二氢吡啶类钙拮抗剂的吸收、分布、代谢与排泄研究概况

二氢吡啶类药物是重要的钙离子通道拮抗剂,是目前临床应用较广的一类抗高血压药物.本文从该类药物的吸收、分布、代谢与排泄方面综述其药代动力学特征,为新药研发及临床应用提供依据.二氢吡啶类药物脂溶性好,易透过细胞膜,但首过效应较强,会对其生物利用度产生较大的影响;表观分布容积较大,血浆蛋白结合率高,可迅速向各组织分布,主要分布于肝、肾等血流速率快的组织;在体内主要经细胞色素P450酶(CYPs)代谢,而CYP3A是参与其代谢的主要亚型,Ⅰ相代谢包括二氢吡啶环氧化、酯健水解及羟化反应,Ⅱ相代谢以葡萄糖醛酸结合为主;主要以代谢产物的形式从尿液、胆汁、粪便排泄,原型药物的排泄量极少.     

10-羟基癸烯酸在动物体内吸收、分布、代谢和排泄

10-癸基癸烯酸(即10-HDA,定位标记为³H-10HDA),经小鼠和大鼠口服后,胃肠道吸收快,峰时均在1h,全身分布迅速广泛,与组织亲和力强,肝中放射性为最高,依次为肾、胰、脂肪、脑、脾、心和肺。平均Vd为9.71/kg。Ig和iv的T1/2β在12.6～22.7h。体内消除较缓慢,31 d内,尿粪中放射性累计排泄分别为给药量的85.4%和13.5%,提取尿和胆汁经分析结果主要以原形药物排出。血浆蛋白结合率为63%。血中放射—性时间曲线符合开放二室模型。     

皂苷类成分吸收分布和代谢及排泄研究进展

皂苷是一类具有多种药理活性的重要天然产物,但由于其生物利用度普遍较低,体内的药效物质基础和作用机制研究尚不够深入,影响了该类成分的新药开发与应用。本文对近年来国内外关于皂苷类化合物体内外代谢等过程研究的文献进行综述,有利于深入探索该类成分的体内药效物质基础和作用机制,为新药研发提供一定的理论依据。     

放射性同位素示踪技术在药物研发过程中的应用

药物的吸收、分布、代谢和排泄过程决定了药物分子在体内的过程和命运。作为常规生物样本检测技术的有效补充,放射性同位素标记示踪技术如今也被广泛应用于药物发现和开发过程中的各个阶段。特别是其高灵敏性、适用范围广的特点使其具有不可比拟的优势。通过对近年来放射性标记技术在药物评价领域中的应用进行了归纳和梳理,为药物研发相关领域研究人员提供可借鉴的参考。     

荷叶碱在大鼠体内的吸收、分布、代谢和排泄研究

目的荷叶碱为荷叶中的主要活性成分,是一种具有调节血脂和治疗肥胖相关疾病的阿朴啡类生物碱。为了更好地指导临床用药,我们建立了荷叶碱在血浆及各组织匀浆中的定量测定方法,并对其在大鼠体内的吸收、分布、代谢和排泄进行了深入研究。方法大鼠静脉和灌胃给予荷叶碱0.2和10 mg·kg~(-1),在不同时间点收集血浆和组织,以盐酸巴马汀为内标,HPLC-MS法测定给药后荷叶碱在血浆和组织中的浓度。大鼠灌胃给予荷叶碱10 mg·kg~(-1),在不同时间点收集尿液和粪便,经处理后HPLC-MS法测定给药后荷叶碱在尿液和粪便中的浓度。结果空白血浆中荷叶碱在2~2000 ng·mL~(-1)浓度范围内呈良好的线性关系,在血浆中绝对回收率为87.5%,样品在长期储存过程中能保持稳定。荷叶碱的绝对生物利用度较低为(1.9±0.8)%。在体内分布中肾>脾>肝>心>肺>脑。荷叶碱在体内主要以原形存在,尚未发现其代谢产物;荷叶碱主要通过肾排泄(80.7%)。结论本研究建立了便捷而且有效定量测定大鼠血浆中荷叶碱的方法,并对荷叶碱在大鼠体内的吸收、分布、代谢和排泄进行了深入研究,为临床应用该药提供了理论依据。     

