The pharmacokinetics and tissue distribution of the glucosylceramide synthase inhibitor miglustat in the rat

Miglustat (Zavesca) is a reversible inhibitor of glucosylceramide synthase, which catalyses the first step in the glucosylceramide biosynthetic pathway, and is approved for therapy in patients with type 1 Gaucher disease. The present report describes the pharmacokinetic profile of miglustat in the rat with a focus on tissue distribution. Experiments were performed with radiolabeled miglustat itself and with a perbutyrated prodrug, the latter being readily converted to miglustat during gastrointestinal absorption and first pass metabolism. Miglustat was well absorbed and exhibited an oral bioavailability of 40-60%. Tissue distribution studies indicated the presence of miglustat in a number of organs and tissues that are considered of importance for the long-term therapeutic benefit, in particular the central nervous system, bone and lung. Miglustat was eliminated via renal clearance by a combination of glomerular filtration and active secretion. Hepatic clearance was negligible, as was the role of metabolism in the overall elimination process of miglustat in the rat.     

The pharmacokinetics and tissue distribution of the glucosylceramide synthase inhibitor miglustat in the rat

Miglustat (Zavesca?) is a reversible inhibitor of glucosylceramide synthase, which catalyses the first step in the glucosylceramide biosynthetic pathway, and is approved for therapy in patients with type 1 Gaucher disease. The present report describes the pharmacokinetic profile of miglustat in the rat with a focus on tissue distribution. Experiments were performed with radiolabeled miglustat itself and with a perbutyrated prodrug, the latter being readily converted to miglustat during gastrointestinal absorption and first pass metabolism. Miglustat was well absorbed and exhibited an oral bioavailability of 40–60%. Tissue distribution studies indicated the presence of miglustat in a number of organs and tissues that are considered of importance for the long-term therapeutic benefit, in particular the central nervous system, bone and lung. Miglustat was eliminated via renal clearance by a combination of glomerular filtration and active secretion. Hepatic clearance was negligible, as was the role of metabolism in the overall elimination process of miglustat in the rat.     

卡铂碳包铁纳米笼壳聚糖微球在大鼠体内的分布和药代动力学研究

目的观察卡铂碳包铁纳米笼壳聚糖微球(carbopla-tin-Fe@C-loaded chitosan nanoparticles,C-Fe@C-CN)经肝动脉注射后结合磁场在正常大鼠体内靶向分布和药动学参数。方法将C-Fe@C-CN用99Tc标记后,观察大鼠体内放射性核素分布情况。建立生物样品中卡铂的石墨炉原子分光光度计测定法,并测定大鼠给药后的血浆及组织中药物浓度。结果核素照片显示99Tc标记的C-Fe@C-CN浓集于靶区肝,其它脏器分布很少。经肝动脉注射C-Fe@C-CN在施加磁场的左肝叶各时间段组织中卡铂浓度较卡铂针剂明显增加(P<0.01),非靶向区组织中药物浓度则明显降低(P<0.01)。C-Fe@C-CN的血浆药-时曲线下面积和平均驻留时间分别是卡铂针剂的3和2.6倍,说明C-Fe@C-CN延长了卡铂在血中的存留时间,增大了血药浓度-时间曲线下面积。结论C-Fe@C-CN在外加磁场的作用下具有很好的肝靶向性及一定的缓释和减毒效果。     

The pharmacokinetics of saccharin in man

1. After intravenous administration of the non-nutritive sweetener, saccharin (10mg/kg), to normal volunteers the plasma concentration-time curve fitted a two-compartment open model with a terminal half-life of 70?min. Renal clearance was high and the dose was recovered quantitatively in the urine. The elimination rate and clearance were decreased significantly by concurrent probenecid administration.

2. After oral administration (2g) more complex and variable plasma concentrationtime curves were obtained and these were reflected in the urinary excretion of saccharin. The fraction absorbed was about 0±85 as determined by the recovery in urine and the area under the plasma concentration-time curves.

3. No indication of saturation of renal elimination was found after oral or intravenous doses that were many times the average daily intake.     

