorte de receptores de transplante renal com imunossupressão de manutenção sem esteroides

Introduction: Chronic kidney disease (CKD) affects 10% of the worldwide population, being renal transplantation the optimal treatment for advanced stages. Post-transplant care involves immunosuppressive therapy, primarily utilizing tacrolimus, to prevent graft-rejection and failure. This study analyzes the correlation between tacrolimus blood levels, dosing, toxicity, and graft-rejection among renal transplant recipients with steroid-free maintenance immunosuppression in Colombia. Methodology: We conducted a retrospective cohort on kidney transplant patients followed at Colombiana de Trasplantes from 07-2019 to 06-2022, including patients with tacrolimus as immunosuppressive therapy that completed at least one year of post-transplant follow-up. Data on tacrolimus levels and transplant outcomes were collected at four intervals post-transplant. Bivariate analysis and unadjusted logistic regression were used to analyze the correlation and association between tacrolimus blood levels and tacrolimus doses, rejection, and toxicity. Results: The study included 368 patients. A weak correlation was found between variability of levels and dose (rho=0.31, p <0.001) but was not significant between tacrolimus doses and categorized blood levels. Acute graft-rejection occurred in 15.5% of patients, while only 3.8% experienced toxicity. No significant differences in rejection rates were observed with tacrolimus blood levels. Conclusions: This study found no significant association between tacrolimus levels and graft-rejection, toxicity or categorized tacrolimus blood levels within the first-year post-transplant. However, the importance of tacrolimus level monitoring is underscored by its variability, influenced by dosing, adherence, and pharmacogenetics. Further research with a larger sample size is needed to improve our understanding of tacrolimus pharmacokinetics and encourage accurate reporting of toxicity in the Colombian population.