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。     

石杉碱甲大鼠在体肠吸收动力学研究

目的研究石杉碱甲在大鼠小肠及各肠段的吸收动力学特征.方法采用大鼠在体方式对石杉碱甲进行了大鼠小肠及各肠段的吸收动力学研究;采用HPLC法测定石杉碱甲在大鼠体内肠吸收循环液中的药物浓度;采用UV法测定循环液中酚红浓度.结果石杉碱甲在小肠中吸收较好且没有特定吸收部位,各肠段吸收速率按十二指肠、空肠、回肠、结肠依次为0.001 0、0.000 9、0.001 1、0.000 9 h-1.结论结肠的吸收速率常数与小肠段相近,药物在肠道的吸收呈现一级吸收动力学,吸收机制为被动吸收,提示适于制备日服一次(24 h)缓释给药制剂.     

齐墩果酸磷酸酯二钠盐的小肠吸收动力学

目的研究齐墩果酸磷酸酯二钠盐(OANa2)大鼠小肠的吸收情况。方法采用大鼠在体、离体小肠回流实验装置,利用高效液相色谱法测定肠循环液中OANa2的含量,采用紫外分光光度法测定肠循环液中酚红的含量。结果在体小肠胆管结扎与不结扎的药物吸收百分率(PA)分别为43.4%、43.7%。实验浓度下,离体小肠上、下段的吸收速率常数(Ka)分别为0.318 h、0.300 h。此外,离体小肠实验在3种不同浓度下的吸收速率常数分别为0.270 h、0.322 h、0.284 h。胆管结扎与不结扎的药物吸收百分率无显著性差异(P>0.05);OANa2在小肠不同肠段的吸收速率常数无显著差异(P>0.05)。结论在实验浓度范围内,OANa2的小肠吸收机制属于被动扩散。     

岩白菜素的大鼠在体肠吸收动力学

目的 研究岩白菜素在大鼠肠道中的吸收机理.方法 采用HPLC测定大鼠在体肠实验中岩白菜素的含量,从吸收部位、药物浓度、pH三方面研究岩白菜素在大鼠小肠中的吸收特性.结果 岩白菜素在全肠段均有吸收,但不同肠段的吸收存在差异.药物浓度和循环液的pH对吸收均有影响.结论 岩白菜素在大鼠肠道内吸收较少,吸收机制可能为被动扩散.     

氟他胺大鼠在体肠吸收动力学研究

目的:研究氟他胺在大鼠小肠各段的吸收动力学特征,为其剂型设计提供依据.方法:采用在体试验法,分别用紫外可见分光光度法及高效液相色谱法(HPLC)测定酚红和氟他胺的浓度.结果:在体全小肠段吸收实验中,药液在体循环6h后,43.58％的药物被肠道吸收;氟他胺在十二指肠、空肠、回肠、结肠的吸收百分率分别为(10.66±2.98)％·cm-1·h-1、(10.12±3.05)％·cm-1·h-1、(10.47±3.1)％·cm-1·h-1、(10.11±3.02)％·cm-1·h-1,四个肠段的肠壁通透系数分别为:(0.587±0.208) cm2·h-1、(0.571±0.193) cm2·h-1、(0.593±0.197) cm2·h-1、(0.539±0.192) cm2·h-1;药物浓度为15.48～68.48 μg· mL-1时,小肠的吸收速率在(0.092±0.010) h-1～(0.090±0.012)h-1之间基本相似;供试药液中聚山梨酯-80的含量分别为1％、2％、5％时,肠的吸收速率分别为:(0.097±0.017)h-1、(0.078±0.012)h-1、(0.073±0.009) h-1.结论:氟他胺在大鼠肠道各部分均有吸收,且吸收呈一级动力学过程,吸收机制为被动扩散;实验范围内,药物浓度和聚山梨酯-80含量对药物的吸收速率无影响;大鼠各肠段的吸收速度无显著性差异,说明氟他胺在整个肠段均有较好的吸收.     