The importance of tissue distribution in pharmacokinetics

The concentration of a drug at its site of action will be affected by the ability of the drug to distribute to and pass through various membranes and tissues. Mechanisms of drug distribution are summarized in this paper and include the differences between intracellular and extracellular pH,active transport systems for drugs, distribution of drugs between fat and water in adipose tissues, the reversible binding of drugs to phospholipids and to various macromolecules including proteins, nucleic acid, and melanin. These mechanisms usually tend to decrease the concentration of unbound drugs at their sites of action, but usually not to the extent one would predict on the basis of in vitrobinding studies. The effects of drug distribution in altering the biological half-lives of drugs in the body are discussed as well as the interrelationship between the kinetic volumes of distribution for drugs and blood flow rates through the organs that eliminate these drugs. These concepts are illustrated for corticosterone levels following intravenous bolus injections and infusions into rats.This paper was presented at the Conference on Pharmacology and Pharmacokinetics: Problems and Perspectives, October 30–November 1, 1972, at the Fogarty International Center, National institutes of Health, Bethesda, Maryland. This paper, in a slightly different format, will be published in the Proceedings of the Conference by Plenum Press, New York.     

The pharmacokinetics and tissue distribution of gomphoside in Wistar rats

The excretion and tissue distribution of [3H]-gomphoside was studied after i.p. and i.v. administration of the cardiac glycoside (1 micrograms/g) to male Wistar rats. Following an intraperitoneal dosage of [3H]-gomphoside, most of the radioactivity (greater than 80%) had been excreted from the body by the end of 48 hours. Biliary excretion played a major role in elimination of [3H]-gomphoside with 90 +/- 15% of radioactivity being collected in 24 hours. Renal excretion formed a minor route of elimination of the cardiac glycoside; only 6 +/- 2% being excreted over 6 days. The distribution of radioactivity to tissues after an intravenous dose was rapid; most of the dose was located in the liver (32%), and the skeletal muscle (31%) 3 minutes after injection. The pharmacokinetics of [3H]-gomphoside could be described by a two-compartment open model with an average elimination half-life of 3.7 hours, and a large volume of distribution (2.3 +/- 0.3 ml/g body weight) characteristic of the commonly used cardiac glycosides (1).     

Brain uptake, pharmacokinetics, and tissue distribution in the rat of neurotoxic N-butylbenzenesulfonamide.

The pharmacokinetics, cerebrovascular permeability, and tissue distribution of the neurotoxic plasticizer N-butylbenzenesulfonamide (NBBS) were determined in rats. A stable isotope-labeled form ([(13)C(6)]NBBS) was used to circumvent ubiquitous contamination that was evident whenever the native form was measured. Plasticizer decline in plasma, following an iv dose of 1 mg/kg, was described by a triexponential decay function. NBBS was cleared from plasma at a rate of 25 ml/min/kg, and 24 h after administration, plasma concentrations represented 0.04% of the administered dose. These data suggest rapid elimination and uptake into tissue; however, NBBS was not accumulated by any of the tissues studied (i.e., liver, kidney, muscle, adipose tissue, and brain). Given the critical interest in NBBS neurotoxicity, the brain uptake of [(13)C(6)]NBBS was further explored in experiments using the in situ brain perfusion technique. During perfusion with protein-free saline for 15-30 s, the single-pass brain extraction for free [(13)C(6)]NBBS was very high (73-100%) with a unidirectional blood-brain barrier transfer constant (K(in)) of > 0.08 ml/s/g. No significant differences were found in [(13)C(6)]NBBS content among the measured brain regions. Plasma protein binding (70%) only slightly lowered the single-pass brain extraction to 48%. In summary, the results demonstrate that NBBS distributes rapidly to tissues, including brain. Though highly lipophilic with a Log octanol/water partition coefficient of 2.17 +/- 0.09, brain:blood ratios (2:1) for NBBS were consistent throughout the experimental duration, with little indication of accumulation.     

Enantioselective pharmacokinetics of etodolac in the rat: tissue distribution, tissue binding, and in vitro metabolism.

