艾片的大鼠在体肠吸收动力学研究

目的:研究艾片的大鼠在体肠吸收动力学。方法:采用大鼠在体单向灌流实验,利用气相色谱法测定艾片中龙脑含量,分别研究灌流流速、药物浓度、吸收部位对艾片吸收的影响。结果:灌流流速、药物浓度、吸收部位对艾片吸收速度常数(Ka)和表观吸收系数(Papp)无显著性影响。结论:艾片的肠吸收机制为被动扩散,其吸收动力学符合一级方程。     

穗花杉双黄酮大鼠在体肠吸收动力学的研究

采用大鼠在体单向肠灌流实验模型,用HPLC-UV法测定灌流液中药物浓度,研究穗花杉双黄酮肠吸收动力学。结果表明穗花杉双黄酮在十二指肠、空肠、回肠和结肠的吸收速率常数（Ka）、药物表观渗透系数（Papp）差异无统计学意义（P>0.05）,提高药物浓度的吸收速率常数基本保持不变。在大鼠各肠段均有吸收,无特定吸收部位,吸收机制为被动扩散。     

川陈皮素自组装前体脂质体大鼠在体肠吸收研究

目的 考察川陈皮素自组装前体脂质体在大鼠肠道的吸收情况。方法 以川陈皮素溶液、普通脂质体为对照,采用单向灌流法,研究不同肠段川陈皮素自组装前体脂质体的大鼠肠道吸收动力学。结果 3种制剂在全肠段都有吸收,在各个肠段,3种制剂的净累积吸收量、Ka和Peff均表现为川陈皮素自组装前体脂质体>川陈皮素普通脂质体>川陈皮素(P<0.05)。结论 川陈皮素自组装前体脂质体可显著促进川陈皮素的口服吸收。     

长春西汀的大鼠在体肠吸收研究

采用单向灌流技术考察长春西汀的大鼠在体肠吸收性质.结果表明,灌流速度对药物吸收速率常数(Ka)和表观吸收系数(Papp)有极显著影响(P＜0.01);药物浓度对Ka和Papp无显著影响(P＞0.05);药物在全肠道吸收较好,吸收窗主要在小肠,且小肠内无明显的特定吸收部位;羟丙基-β-环糊精在1%～4%范围内对药物的肠吸收无显著影响.     

原儿茶醛大鼠小肠吸收机理的研究

目的:研究原儿茶醛的小肠吸收机理。方法:利用大鼠在体肠吸收模型,以高效液相色谱法测定原儿茶醛的表观小肠吸收速率。结果:原儿茶醛在低、中、高3种浓度下的表观小肠吸收速率分别为1.1341/h、1.1 637/h、1.0 847/h。结论:原儿茶醛大鼠小肠吸收机理为被动扩散。     

盐酸麻黄碱的大鼠肠吸收研究

目的：研究盐酸麻黄碱的肠吸收机制。方法：利用大鼠在体单向肠灌流模型,采用HPLC法测定灌流液中盐酸麻黄碱含量,分别考察灌流速度、盐酸麻黄碱质量浓度、不同肠段以及P-糖蛋白抑制剂对盐酸麻黄碱肠吸收的影响。结果：灌流速度对盐酸麻黄碱吸收速率常数（Ka）和表观吸收系数（Papp）有极显著影响（P〈0.01）;灌流液中盐酸麻黄碱质量浓度对Ka和Papp无显著影响（P〉0.05）;盐酸麻黄碱在小肠各肠段（十二指肠、空肠和回肠）的Ka和Papp无显著性差异（P〉0.05）,但其Ka值显著大于在结肠处的值（P〈0.05）,而各肠段的Papp无显著性差异（P〉0.05）,P-糖蛋白抑制剂对盐酸麻黄碱在各肠段的Ka和Papp无显著影响（P〉0.05）。结论：盐酸麻黄碱在大鼠肠道内的吸收机制为被动扩散,不存在饱和吸收;其在全肠道吸收较好,吸收窗主要在小肠,且小肠内无明显的特定吸收部位;盐酸麻黄碱可能不是P-糖蛋白的底物。     

头孢唑肟致尿毒症透析患者中枢神经系统不良反应1例

目的研究连翘苷在大鼠小肠的吸收特性。方法采用外翻肠囊法建立连翘苷大鼠小肠吸收模型,HPLC测定连翘苷的含量,分别进行大鼠小肠的十二指肠、空肠、回肠3个肠段、不同浓度吸收特性研究,以及P-糖蛋白（P-gp）抑制剂盐酸维拉帕米和吸收促进剂吐温-80对连翘苷吸收的影响研究。结果连翘苷浓度为10,20,40μg.mL-1 3个浓度时,吸收速度常数ka无显著性差异（P〉0.05）;在不同肠段中的吸收,通过量由多到少依次为回肠〉空肠〉十二指肠;加入盐酸维拉帕米和吐温-80的小组与正常组相比,吸收速度常数ka无显著性差异（P〉0.05）。结论在试验剂量范围内,连翘苷的吸收呈一级动力学过程,吸收机制主要为被动扩散;连翘苷不是P-糖蛋白的底物。     