芒果苷大鼠肠吸收特性研究

目的研究芒果苷在大鼠肠道的吸收动力学特征。方法采用大鼠在体肠循环实验,用超高效液相色谱法和紫外分光光度法分别测定芒果苷和酚红的浓度,考察药物浓度、pH值和不同肠段对芒果苷吸收的影响,并与知母水煎液比较芒果苷在大鼠肠道吸收的差异。结果芒果苷浓度为2.0,5.0,10.0,20.0μg.mL-1时,吸收速率常数(ka)分别是0.0541,0.0467,0.0491,0.0220 h-1,吸收百分率(Fa)分别是14.05%,13.14%,12.43%和5.82%;随肠液pH升高,ka和Fa依次增加;芒果苷在肠段内吸收存在差异,各肠段的吸收速率常数按结肠、十二指肠、回肠和空肠依次下降;知母水煎液组中,肠循环液中芒果苷含量的上升和新芒果苷含量的下降呈同步变化。结论芒果苷在大鼠小肠段的吸收存在高浓度饱和现象,并且受到药物浓度、肠循环液pH值、肠段等因素的影响。     

雷帕霉素自微乳化释药系统的大鼠在体单向灌流肠吸收

目的:考察雷帕霉素自微乳化制剂的大鼠在体单向灌流肠吸收特征。方法:采用大鼠在体小肠单向灌流实验模型,以高效液相色谱法测定灌流液中药物浓度,分别研究不同药物浓度、不同吸收部位、不同灌流速度以及胆管结扎与否对雷帕霉素自微乳化制剂大鼠肠吸收的影响。结果:药物浓度和胆管结扎与否对雷帕霉素微乳的吸收百分率(P%)、吸收速率常数(Ka)以及表观吸收系数(Papp)无显著性影响(P>0.05);灌流速度和大鼠肠段不同吸收部位对P%、Ka以及Papp有显著性影响(P<0.05),其中回肠的P%、Ka和Papp值显著大于其余各肠段(P<0.05),结肠段吸收参数值显著低于十二指肠、空肠、回肠段(P<0.05);同等药物质量浓度下,自微乳化制剂的肠吸收参数值显著高于市售口服液制剂。结论:雷帕霉素自微乳化制剂吸收速率常数不受药物质量浓度的影响而与灌流速度和大鼠肠段不同吸收部位有关(P<0.05)。胆汁排泄和胆汁分泌在本实验条件下不影响药物肠道吸收。药物在大鼠小肠主要通过被动扩散方式吸收,RAPA微乳在整个肠段均有吸收,其中回肠吸收最好,且全肠吸收效果优于市售雷帕霉素口服液。     

左羟丙哌嗪的大鼠在体肠吸收特性

目的研究左羟丙哌嗪大鼠的在体肠吸收特性。方法采用大鼠在体小肠循环灌注模型,用HPLC同时测定灌注液中酚红和左羟丙哌嗪的含量。结果左羟丙哌嗪12.8~80.0μg.ml-1与小肠吸收量呈线性关系,吸收速率常数Ka几乎不变;各肠道间Ka值无显著性差异(P>0.05),十二指肠、空肠、回肠和结肠的Ka值分别为0.039±0.004、0.042±0.010、0.037±0.003、0.034±0.004 h-1。结论左羟丙哌嗪浓度12.8~80.0μg.ml-1在小肠段的吸收呈一级动力学过程,吸收机制为被动扩散,主要吸收部位在小肠段,且无特定的吸收窗。     

