Effect of Anions on Adsorption of Bile Salts by Colestipol Hydrochloride

The Langmuir affinity constant and adsorptive capacity for the adsorption of citrate anion or cholate anion by colestipol hydrochloride at pH 7.5, 37°C, were similar. Prior exposure of colestipol hydrochloride to citrate anion caused the adsorption of cholate anion to decrease slightly in comparison to a control utilizing only cholate anion. The concentration of citrate anion was found to be directly related to the decrease in cholate anion adsorption. Simultaneous exposure of colestipol hydrochloride to citrate and cholate anions at pH 7.5, 37°C, resulted in the same adsorption of cholate anion as sequential exposure to citrate anion followed by cholate anion. Sequential exposure of colestipol hydrochloride to simulated gastric fluid and simulated intestinal fluid containing cholate anion resulted in a small decrease in cholate adsorption which was attributed to competition with phosphate anion in simulated intestinal fluid. Pepsin in the simulated gastric fluid did not affect adsorption of cholate anion from simulated intestinal fluid. Preexposure to components of tomato juice and orange juice also slightly reduced the adsorption of cholate anion by colestipol hydrochloride.     

Effect of ethanol and pH on the adsorption of acetaminophen (paracetamol) to high surface activated charcoal, in vitro studies

BACKGROUND: Paracetamol (acetaminophen) intoxication often in combination with ethanol, is seen commonly in overdose cases. Doses of several grams might be close to the maximum adsorption capacity of the standard treatment dose (50g) of activated charcoal. The aim of this study was to determine the maximum adsorption capacity for paracetamol for two types of high surface-activated charcoal [Carbomix and Norit Ready-To-Use (not yet registered trademark in Denmark) both from Norit Cosmara, Amersfoort, The Netherlands] in simulated in vivo environments: At pH 1.2 (gastric environment), at pH 7.2 (intestinal environment), and with and without 10% ethanol. METHODS: Activated charcoal, at both gastric or intestinal pHs, and paracetamol were mixed, resulting in activated charcoal-paracetamol ratios from 10:] to 1:1. In trials with ethanol, some of the gastric or intestinal fluid was replaced with an equivalent volume of ethanol, resulting in an ethanol concentration of 10% v/v. After incubation, the concentration of unabsorbed paracetamol was analyzed by high-performance liquid chromatography. The maximum adsorption capacity of paracetamol to activated charcoal was calculated as mg paracetamol adsorbed/g activated charcoal, using Langmuir's isotherm. RESULTS: Carbomix [95% confidence limits are shown in square brackets]: 623.7 [612.8;634.5] mg paracetamol adsorbed/g activated charcoal (pH 1.2), 626.2 [611.6;640.9] mg paracetamol adsorbed/g activated charcoal (pH 7.2); Norit Ready-To-Use: 693.6 [676.8;710.5] mg paracetamol adsorbed/g activated charcoal (pH 1.2), 722.6 [687.4;757.9] mg paracetamol adsorbed/g activated charcoal (pH 7.2). For experiments with ethanol (10% v/v) the results with Carbomix were 465.7 [449.2;482.2] mg paracetamol adsorbed/g activated charcoal (pH 1.2), 498.6 [481.8;515.6] mg paracetamol adsorbed/g activated charcoal (pH 7.2); with Norit Ready-To-Use: 617.2 [606.6;627.7] mg paracetamol adsorbed/g activated charcoal (pH 1.2), 640.6 [624.9;656.4] mg paracetamol adsorbed/g activated charcoal (pH 7.2). CONCLUSION: Under conditions simulating immediate treatment with charcoal, a standard dose of 50 g of either of the two tested activated charcoals adsorbed a sufficient amount of paracetamol to be beneficial in the treatment of the majority of overdoses of this drug. For both types of activated charcoal, with or without ethanol, there was no significant difference in the adsorption of paracetamol at pH 1.2 and 7.2. Norit Ready-To-Use had a larger maximum adsorption capacity than Carbomix, and was not as sensitive as Carbomix to environmental changes (pH and ethanol). The presence of 10% ethanol lowered the adsorption capacity of the two tested activated charcoal preparations by an amount that might be clinically relevant in cases of intoxications by high-gram doses.     