盐酸莫西沙星在正常和模拟失重大鼠中肠吸收特性研究

目的:研究盐酸莫西沙星在SD大鼠肠道不同部位的吸收特性,并对比盐酸莫西沙星在正常和模拟失重大鼠中肠吸收变化。方法:建立大鼠在体单向肠灌流模型,采用HPLC法分别研究了不同浓度(1,2,4 mg·ml^-1)、不同肠段(十二指肠、空肠、回肠)的盐酸莫西沙星吸收情况,并对比正常和模拟失重1,2,3,4周大鼠的肠吸收变化。结果:不同浓度的盐酸莫西沙星在SD大鼠各肠段的有效渗透系数(Peff)差异无统计学意义(P>0.05),表明盐酸莫西沙星在SD大鼠小肠内吸收无明显变化,且无自身浓度抑制作用,主要以被动转运方式吸收。盐酸莫西沙星在十二指肠、空肠、回肠的吸收相近(P>0.05),莫西沙星不存在特异性的吸收部位。比较正常与各模拟失重组吸收参数发现,模拟失重1周和2周的吸收速率参数(Ka)无明显变化,模拟失重3周时,Ka增大了约1倍,与正常组比较差异有统计学意义(P<0.05),到模拟失重4周时,Ka又接近正常水平。结论:盐酸莫西沙星在大鼠小肠吸收方式以被动转运为主,在肠道中易吸收,且不存在特异性吸收部位。模拟失重会加快莫西沙星在肠道的吸收,且模拟失重3周时,变化最明显。该结果提示机体进入失重环境后有必要随时间调整莫西沙星的服用量。     

戟叶马鞭草苷大鼠在体肠吸收动力学研究

目的:建立同时测定肠循环液中戟叶马鞭草苷与酚红浓度的高效液相色谱(HPLC)法,探讨戟叶马鞭草苷在大鼠各肠段的吸收动力学特征与不同药物浓度对肠吸收的影响。方法:采用大鼠在体肠灌流吸收实验,以HPLC法对肠循环液中的戟叶马鞭草苷与酚红进行分析。色谱柱为DiamonsilTMC18(250mm×4.6mm,5μm),流动相为乙腈-0.05%磷酸溶液(梯度洗脱),流速为1.0mL·min-1,检测波长为238nm(戟叶马鞭草苷)和430nm(酚红),柱温为30℃。结果:戟叶马鞭草苷浓度在50～200μg·mL-1范围内,其在肠道内的吸收量与浓度成正比例关系。不同药物浓度(50、100、200μg·mL-1)条件下的吸收速率常数(Kα)分别为(69.2±4.3)、(70.9±4.1)、(69.3±3.2)h-1,无显著性差异(P>0.05);在十二指肠、空肠、回肠、结肠的Kα分别为(0.0405±0.0039)、(0.0365±0.0032)、(0.0379±0.0045)、(0.0349±0.0037)h-1,无显著性差异(P>0.05)。结论:戟叶马鞭草苷在大鼠肠道的吸收符合一级动力学过程,吸收机制为被动扩散。戟叶马鞭草苷在整个肠道均有吸收,故可以将其研制成缓、控释制剂。     

5-氟尿嘧啶口服微乳的制备及其大鼠肠吸收作用研究

目的:制备5-氟尿嘧啶(5-Fu)口服微乳,并考察其在大鼠肠吸收的作用。方法:以肉豆蔻酸异丙酯为油相、单辛/癸酸甘油酯为乳化剂,借助伪三元相图法对不同5-Fu微乳处方进行评价;用外翻肠囊法制备肠吸收离体模型,考察5-Fu微乳的吸收部位和促吸收效果。结果:选择肉豆蔻酸异丙酯-单辛/癸酸甘油酯-无水乙醇-水(Km=1∶2)体系作为5-Fu微乳的载药体系;与其溶液比较,5-Fu微乳可明显改善药物的肠吸收,小肠中后段是其最佳吸收部位,90min时累积吸收率微乳是溶液的3倍。结论:所制备的5-Fu微乳性质稳定、肠吸收效果良好。     

