ABSTRACT
Objective To study the effect of cefetamet hydrochloride injection on the activity of 3 kinds of cytochrome P450 (CYP450) isoforms (CYP1A2, CYP3A4 and CYP2E1) in rat liver microsomes. Methods The SD rats were randomly divided into two groups: control group and cefetamet hydrochloride (CH) group, with each group containing 3 male rats and 3 female rats. The CH group was injected with cefetamet hydrochloride into the tail vein at 50 mg/(kg • d), twice a day for 7 days. A HPLC method was used for simultaneous determination of the production of metabolites and the degradation of the prototype probe substrates of 3 kinds of CYP450 isoforms, so as to evaluate the activity of hepatic CYP450. The analytical column was Diamonsil C18 column (150 mm X 4. 6 mm, 5 Fm), with the flow rate being 1. 0 mL/min. The mobile phase consisted of methanol (0. 1% formic acid) (A)-water (0. 1% formic acid)(B), 0-5 min; 18%A, 5-10 min; 18%-60%A, 10-15 min: 60%A and detected at 247 nm for determination of CYP1A2 activities; methanol (A)-water (0. 02% formic acid)(B), 0-11 min: 40%-60%A and detected at 223 nm for determination of CYP3A4 activities; and methanol (A)-water, 0-10 min: 37%-75%A and detected at 287 nm for determination of CYP2E1 activities. Results Probe substrates and their metabolites showed good linearity within the determining range (r≥0. 999 7). The precision of the method was 0. 05). Conclusion CH injection can significantly induce hepatic microsome CYP3A4 expression in SD rats, but has no induction or inhibition effect on CYP1A2 and CYP2E1, indicating that potential drug-drug interaction might occur when CH injection is coadministered with drugs metabolized by CYP3A4.
ABSTRACT
Objective To retrospectively investigate the effects of CYP3A5 * 3,CYP3A4 * 18B and CYP3A5-CYP3A4 phenotype on the C0,D and C0/D of tacrolimus (Tac) in renal transplantation recipients.Methods The CYP3A5 * 3 and CYP3A4 * 18B genotypes of the 61 patients were detected by DNA direct sequencing,and the C0 was detected by ELISA.The differences of C0,D and C0/D on the day 14,and month 1,2 and 3 after transplantation were compared among different genotypes of recipients treated with Tac.Results The frequency of the CYP3A5 * 3 and CYP3A4 * 18B was 74.6％ and 26.2％ respectively.When the D of the recipients with CYP3A5 * 1 ( * 1/* 1 + * 1/* 3)was 1.3-1.6 times to theCYP3A5*3/*3,theC0 of *3/*3 group was 1.1-1.5 times to the * 1group,and the C0/D was 1.8 2.4 times to the CYP3A5 * 1.For CYP3A4,the D of CYP3A4 * 18B group ( * 1/* 18B+ * 18B/* 18B) was 1.2-1.5 times to the CYP3A5 * 1/* 1,but the C0 of 1/* 1was 1.2-1.4 times to the * 18B,the C0/D was 1.5-1.8 times to the * 18B.For the CYP3A5 CYP3A4 phenotype,the D of the recipients with AAAA was 1.3-1.7 times to the GG-GG,the C0 of GG-GG was 1.5-2 times to the AA-AA,the C0/D of the recipients with G@GG was 2.5-3 times to the AA-AA.In the recipients with C0/D above or below the median of C0/D,the distribution of CYP3A5,CYP3A4 and CYP3A5-CYP3A4 phenotypes was different significantly.Conclusion There is a significant correlation between the CYP3A5,CYP3A4 and pharmacokinetics of Tac.It's more powerful evaluating the CYP3A5-CYP3A4 phenotype rather than just one genotype of the recipients.So detecting the CYP3A5 * 3 and CYP3A4 * 18B genotypes prior to transplantation is meaningful for us to determine an appropriate initial and long-time dosage of Tac.
ABSTRACT
AIM To express recombinant human cytochrome P450 3A4 mutants CYP3A4.3, CYP3A4.4, CYP3A4.5 and CYP3A4.18, and to employ them for in vitro metabolism studies of CYP3A4. METHODS Use Bac-to-Bac baculovirus expression system to recombinant baculovirus carrying cDNA of CYP3A4 mutants CYP3A4.3, CYP3A4.4, CYP3A4.5 and CYP3A4.18. Spodoptera frugiperda 9 (Sf9), cells were co-infected by recombinant viruses of CYP3A4 mutants, human NADPH-P450 oxidoreductase and cytochrome b5 to obtain recombinant proteins CYP3A4.3, CYP3A4.4, CYP3A4.5 and CYP3A4.18 with metabolic activity. RESULTS The mRNA transcription of CYP3A4 mutants in Sf9 cells were validated by RT-PCR. Testosterone and 7-benzyloxy-4-(trifluoromethyl) coumarin were metabolized by the lysates of Sf9 cells infected by the recombinant viruses. CONCLUSION CYP3A4 mutants CYP3A4.3, CYP3A4.4, CYP3A4.5 and CYP3A4.18 with metabolic activity were successfully expressed by baculovirus-insect cell expression system. The results indicated that recombinant CYP3A4. 5 showed lower activity comparing to the wild type protein towards testosterone, while CYP3A4. 18 with higher activity, and for CYP3A4.3 and CYP3A4.4 showing similar activity to the wild type protein.