The effect of food and ice cream on the adsorption capacity of paracetamol to high surface activated charcoal: in vitro studies

The effect of added food mixture (as if food was present in the stomach of an intoxicated patient) or 4 different types of ice cream (added as a flavouring and lubricating agent) on the adsorption of paracetamol (acetaminophen) to 2 formulations of activated charcoal was determined in vitro and compared with results from previous investigations showing a maximum adsorption capacity to the two activated charcoal-water slurries at about 0.62-0.72 g paracetamol/g activated charcoal. Activated charcoal (Carbomix or Norit Ready-To-Use), simulated gastric (pH 1.2) or intestinal (pH 7.2) fluid, and paracetamol were mixed with either food mixture or ice cream followed by one hr incubation. The maximum adsorption capacity of paracetamol to activated charcoal was calculated using Langmuirs adsorption isotherm. Paracetamol concentration was analyzed using high pressure liquid chromatography. In the presence of food, the paracetamol adsorption capacity of the 2 activated charcoals was reduced by max. 19% (P<0.05) for Carbomix(R) and by max. 11% (P<0.05) for Norit Ready-to-use compared to control without food (Hoegberg et al. 2002). Depending on which type of ice cream was mixed with the charcoal, the reductions compared to control (Hoegberg et al. 2002) varied between 11% and 26%. Even though a reduction in drug adsorption to activated charcoal was observed when food mixture or ice cream was added, the remaining adsorption capacity of both types of activated charcoal theoretically was still able to provide an effective gastrointestinal decontamination.     

蒙脱石散对氧氟沙星体外吸附作用研究

目的:研究蒙脱石散对氧氟沙星的体外吸附作用。方法:取不同剂量的氧氟沙星与蒙脱石散分别混合于人工胃液和人工肠液中,(37±0.5)℃水浴恒温1h后过滤,采用紫外分光光度法测定氧氟沙星的含量变化。结果:在人工胃液和人工肠液中,蒙脱石散对氧氟沙星的吸附率分别为(99.76±0.01)%和(99.55±0.02)%。结论:蒙脱石散在人工胃液和人工肠液中对氧氟沙星有强大的吸附作用,应避免同时服用2药。     

The effects of surface lactone hydrolysis and temperature on the specific and nonspecific interactions between phenobarbital and activated carbon surfaces

The effect of hydrolyzing lactone functional groups on the surfaces of different activated carbons upon the specific and nonspecific interactions between phenobarbital and activated carbon surfaces was studied. The effect of temperature on both specific and nonspecific interactions was also studied. The increase in OH groups on the surfaces of activated carbons, as a result of hydrolyzing surface lactone groups, caused an increase in the specific adsorption capacity (K(2)) for phenobarbital without having a significant effect on the hydrophobic bonding capacity (K(HB)). Increasing the temperature at which the adsorption experiment was carried out, on the other hand, resulted in a decrease in K(HB) without having a significant effect on K(2). The decrease in K(HB) per unit temperature increase was the same regardless of the activated carbon. These results are in very good agreement with the modified-Langmuir-like equation (M-LLE).     

Removal of ciprofloxacin in simulated digestive media by activated charcoal entrapped within zinc-pectinate beads

Beads made of a zinc-pectinate matrix containing activated charcoal were designed for the adsorption of colonic residual antibiotics responsible of the emergence of resistance. Bead stability was shown to correlate with bead zinc content, 0.08 mg/mg being the minimal amount of zinc that protects the egg-box structure against total disintegration. Moreover, the stability in simulated gastro-intestinal media was shown to be related to the composition of the incubation medium. Indeed, gastric medium was shown to extract a large amount of zinc inducing an early disintegration of the beads in the intestinal medium, making necessary their protection by gastro-resistant capsules. Simulated intestinal medium buffered by phosphate was not adapted for the disintegration studies since the formation of a zinc phosphate precipitate on beads surface enhances their resistance to further degradation by pectinases contained in colonic medium. On the other hand, beads incubated in HEPES were stable in intestinal medium and nicely degraded by pectinases contained in simulated colonic medium. Despite this stability, coating with Eudragit RS^® was needed to prevent the early adsorption of antibiotics in intestinal medium. Adsorption studies in the simulated colonic medium show that the adsorption capacity of activated charcoal is not modified after its encapsulation within pectin beads making the elimination of ciprofloxacin reaching the colon clinically feasible.     

