重组水蛭素-2鼻腔喷雾剂的药代动力学和药效学

目的研究重组水蛭素-2(rHV2)喷雾剂鼻腔给药后在大鼠体内的药代动力学过程及其抗凝血作用。方法采用呈色肽法测定大鼠鼻腔给予rHV2喷雾剂后血浆中rHV2的浓度，并计算其药代动力学参数；考察rHV2鼻腔喷雾剂对正常大鼠和弥散性血管内凝血模型(DIC)家兔凝血时间的影响。结果rHV2喷雾剂鼻腔给药后，rHV2的体内过程符合一室模型，其相对生物利用度为28.53%；rHV2鼻腔喷雾剂可使正常大鼠活化的部分凝血活酶时间(APTT)和凝血酶时间(TT)明显延长，使DIC模型家兔的APTT凝血时间明显缩短，接近正常值。结论药代动力学和药效学结果证明，rHV2鼻腔喷雾剂有望成为rHV2鼻腔给药的有效制剂。     

重组水蛭素-2鼻腔黏附纳米粒及其冻干粉药代动力学和抗凝活性研究

目的:对重组水蛭素-2(rHV2)鼻腔壳聚糖(CS)黏附纳米粒及其冻干粉进行药代动力学和抗凝活性评价。方法:采用呈色肽比色法检测rHV2血药浓度;以正常麻醉大鼠为模型,测定经鼻腔给予rHV2生理盐水溶液、rHV2纳米粒溶液及其纳米粒冻干粉复溶液的药-时曲线,计算药代动力学参数及与rHV2生理盐水溶液皮下注射给药的相对生物利用度;同时以部分凝血活酶时间(APTT)为指标比较它们的抗凝活性。结果:rHV2纳米粒比其生理盐水溶液鼻腔给药的相对生物利用度提高了8.99倍,rHV2纳米粒冻干粉复溶液也较其生理盐水溶液鼻腔给药的相对生物利用度提高了8.48倍。rHV2纳米粒及其冻干粉鼻腔给药后,均表现出显著的抗凝血活性,而rHV2生理盐水鼻腔给药则基本无效。结论:制备的rHV2鼻腔壳聚糖黏附纳米粒制剂具有较高的生物利用度,制成冻干粉后,仍保持较高的生物利用度。由于rHV2冻干粉制剂稳定性更高,有望成为rHV2经鼻腔给药的有效制剂。     

重组水蛭素Ⅲ滴眼液的组织分布和排泄研究

为了研究重组水蛭素Ⅲ(recombinant hirudin Ⅲ,rHVⅢ)滴眼剂在新西兰兔中的组织分布和粪尿排泄,用氯胺-T法将放射性同位素125I标记到rHVⅢ的酪氨酸残基上,通过同位素示踪方法考察滴眼给药后125I-rHVⅢ在新西兰兔体内的组织分布和粪尿排泄。结果发现新西兰兔滴眼给予125I-rHVⅢ后,125I-rHVⅢ主要通过肾脏排出,给药后120 h通过尿液排出放射性活度占总放射性活度的(81.54±10.78)%,同时通过粪便排出的放射性活度仅为(6.20±2.05)%。将放射性活度高的尿液,经RP-HPLC分离,实验结果表明尿液中存在重组水蛭素Ⅲ原型且比例达23.52%以上。组织分布实验结果表明,rHVⅢ原型及其代谢物在肾脏、血浆分布最多,脑中几乎无分布;rHVⅢ原型及其代谢物在眼部主要分布在角膜及巩膜,房水也有分布,而玻璃体和晶状体几乎没有分布。因此,rHVⅢ主要通过肾脏代谢并以原型和代谢物的形式通过尿液排出体外。     