The nonsteroidal anti-inflammatory agent etodolac (ET) exhibits stereoselectivity in its pharmacokinetics following administration to humans and rats. To underline the factors responsible for this stereoselectivity, the tissue distribution, in vitro tissue binding, and microsomal metabolism of ET enantiomers were studied in the rat. Following iv administration of racemic ET, the S:R AUC ratios in tissues were stereoselective, and different from that in plasma. Binding of enantiomers to tissues was stereoselective, although it did not relate well with in vivo tissue distribution. Rather, the tissue distribution of enantiomers appeared to be better explained by the unbound fractions of enantiomers in plasma. With respect to in vitro glucuronidation by liver microsomes, the Vmax of S-ET was 3.4-fold greater than that of R-ET; the enantiomers possessed similar Km. There appeared to be stereoselectivity in the oxidative metabolism of ET enantiomers by liver and kidney microsomes, in favor of the R-enantiomer. The lower AUC in rat plasma of pharmacologically active S-ET as compared with its antipode is due to its relatively greater distribution to tissues, owing to a lesser degree of binding to plasma proteins, and to its higher rate of glucuronidation.     

冬凌草甲素固态类脂纳米粒在小鼠体内的组织分布及兔体内的药代动力学

目的考察冬凌草甲素固态类脂纳米粒在动物体内的组织分布及药代动力学特性。方法建立生物样品中冬凌草甲素的HPLC测定法，比较冬凌草甲素普通注射液和固态类脂纳米粒注射液的体内分布特点与药代动力学参数。结果冬凌草甲素固态类脂纳米粒在肝、脾、肺、心及肾中的相对摄取率分别为4.25%，3.44%，1.19%，0.52%和0.60%。静脉注射后的药-时曲线表明体内过程符合三室模型，其各相半衰期分别为T_1/2π=0.087 h，T_1/2α=1.65 h，T_1/2β=32.36 h，中心分布容积V_C=0.66 mL·kg^-1。结论冬凌草甲素固态类脂纳米粒能够增强药物的肝脾靶向性，提高药物生物利用度，并在一定程度上延长药物在动物体内的循环时间。固态类脂纳米粒可能成为冬凌草甲素的一种新型药物载体。     

HPLC测定蛇床子素在大鼠血浆及组织中药代动力学研究进展

蛇床子素的药代动力学稳定,药理作用广泛,具有较高的潜在开发价值。本文旨在对蛇床子素在大鼠血浆及组织中的药代动力学作一综述,为其今后开发利用提供参考。     

紫杉醇纳米混悬剂在大鼠体内的药动学和小鼠的组织分布

目的:考察紫杉醇纳米混悬剂在大鼠体内的药动学及小鼠体内的组织分布情况。方法:将紫杉醇注射液和紫杉醇纳米混悬剂2种制剂静脉给药后,采用HPLC法分别测定给药后5,10,15,30min及1,2,4,6,8,12h时大鼠的血药浓度,给药后5,15,30min及1,2,4,8,12h时紫杉醇在小鼠心、肝、脾、肺、肾、脑组织中的含量,对2种制剂的体内生物分布特征和靶向性进行评价。结果:大鼠血浆中,紫杉醇纳米混悬剂和紫杉醇注射液的消除相半衰期分别为(5.6±0.7)和(3.8±0.4)h;AUC分别为(5.2±0.4)和(20.3±1.1)mg.h.L-1;MRT分别为(3.2±0.4)和(2.8±0.3)h;Cl分别为(2.05±0.22)和(0.56±0.19)L.kg-1.h-1。与紫杉醇注射液相比,紫杉醇纳米混悬剂在肝、脾、脑组织中的药物含量显著增加。结论:相对于市售紫杉醇注射液,紫杉醇纳米混悬剂向靶部位富集,显著降低了非靶器官的药物浓度,可减轻制剂不良反应,使药物在血浆中的循环时间延长。     

