Impact of cytochrome p450 3A5 genetic polymorphism on tacrolimus doses and concentration-to-dose ratio in renal transplant recipients.
BACKGROUND
Tacrolimus pharmacokinetic characteristics vary greatly among individuals. Tacrolimus is a substrate of cytochrome p450 (CYP), of subfamily CYP3A. CYP3A activity is the sum of the activities of the family of CYP3A genes, including CYP3A5. Subjects with the CYP3A5*1/*1 genotype express large amounts of CYP3A5. Heterozygotes (genotype CYP3A5*1/*3) also express the enzyme. We postulated that CYP3A5 polymorphism is associated with tacrolimus pharmacokinetic variations.


METHODS
CYP3A5 genotype was evaluated in 80 renal transplant recipients and correlated with the daily tacrolimus dose and concentration-to-dose ratio.


RESULTS
The frequency of the homozygous CYP3A5*1 genotype (CYP3A5*1/*1) was 5%, and 11% of subjects were heterozygous (CYP3A5*1/*3). The mean doses required to obtain the targeted concentration-to-dose ratio were significantly lower in patients with the CYP3A5*1/*1 genotype.


CONCLUSIONS
Determination of CYP3A5 genotype is predictive of the dose of tacrolimus in renal transplant recipients and may help to determine the initial daily dose needed by individual patients for adequate immunosuppression without excess nephrotoxicity.
INSERM UMR S490, Centre Universitaire des Saints-Pères, Paris, France. eric.thervet@sls.ap-hop-paris.fr.
Eric
E
Thervet
Dany
D
Anglicheau
Barry
B
King
Marie-Hélène
MH
Schlageter
Bruno
B
Cassinat
Philippe
P
Beaune
Christophe
C
Legendre
Ann K
AK
Daly
D000328:Adult; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D011110:Polymorphism, Genetic; D011237:Predictive Value of Tests; D016559:Tacrolimus / Q000008:administration & dosage*
D007166:Immunosuppressive Agents; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; C510164:CYP3A5 protein, human; D051544:Cytochrome P-450 CYP3A; D016559:Tacrolimus