马洛替酯单向灌流法大鼠在体肠吸收机制研究

目的:考察马洛替酯在大鼠体内肠吸收机制。方法:采用大鼠在体单向灌流法进行肠吸收实验,利用高效液相色谱法测定灌流流出液中马洛替酯的浓度,按重量法计算动力学参数。结果:马洛替酯在十二指肠、空肠、回肠和结肠的吸收速率常数(Ka)、有效渗透系数(Peff)差异均有统计学意义(P<0.05);供试液的浓度对十二指肠的Ka值和Peff值差异无统计学意义(P>0.05)。结论:马洛替酯在大鼠体内肠吸收机制为被动扩散,不存在饱和吸收,且以肠道中上部的吸收为主。     

在体单向肠灌流模型研究槲皮素的大鼠肠吸收特性

目的考察银杏中活性黄酮成分槲皮素在大鼠肠道的吸收特性。方法以酚红为标示物,采用在体单向肠灌流模型,HPLC法测定槲皮素在体肠灌流的浓度变化,研究槲皮素在小肠内的吸收情况。结果槲皮素在（1．01～20．18ug／mL）浓度范围内其肠管通透率和血管通透率均基本保持不变,各浓度间无显著性差异（P〉0．05）。结论药物浓度对槲皮素通透率无影响,其吸收机制可能为被动扩散。     

芒果苷大鼠在体肠道吸收机制研究

目的:研究芒果苷大鼠在体肠道吸收机制。方法:采用大鼠在体肠段灌流模型,建立高效液相色谱/紫外分光光度法测定肠循环液中芒果苷的浓度,研究不同芒果苷浓度、胆汁及吸收部位对芒果苷吸收参数的影响。结果:芒果苷在5.0~25.0μg.mL-1浓度范围内对小肠吸收速率常数(Ka)无影响;在12.5μg.mL-1浓度下对结扎胆管大鼠的小肠Ka有影响;各肠段的Ka回肠>空肠>结肠>十二指肠,分别为0.164、0.132、0.125、0.107h-1。结论:芒果苷的吸收符合一级动力学特征,吸收机制为被动扩散;芒果苷在各肠段均有较好的吸收,胆汁使芒果苷在小肠的透过系数增大。     

Intestinal Water and Solute Absorption Studies: Comparison of in Situ Perfusion with Chronic Isolated Loops in Rats

The effects of lumenal glucose on jejunal water transport and the influence of glucose-induced water absorption on solute uptake from single-pass perfusions are compared in anesthetized rats in situ and isolated chronic loops in unanesthetized rats in vivo. While the magnitudes of solute membrane permeabilities are consistently higher in the chronic loop system, the effects on water transport and its promotion of jejunal solute uptake are comparable between the two experimental systems. The effect of glucose-induced water absorption on the enhanced/baseline jejunal uptake ratio of the hydrophilic drug, acetaminophen, is greater than that for the lipophilic drug, phenytoin, in both experimental systems. The fact that chronic loop effective solute permeabilities were equivalent to solute membrane permeabilities in situ is consistent with greater lumenal fluid mixing in vivo. In addition, in situ body temperature affects the uptake of phenytoin but not acetaminophen, water, or glucose. This suggests that active and paracellular solute transport is not compromised in situ, while membrane partitioning and diffusion of lipophilic species are more sensitive to experimental conditions.     

在体单向灌流法研究加巴喷丁的大鼠肠吸收

采用在体单向灌流法考察加巴喷丁的大鼠肠吸收特性.结果表明,加巴喷丁在小肠各段(十二指肠段、空肠段和回肠段)和结肠均有吸收.低、中浓度(1和10 mmol/L)时药物在小肠各段的吸收速率常数(Ka)和有效渗透系数(Peff)显著大于结肠段(P＜0.05),高浓度(50 mmol/L)时十二指肠段的吸收显著大于结肠段(P＜0.05).加巴喷丁浓度对其在小肠各段的吸收有显著影响,低浓度组小肠各段药物的Ka和Peff显著大于高浓度组(P＜0.05),而药物浓度对结肠段的吸收无显著影响.     