蛇毒神经生长因子在大鼠体内的药物代谢动力学与周围神经分布

用［¹²⁵I］标记结合高效液相色谱法和酸沉法研究大鼠体内蛇毒神经生长因子(vNGF)药物代谢动力学. ［¹²⁵I］vNGF体外有刺激神经突起生长活性. 药后血清存在游离和结合［¹²⁵I］vNGF及［¹²⁵I］降解物. 12 mg·kg^-1 iv后t_1/2α为0.13 h，t_1/2β为3.8 h；12和48 mg·kg^-1 im 后t_1/2β为7.1和4.1 h，AUC与剂量呈正比，CL_S相近， 生物利用度为0.62. 体外［¹²⁵I］vNGF与血清最大结合率24.6%±0.4%，平衡解离常数3.2±0.3 nmol·L^-1. im后颈上神经节，注药侧和对侧坐骨神经放射性明显高于血清，注药侧最高，不被100倍非标vNGF抑制. 主要经尿排泄，2 d排出约86%.     

蛇毒神经生长因子在大鼠体内的药物代谢动力学与周围神经分布

用［１２５Ｉ］标记结合高效液相色谱法和酸沉法研究大鼠体内蛇毒神经生长因子（ｖＮＧＦ）药物代谢动力学．［１２５Ｉ］ｖＮＧＦ体外有刺激神经突起生长活性．药后血清存在游离和结合［１２５Ｉ］ｖＮＧＦ及［１２５Ｉ］降解物．１２ｍｇ·ｋｇ－１ｉｖ后ｔ１／２α为０．１３ｈ，ｔ１／２β为３．８ｈ；１２和４８ｍｇ·ｋｇ－１ｉｍ后ｔ１／２β为７．１和４．１ｈ，ＡＵＣ与剂量呈正比，ＣＬＳ相近，生物利用度为０．６２．体外［１２５Ｉ］ｖＮＧＦ与血清最大结合率２４．６％±０．４％，平衡解离常数３．２±０．３ｎｍｏｌ·Ｌ－１．ｉｍ后颈上神经节，注药侧和对侧坐骨神经放射性明显高于血清，注药侧最高，不被１００倍非标ｖＮＧＦ抑制．主要经尿排泄，２ｄ排出约８６％．     

转运体在药物胆汁排泄中的作用

目的:综述转运体在药物胆汁排泄中的作用。方法:以近几年国内外研究文献为基础,从转运体介导药物的胆汁排泄过程、介导药物胆汁排泄的转运体、药物相互作用、转运体的基因多态性等方面进行综述。结果:转运体对药物体内经胆汁排泄过程、临床用药安全性、用药后的个体差异等方面均存在影响。结论:随着对转运体认识的不断深入,其将在药物设计、临床合理用药、个体化治疗等方面发挥重要作用。     

Caco-2细胞系及其在药物吸收、代谢中的应用

由于小肠的生理结构适用于药物吸收 ,所以口服给药是最广泛、最方便的给药途径之一 ,因此研究药物在肠道的吸收与代谢就显得十分必要。目前用于药物吸收的实验方法主要有 :在体肠回流法 ,肠襻法 ,分离肠粘膜法、外翻囊法等 [1 ]。由于这些方法存在采用动脉组织及其它一些局限性 ,近年来人们尝试使用人肠细胞培养系统来研究药物在肠道的吸收和代谢 ,以快速筛选口服药物。Caco-2细胞模型被认为是目前最好的体外吸收模型 ,可用于快速评估新药的细胞渗透性、阐明药物转运的途径、评价提高膜通透性的方法、确定被动扩散的药物最合适的理化性质和…     

