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Objective To establish a sensitive method for the determination of rhodamine 123 (Rh123) in rat plasma by high performance liquid chromatography (HPLC).Methods The plasma samples were extracted by acetonitrile,and then separated on a Hypersil BDS C18 colunm (4.6 mm×100 mm,5 μm) equipped with a guard column kept at 25 ℃.The mobile phase consisted of acetonitrile and phosphate buffer (0.02 mol·L-1,pH4.0) (60:40) and was pumped at a constant rate of 1.0 mL·min-1.The peak was detected using a fluorescence detector set at FLD1A:Ex=485 nm,Em=546 nm.Results In this study,the method was validated for the Rh123 range of 0.1 to 32.0 μg·L-1,and the lower limit of quantitation (LLO Q) was 0.1 μg·L-1.The intra-and inter-day precisions for Rh123 were less than 7%,and the mean recoveries of Rh123 were 87.93%,89.03%,86.11% at low,mid,and high concentrations,respectively.Conclusion A simple,rapid and reproducible HPLC method was developed for the determination of Rh123 in rat plasma,which was an applicable method in modeling and description of the possible pharmacological interactions between the medicines and P-glycolprotein transporter.
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Objective To examine the effect of berberine hydrochloride ( BER ) on the pharmacokinetic profiles of midazolam,a substrate of CYP3A,in rats. Methods The rats were intragastrically given different doses of BER (50,100, 200 mg?kg-1) or ketoconazole (75 mg?kg-1) for 10 days.Single-pass duodenum perfusion of 20 mg?kg-1 MDZ was performed and the inguinal artery was cannulated for blood sampling.Plasma concentrations of MDZ and 1'-OH-MDZ were analyzed by high performance liquid chromatography ( HPLC) with the CYP3A inhibitor ketoconazole serving as positive control. Results BER (50,100,200 mg?kg-1) and ketoconazole (75 mg?kg-1) could significantly increase the AUC(0-t),AUMC(0-t)and Cmax of MDZ in a dose-dependent manner ( P<0.05) ,and reduce the clearance rate ( CLz ) of MDA and its apparent volume of distribution in the body ( Vz ) ( P<0. 05). But they failed to dramatically affect the half-life ( t1/2z ) and the peak time ( tmax ) of MDZ. Additionally,BER ( 100,200 mg?kg-1 ) and ketoconazole ( 75 mg?kg-1 ) could significantly dose-dependently decrease the AUC(0-t),AUMC(0-t)and Cmaxof 1'-OH-MDZ,and profoundly increase the CLz,tmax and Vz of 1'-OH-MDZ (P<0.05),but they had no remarkable influences on the t1/2z.The ratio of AUC(1'-OH-MDZ)/AUC(MDZ) was decreased with the increase of BER concentration. Conclusion BER can inhibit the in vivo metabolism of MDZ in a dose-dependant manner, which is associated with the suppression of the activity of CYP3A.
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Objective: To establish an HPLC-fluoremetry method for determination of the plasma concentration of mycophenolic acid ( MPA) in renal transplantation patients. Methods:The sample was subjected to precipitate proteins using acetonitrile, and the supernatant (20 μl) was used for the sample injection and determination on a Hypersil BDS C18 (250 mm × 4. 6 mm, 5 μm) column with temperature at 25℃. The mobile phase consisted of acetonitrile-methanol-0. 2 mol·L-1 dipotassium hydrogen phosphate buffer (pH=9. 0)( 18∶2∶80)with the flow rate of 1. 0 ml·min-1. The excitation wavelength (Ex) was 342 nm and the emission wave-length ( Em) was 425 nm. Results:The endogenous plasma impurities and drug combinations had no interference with the determina-tion. The calibration curve was linear over the range of 0. 25-50. 00 mg·L-1(r=0. 999 7), and the lower limit of quantification was 0. 25 mg·L-1 . The mean methodological recovery was 99. 12% and the mean extraction recovery was 93. 27%, the intra-day RSD was less than 2% and the inter-day RSD was less than 6%. Totally 10 cases of renal transplantation patients were with mycophenolate mofetil at the dose of 0. 5-1. 75 g·d-1 , and MPA in plasma was within the range of 0. 43-21. 58 mg·L-1 . Conclusion:The method is rapid, sensitive, accurate and convenient, which can be used in the quantitative determination of plasma concentration of MPA in re-nal transplantation patients.
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Immunosuppressive drugs used in organ transplantation are highly effective in preventing acute rejection. However,the clinical use of the drugs is complicated by the fact that they display highly variable pharmacokinetics and pharmacodynamics among in-dividual patients. The influence of genetic variation on the interindividual variability in immunosuppressive drug disposition,efficacy and toxicity has been explored in recent years. The review summarized all kinds of immunosuppressants and their relationship with ge-netic polymorphisms,including the SNPs of related enzymes about pharmacokinetics and pharmacodynamics,the SNPs of donor and tar-get site. The review focused on the current situation and progress in the related research areas.