Studies on pharmacokinetics and tissue distribution of oridonin nanosuspensions

The purpose of the present study was to investigate the effects of particle size on the pharmacokinetics and tissue distribution of oridonin nanosuspensions after intravenous administration. Two oridonin nanosuspensions with markedly different size were prepared by high pressure homogenization method. The particle size of nanosuspension A is 103.3+/-1.5nm, while B is 897.2+/-14.2nm. Dissolution studies showed that complete dissolution could be obtained within 10min for nanosuspension A, however, nanosuspension B showed a slower dissolution, only 85.2% dissolved by 2h. The pharmacokinetics and tissue distribution of oridonin nanosuspensions A and B were studied after intravenous administration using New Zealand rabbits and Kunming mice as experimental animals, respectively. An Oridonin control solution was studied parallelly. The results showed that oridonin nanosuspension A exhibited pharmacokinetic and biodistribution properties similar to solution due to its rapid dissolution in blood circulation. Oridonin nanosuspension B, however, showed a high uptake in RES organs, meanwhile exhibited a markedly different pharmacokinetic property compared to nanosuspension A. These differences could be attributed to the different particle size of the two nanosuspensions considering their zeta potential had no significant difference. In conclusion, particle size showed obvious effects on pharmacokinetics and tissue distribution of nanosuspensions.     

SN-38脂质体的药动学及组织分布学特征

目的研究SN-38脂质体大鼠体内药动学及小鼠组织分布学特征,为进一步非临床研究提供一定的实验基础。方法以盐酸伊立替康注射液(irinotecan,简称CPT-11)为参比制剂,大鼠尾静脉单次给予不同剂量的SN-38脂质体,于不同时间点眼框取血;小鼠尾静脉给予单剂量的SN-38脂质体,于2 h处死,取心、肝、脾、肺、肾等组织匀浆。并且建立HPLC法,用于大鼠血浆及小鼠组织样品中SN-38的含量测定。结果低、中、高3种剂量的SN-38脂质体在大鼠体内均消除较快,其t1/2无明显差异,AUC则随剂量的增加而增加。小鼠尾静脉注射SN-38脂质体后,主要聚集在肝、脾、肺中,且其在心、肾组织中的含量低于对照组。结论 SN-38脂质体在大鼠体内呈线性动力学消除。小鼠组织分布结果表明其对于肝、脾等网状内皮细胞丰富的组织靶向性强,能够提高该器官的治疗指数;同时还可降低对心、肾组织的毒性及不良反应。     

HPLC study of pharmacokinetics and tissue distribution of morroniside in rats

Morroniside is an important constituent of traditional Chinese medicines Fructus Corni with several bioactivities. An HPLC method for determination of morroniside in rat plasma and tissues was developed and the pharmacokinetic and tissue distribution characteristics of morroniside after intravenous and oral administrations were investigated. The bio-samples were prepared based on a simple protein precipitation and the separation of morroniside was achieved on a C(18) column with a mobile phase consisted of acetonitrile-methanol-0.1% formic acid (10:10:80, v/v) at a flow rate of 1.0 ml/min. Chromatograms were monitored at 239 nm and the temperature of column was kept at 25 degrees C. Pharmacokinetic study found that morroniside was absorbed and eliminated rapidly in rat and manifested linear dynamics at 10-40 mg/kg range and absolute bioavailability of morroniside was lower. Tissue distribution showed the highest level was observed in small intestine, then in kidney and stomach, but no morroniside was detected in brain, which indicated that small intestine, kidney and stomach were major distribution tissues of morroniside in rats, and morroniside had difficulty in crossing the blood-brain barrier. It was also found there was no long-term accumulation of morroniside in rat tissues.     

紫杉醇注射液在小鼠体内的药代动力学及组织分布

目的:建立血清中紫杉醇的分析测定方法,进行紫杉醇注射液在小鼠体内的药代动力学研究。方法:采用固相萃取方法进行血清样品预处理。色谱柱为Intertex C18(150 mm×4.6 mm,5μm),流动相为磷酸水溶液(pH3.0)-乙腈(50∶50),流速为1 mL.min-1,检测波长为227 nm。结果:紫杉醇在血清和组织中的浓度范围分别为0.39~100.00μg.mL-1和0.39~25.00μg.mL-1,准确度均在85%~115%,稳定性RSD均小于15%,小鼠静脉注射紫杉醇注射液后在小鼠体内代谢符合三房室模型(W=1/C2)。结论:本方法简便快捷,灵敏准确,本文建立的紫杉醇血药浓度测定方法和紫杉醇注射液在小鼠体内的药代动力学参数,为紫杉醇其他制剂的研究提供参考。     