重组水蛭素肠溶胶囊单次和多次给药在Beagle犬体内的药动学研究

目的:研究重组水蛭素肠溶胶囊单次和多次给药在Beagle犬体内的药动学特征。方法:取12只Beagle犬按随机对照法分为单次ig组和单次iv组,每组6只,按0.2 mg/kg ig或iv重组水蛭素,收集血样;清洗2周后12只犬按0.2 mg/kg ig重组水蛭素,连续给药7 d,收集血样,作为多次ig组。采用酶联免疫吸附法测定血浆中重组水蛭素浓度,以DAS 2.0软件计算药动学参数。结果:单次ig和单次iv重组水蛭素在Beagle犬体内药动学特征均符合二室模型,ig重组水蛭素肠溶胶囊的绝对生物利用度为(14.908±1.868)%;单次ig组和多次ig组犬体内重组水蛭素的t_(peak)分别为(2.105±0.243)、(3.000±0.000)h,t_(1/2β)分别为(8.660±2.965)、(14.870±2.710)h,c_(max)分别为(10.700±0.872)、(12.05±1.587)ng/m L,AUC_(0-1 440 min)分别为(55.250±4.386)、(58.978±6.002)ng·h/m L,两组间差异无统计学意义(P>0.05)。结论:ig重组水蛭素肠溶胶囊可一定程度被吸收入血;连续多天ig重组水蛭素肠溶胶囊在犬体内不产生蓄积,不改变其药动学特征。     

重组水蛭素Ⅲ多克隆抗体的制备

目的:制备重组水蛭素Ⅲ(rHV3)多克隆抗体。方法:分别用戊二醛法与碳二亚胺法处理抗原,电泳检测rHV3自身交联及与牛血清白蛋白(BSA)交联结果;分别免疫家兔、豚鼠和大鼠后取血清,双向免疫扩散试验测定效价。结果:rHV3交联BSA后作为抗原免疫豚鼠和家兔产生了抗体,抗体效价1∶16。结论:rHV3交联BSA作为rHV3抗原免疫家兔、豚鼠可以产生rHV3多克隆抗体。     

重组水蛭素-2在家兔鼻黏膜中降解的体外实验

目的考察重组水蛭素-2(rHV2)在家兔鼻黏膜中的降解情况。方法建立用HPLC测定家兔鼻黏膜和肠黏膜组织匀浆液中rHV2浓度的方法；测定不同浓度rHV2在家兔鼻黏膜组织匀浆液中及rHV2在不同pH值的家兔鼻黏膜组织匀浆液中的降解；比较家兔鼻黏膜和肠黏膜组织匀浆液对rHV2的降解；考察rHV2在家兔鼻黏膜酶提取液中的稳定性以及加入酶抑制剂对rHV2在家兔鼻黏膜组织匀浆液降解的抑制作用。结果rHV2在鼻黏膜匀浆液中的降解具有明显的药物浓度和pH依赖性；rHV2在鼻黏膜匀浆液中的稳定性优于在肠黏膜匀浆液中的稳定性；鼻黏膜酶提取液对rHV2的降解作用较小；酶抑制剂杆菌肽对rHV2在鼻黏膜匀浆液中的降解具有一定的抑制作用。结论与口服给药途径相比，rHV2鼻腔给药更有优势。     

重组水蛭素-2鼻腔黏附纳米粒的体外评价

目的:对制备的重组水蛭素-2(rHV2)壳聚糖鼻腔黏附纳米粒进行体外评价。方法:测定纳米粒的形态、粒径大小分布及表面电位;以超速离心测定纳米粒在不同介质中的释放度;采用在体蟾蜍上腭纤毛运动试验法考察纳米粒的纤毛毒性。结果:制备的rHV2壳聚糖纳米粒呈较为均匀分散的颗粒状,平均粒径为213.2 nm,纳米粒带正电荷,Zeta电位值为+30.61 mV,体系相对稳定性较高;rHV2纳米粒在乙酸缓冲液中的累积释放百分数明显高于在磷酸缓冲液中的累积释放百分数;rHV2纳米粒溶液的纤毛毒性较小(与生理盐水组相比,P>0.05)。结论:壳聚糖鼻腔黏附纳米粒有望成为rHV2鼻腔给药的递释系统。     

重组水蛭素Ⅲ口服乳糜微粒的研究

为了实现重组水蛭素Ⅲ口服给药途径并验证其药效.将其制成乳糜微粒,比较了3种制备方法,确定了逆相蒸发法为rHV3乳糜微粒的最佳制备方法.优化了制备条件,通过正交实验确定了rHV3乳糜微粒配方,制得的rHV3乳糜微粒的包封率为(65.08±1.96)%.在-20℃保存条件下rHV3乳糜微粒稳定性良好.药效学实验结果表明,口服rHV3乳糜微粒具有良好的抗凝和抗栓作用.     

