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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.
CYP3A5 genetic variations impact tacrolimus (immunosuppressant) levels after switching formulations. Tacrolimus dose adjustments for kidney transplant patients should consider CYP3A5 genotype for optimal exposure control.
Area of Science:
- Pharmacogenomics
- Transplant medicine
- Drug metabolism
Background:
- Tacrolimus is a vital immunosuppressant for organ transplant recipients.
- Different tacrolimus formulations exhibit varied pharmacokinetic profiles.
- CYP3A5 genetic polymorphisms influence drug absorption and elimination.
Purpose of the Study:
- To assess the impact of CYP3A5 polymorphisms on tacrolimus exposure.
- To evaluate tacrolimus pharmacokinetics after switching from immediate-release (Tac-IR) to prolonged-release (Tac-LCP) formulations.
- To determine if CYP3A5 genotype influences dose requirements and exposure variability during formulation conversion in kidney transplant recipients.
Main Methods:
- Intensive pharmacokinetic sampling in 19 kidney transplant recipients before and after switching tacrolimus formulations.
- Genotyping for CYP3A5 polymorphisms.
- Comparison of tacrolimus exposure parameters (C0, Cmax, AUC0-24h) between CYP3A5 expressers and non-expressers.
Main Results:
- CYP3A5*1 expressers required higher Tac-IR doses for comparable exposure.
- Post-conversion to Tac-LCP, CYP3A5*1 expressers showed similar C0 but higher Cmax and AUC0-24h compared to non-expressers.
- Dose-normalized exposure revealed a lower conversion rate in CYP3A5*1 expressers.
Conclusions:
- CYP3A5 genotype is crucial for guiding tacrolimus dose adjustments during Tac-IR to Tac-LCP conversion.
- Predose concentration (C0) may underestimate exposure in CYP3A5*1 expressers.
- Area-under-the-curve (AUC0-24h) is a more reliable indicator for dose adjustments in these patients.
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