不同pH值条件下蒙脱石散对配伍药物体外吸附作用的影响

目的研究在不同pH值人工胃液和人工肠液中蒙脱石散对常与其配伍药物诺氟沙星、氧氟沙星、萸连片、雷尼替丁、法莫替丁、阿昔洛韦、利巴韦林的体外吸附作用。方法取蒙脱石散分别加入到用不同pH人工胃液和人工肠液溶解的上述药物溶液中,用高效液相色谱法测定药物含量,计算吸附率。结果蒙脱石对萸连片中巴马汀、小檗碱的吸附率达95%以上;对诺氟沙星、氧氟沙星吸附率达80%左右;对阿昔洛韦、利巴韦林吸附率比较小,在10%以下;对法莫替丁和雷尼替丁的吸附率随着pH值的增加而降低。结论蒙脱石散对上述药物有不同的吸附作用,吸附率大的药物配伍应用时注意服药间隔时间。     

金属改性玉米秸秆生物质炭吸附恩诺沙星的机理研究

目的 提高传统玉米秸秆生物质炭对抗生素的吸附能力,研究生物质炭对恩诺沙星的吸附机理。方法 利用FeCl3和ZnCl2对玉米秸秆生物质炭进行铁改性和锌改性,运用SEM、FTIR、XRD等分析方法研究改性前后生物质炭的性质和结构,并进行吸附试验。结果 铁改性和锌化生物质炭表面含氧官能团数量增加,微孔所占体积增大,比表面积分别增大了9.7和8.1倍;XRD图谱显示改性后生物质炭结晶性降低,稳定性下降。铁改性和锌化后的生物质炭,对恩诺沙星的最大吸附量分别提高了21.30%和10.81%,准二级动力学方程跟Langmuir方程能很好的描述3种炭的吸附过程,吸附热力学分析显示3种炭对恩诺沙星的吸附是一个自发、吸热、无序的过程。结论 经过铁改性和锌改性后,能够增大生物质炭的比表面积及孔隙结构,使得生物质炭能够提供更多的吸附位点,从而增强其对恩诺沙星的吸附能力。     

金属改性玉米秸秆生物质炭吸附恩诺沙星的机理研究

目的 提高传统玉米秸秆生物质炭对抗生素的吸附能力，研究生物质炭对恩诺沙星的吸附机理。方法 利用FeCl3和ZnCl2对玉米秸秆生物质炭进行铁改性和锌改性，运用SEM、FTIR、XRD等分析方法研究改性前后生物质炭的性质和结构，并进行吸附试验。结果 铁改性和锌化生物质炭表面含氧官能团数量增加，微孔所占体积增大，比表面积分别增大了9.7和8.1倍；XRD图谱显示改性后生物质炭结晶性降低，稳定性下降。铁改性和锌化后的生物质炭，对恩诺沙星的最大吸附量分别提高了21.30%和10.81%，准二级动力学方程跟Langmuir方程能很好的描述3种炭的吸附过程，吸附热力学分析显示3种炭对恩诺沙星的吸附是一个自发、吸热、无序的过程。结论     

A study on adsorptive properties of activated carbons produced from rice-straw

Activated carbons from rice-straw can be used as an adsorbents for the purification of water were prepared and evaluated. The adsorptive capacities of activated carbons were measured by iodine, potassium permanganate, phenol and metals. It was observed by electron microscope (SEM) and IR spectrum that organic components in the rice-straw and its carbonization product were disappeared, slit-shaped and porous structures were formed by activation. There was no relationship between temperature and adsorption of iodine but adsorption of potassium permanganate increased as temperature rose. The adsorption of the phenol was greater than 99%. The adsorption data of phenol at 25°C obeyed the Freundlich's isotherm. Various metals except sodium were not removed by activated carbon.     

