New hepatocellular diffusion model for analysis of hepatobiliary transport processes of drugs

A new hepatocellular diffusion model was developed to kinetically evaluate the hepatobiliary transport processes of drugs in the perfusion system, based on the physiological structure of the liver. Since the equations describing the hepatocellular diffusion phenomena were derived as image forms in the Laplace domain, the fast inverse Laplace transform (FILT) was adopted to manipulate the image equations. Cefixime and cefpiramide were selected as model drugs. The concentrations in the perfusate and the excreted amounts into the bile were simultaneously measured at appropriate intervals after the rapid administration of each drug into the portal vein. The hepatocellular diffusion model was fitted to the biliary excretion profiles from rat livers, by means of a nonlinear least squares program, MULTI(FILT). According to this model, the hepatobiliary transport process of drug is kinetically separated into three steps, that is, the diffusion into and through the hepatocytes, the transfer from the hepatocytes into the bile canaliculi, and the movement through the bile canaliculi to the outlet of bile duct. These steps are characterized by the diffusion rate constant through hepatocytes (k_dif), the permeability rate constant into the bile canaliculi (k_bmc) and the transit time through the bile canaliculi to the outlet of bile duct ( ), respectively. It was demonstrated that k_dif of cefixime (0.023min¹) was significantly smaller than that of cefpiramide (0.044 min¹), while the differences in k_bmc and were not obvious between cefixime and cefpiramide. k_bmc and of both drugs were about 1.2 min¹ and about 1.0 min, respectively. These parameters were correlated to the excretion ratio into the bile (F_bile) and the mean transit time from the sinusoid through the hepatocytes to the outlet of bile duct ( ).     

头孢匹胺在重症急性胰腺炎小鼠中血胰屏障通透性的实验观察

目的：研究头孢匹胺（CPM）在重症急性胰腺炎（SAP）小鼠血胰屏障的通透性,为头孢匹胺防治胰腺组织感染提供理论依据。方法以20%L-精氨酸2 g·kg-1体重腹腔注射方法复制SAP模型。正常对照组和SAP模型组小鼠均尾静脉注射头孢匹胺42.5 mg·kg-1,在规定时间点取样,用高效液相色谱法（HPLC）测定血浆和胰腺组织中药物的浓度。结果头孢匹胺在正常动物组和SAP模型组血浆和胰腺中的处置均符合一室模型。正常动物组CPM对血胰屏障平均穿透率（PR）可达（49.2±38.4）%,血浆和胰腺组织中的t1/2分别为1.42 h和1.14 h,AUC分别为122.73 mg·h·L-1和69.88 mg·h·kg-1。SAP模型组PR平均可达（56.±34.7）%,与正常动物组相比无显著性差异,胰腺组织中t1/2、C0及AUC0-∞与正常动物组相近。结论头孢匹胺在SAP小鼠胰腺中有良好的分布,值得向临床推荐用于预防和治疗胰腺感染。     

HPSEC法测定注射用头孢匹胺钠中聚合物的含量

目的建立HPSEC法对头孢匹胺钠中聚合物进行测定。方法采用TSKgelG2000SWXL色谱柱（7．8mmLD×30cm）;检测波长为254nm;以外标法测定聚合物的含量,并与头孢聚合物测定的文献方法进行比较。结果在该条件下头孢匹胺钠和聚合物峰分离良好;本法的定量限（S／N=9）为9ng;检测限（S／N=3）为3ng,本法测定的聚合物含量高于文献方法的结果。结论本方法简便、准确度高、灵敏度高,可有效的测定头孢匹胺钠中聚合物的含量。     

头孢匹胺治疗下呼吸道感染的临床疗效

目的 :评价头孢匹胺对下呼吸道感染的临床疗效及安全性。方法 :选择下呼吸道感染病人 4 2例 ,男性 2 7例 ,女性 15例 ,年龄 (6 2±s11)a ,给予头孢匹胺 2 g ,ivbid ,疗程 7～ 10d。结果 :34例病人痰细菌培养阳性 (81% ) ,革兰阴性杆菌占 97% ,β 内酰胺酶阳性率为 6 6 %。经头孢匹胺治疗 ,有效率为74 % ,细菌清除率为 5 6 %。不良反应发生率为 2 %。结论 :头孢匹胺治疗下呼吸道感染是一个安全有效的抗菌药物。     

Analysis of Hepatic Transport of Cefpiramide in Rats with Obstructive Jaundice by Using Isolated Hepatocytes

The mechanism of the diminished biliary clearance of cefpiramide (CPM) in rats with obstructive jaundice (OJ) was investigated by using isolated hepatocytes. The kinetics of CPM uptake by hepatocytes isolated from normal rats and rats with OJ could be explained by the combination of saturable carrier-mediated and nonsaturable first-order rate processes. The maximum uptake rate (V _max) of the carrier-mediated process was significantly decreased in OJ, compared with normal hepatocytes, while the Michaelis constant (K _m) and the first-order rate constant (k _d) were not significantly different. This result indicated that the number of CPM transport carriers was decreased in OJ hepatocytes. Further, no CPM uptake occurred from the serum of OJ rats into normal hepatocytes. Partial recovery of CPM uptake after treatment of OJ serum with activated charcoal suggested the accumulation of inhibitors of CPM uptake in OJ serum.     

