Population Pharmacokinetics Of Acyclovir In Patients With Viral Encephalitis

Objectives 1 To establish determination method of Acyclovir concentration in plasma by ultra performance liquid chromatography and mass spectrometry(UPLC-MS) for its pharmacokinetic research. 2 By analyzing the influencing factors of interindividual variability of serum concentration, to construct the Acyclovir population pharmacokinetic model of viral encephalitis patients, which will provide the basis for Acyclovir individualization.Methods 1 Chromatographic conditions: Column [Acquity UPLC BEHC18(2.1mm * 50 mm, 1.7um)], mobile phase was methanol – 0.01%formic acid(60: 40, V / V), flow rate 0.20 ml ? min-1. MS conditions: ion source electrospray ionization(ESI-), multiple reaction monitoring(MRM),detected ion pairs(m / z) 255.0 ? 152.0, capillary voltage 3.7KV, cone voltage 30 V, the collision energy of 20 V. Plasma samples were pre-processed by liquid-solid extraction before sample injection. 2 The MDR1C3435 T gene was determined by PCR-RFLP. 3 The study involved the cases of viral encephalitis patients receiving acyclovir therapy. Gender, age, height, weight, liver and kidney function, MDR1 gene type and comedication information were recorded. Population pharmacokinetics model of acyclovir was established by NONMEM. The graphic method was used to investigate the pros and cons of the fitting model, non parametric bootstrap method(bootstrap) evaluates stability and validity of the model, normal prediction distribution error(NPDE) validation were used to investigate the predictive ability of the model.Results 1 Acyclovir serum concentrations were determined by UPLC-MS/MS. Its standard curve regression equation was ?=1.4873x-5.7439(r=0.9996,n=6),and concentration(C) linear relationship was in 50~1600ng·m L-1. Its extraction recovery was 83.5%±3.1, while method recoveries was 99.6% ± 6.4. The limit of detection was 1ng·m L-1(S/N?3). 2 The MDR1 C3435 T genotype CC, CT and TT of 56 virus encephalitis patients were 22 cases(39.2%), 29 patients(51.8%) and 5 cases(9.0%) respectively, Its distribution frequency is in accordance with the law of equilibrium of Hardy-weinberg.(P > 0.05). 3 The final PPK model is as follow:V =72.5(L) Creatinine clearance(CLcr) is the main factor affecting acyclovir pharmacokinetic parameters.Conclusions 1 The established UPLC-MS/MS method for determination of human plasma acyclovir concentration is sensitive, reproducibility, simple, inexpensive and low toxicity, which can be used for drug monitoring and pharmacokinetics study in clinical routine treatment? 2 The method of MDR1C3435 T genotyping with PCR-RFLP is simple and accurate,which was in accordance with the requirements of clinical research. 3 The population pharmacokinetics model of acyclovir in patients with viral encephalitis is stable, and has a good predictive ability, which can provide the basis for its individualization drug.