In vitro adsorption of tilidine HCl by activated charcoal

In vitro studies were carried out in order to determine the adsorption of tilidine HCl, a narcotic analgesic, by activated charcoal (max. adsorption capacity 185.5 mg/g of charcoal). The path of the adsorption isotherms at pH 1.2 and 7.5 suggests that the in vivo adsorption of tilidine HCl may be increased when the drug passes from the stomach to the intestine, unless the intestinal content exerts a displacing effect. Nevertheless, the adsorption was dependent on the quantity of activated charcoal used, becoming more complete when the quantity of activated charcoal was increased. The effects of additives on the adsorption capacity of activated charcoal were also investigated in vitro. Ethanol, sorbitol and sucrose significantly reduced drug adsorption, while cacao powder, milk and starch had no effect on tilidine adsorption. At an acid pH, Federa Activated Charcoal significantly adsorbed more drug than either Norit A or Activated Charcoal Merck.     

A Surface Energy Analysis of Mucoadhesion: Contact Angle Measurements on Polycarbophil and Pig Intestinal Mucosa in Physiologically Relevant Fluids

The possible role of surface energy thermodynamics in mucoadhesion was investigated with Polycarbophil and pig intestinal mucosa. In separate experiments, the surface energy parameters of the substrate (mucosa) and the adhesive (polymer film) were determined by contact angle measurements on captive air/octane bubbles in three physiologically relevant test fluids (isotonic saline, artificial gastric fluid, and artificial intestinal fluid). Whereas the swollen Polycarbophil films were relatively hydrophilic as indicated by small water contact angles (22, 23, and 16°), the water contact angles measured on mucosal tissue were significantly larger (61, 48, and 57°). Hence, mucus was found to possess an appreciable hydrophobicity. The measured adhesive performance (force of detachment) between Polycarbophil and pig small intestinal mucosa was highest in non-buffered saline medium, intermediate in gastric fluid, and minimal in intestinal fluid. In agreement with this trend, the mismatch in surface polarities between substrate and adhesive, calculated from the contact angle data, increased in the same order.     

微晶次硝酸铋对安定吸附作用的研究

用体外实验法,研究微晶次硝酸铋于人工胃液中37℃时对安定的吸附作用。微晶次硝酸铋吸附安定,符合Freundlich吸附等温式及Langmuir吸附等温式,有可能为单分子层吸附。在每次服用剂量2.5～5mg范围内,每1g微晶次硝酸铋,可吸附安定2～3.4mg,安定主要以阳离子通过静电力被吸附。被吸附的安定于人工肠液中,可进行不同程度的脱吸而再释出。     

Magnesium modified activated carbons derived from coconut shells for the removal of fluoride from water

Fluoride presence in water has been recognized as one of the major water related global problems, rendering the development of effective technologies for its removal as a very significant issue, for improving human health and well-being in the affected areas. Among the commonly applied technologies for fluoride removal, adsorption has gained great attention because it offers efficiency, low-cost treatment and simple operation. The present study aimed at developing novel adsorbents, namely activated carbon modified by magnesium or/and lanthanum and silica for fluoride removal. The structure and the morphology of resulted modified activated carbons (AC-Mg and AC-Si-Mg-La) were studied in detail by the application of BET, XRD, FTIR and SEM techniques. The proposed adsorbent materials were tested for the treatment of fluoride containing waters. The effects of the adsorbent's dosage, initial concentration of pollutant, pH value of the water and regeneration efficiency were examined. According to the obtained results, the maximum adsorption was observed at pH 8, after 4 h of reaction and 0.2 g/L of adsorbent dose. Langmuir-Freundlich isotherm model and pseudo-second order kinetic model fitted the experimental data sufficiently. At pH 8 a maximum adsorption capacity of 36.56 mg/g for AC-Mg and 54.48 mg/g for AC-Si-Mg-La, was found. Repeated adsorption and regeneration studies showed only a 10% decrease of adsorption capacity after 4 regeneration cycles of operation.     

Inhibition by leukotriene inhibitors, and calcium and platelet-activating factor antagonists, of acute gastric and intestinal damage in arthritic rats and in cholinomimetic-treated mice.