眼镜蛇神经毒素分离纯化及其经大鼠直肠给药吸收的实验研究

目的 利用色谱技术从眼镜蛇粗毒中分离纯化神经毒素,探索神经毒素经大鼠直肠途径给药后的吸收情况和镇痛活性。方法 通过CM Sepharose Fast Flow阳离子交换色谱和Sephadex G-50凝胶过滤色谱两步法分离纯化神经毒素。采用免疫组织化学技术观察神经毒素在大鼠直肠组织中的分布。利用Shotgun质谱技术和数据库检测大鼠血浆神经毒素片段。利用HE染色观察神经毒素对大鼠直肠组织结构的影响。利用醋酸扭体法测定神经毒素直肠给药后镇痛活性。结果 通过色谱分离纯化得到电泳纯的神经毒素。神经毒素直肠给药3 h后直肠黏膜组织内神经毒素分布明显,阳性面积比率、平均光密度值、H-SCORE值与对照组相比差异明显(P<0.01)。质谱检测到大鼠血浆中神经毒素有关片段。HE染色表明神经毒素对大鼠直肠组织没有损伤,组织结构无明显病理变化。醋酸扭体法测定小鼠直肠给药神经毒素3 h后扭体抑制率达50%,提示具有镇痛活性。结论 眼镜蛇神经毒素可以通过直肠吸收入血并且发挥镇痛作用,为后续研究眼镜蛇神经毒素直肠给药制剂提供实验依据。     

重组水蛭素肠溶包衣微丸的制备及体外释放行为考察

目的研制重组水蛭素口服肠溶包衣微丸,并对其在不同pH释放介质中的释放行为进行考察,为重组水蛭素口服制剂的研究与开发提供实验依据。方法以羟丙甲基纤维素酞酸酯(HP55)为包衣材料,利用离心造粒机和流化床包衣设备制备重组水蛭素肠溶包衣微丸;采用二喹啉甲酸(BCA)法测定重组水蛭素肠溶包衣微丸的药物含量。结果所制备的重组水蛭素肠溶包衣微丸药物含量质量分数为3.513%。pH梯度释放实验结果表明,所研制的包衣微丸人工胃液中2 h药物仅释放4.98%;pH 5.8释放介质中继续释放,0.5 h释放82.13%,1 h释放95.47%;pH 7.2释放介质中继续释放,0.5 h释放97.53%,1 h释放98.33%。结论重组水蛭素肠溶包衣微丸在人工胃液中几乎不释药,可避免水蛭素被胃蛋白酶所降解;在人工肠液中药物释放快速而且完全,有利于水蛭素在肠道中的吸收。     

Evaluation of the contribution of the nasal cavity and gastrointestinal tract to drug absorption following nasal application to rats