毛蕊花糖苷在大鼠体内吸收、分布及排泄研究

目的:采用液相色谱-质谱联用(LC-MS/MS)法测定大鼠血浆及组织样品中毛蕊花糖苷的浓度,并探讨其在大鼠体内吸收、分布及排泄研究。方法:SD大鼠灌胃给予毛蕊花糖苷20,40,80,160 mg·kg^-1后,于不同时间点采血,给予40 mg·kg^-1剂量进行分布和排泄试验,测定血浆、组织和排泄物中的毛蕊花糖苷浓度,并用DAS 2.0软件拟合并计算药动学参数。结果:大鼠给药20,40,80,160 mg·kg^-1的毛蕊花糖苷后,药时曲线呈二室开放模型,主要药动学参数t_max,C_max,t_1/2α,AUC_0-t,AUC_0-∞,CL/F,V/F分别为(17.50±10.37)min、(0.313±0.04)mg·L^-1、(6.79±12.10)min、(21.39±4.03)mg·L^-1·min^-1、(22.39±3.89)mg·L^-1·min^-1、(1.83±0.30)L·min^-1·kg^-1、(179.10±52.77)L·kg^-1。大鼠给予40 mg·kg^-1的毛蕊花糖苷后,毛蕊花糖苷在尿液和粪便中36 h内的累积排泄百分数分别为(0.037±0.005)%、(0.004 2±0.000 8)%,胆汁中12 h内的累积排泄率基本为零。结论:毛蕊花糖苷在大鼠体内吸收符合一级动力学,分布在小肠和肺浓度最高,其次为胃和肌肉,其他组织都有少量的分布;且通过尿液、粪便和胆汁排泄量较少,其可能主要通过代谢过程进行消除。     

微透析技术在药物靶组织分布和代谢研究中的应用

微透析技术是一项新兴的在体研究技术，近年来已广泛应用于药物在靶组织分布和代谢研究，对于阐明药物体内过程、疗效和安全性有重要意义，为新药研发与临床合理用药提供科学依据。现通过检索分析相关文献，就微透析技术的概况、微透析探针、透析液的分析及微透析技术在药物靶组织分布和代谢研究中的应用作一综述。     

Human radiolabeled mass balance studies: objectives,utilities and limitations

The determination of metabolic pathways of a drug candidate through the identification of circulating and excreted metabolites is vitally important to understanding its physical and biological effects. Knowledge of metabolite profiles of a drug candidate in animals and humans is essential to ensure that animal species used in toxicological evaluations of new drug candidates are appropriate models of humans. The recent FDA final guidance recommends that human oxidative metabolites whose exposure exceeds 10% of the parent AUC at steady‐state should be assessed in at least one of the preclinical animal species used in toxicological assessment. Additional toxicological testing on metabolites that have higher exposure in humans than in preclinical species may be required. The metabolite profiles in laboratory animals and humans are generally accomplished by mass balance and excretion studies in which radiolabeled drugs are administered to these species. The biological fluids are collected, analysed for total radioactivity and evaluated for a quantitative profile of metabolites. Thus, these studies not only determine the rates and routes of excretion but also provide very critical information on the metabolic pathways of drugs in preclinical species and humans. In addition, these studies are required by regulatory agencies for the new drug approval process. Despite the usefulness of these radiolabeled mass balance studies, there is little concrete guidance on how to perform or assess these complex studies. This article examines the objectives, utilities and limitations of these studies and how these studies could be used for the determination of the metabolite exposure in animals and humans. Copyright © 2009 John Wiley & Sons, Ltd.     

Preclinical absorption,distribution, metabolism and excretion (ADME) characterization of ICAM1988, an LFA-1/ICAM antagonist,and its prodrug

1. Intercellular adhesion molecule (ICAM)-1988 is a small molecule lymphocyte function-associated antigen-1 (LFA-1) antagonist being considered for its anti-inflammatory properties. Following intravenous administration of ICAM1988, clearances in mice, rats, dogs, and monkeys were 17.8, 3.31, 15.4, and 6.85 ml min^?1 kg^?1, respectively.

2. In mass balance studies using [¹⁴C]-ICAM1988 in rats dosed intravenously, unchanged ICAM1988 contributed to 25.1% of the dose.