在体单向肠灌流模型研究维胺酯的大鼠肠吸收特性

目的研究维胺酯在大鼠小肠的吸收动力学特性。方法采用在体单向灌流模型,对维胺酯进行了大鼠小肠吸收动力学实验,以紫外可见分光光度法和高效液相色谱法分别测定循环液中酚红和维胺酯的含量,计算吸收性能参数。结果不同剂量维胺酯在小肠的吸收速率常数Ka差异无统计学意义(P>0.05),胆管结扎与不结扎对吸收速率无明显影响;维胺酯在小肠各部位吸收速率常数Ka按十二指肠、空肠、回肠、结肠顺序依次下降。结论维胺酯在大鼠各肠段均有吸收,在肠道的吸收呈现一级吸收动力学,吸收机制为被动扩散。     

在体单向灌流法研究β-蜕皮甾酮大鼠在体肠吸收特性

目的考察β-蜕皮甾酮的肠道吸收特性,探究β-蜕皮甾酮生物利用度低的原因。方法采用大鼠在体单向肠灌流模型,运用HPLC法测定药物浓度。分别考察小肠吸收部位(十二指肠、空肠、回肠、结肠),药物浓度,灌流液pH值,肠道菌群对β-蜕皮甾酮吸收的影响。结果β-蜕皮甾酮在不同肠段的吸收速率常数(K_a)由高到低依次为回肠、结肠、空肠、十二指肠;以β-蜕皮甾酮浓度为50、100、200μg·mL~(-1)的含药缓冲液在空肠进行吸收实验,K_a和小肠有效渗透系数(P_(eff))差异无统计学意义;药物的吸收程度在空肠随pH值升高而增加;大鼠肠道菌群失衡会干扰β-蜕皮甾酮的吸收。结论β-蜕皮甾酮在各个肠段均有吸收,但在肠道下部吸收较好;吸收机制为被动扩散;药物在碱性环境下吸收较好;肠道菌群对β-蜕皮甾酮吸收有显著影响。     

Apparent dose-dependent oral absorption of cyclosporin a in rats

The oral absorption of cyclosporin A (CyA) was studied in rats after 6, 12, 18, and 23 mg kg^?1 doses were given in an olive oil solution to determine if CyA absorption from the gastrointestinal tract was dose-dependent. Using serial blood samples obtained at various times after the respective doses, analysis of the resultant blood CyA concentration–time curves suggested that the rate of CyA absorption for all four doses was an apparent zero-order process. Moreover, the rate of CyA absorption appeared to be dose-dependent, increasing as the dose of CyA increased. Similarly, the extent of CyA absorption (F) also exhibited dose-dependent characteristics in this study. F is increased from 0·13 after the 6 mg kg^?1 dose to 0·22 with the 18 and 23 mg kg^?1 doses (p < 0·05). In the present investigation, the observed values for the duration of drug absorption (T), terminal first-order rate constant (β) and corresponding elimination half-life (T_1/2β) of approximately 4–5 h, 0·030 h^?1 and 21–28 h, respectively, were similar for all CyA doses. Moreover, no difference in β was observed after oral or intravenous drug administration. Absorption lag times of 1–2 h were found. The results suggested that the apparent dose-dependent absorption of CyA observed in the present study was possibly related to the effects of olive oil on gastric emptying and that CyA might be unstable in the gastric fluids and/or metabolized by the gastric mucosa.     

药物的肠吸收与处置研究进展

对近几年药物肠吸收与处置方面的研究进展进行了综述。包括:特定部位吸收、代谢的认识和利用,与药物首过效应有关的肠壁外泌及代谢作用的介绍,促进药物肠道吸收的方法及常用研究模型的比较。     

Estimate of Volume/Flow Ratio of Gastrointestinal (GI) Fluids in Humans Using Pharmacokinetic Data

Based on the mixing tank and tube models for drug absorption, the apparent absorption rate constant is shown to be related to the fraction of dose absorbed as a function of the volume/flow ratio of GI fluids. This analysis applies to drugs that are absorbed according to first-order kinetics, without limitation by dissolution rate, lumenal decomposition, or first-pass metabolism. Analysis of pharmacokinetic data of drugs that fit these criteria and are absorbed to varying extents enabled the estimation of the volume/flow ratio of GI fluids in humans; it was found to be 1.6 ± 0.3 (SE) hr using a mixing tank model and 0.32 ± 0.05 hr using a tube model. These findings are discussed with respect to volume and flow parameters used in the design of various types of drug absorption studies.     