Drugs applied to the nose in in vivo physiologic condition undergo absorption from the nasal cavity and the gastrointestinal (GI) tract because drug solution in the nasal cavity, together with mucus layer, is cleared to pharynx and then to the GI tract by coordinated beat of the cilia on nasal epithelial cells. The purpose of this study was to develop evaluate the contribution of the nasal cavity and the GI tract to drug absorption following nasal application and to clarify the relation to the transepithelial permeability of the drug (the permeability to Caco-2 monolayer, P(Caco-2)). Male Wistar rats received intravenous, nasal, and oral drug administration and drug concentration-time profiles in plasma were determined. Fractional absorption after nasal application (Fn) and oral administration (Fpo) were calculated from the area under the curve following intravenous injection (AUCiv), nasal application (AUCn), and oral administration (AUCpo) as AUCn/AUCiv and AUCpo/AUCiv, respectively. Fractional absorption from the nasal cavity (F(NC)) and the GI tract (F(GI)) following nasal application was calculated as (Fn-Fpo)/(1-Fpo) and Fpo(1-F(NC)), respectively. The shape of the curve between F(NC) and P(Caco-2) was similar with the one observed in the case of oral bioavailability except the curve shifted right. It is noteworthy that the relation between F(GI) and P(Caco-2) showed a bell-shaped curve with peak at 10(-6) cm/s of P(Caco-2). Highly permeable drug is primarily absorbed through the nasal mucosa before it is cleared to the GI tract. With the decrease in P(Caco-2), the larger amount of the drug is cleared to the GI tract and absorption from the GI tract is increased. Poorly permeable drug, on the other hand, was absorbed neither from the nasal was nor the GI tract. These findings suggest that the primary absorption site of drug after nasal application is decided by mucociliary clearance and absorption through the nasal mucosa.     

Absorption of oral enalapril in germ-free and microbially-associated rats

The effect of microbial status and presence of food in the gastrointestinal (GI) tract on absorption of an orally administered antihypertensive drug [14C]-enalapril (1 mg/10 microCi/kg body weight) was studied in non-fasted and fasted germ-free (GF) and microbially-associated (MA) rats. The absorption was evaluated from blood samples taken 0.5, 2 and 4 h after the administration of enalapril. Drug levels in the lungs, liver, and duodenal mucosa were also measured by counting [14C]-radioactivities at 4 h after the drug administration. During the 4 h monitoring period enalapril was poorly absorbed in non-fasted rats as compared to fasted animals. In non-fasted rats, the absorption of enalapril was slightly slower in GF than in MA rats. In fasted rats, no difference was found between GF and MA animals. The results show that food in the GI tract substantially lowers or retards the absorption of enalapril in rats. The GF status of the GI tract, however, did not substantially affect the absorption of the ester-type drug enalapril.     

Difference in absorption of the two structurally similar flavonoid glycosides, hyperoside and isoquercitrin, in rats.

The present study was to investigate oral absorption of the two similar flavonoid glycosides, isoquercitrin (IQ, quercetin-3-O-glucoside) and hyperoside (HP, quercetin-3-O-galactoside) in rats. Two groups of male SD rats received an oral dose of either IQ (4.5 mg/kg) or HP (6.0 mg/kg). Blood samples were collected via jugular vein at time intervals after drug administration and the plasma concentrations of the studied compounds were analyzed by HPLC. The stability of IQ and HP in the GI tract was also measured by incubation with various GI contents from rats. The results showed that unchanged IQ was barely detectable whereas the glucuronidated quercetin (the aglycone of IQ) was found to be the major form in plasma after oral administration of IQ. In contrast, HP could not be detected in plasma neither as unchanged form nor its aglycone or conjugated aglycone form. Additional in vitro stability studies demonstrated that HP is more stable than IQ in the GI tract. This suggests that IQ could be hydrolyzed easier than HP to its aglycone in GI tract before being absorbed. In conclusion, IQ, as a flavonoid glucoside, could be rapidly absorbed and transformed into glucuronidated quercetin and such absorption might be related to the hydrolysis of the type of sugar moieties attached to its aglycone molecule.     

Gastrointestinal transit and mucoadhesive characteristics of complexation hydrogels in rats

The aim of this study was to investigate the gastrointestinal (GI) transit and mucoadhesive properties of complexation hydrogels, poly(methacrylic acid-grafted-ethylene glycol). The fluorescent labeled complexation hydrogels containing different molar ratios of methacrylic acid/ethylene glycol and different particle diameters were synthesized by free radical solution polymerization. The GI transit profiles of microparticles after oral administration to rats were evaluated by determining the polymer remaining in the stomach and the small intestine. Moreover, the mucoadhesion to the duodenal mucosa was evaluated by an in situ perfusion method. The ethylene glycol content and particle size of the hydrogels influenced significantly the GI transit and mucoadhesive capacities. The microparticles composed of polymers prepared from 1:1 ratio of methacrylic acid/ethylene glycol and having diameters of <53 microm showed the strongest mucoadhesive capacity. These findings indicated that the hydrogels may be a promising tool for improving oral bioavailability of various drugs, which are poorly absorbed from the GI tract.     