3. In rats, the systemic bioavailability of ICAM1988 was improved to 0.28 when the drug was administered orally as its isobutyl ester, ICAM2660. In rats, this was consistent with the complete in vitro conversion of ICAM2660 to ICAM1988 in plasma, and liver and intestinal S9.

4. In dogs and monkeys, ICAM2660 did not improve the bioavailability of ICAM1988. This is consistent with limited in vitro conversion of ICAM2660 to ICAM1988 in plasma and liver S9.

5. In human in vitro studies, ICAM2660 conversion to ICAM1988 in liver was similar to rats while no conversion in plasma and intestinal S9 fractions were observed. Based on the in vitro metabolism similarities of human and rat, it would be anticipated that in human oral administration of ICAM2660 would improve the systemic exposure of ICAM1988.

     

Determination of drug-like properties of a novel antileishmanial compound: In vitro absorption, distribution, metabolism, and excretion studies

In drug discovery research, the compounds should not only to be potent and selective but also must possess acceptable pharmacokinetic properties such as absorption, distribution, metabolism, and excretion (ADME) to increase success rate in clinical studies.

Objective:

Exploration of drug-like properties of 2-(2-methylquinolin-4-ylamino)-N-phenyl acetamide, a potent antileishmanial compound by performing some in vitro ADME experiments along with validation of such studies.

Materials and Methods:

Experimental protocols were established and validated for stability (in PBS pH7.4, simulated gastric and intestinal fluid), solubility, permeability, distribution coefficient (Log D), plasma protein binding and metabolism by rat liver microsomes by using spectrophotometer or HPLC. Methods were considered valid if the results of the standard compounds matched with reported results or within acceptable range or with proper ranking (high-medium-low).

Results:

The compound was found to be stable (>95% remaining) in all stability studies and aqueous solubility was 299.7 ± 6.42 μM. The parallel artificial membrane permeability assay (PAMPA) indicated its medium permeability (Log Pe = −5.53 ± 0.01). The distribution coefficients (Log D) in octanol/PBS and cyclohexane/PBS systems were found to be 0.54 and −1.33, respectively. The plasma protein binding study by the equilibrium dialysis method was observed to be 78.82 ± 0.13% while metabolism by Phase-I enzymes for 1 hour at 37°C revealed that 36.07 ± 4.15% of the compound remained after metabolism.

Conclusion:

The methods were found to be very useful for day-to-day ADME studies. All the studies with the antileishmanial compound ascertained that the compound bears optimum pharmacokinetic properties to be used orally as a potential drug for the treatment of leishmaniasis.     

Use of nano-electrospray for metabolite identification and quantitative absorption, distribution, metabolism and excretion studies

Determination of the pharmacokinetics and metabolite identification have been an integral part of drug discovery and development to ensure that drugs have appropriate absorption, distribution, metabolism and excretion properties. Liquid chromatography interfaced with a mass spectrometer has greatly facilitated these studies. Nano-electrospray has distinct sensitivity advantages and the increased amount of time available to perform mass spectrometric experiments facilitates structural characterization of metabolites. The recently developed silicon chip-based nano-electrospray devices are more practical than pulled capillaries. The use of these devices for the determination of pharmacokinetics and metabolite identification will be described and particular attention will be paid to the distinct advantages and disadvantages these devices offer.     

Pharmacokinetics,distribution, metabolism,and excretion of the dual reuptake inhibitor [14C]-nefopam in rats

1.?This study examined the pharmacokinetics, distribution, metabolism, and excretion of [¹⁴C] nefopam in rats after a single oral administration. Blood, plasma, and excreta were analyzed for total radioactivity, nefopam, and metabolites. Metabolites were profiled and identified. Radioactivity distribution was determined by quantitative whole-body autoradiography.

2.?The pharmacokinetic profiles of total radioactivity and nefopam were similar in male and female rats. Radioactivity partitioned approximately equally between plasma and red blood cells. A majority of the radioactivity was excreted in urine within 24?hours and mass balance was achieved within 7 days.

