What is the difference in tacrolimus dosing between CYP3A5 expressers and non-expressers?

CYP3A5*1 expressers metabolize tacrolimus faster; recommended starting dose is 50-100% higher than non-expressers (*3/*3); African-Americans have higher *1 frequency (70%) vs Caucasians (20%), explaining racial dose differences.

What CPIC guideline covers tacrolimus pharmacogenomics?

CPIC guidelines for CYP3A5 and tacrolimus recommend: *1/*1 "increased metabolizer": increase dose by 1.5-2x standard; *1/*3 intermediate: increase by 1.5x; *3/*3 "poor metabolizer": standard dose.

Does CYP3A5 genotyping improve transplant outcomes?

Prospective studies show CYP3A5-guided dosing reduces time to therapeutic trough range from 50% at day 3 to 75% at day 3; fewer rejection episodes in guided vs standard dosing in some trials.

What other genes affect tacrolimus levels beyond CYP3A5?

CYP3A4*22 reduces tacrolimus metabolism; ABCB1 (P-gp) variants affect intestinal absorption; CYP3A4 and ABCB1 combined with CYP3A5 explain ~20% of inter-individual variability in tacrolimus pharmacokinetics.

Can CYP3A5 testing replace therapeutic drug monitoring?

No - CYP3A5 genotyping guides initial dosing but TDM (trough monitoring) remains essential as environment, drug interactions, food effects, and disease state also significantly impact tacrolimus levels post-transplant.

Tacrolimus CYP3A5 Pharmacogenomics Dose Predictor

Predicts initial tacrolimus dose based on CYP3A5 genotype (*1 expressers vs *3 non-expressers), kidney vs liver transplant, and race-based metabolizer status to reduce time to therapeutic range.

Use the full interactive calculator below, or

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Tacrolimus CYP3A5 Pharmacogenomics Dose Predictor

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Frequently Asked Questions

What is the difference in tacrolimus dosing between CYP3A5 expressers and non-expressers?

What CPIC guideline covers tacrolimus pharmacogenomics?

Does CYP3A5 genotyping improve transplant outcomes?

What other genes affect tacrolimus levels beyond CYP3A5?

Can CYP3A5 testing replace therapeutic drug monitoring?