托美丁在大鼠肠道的吸收动力学

目的:研究托美丁在大鼠各肠段的吸收动力学特征。方法:采用大鼠离体肠外翻模型,用HPLC法对托美丁进行检测,计算托美丁在肠道的吸收参数。结果:托美丁在全肠段均有良好吸收,吸收速率按空肠、十二指肠、结肠、回肠的顺序依次下降,吸收速率常数依次为0.292 8,0.214 5,0.186 9,0.080 9 h-1。结论:托美丁在大鼠整个肠段的吸收呈现一级动力学特征,吸收机制为被动扩散。     

大鼠在体吸收连翘苷的机理研究

目的研究连翘苷在大鼠消化道内的吸收机理。方法采用HPLC测定大鼠在体实验中连翘苷的含量,分别进行大鼠原位胃吸收、结肠、小肠全肠段、分肠段(十二指肠、空肠、回肠)合用吸收促进剂(SDS、牛胆盐、冰片、卡波姆)的连翘苷吸收机理研究。结果连翘苷各时间点含量几乎不变。结论口服连翘苷在大鼠消化道内并无吸收。     

The effect of aniline derivatives on absorption of fluid,glucose and sodium in isolated duodenal segments from rats

Summary Paracetamol (5–15 mmol · l^–1), phenacetin (1–3 mmol · l^–1) and acetanilide (5–20 mmol · l^–1) enhanced fluid, glucose and sodium absorption of isolated duodenal segments from rats. In a high concentration paracetamol (30 mmol · l^–1) and acetanilide (25 mmol · l^–1) inhibited these parameters. The coupling coefficeint of 2:1 in sodium-glucose cotransport was not changed under the influence of the aniline derivatives. Phlorizin (10^–5 mol · l^–1) completely abolished the stimulatory effect of these drugs. Also in presence of 3-O-methylglucose instead of glucose in the perfusion medium a paracetamol dependent increase in fluid absorption was seen, whereas the absorption of mannitol was unchanged. The results suggest, that the increase in sodium and fluid absorption caused by aniline derivatives is due to the stimulation of active glucose transport. A cytotoxic effect may explain the decrease of absorption at high concentrations of these substances.     

Effect of bupropion on cimetidine and ranitidine absorption in rats

Cimetidine and ranitidine absorption were studied in rats, alone or in combination with concurrent but separate bupropion oral administration. Blood samples were collected before and 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, 4.5, and 6.0 h after dosing. In ranitidine-treated rats, an extra blood sample at 8 h was collected. Assays of cimetidine and ranitidine were carried out using a HPLC method. Mean cimetidine plasma concentrations on concurrent bupropion administration at 0.25 and 0.5 h were approximately 2 and 1.5 times compared to the control. Similarly, mean ranitidine plasma concentrations with bupropion combination at 0.25 and 0.5 h were significantly different and approximately 2 and 3 times higher. Time of maximum concentration for cimetidine and ranitidine on combination were reduced to almost half of the control value. However, only the time of maximum concentration for cimetidine showed statistically significant difference. No significant differences were observed between AUCs, maximum concentrations, and half-lives of cimetidine and ranitidine compared to their respective controls. The results suggest that concurrent bupropion administration may affect the rate but not the extent of absorption of cimetidine and ranitidine.     

Disposition of bromodichloromethane in humans following oral and dermal exposure.

