Biomedical subjects

Meiyu Shen

Publications and source records attributed to Meiyu Shen.

3 recordsLinked to original sources

PubMed2004

Population pharmacokinetics of cisplatin in adult cancer patients.

PURPOSE: To characterize the pharmacokinetics of the anticancer agent cisplatin, and explore the influence of patient covariates and interoccasion variability on drug disposition. METHODS: Data were obtained from 285 patients (519 complete curves; 3483 plasma samples) who received the drug as a 3-h intravenous infusion at a mean dose of 144 mg (range 75-210 mg). The population model was built with the use of NONMEM, performing generalized-additive modeling to identify candidate covariates including body-surface area (BSA), age, sex, height, weight, hematocrit, total protein, albumin, serum creatinine, and creatinine clearance, and using a backward deletion protocol to obtain the final models for clearance (CL) and volume of distribution (V). RESULTS: The final model was a one-compartment linear model with BSA (in meters squared) as the only significant covariate that impacted on both CL and V: TVCL (in liters per hour)=51.7+26.3x(BSA-1.855) and TVV (in liters)=41.1+24.6x(BSA-1.855), where TVCL and TVV are referred to as typical values that could be used a priori in dosage regimen design. The interindividual and interoccasion variability estimates for CL and V were 16.82 and 20.35%, and 13.93 and 22.91%, respectively. CONCLUSION: A population pharmacokinetic model for cisplatin has been developed that incorporates measures of body size to predict clearance. In this patient population, cisplatin pharmacokinetics were not associated with age, sex, or measures of renal dysfunction.

Adult↗

PubMed2004

Three-stage sequential statistical dissolution testing rules.

The U.S. Pharmacopoeia (USP) general monograph provides a standard for dissolution compliance with the requirements as stated in the individual USP monograph for a tablet or capsule dosage form. The USP monograph sets performance limit on dissolution in terms of a specific percentage Q that the drug product is required to be dissolved at a specified time. Japan Pharmacopoeia provides acceptance rules different from USP. However the objective of the acceptance rules was not defined in terms of the inference of the whole lot by either USP, European Pharmacopoeia (EP) or Japan Pharmacopoeia (JP). The operating characteristics' curves of these rules are all shown to be sensitive to the true mean dissolution and do not reject a lot which has a large percentage of tablets that dissolve with less than the specified limit Q. This is especially true when the mean dissolution is close to the specification value. We proposed that the goal of the dissolution test sampling plan is to accept a lot at least 90% of the tablets dissolved more than a pre-specified amount Q at the specific time. The group sequential procedure derived accordingly is shown to outperform both USP and JP in controlling the type I error rate under normality assumption.

Algorithms↗

PubMed2002

Population pharmacokinetic and limited sampling models for carboplatin administered in high-dose combination regimens with peripheral blood stem cell support.

OBJECTIVE: By means of a nonlinear mixed effect modeling technique, a population pharmacokinetic (PK) model was developed to evaluate the effects of a variety of covariates on clearance and other pharmacokinetic parameters of ultrafilterable carboplatin administered in high-dose combination regimens with peripheral blood stem cell support. In addition, single-sample and two-sample limited sampling models (LSMs) were derived to estimate carboplatin's AUC that could be used in the design of drug dosing regimens. METHODS: A total of 44 female patients with advanced ovarian cancer participated in two phase I studies. All 44 patients received a high-dose carboplatin chemotherapy with other anticancer drugs. A population PK model was applied to the plasma concentration-time data of ultrafilterable carboplatin using the NONMEM and Xpose computer programs. The Xpose program utilized a general additive modeling technique to identify significant patient covariates and PK parameter relationships. The resultant PK model was validated using a bootstrap method. Stepwise linear regression analyses were used to develop LSMs based on the correlation between carboplatin's AUC and plasma concentrations. RESULTS: The best structural covariate-free model for high-dose carboplatin was a linear two-compartment model with an exponential error model to account for intersubject variability and a CCV error model to account for intrasubject variability. Subsequently, a final covariate model for clearance (l/min) was obtained as follows: TVCL=0.101+0011*(WT-62.35)-0.0658*(SCR-0.65) where WT is body weight (kg) and SCR is serum creatinine (mg/dl). Both WT and SCR were found to significantly influence carboplatin's total clearance. It was determined that the best single-sample LSM was AUC(LSM)=0.553*C(240min) ( r=0.998). CONCLUSION: Both a population PK model and a LSM for high-dose carboplatin were developed following its administration in combination chemotherapeutic regimens with peripheral blood stem cell support. In both cases, the models performed well when analyzed in the context of the retrospective and bootstrap analyses. Prospective studies in ovarian cancer patients should be conducted to further tailor the current models.

Adult↗