Study on the characteristics of pectin-ketoprofen for colon targeting in rats

Pectin-ketoprofen (PT-KP) prodrug with the potential for colon targeted delivery has been evaluated. A sensitive HPLC method was established for the determination of concentration of ketoprofen (KP) in rats. This method was also used to evaluate the colon targeting property of PT-KP. KP or PT-KP was given to rats by oral administration at a dosage of 10mg/kg. Plasma and the different parts of gastrointestinal (GI) tract were taken after 2, 4, 6, 8, 10 and 12h of oral administration of KP or PT-KP to rats and the concentration of KP was measured by HPLC. Preliminary experiments show KP distributes mainly in stomach, proximal small intestine and distal small intestine. However, KP released from PT-KP mainly distributes in cecum and colon. Therefore, this approach suggests that PT-KP prodrug has a good colon targeting property.     

Baicalin, the predominant flavone glucuronide of scutellariae radix, is absorbed from the rat gastrointestinal tract as the aglycone and restored to its original form

When baicalin was orally administered to conventional rats, it was detected in their plasma for 24 h after administration, but baicalein, the aglycone of baicalin, was not detected. However, when baicalin was given to germ-free rats, only a small amount of baicalin was detected in their plasma within 2 h after the administration, its AUC0-lim (the area under the concentration-time curve from 0 to last determination time) being 12.0% of that in conventional rats. Subsequently, a considerable amount (55.1 +/- 6.2%) of baicalin was recovered from the gastrointestinal tract even 4 h after administration. When baicalein was orally administered to conventional rats, however, baicalin appeared rapidly in their plasma at an AUC0-lim value similar to that obtained after oral administration of baicalin, despite the absence of baicalein in plasma. When intestinal absorption was evaluated by the rat jejunal loop method, baicalein was absorbed readily, but only traces of baicalin were absorbed. Moreover, in conventional rats a small amount (13.4 +/- 3.1%) of baicalin and an appreciable amount (21.9 +/- 3.4%) of baicalein were recovered from the gastrointestinal tract even 4 h after oral administration of baicalin, but only a small amount (3.93 +/- 1.43%) of baicalein was detected in the intestinal tract 1 h after administration of baicalein. Baicalin was transformed to baicalein readily by the rat gastric and caecal contents. When baicalin was administered orally to conventional rats, an appreciable amount of baicalein was recovered in their gastrointestinal tracts. Moreover, baicalein was efficiently conjugated to baicalin in rat intestinal and hepatic microsomes. These results indicate that baicalin itself is poorly absorbed from the rat gut, but is hydrolysed to baicalein by intestinal bacteria and then restored to its original form from the absorbed baicalein in the body.     

Toxicokinetics of 14C-endosulfan in male Sprague-Dawley rats following oral administration of single or repeated doses

Endosulfan (ES), an organochlorine (OC) insecticide that belongs to the cyclodiene group, is one of the most commonly used pesticides to control pests in vegetables, cotton, and fruits. The toxicokinetics of 14C-endosulfan following oral administration of a single dose of 5 mg/kg body weight was investigated in male Sprague-Dawley rats. Three rats were sacrificed 30 min, 1 h, 2 h, 4 h, and 8 h after dosing. 14C-endosulfan radioactivity was detected in all tissues at each time point. In a separate experiment urine and feces were collected for 96 h. The total radioactivity recovered in the excreta for 4 days was 106.8% +/- 26.2%, with fecal elimination the major route of elimination route (94.4% +/- 21.4%). The cumulative excretion in the urine for 4 days was 12.4% +/- 4.8%. Radioactivity 8 h after administration was highest in gastrointestinal (GI) tract tissue (20.28 +/- 16.35 mg ES eq./L) and lowest in muscle (0.18 +/- 0.06 mg ES eq./L). The toxicokinetic parameters obtained from 14C-endosulfan-derived radioactivity in blood were distribution half-life (T1/2 x) = 31 min and terminal elimination half-life (T1/2 y) = 193 h. Blood concentration reached its maximum (Cmax) of 0.36 +/- 0.08 mg ES eq./L 2 h after the oral dose. Endosulfan was rapidly absorbed into the GI tract in rats, with an absorption rate constant (ka) of 3.07 h(-1).     

