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Updated: Jan 9, 2026

Quantification of the Immunosuppressant Tacrolimus on Dried Blood Spots Using LC-MS/MS
Published on: November 8, 2015
Tacrolimus Conversion in CYP3A5*1 Expressers: From Immediate-Release to LCP Formulation
Anna Vidal-Alabró1, Pere Fontova1,2, Zeyar Mohammed Ali1,3
1Nephrology Department, Hospital Universitari de Bellvitge-IDIBELL, Barcelona, Spain.
Background:
Tacrolimus is the most commonly used immunosuppressant drug in solid organ transplant recipients. Different formulations of tacrolimus have distinct pharmacokinetic profiles due to differences in absorption and elimination. This study aimed to investigate the influence of CYP3A5 polymorphisms on tacrolimus exposure after conversion from immediate-release tacrolimus (Tac-IR) to prolonged-release tacrolimus (Tac-LCP) in stable kidney transplant recipients.
Methods:
Intensive pharmacokinetic sampling was performed in 19 kidney transplant recipients before and 1 month after switching from Tac-IR to Tac-LCP. Patients were genotyped for CYP3A5 polymorphisms.
Results:
Patients expressing CYP3A5*1 required a significantly higher dose of Tac-IR than nonexpressers to achieve similar predose concentrations (C 0 ), maximum concentrations (C max ), and area-under-the-curve values (AUC 0-24h ). After switching to Tac-LCP, CYP3A5*1 expressers had similar C 0 values but significantly higher C max and AUC 0-24h values compared with nonexpressers . Dose-normalized exposure showed that CYP3A5*1 expressers had a lower conversion rate than nonexpressers (0.58 versus 0.807).
Conclusions:
These results suggest that CYP3A5 genotype should be considered when adjusting the tacrolimus dose during conversion from Tac-IR to Tac-LCP. C 0 values may not adequately reflect the higher exposure observed in CYP3A5*1 expressers , highlighting the importance of AUC 0-24 h in guiding dose adjustment.
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