Population pharmacokinetic modeling and evaluation of propofol from multiple centers / 药学学报

In order to successfully develop the effective population pharmacokinetic model to predict the concentration of propofol administrated intravenously, the data including the concentrations across both distribution and elimination phases from five hospitals were analyzed using nonlinear mixed effect model (NONMEM). Three-compartment pharmacokinetic model was applied while the exponential model was used to describe the inter-individual variability and constant coefficient model to the intra-individual variability, accordingly. Covariate effect including the body weight on the parameter CL, V1, Q2, V2, Q3 and V3 were investigated. The performance of final model was assessed by Bootstrapping, goodness-of-fit and visual predictive checking (VPC). The context-sensitive half-times and the infusion rates necessary to maintain the concentration of 1 microg x mL(-1) were simulated to six subpopulations. The results were as follows: the typical value of CL, V1, Q2, V2, Q3 and V3 were 0.965 x (1 + 0.401 x VESS) x (BW/59)(0.578) L x min(-1), 13.4 x (AGE/45)(-0.317) L, 0.659 x (1 + GENDER x 0.385) L x min(-1), 28.8 L, 0.575 x (1 + GENDER x 0.367) x (1 - 0.369 x VESS) L x min(-1) and 196 L respectively. Coefficients of the inter-individual variability of CL, V1, Q2, V2, Q3 and V3 were 29.2%, 46.9%, 35.2%, 40.4%, 67.0% and 49.9% respectively, and the coefficients of residual variability were 24.7%, 16.1% and 22.5%, the final model indicated a positive influence of a body weight on CL, and also that a negative correlation of age with V1. Q2 and Q3 in males were higher than those in females at 38.5% and 36.7%. The CL and Q3 were 40.1% increased and 36.9% decreased in arterial samples compared to those in venous samples. The determination coefficient of observations (DV)-individual predicted value (IPRED) by the final model was 0.91 which could predict the propofol concentration fairly well. The stability and the predictive performance were accepted by Bootstrapping, the goodness-of-fit and VPC. The context-sensitive half-times and infusion rates necessary to maintain the concentration of 1 microg x mL(-1) were different obviously among the 6 sub-populations obviously. The three-compartment model with first-order elimination could describe the pharmacokinetics of propofol fairly well. The involved fixed effects are age, body weight, gender and sampling site. The simulations in 6 subpopulations were available in clinical anesthesia. The propofol anesthesia monitor care could be improved by individualization of pharmacokinetic parameter estimated from the final model.

Population pharmacokinetic study of tacrolimus in patients with hematopoietic stem cell transplant / 药学学报

The present study is to establish the population pharmacokinetic (PPK) model of tacrolimus and to estimate PPK parameters of tacrolimus for the individualization of tacrolimus administration in patients with hematopoietic stem cell transplant. A total of 671 blood samples were collected from 68 hematopoietic stem cell transplant patients and clinical data were retrospectively collected from the medical records of these patients. Population pharmacokinetical analysis was performed using the nonlinear mixed-effect model (NONMEM) program. The Bootstrap and data splitting were used simultaneously to validate the final population pharmacokinetical models. The basic structural model was best described as one-compartment pharmacokinetical model with first-order absorption and elimination. A number of covariates including demographic characteristic, biochemical and hematological index, combined drugs, inter-occasion variability (IOV) and other variables, e.g. primary disease, post operation days (POD), the type of transplantation and the sources of donor, were screened for their influence on the pharmacokinetic parameters of tacrolimus. The population typical values of tacrolimus CL, V, F were 12.1 L x h(-1), 686 L, 42.2%; and the inter-individual variability of these parameters were 23.5%, 96.4%, 43.8%, respectively. The absorption rate constant was fixed 4.3 h(-1). The residual error between observed and model- predicted concentration was 3.03 ng x mL(-1). The CYP enzyme inhibitor (INHI), POD and age were identified to be the main covariates that influence tacrolimus CL, and hemoglobulin (HGB) was the main covariate that may explain the variability in tacrolimus V. The IOV of CL, V, F were 22.2%, 6.23%, 30.3%, respectively. The population pharmacokinetic data obtained in the present study have significant clinical value for the individualization of tacrolimus therapy in hematopoietic stem cell transplant patients.

