Genotype-based tacrolimus dosing guidelines: with or without CYP3A4*22?
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Updated: Feb 19, 2026

Quantification of the Immunosuppressant Tacrolimus on Dried Blood Spots Using LC-MS/MS
Published on: November 8, 2015
Laure Elens1,2, Vincent Haufroid2,3
1Department of Integrated PharmacoMetrics, PharmacoGenomics & PharmacoKinetics, Louvain Drug Research Institute, Université Catholique de Louvain, 1200 Brussels, Belgium.
Aim:
To test the relevance of revisiting the genotype classification based on CYP3A5*3 solely by incorporating CYP3A4*22 information.
Methods:
Discriminant analysis of principal component was performed to evaluate the relevance of either the CYP3A (CYP3A5 + CYP3A4 genotypes) or CYP3A5*3 classification variables. This analysis was based on a linear combination of noncompartmental pharmacokinetics parameters.
Results:
Discriminant analysis of principal component gave better results with CYP3A compared with CYP3A5*3 clustering. The centroid means of the pharmacokinetics variables were significantly different with CYP3A genotype clustering (p = 0.04) but not with CYP3A5*3 solely (p = 0.06). Canonical plots reveal a better delimitation of clusters with CYP3A genotype compared with CYP3A5*3 and the reciever operating characteristic curves confirm this better discriminative power.
Conclusion:
We provide strong arguments of incorporating CYP3A4*22 genotype in practice to fine-tune the existing Clinical Phamacogenetics Implementation Consortium guidelines in the Caucasian population.
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