阿德福韦酯在大鼠体内的药代动力学和组织分布特性研究

目的研究阿德福韦酯在大鼠的体内过程特性及绝对生物利用度,为临床合理用药提供依据.方法大鼠随机分组,分别一次性灌胃给药阿德福韦酯3.0,1.0,0.3 mg·Kg-1,静脉注射0.54 mg·Kg-1,采用高效液相色谱法检测阿德福韦在生物样品中的含量,并计算药代动力学参数.大鼠口服阿德福韦酯后于0.7,3,6h测定各组织的药物浓度.口服阿德福韦酯1.0 mg·Kg-1,24h内收集胆汁,测定药物胆汁排出率.用平衡透析法测定药物的人血清蛋白结合率.结果该药药代动力学过程符合无滞后时间的二室模型,高、中、低三个剂量的AUC(0～∞)分别为10.7±1.19,3.91±0.315,1.54±0.074 μg·mL-1·h;tmax在0.62～0.76 h之间,Cmax与给药剂量成正比,分别为2.26±0.299,0.758±0.0529,0.388±0.0269 μg·mL-1;t1/2 为5.0～7.3 h;绝对生物利用度为分别为(53±5.2)%,(51±8.1)%,(42±6.0)%.静脉注射给药阿德福韦后t1/2(ke) 为7.5±0.16 h,AUC(0～∞)为 6.35±1.58 μg·mL-1·h.母体药物阿德福韦在组织中分布情况为肾>肝>胃,其他组织中的浓度均远低于血浆中浓度.胆汁累积排泄率低于2%,在0.10～4.0μg·mL –1的浓度范围内,人血清蛋白结合率为<5%.结论阿德福韦酯在动物体内迅速吸收,消除半衰期较长,胆汁不是该药的主要排泄途径,血液及主要脏器无药物蓄积.阿德福韦是生物样品中检测到的唯一代谢产物.     

冰片对卡马西平药动学及脑组织分布的影响

目的:考察冰片对卡马西平在大鼠体内药动学及脑组织分布的影响。方法:大鼠随机分为2组,分别给予溶媒、冰片灌胃7天,并于第7天灌胃20min后,给予卡马西平(120mg.kg-1,ig),在不同时间点采集血样及脑组织样品,测定血浆与脑组织中卡马西平的浓度,并用药动学统计软件DAS2.0计算药动学参数。结果:冰片组与溶媒对照组卡马西平的药动学参数为:t1/2β(h)(3.5±0.6)vs(10.1±0.4),AUC(0-8)(mg.L-1.h)(12.1±1.6)vs(5.4±0.6),AUC(0-∞)(mg.L-1.h)(17.5±3.0)vs(8.5±0.8),tmax(h)(0.38±0.035vs(0.25±0.012)、Cmax(mg.L-1)(4.07±0.19)vs(2.24±0.21),2组t1/2β、AUC(0-t)、AUC(0-∞)、Cmax间差异显著(P<0.05);冰片组与溶媒对照组相比15,120min时脑组织中卡马西平浓度显著升高(P<0.05)。结论:冰片提高了卡马西平的生物利用度,并增加了其脑组织分布。     

The tissue distribution, metabolism, and excretion of octachlorostyrene in the rat

The tissue distribution, metabolism, and elimination of 14C-octachlorostyrene (OCS) were studied in the rat. OCS was absorbed in the gastrointestinal tract after oral administration and distributed in all tissues examined. The highest concentrations were found in fat followed by adrenal glands, skin, and lungs. Decay of radioactivity in the tissues followed first-order kinetics. Approximately 8% of an iv dose was excreted in feces during 7 days after administration, while negligible amounts were found in the urine. More than 90% of the radioactivity in feces was due to the unchanged compound, while pentachlorophenyldichloroacetic acid and heptachlorostyrene in equal proportions accounted for the remaining 10%. A small amount (1%) of the dose was detected in the expired air as carbon dioxide.