A Population Approach to Enzyme Characterization and Identification: Application to Phenacetin O-Deethylation

Purpose. To determine the enzyme kinetics (EK) and identify the human cytochrome(s) P450 (CYP) involved in the deethylation of phenacetin to acetaminophen using a population-based method. Methods. A sparse data set was generated from incubations containing human liver microsomes (n = 19) with phenacetin. Estimates of the EK parameters were obtained by fitting the concentration-velocity data to Michaelis-Menten models by using nonlinear mixed effects modeling. Relationships between the EK parameters and the CYP activities determined for these liver microsomes were examined. Results. A two-enzyme kinetic model with a saturated, low K_M enzyme and an unsaturated, high K_M enzyme capable of forming acetaminophen best fit the data. The population estimates of the EK parameters were V_max1, 911 pmol/min/mg protein; K_M1, 11.3 M; and Cl_int2 0.4 l/min/mg. The coefficients of variation for interliver variability in V_max1 and residual error of the model were 39% and 15%, respectively. When the selective catalytic activities were examined as potential covariates, 7-ethoxyresorufin O-deethylation (CYP1A2) activity was found to be associated with the low K_M enzyme, however, the high K_M enzyme(s) could not be identified. Conclusions. The population approach characterized the EK parameters and identified the low K_M enzyme responsible for phenacetin O-deethylation as CYP1A2. Population modeling of EK provides valuable information on inter- and intraliver variability in CYP dependent activities.     

激素治疗中的药物经济学分析

目的：探讨复方乙酰水杨酸片中非那西丁和咖啡因的含量测定方法。方法：在乙醇中溶解样品,用０２ｍｏｌ／ＬＮａＯＨ水解乙酰水杨酸后,以ｐＨ６５磷酸盐缓冲液为溶剂进行定量,采用多元回归分光光度法。结果：非那西丁和咖啡因的平均回收率分别为９９８％和９９９％,ＲＳＤ为０７２％和０５２％。结论：样品的测定结果同部颁标准法比较在准确度上无显著差异。     

胶束动电毛细管色谱法分离测定去痛片中的4种组分

目的　建立一种用胶束动电毛细管色谱法测定去痛片中各组分含量的方法。方法　用硼酸·氢氧化钠·十二烷基磺酸钠为缓冲液进行分离,以茶碱为内标,254 nm为测定波长。结果　样品中咖啡因、氨基比林、非那西丁、苯巴比妥等4组分完全分离且呈良好线性关系,其加样回收率为98.26%~101.87%。结论 本方法简便、准确,可作为该制剂各组分含量的测定方法。     

高效液相色谱法测定小儿克感敏颗粒中4种有效成分

目的:用反相高效液相色谱法测定小儿克感敏颗粒中氨基比林、咖啡因、马来酸氯苯那敏、非那西丁4种有效成分的含量。方法:采用LUNA C18(250 mm×4.6 mm,5μm)色谱柱,流动相为甲醇-乙腈-0.05 mol·L-1磷酸二氢铵(内加0.1％三乙胺,磷酸调pH=2.7)(90:210:700),流速1 mL·min-1,检测波长为261 nm。结果:测得上述4种有效成分RSD(n=5)分别为:0.9％,0.9％,0.5％,0.5％;平均回收率(n=3)分别为:100.5％,100.1％,99.5％,99.0％。结论:本研究建立了一种快速、准确、灵敏的HPLC测定小儿克感敏颗粒中4种主要成分的方法。     

BP网络光度法用于去痛片中氨基比林和非那西丁的测定

目的：探讨去痛片含量测定的紫外分光光度法。方法：采用BP网络光度法测定去痛片中氨基比林和非那西丁二组分的含量,结果：二组分的平均回收率及RSD分别为99．7％,1．85,99．8％,1．0％,结论：S一法简便、准确。     

A dispersion model of hepatic elimination: 3. Application to metabolite formation and elimination kinetics

A dispersion model of hepatic elimination is presented to describe metabolite formation and elimination kinetics within the liver, consistent with the known physiology and biochemistry of this organ. The model is based on the spread in residence times of blood flowing through the liver. This dispersion model is shown to be more consistent with transient and steady-state data obtained after the single passage of phenacetin and acetaminophen through the liver (both normal and retrograde perfusions) than other models of hepatic elimination. The dispersion model is suitable for the evaluation of enzyme heterogeneity using experimentally obtained metabolite data.     

紫外分光光度法同时测定小儿复方苯巴比妥片剂中的4组分

目的 :建立小儿复方苯巴比妥片剂中 4组分含量的检测方法。方法 :采用紫外分光光度法 ,不经分离 ,直接测定 4组分的含量。结果 :可同时测定模拟样和复方小儿苯巴比妥片剂试样中阿司匹林、非那西丁、咖啡因和苯巴比妥的各自含量。平均回收率分别为 99.0 % ,98.9% ,99.8%和 10 1%。相对标准偏差 (RSD)分别为 2 .0 % ,2 .0 % ,2 .9%和 2 .2 %。结论 :本法简便、快速、可靠 ,可用于复方药物质量的监控。     

吡拉西坦片的HPLC测定

以非那西丁为内标，采用ＨＰＬＣ法测定吡拉西坦（脑复康）片的含量。平均回收率为９９．５％，ＲＳＤ为０．６％。方法准确，简便。     

The effects of stannous chloride on the humoral immune response of mice

In vitro experiments showed that excised ethmoturbinates of late gestational fetuses and neonatal rats have a marked ability to metabolize [14C-ethyl]phenacetin as determined by 14CO2 formation. Autoradiography of fetuses injected in utero with [14C-ethyl]phenacetin on day 22 of gestation showed a selective uptake and binding of radioactivity in the mucosa of the ethmoturbinates.     

HPLC法测定大鼠血浆、微粒体中非那西丁与其代谢物含量及其应用

<正>细胞色素P450 1A2亚家族是近年来药物代谢研究领域的热点之一,与许多药物的相互作用有关[1]。非那西丁是CYP1A2酶的特异性底物,被广泛选择作为底物用于体内外测定酶活性[2]。本研究建立大鼠血浆、微粒体中非那西丁与其代谢物对乙酰氨基酚含量的HPLC测定方法,并对血浆样品进行方法学考察,为进一步确证药物及化学异物对CYP1A2酶活性的影响提供可靠的方法学基础。同时,应用所建立的方法以体内、体外方式评价了甘草水提液对