Population pharmacokinetics of norvancomycin / 中国感染与化疗杂志

85 mL/min),CL=6.0?(WT/60)~(0.52).④The increased volume of peripheral distribution (V_2) was observed when norvancomycin was co-administered with diuretics;④Reduced drug clearance,prolonged t_(1/2),and increased values of AUC_(24) were found in elderly patients.Conclusions Renal function impairment and age have significant impact on PK parameters of norvancomycin.Dosing regimens of norvancomycin were finally established for different patients on the basis of important PPK parameters generated from different groups of patients.

Rapid analysis of antiepileptic drugs in human plasma by micellar electrokinetic capillary chromatography / 药学学报

<p><b>AIM</b>To develop a rapid and feasible method based on micellar electrokinetic capillary chromatography (MECC) for the simultaneous determination of antiepileptic drugs (AEDs)--phenytoin (PHT), phenobarbital (PB), carbamazepine (CBZ), primidone (PRM) and clonazepam (CZP) in human plasma.</p><p><b>METHODS</b>Several factors that impact the separation of AEDs with MECC were investigated, such as concentration of sodium dodecyl sulfate (SDS), buffer compositions, pH, organic modifier, internal diameter and temperature, and an optimized MECC running condition was obtained the running buffer consisted of 8 mmol x L(-1) phosphate, 3 mmol x L(-1) sodium tetraborate, and 50 mmol x L(-1) sodium dodecylsulfate (SDS) (pH 8.0), containing acetonitrile (ACN) (18%) as organic modifier. Detection at 210 nm, run at 25 kV at 30 degrees C in a untreated fused silica capillary (50/45.5 cm length, 50 microm ID).</p><p><b>RESULTS</b>The reproducibility of both migration time and relative peak area with MECC analysis were appropriate for the intra- and inter-assay coefficients. The evaluated drugs concentration intervals of PRM 1.0-40.0 microg x mL(-1), PB 1.0-60.0 microg x mL(-1), PHT 1.0-40.0 microg x mL(-1), CBZ 1.0-40.0 microg x mL(-1), CZP 0.2-8.0 microg x mL(-1) were linear with correlation coefficients higher than 0.999 1, and coefficients of the variation of the points of the calibration curve lower than 10%. The recoveries of AEDs varied from 80.0% to 100.0%, depending on the drug, with coefficients of the variation lower than 10.0%.</p><p><b>CONCLUSION</b>The MECC technique is showed to be rapid, simple, efficient and low cost when applied to monitoring therapeutic drugs in patient treated with a combination of PHT and other AEDs such as hepatic enzyme-inducing agents.</p>

Albumin kinetics in patients with severe sepsis / 中华外科杂志

<p><b>OBJECTIVE</b>To explore the mechanism of hypoalbuminemia in patients with severe sepsis.</p><p><b>METHODS</b>I(125)-labeled albumin was administered intravenously to 10 health volunteers and 10 patients with severe sepsis. Blood samples were taken at 0, 1, 2, 4, 8, 12, 24 hours and 2, 3, 4, 5, 6, 7, 9, 11, 13, 15, 18, 22, 25 days for the measurement of the dose of gamma-radiation and the curve of concentration and time. Then the half-life time (t(1/2)), apparent volume of distribution (V(d)) and transportation rate (K(12)) from center compartment to side compartment of albumin were calculated.</p><p><b>RESULTS</b>The half-life time in septic group was obviously shorter than that in control group (8.2 +/- 1.4 vs. 12.5 +/- 1.7, P < 0.01). The transportation rate in the septic group was higher than that in the control group [(4.4 +/- 1.9) x 10(-2)/h vs. (2.4 +/- 0.6) x 10(-2)/h, P < 0.05]. There was no significant difference in apparent volume of distribution between the two groups.</p><p><b>CONCLUSIONS</b>In patients with severe sepsis, the distribution rate of albumin from vessel to tissue was obviously increased and the decomposition rate of albumin was markedly improved.</p>