Exposure to bromodichloromethane (BDCM), one of the most prevalent disinfection byproducts in drinking water, can occur via ingestion of water and by dermal absorption and inhalation during activities such as bathing and showering. The objectives of this research were to assess BDCM pharmacokinetics in human volunteers exposed percutaneously and orally to (13)C-BDCM and to evaluate factors that could affect disposition of BDCM. Among study subjects, CYP2E1 activity varied fourfold; 20% had the glutathione S-transferase theta 1-1 homozygous null genotype; and body fat ranged from 7 to 22%. Subjects were exposed to (13)C-BDCM in water (target concentration of 36 mug/l) via ingestion and by forearm submersion. Blood was collected for up to 24 h and analyzed for (13)C-BDCM by solid-phase microextraction and high-resolution GC-MS. Urine was collected before and after exposure for mutagenicity determinations in Salmonella. After ingestion (mean dose = 146 ng/kg), blood (13)C-BDCM concentrations peaked and declined rapidly, returning to levels near or below the limit of detection (LOD) within 4 h. The T(max) for the oral exposure ranged from 5 to 30 min, and the C(max) ranged from 0.4 to 4.1 ng/l. After the 1 h dermal exposure (estimated mean dose = 155 ng/kg), blood concentrations of (13)C-BDCM ranged from 39 to 170 ng/l and decreased to levels near or below the LOD by 24 h. Peak postdose urine mutagenicity levels that were at least twice that of the predose mean level occurred in 6 of 10 percutaneously exposed subjects and 3 of 8 orally exposed subjects. These results demonstrate a highly significant contribution of dermal absorption to circulating levels of BDCM and confirm the much lower oral contribution, indicating that water uses involving dermal contact can lead to much greater systemic BDCM doses than water ingestion. These data will facilitate development and validation of physiologically based pharmacokinetic models for BDCM in humans.     

在体单向肠灌流模型研究绞股蓝皂苷的肠吸收特性

目的：对绞股蓝皂苷在大鼠小肠各肠段的吸收情况进行研究。方法：采用大鼠在体肠灌流法,应用HPLC-ELSD法测定肠吸收循环液中绞股蓝皂苷A、人参皂苷Rb₁和人参皂苷Rd的浓度。结果：3种绞股蓝皂苷的吸收系数（K_a）和渗透系数（P_eff）在小肠各肠段的吸收具有较大差异,渗透系数（P_eff）表明3种绞股蓝皂苷在不同肠段的吸收为空肠>十二指肠 > 回肠 > 结肠;在0.05~1.0 g·L^-1内,随着浓度的上升,绞股蓝皂苷会出现过饱和现象;加入地高辛后,人参皂苷Rb₁的渗透系数显著下降（P<0.05）,而加入维拉帕米后,人参皂苷Rd的渗透系数增加极显著性（P<0.01）。结论：绞股蓝皂苷受吸收部位影响较大,空肠是该类皂苷的主要吸收部位,其不完全依赖浓度梯度而进行转运,小肠吸收机制不完全为被动转运,载体蛋白有可能参与了转运,绞股蓝皂苷可能是P-糖蛋白的底物。     

Apparent dose-dependent absorption of chlorothiazide in dogs

The purpose of this study was to determine the effect of oral dose on the absorption of chlorothiazide in the dog. Chlorothiazide was quantitatively excreted in the urine after administration of 50-mg and 250-mg intravenous doses. In contrast, the urinary recovery of chlorothiazide after oral administration showed appreciable interanimal variation and decreased from 70.4% to 26.7% on the average as the oral dose was increased from 125 mg to 750 mg. Oral administration of a single 15-mg dose of propantheline bromide (a potent inhibitor of gastric emptying and intestinal motility) at –1 hr increased the absorption of a 250 mg oral dose of chlorothiazide in three out of four dogs. These results suggest that chlorothiazide absorption is dose dependent and apparently site specific.This research was supported in part by Grants GM 20852 and GRS-RR0545415 from the National Institutes of Health, Bethesda, Md.This article was presented in part before the Basic Pharmaceutics Section Meeting, APhA Academy of Pharmaceutical Sciences, Hollywood, Florida, November 1978.