Absorption of rivastigmine from different regions of the gastrointestinal tract in humans

The objective of this study was to evaluate the rate and extent of absorption and metabolism of rivastigmine (Exelon), ENA 713) after site-specific delivery of the drug in the gastrointestinal (GI) tract using a naso-intestinal intubation technique. Healthy adult subjects (n = 7) received, on four separate occasions, a 3-mg dose of a rivastigmine solution (2 mg/mL) orally and via a naso-intestinal tube to three GI sites (jejunum, ileum, and ascending colon). On each of the 3 treatment days for regional GI dosing, the tube was progressed to each of the three GI sites, which was determined by a radiographical technique prior to dosing. On the fourth day, following tube withdrawal, the subject received a 3-mg oral dose of a rivastigmine solution. Plasma samples were obtained at different multiple time points, and the plasma concentrations of rivastigmine and its metabolite, NAP 226-90, were determined using a gas chromatography/mass spectrometry (GC/MS) method. Rivastigmine was rapidly absorbed following both oral administration and site-specific delivery to different regions of the GI tract (jejunum, ileum, and ascending colon). Compared with oral administration (AUV(0- infinity ) = 21 ng*h/mL, C(max) = 12.8 ng/mL, and t(max) = 0.87 h), delivery of the drug directly into the ileum, jejunum, and ascending colon did not change the extent of absorption, but the time to peak concentration appeared to be smaller (mean t(max) ranged from 0.4-0.6 h, with no change in C(max)). The relative bioavailability of rivastigmine from all three regions of the GI tract was comparable to that following oral administration. The metabolite levels (AUC, C(max)) were also similar among the three different regions of the GI tract when compared to the oral dose. It was concluded that rivastigmine is rapidly and equally well absorbed following an oral dose and after specific delivery to different regions of the small intestine and ascending colon. GI metabolism of rivastigmine to its major metabolite, NAP 226-90, occurs to a similar extent in different segments of the GI tract.     

A distribution study with (14)C-otilonium bromide in the rat: evidence for selective tropism for large intestine after oral administration.

The aim of this study was to determine the plasma levels and the tissue distribution of otilonium bromide, measured as total radioactivity, after oral administration of 2 mg/kg of (14)C-labeled drug to rats. Radioactivity levels were very low in the plasma (ranging from 2.7 ng Eq/ml at 1.5 h to 0.6 ng Eq/ml at 24 h) as compared with those found in the gastrointestinal (GI) tract, indicating negligible systemic otilonium bromide absorption. Results from both quantitative radioluminography of whole body tissue distribution and radioassay of dissected parts of the GI tract carried out with liquid scintillation counting clearly demonstrate the presence of radioactive compounds in the walls of the GI tract at all sacrifice times. In the other tissues and organs examined, radioactivity was only found in trace amounts in the liver. The presence of radioactivity in the GI walls reflected the transit kinetics of drug-enriched contents. The radioactivity in large intestine walls was measurable at otilonium bromide concentrations in the range of micromole equivalents/kg, from 4 to 8 h after drug administration. Total body radioactivity recovery was 95, 101, 24, and 9% at 1.5, 4, 8, and 24 h, respectively. In conclusion, orally administered (14)C-otilonium bromide is poorly absorbed systemically, as indicated by the very low plasma radioactivity levels, but it is able to effectively penetrate into the large intestine walls, a recognized target for drugs oriented toward irritable bowel syndrome therapy.