Influence of Anesthetic Regimens on Intestinal Absorption in Rats

We compared the influence of anesthetic regimens using urethane (U), pentobarbital (P), ether (E), and ketamine/midazolam (K) on the intestinal absorption of several probes using a single-pass per-fusion technique in rats. The selected probes were D-glucose (1 mM) for the resistance of the unstirred water layer (UWL), D-glucose (100 mM) for the capacity of carrier-mediated D-glucose transport, L-glucose, and urea for membrane-limited passive transport, and tritiated water (³H₂O) for blood flow at the absorption site. The absorbed fraction of D-glucose (1 mM) was the smallest for U and the largest for P, suggesting that the resistance of UWL is the largest for U and the smallest for P. The absorbed fraction of D-glucose (100 mM) was the largest for P (U = E = K < P), suggesting a higher capacity of carrier-mediated D-glucose transport for P. The absorbed fraction of urea was similar for all anesthetics, while that of L-glucose was the smallest for K (U = P = E > K). Although the results for these two markers of membrane-limited passive transport were inconsistent, the passive permeability of the intestinal membrane may be lower when treating with K. The intestinal absorptions of D-glucose (1 and 100 mM), L-glucose, and urea were, in general, lower with any of the anesthetics than under nonanesthesia (N), suggesting increased resistance of UWL and decreased intestinal membrane permeability by carrier-mediated and passive transport under anesthesia. The only exception was the absorption of D-glucose (100 mM) under P, which was comparable to that under N. The results were similar when considering the membrane permeability clearance estimated by correcting for the resistance of UWL. The blood flow at the absorption site, estimated from the absorption of ³H₂O, was decreased under U, compared with N, and increased under K(U

in vivo.     

Effect of Oleic Acid Vesicles on Intestinal Absorption of Carboxyfluorescein in Rats

The effect of oleic acid vesicles (ufasomes) on the intestinal absorption of entrapped carboxyfluo-rescein (CF) was investigated by an in situ closed–loop method in rats. Entrapment of CF in ufasomes enhanced the absorption of CF at the earlier stage following intraduodenal administration, and the threshold concentration of the fatty acid for promoting the absorption of CF was approximately 8 mM. The absorption of CF from the large intestine was promoted much more effectively than from the small intestine. These studies suggest that ufasomes have potential as carriers for the oral administration of poorly absorbable drugs.     

Simultaneous Prediction of Intestinal Absorption and Metabolism Using the Mini-Ussing Chamber System

The purpose of this study was to investigate the possibility of simultaneous prediction of the intestinal absorption and metabolism in a mini-Ussing chamber equipped with rat intestinal tissues, based on the transport index (TI). TI value was defined as the sum of drug amounts, by mass balance method, transported to the basal-side component and drug amounts accumulated in the tissue, which are normalized by area under the curve of the drug in the apical compartment. Midazolam and nifedipine with high permeability were used as typical P450 substrates to examine the possibility of simultaneous prediction of intestinal absorption and metabolism. The metabolite formation of both compounds was observed and ketoconazole strongly inhibited the metabolite formation of both compounds in rat intestinal tissues, leading to the improvement of the TI value to a statistically significant extent for both compounds. TI ratio of nifedipine between in the presence and absence of ketoconazole was larger than that of midazolam, which was consistent with the reported lower value of fraction absorbed multiplied by intestinal availability of nifedipine. Therefore, the mini-Ussing chamber, equipped with animal intestinal tissues, showed potential to predict the intestinal absorption and metabolism simultaneously.     

Enhanced Intestinal Absorption of Cyclosporine in Rats Through the Reduction of Emulsion Droplet Size

The intestinal absorption of cyclosporine was measured in situ in rats using an olive oil emulsion prepared by either stirring or homogenization. The surface area of the homogenized dosage form was twice that of the stirred dosage form. The apparent permeability of cyclosporine from the homogenized emulsion was about twice that of the emulsion prepared by stirring. The examination of absorption in different intestinal segment lengths suggested the presence of an absorption window. The absorption of cyclosporine appeared to be concentration independent and, therefore, non-carrier mediated. The dependence of absorption upon the intestinal perfusion rate suggested that the stagnant aqueous layer is the rate-limiting barrier in cyclosporine absorption. These results indicate that the bioavailability of cyclosporine administered in an emulsion can possibly be increased by enhancing its rate of absorption through the reduction of droplet size.     

杜仲提取物中4个主要成分的大鼠在体肠吸收

考察了杜仲提取物中京尼平苷酸(1)、新绿原酸(2)、绿原酸(3)和隐绿原酸(4)在大鼠小肠的吸收动力学特性.采用大鼠在体肠循环灌流模型,建立了UPLC-MS/MS法测定1～4,考察了pH值、样品浓度、胆汁和P-糖蛋白(P-gp)抑制剂对1～4在体肠吸收的影响.结果显示,1在pH 7.4条件下吸收较差,2、4在不同pH值下的吸收有显著差异,而3对pH值不敏感.2、3在中浓度样品溶液(4.0 mg/ml)的3h累积吸收率(A)显著高于高浓度样品(8.0 mg/ml),两者在高浓度下的吸收存在饱和现象.胆汁对1～4的吸收均有显著抑制作用.1～4在整个肠段均有吸收,主要吸收部位在小肠;P-gp抑制剂不影响杜仲提取物的肠吸收,提示1～4可能不是P-gp的底物.