Tacrolimus population pharmacokinetic models according to CYP3A5/CYP3A4/POR genotypes in Chinese Han renal transplant patients.

AIM: To develop a population pharmacokinetic (PK) model of tacrolimus in Chinese Han renal transplant population and establish the influence of different covariates (especially different CYP3A5/3A4/POR genotype) on PK properties. MATERIALS & METHODS: Trough tacrolimus concentrations, clinical characteristics and CYP3A5/CYP3A4/POR genotypes were collected from 141 adult renal transplant recipients after transplantation. The population PK analysis was carried out using the nonlinear mixed-effect modeling software NONMEM version 3.4.2. RESULTS: Tacrolimus PK profiles exhibited high interpatient variability. A two compartment model with first-order input and elimination described the tacrolimus PK profiles in the studied population. Among the genotypes, only CYP3A5 genotype was confirmed to have clinical significance. CONCLUSION: Our final model confirmed that CYP3A5*3 plays a more significant role in tacrolimus PK and could affect the blood concentrations and CL/F (clearance rate/bioavailbility). This model is expected to help to improve individualized tacrolimus dosing.

UGT1A1 Gene Polymorphism Predicts Irinotecan-Induced Severe Neutropenia and Diarrhea in Chinese Cancer Patients.

BACKGROUND: Irinotecan was widely used in colon cancer and lung cancer, etc., and adverse reactions occur some times. The primary aim of this research is to investigate the association between UGT1A1 gene polymorphisms and irinotecan-related adverse effect in Chinese Han population with a novel kind of gene chip technology. METHODS: UGT1A1*6/*28 gene polymorphisms were detected by PCR and gene chip as well as sequencing. The correlation between UGT1A1 gene polymorphisms and severe delayed diarrhea or neutropenia and effect on response rate and progression-free survival were analyzed. RESULTS: A total of 106 patients receiving irinotecan-based regimens and with detected UGT1A1 gene polymorphisms were enrolled in this research. According to our results, no significant differences of severe diarrhea were found in patients with UGT1A1*6 genotypes (p = 0.608). However, the incidence of severe diarrhea in patients with TA7/7 genotype (66.7%, 4/6) was significantly higher than that in patients with TA6/7 (31.5%, 6/19) or TA6/6 (1.28%, 1/78) genotypes (p < 0.001). The incidence of severe hematologic toxicity in patients with AA (100%, 2/2) was significantly higher than that in patients with GA (33.3%, 7/21) or GG genotype (7.23%, 6/83) (p = 0.011). CONCLUSIONS: In terms of irinotecan-based regimens in cancers, UGT1A1*6 plays a more vital role in hematologic toxicity (p = 0.011) whereas UGT1A1*28 get more involved in diarrhea (p < 0.001).