3.?Intact nefopam was a minor component in plasma and excreta. Numerous metabolites were identified in plasma and urine generated by multiple pathways including: hydroxylation/oxidation metabolites (M11, M22a and M22b, M16, M20), some of which were further glucuronidated (M6a to M6c, M7a to M7c, M8a and M8b, M3a to M3d); N-demethylation of nefopam to metabolite M21, which additionally undergoes single or multiple hydroxylations or sulfation (M9, M14, M23), with some of the hydroxylated metabolites further glucuronidated (M2a to M2d).

4.?Total radioactivity rapidly distributed with highest concentrations found in the urinary bladder, stomach, liver, kidney medulla, small intestine, uveal tract, and kidney cortex without significant accumulation or persistence. Radioactivity reversibly associated with melanin-containing tissues.     

Use of a semi-physiological pharmacokinetic model to investigate the influence of itraconazole on tacrolimus absorption,distribution and metabolism in mice

1.?The aim of this study was to investigate the influence of itraconazole (ITCZ) on tacrolimus absorption, distribution and metabolism by developing a semi-physiological pharmacokinetic model of tacrolimus in mice.

2.?Mice were randomly divided into four groups, namely control group (CG, taking 3?mg kg^?1 tacrolimus only), low-dose group (LDG, taking tacrolimus with 12.5?mg kg^?1 ITCZ), medium-dose group (MDG, taking tacrolimus with 25?mg kg^?1 ITCZ) and high-dose group (HDG, taking tacrolimus with 50?mg kg^?1 ITCZ).

3.?Liver clearance (CL_li) decreased significantly (**p?<?0.01) in LDG (35.3%), MDG (45.2%) and HDG (58.7%) mice compared to CG mice. With respect to gut clearance (CL_gu), significant (**p?<?0.01) decrease was also revealed in LDG (35.9%), MDG (50.2%) and HDG (64.6%) mice. A significant (**p?<?0.01) higher tacrolimus brain-to-blood partition coefficient (K_t,br) was found in MDG (25.3%) and HDG (55.9%) mice than in CG mice. Moreover, a significant (*p?<?0.05) increase (16.3%) was found in the absorption rate constant (K_a) in HDG mice compared to CG mice. There was a significant (**p?<?0.01) association between ITCZ dose and the change in CL_gu (ΔCL_gu, r=??0.790), the change in CL_li (ΔCL_li, r=??0.787) and the change in K_t,br (ΔK_t,br, r?=?0.727), while the association between ITCZ dose and the change in K_a (ΔK_a) was not significant (p?>?0.05).

4.?These findings could be useful in predicting the efficacy and toxicity of tacrolimus, and drug–drug interaction of ITCZ and tarcolimus in human.     

Assessment of exposure of metabolites in preclinical species and humans at steady state from the single-dose radiolabeled absorption, distribution, metabolism, and excretion studies: a case study

The exposure of a drug candidate and its metabolites in humans and preclinical species during drug development needs to be determined to ensure that the safety of drug-related components in humans is adequately assessed in the standard toxicology studies. The in vivo radiolabeled studies in preclinical species and human volunteers provide the total fate of the drug-derived radioactivity including the relative abundance of metabolites. Here, we describe how the single-dose radiolabeled human studies could provide the exposure of circulating metabolites at steady state using a case study of an extensively metabolized drug, lixivaptan. After an oral dose of [(14)C]lixivaptan to humans, a total of nine metabolites were detected in the systemic circulation; eight of them exceeded 10% of the parent exposure (2-41% of total radioactivity). The plasma samples were profiled for all subjects at each time point by high-performance liquid chromatography, and metabolites were quantified using a radioactive detector. On the basis of single-dose area under the concentration-time curve (AUC) values, exposure of six human metabolites was greater at least in one preclinical species used in toxicology evaluation. On the basis of the t(1/2) of lixivaptan and two major metabolites from a single dose in humans, their AUC and C(max) values were simulated at the steady state. The simulated exposure (C(max) and AUC) values of parent drug and the two most abundant metabolites were similar to those from a 7-day clinical study obtained using a validated liquid chromatography-mass spectrometry assay, suggesting that a well designed single-dose radiolabeled human study can help in addressing the metabolites in safety testing-related issues.