高效液相色谱法测定小鼠血浆头孢匹胺钠的含量

目的:建立小鼠血浆中头孢匹胺钠HPLC检测方法,为临床上头孢匹胺钠血药浓度监测提供试验依据。方法:样品处理采用25%高氯酸(v/v)沉淀蛋白质。PLATISILTMC18(250 mm×4.6 mm,5μm)色谱柱,流动相为甲醇-三乙胺醋酸(三乙胺14 mL,冰醋酸5.7 mL,加蒸馏水定容至100 mL)-水(10∶0.2∶89.8),1 mol.L-1醋酸调节pH5.38,流速为0.8 mL.min-1;检测波长为254 nm。结果:所建立方法在0.2～250.0μg.mL-1范围内线性良好,方法平均回收率为96.1%,平均提取回收率为77.7%;日内变异RSD小于5%。小鼠尾静脉给药150 mg.kg-1后1 h血浆头孢匹胺钠浓度为(196.1±11.9)μg.mL-1,24 h血药浓度降至(0.5±1.6)μg.mL-1,采用DAS2.0程序求得药物动力学参数t1/2为3.41 h,MRT为3.24 h。结论:该法准确、灵敏、快速,内源性成分无干扰,适用于血浆中头孢匹胺钠的分析测定。     

头孢匹胺钠在两种替硝唑注射液中的稳定性考察

目的：考察头孢匹胺钠与替硝唑注射液，替哨唑葡萄糖注射配伍的稳定性。方法：按临床使用剂量在两种替硝唑输液中分别加入头孢匹胺钠，在25℃下于0,1,2,4,6h内用紫外分光光度法测定头孢匹胺钠，替硝唑的含量，结果：在0-6h内两种混和液外观，PH值基本不变，主要成分头孢匹胺钠，替硝唑的含量没有明显变化。结论：头孢匹胺钠能够与替硝唑注射液，替硝唑葡萄注射液配伍。     

Quantitative Evaluation of Capacity-Limited Hepatobiliary Transport Based on Hepatocellular Diffusion Model by MULTI(FEM)

The dose-dependency of hepatic uptake and hepatobiliary transport of a drug was evaluated by means of a nonlinear least square program incorporating the finite element method, MULTI(FEM). A perfusion experiment using isolated rat livers following a pulse input (i.e., under non-steady-state conditions) was performed at three dose levels of cefpiramide as a model drug. The hepatic extraction ratio (E_H) of cefpiramide decreased with an increase in dose, which demonstrates that the hepatic uptake is capacity-limited. The outflow time-profiles from the liver were represented by a two-compartment dispersion model with central Michaelis–Menten elimination, and the maximal elimination rate per central compartment volume (V_max) and the Michaelis constant (K_m) were estimated to be 1420 g/ml/min and 235 g/ml, respectively. The biliary mean transit time increased slightly with an increase in dose. The hepatocellular diffusion model under non-steady-state conditions considering nonlinear transport across the bile canalicular membrane was adopted to evaluate dose-dependency in the biliary excretion of cefpiramide. The maximal penetration velocity across the bile canalicular membrane per liver and the affinity constant of penetration across the bile canalicular membrane were estimated to be 40.1 g/min and 123 g, respectively. Considering that the volume of a rat liver (A_H.L) is approximately 10 ml, the Michaelis constant of penetration (k _m ^bmc ), which is an apparent parameter, was estimated to be approximately 12.3 g/ml. In conclusion, MULTI(FEM) is useful for evaluation of capacity-limited local disposition.     

HPLC测定血浆和尿液中头孢匹胺的浓度

 目的 建立头孢匹胺在人体血浆和尿液中的快速HPLC测定方法。方法 血浆和尿液样品经去蛋白、解离处理后,用RP-HPLC进行分析。采用Discover ODS C₁₈柱250 mm×4.6 mm,5 μm,流动相为甲醇-三乙胺醋酸液-水＝640∶3∶1357,pH 5.38,紫外检测波长为254 nm,乙酰苯胺为内标。结果 血浆和尿液中头孢匹胺回收率为(99.58±2.94)%和(98.72±1.97)%,在1.25～160 μg·ml^-1和2.5～160 μg·ml^-1范围内线性良好(r=0.999),日内、日间 RSD 均小于5%,重现性良好,RSD 小于7%。结论 本法简便、准确、灵敏、经济,适于体内药物分析。     

双空白对照头孢匹胺钠与奥硝唑氯化钠配伍实验

目的:建立双空白对照平行实验考察两种药物理化性质方面配伍合理性评价的方法。方法:注射用头孢匹胺钠1．0 g溶于奥硝唑氯化钠注射液100 mL中制得配伍溶液,注射用头孢匹胺钠1．0 g溶于0．9％氯化钠注射液100 mL及奥硝唑氯化钠注射液同为空白对照溶液,于20℃密闭放置0～4 h时,分别对其进行溶液外观、pH值和紫外吸收光谱检查,在波长273、320和357．5 nm处,用紫外分光光计分别测定其中头孢匹胺与奥硝唑含量,所得结果并进行统计学分析。结果:在0～4 h内,溶液外观、pH值和紫外吸收光谱基本不变化;空白对照溶液中所含头孢匹胺钠及奥硝唑的相对百分含量与配伍溶液中所含两药的相对百分含量无显著性差异(P<0．5)。结论:双空白对照平行实验考察注射用头孢匹胺钠在奥硝唑氯化钠注射液中配伍在本次实验范围内是合理的。