The leukotrienes, platelet activating factor and intracellular calcium have been implicated in the development of gastro-intestinal lesions induced by non-steroidal anti-inflammatory drugs (NSAIDs) but the relative significance of these inflammatory mediators in lesion formation has not been established in sensitive and specific models of gastro-intestinal ulceration. In the present study the effects of drugs affecting 5-lipoxygenase activity, the actions of platelet activating factor and intracellular calcium on the development of gastric and intestinal ulceration induced by NSAIDs were investigated in highly sensitive models of ulcerogenicity induced by treatment with either the cholinomimetic, acetyl-beta-methyl choline chloride, in mice (gastric mucosal lesions) or adjuvant-induced polyarthritis in rats (gastric and intestinal mucosal lesions) as well as in normal mice (intestinal mucosal lesions). The 5-lipoxygenase inhibitors, such as MK-886 (3-[1-(4-chlorobenzyl)-3-t-butyl-thio-5-isopropylindol-2-yl]-2,2-+ ++dimethylpropanoic acid), given at doses shown to reduce the indomethacin-induced increase in mucosal leukotriene B4 concentrations were found to partially prevent the development of gastric and intestinal lesion induced by indomethacin and gastric lesions from aspirin, but the same doses of MK-886 did not affect gastric lesions from diclofenac. Pretreatment with these inhibitors at both 3-5 h and 0-0.25 h was required to achieve protection against gastric mucosal damage from indomethacin. Immediate prior administration of platelet activating factor antagonists (e.g. WEB-2086) with the 5-lipoxygenase inhibitors did not affect gastric or intestinal lesions induced by indomethacin. The calcium antagonist, verapamil, was slightly protective against gastric and intestinal lesions induced by indomethacin. Gastric lesions were further prevented by combinations of a single dose of verapamil with a platelet activating factor antagonist but not combined with a 5-lipoxygenase inhibitor; other combinations of verapamil with lipoxygenase inhibitors or platelet-activating factor antagonists being without inhibitory effects on gastric or intestinal lesions compared with the drugs alone. These results show that 5-lipoxygenase products and intracellular calcium play a major role in acute gastric and intestinal damage by the NSAIDs, but platelet-activating factor has little or no appreciable involvement.     

Phosphopyridoxal cyclic compounds with histamine and histidine. 6: The formation of phosphopyridoxal cyclic compounds with histamine and histidine in the presence of biological material.

We have studied the dynamics of cyclic compound formation between histamine or histidine and pyridoxal 5'-phosphate (Hi-PLP or His-PLP) in incubates of rat gastric mucosa histidine decarboxylase (HD), rat intestinal diamine oxidase (DAO) or homogenates of either rat liver, intestine or gastric mucosa. For gastric mucosa HD, liver and gastric mucosa homogenates, the rate of cyclization was slightly decreased; however, the rate was significantly inhibited with intestinal DAO or intestinal homogenate. Binding of PLP by tissue components was measured; free PLP was bound abundantly by rat intestinal DAO and by rat intestinal homogenate. A possible mechanism by which intestinal tissues inhibit cyclic compound formation is discussed.     

Carboxymethyl starch: Chitosan monolithic matrices containing diamine oxidase and catalase for intestinal delivery

The capacity of carboxymethyl starch (CMS):Chitosan monolithic tablets to protect diamine oxidase and/or catalase therapeutic enzymes against simulated gastric fluid (SGF) and to control their delivery in simulated intestinal fluid (SIF) was investigated. Enzyme formulations loaded with grass pea seedlings diamine oxidase (PSDAO) vegetal extract, catalase, or PSDAO associated to catalase, were obtained by direct compression. The CMS:Chitosan (1:1) matrix afforded a good gastric protection to PSDAO and to catalase, when each enzyme was formulated separately. Variable amounts of DAO were delivered in the SIF containing pancreatin, with maximal release reached at about 8h, a time convenient for tablets to attain the colon. Up to 50% of the initial enzymatic activity of catalase formulated with CMS:Chitosan was found after 8 h in SIF. For the CMS:Chitosan tablets of bi-enzymatic formulations containing PSDAO:Catalase, the releases of DAO and of catalase were synchronized. The hydrogen peroxide (product of DAO activity) was decomposed by the catalase liberated in the same SIF environment. The proposed formulations could allow novel therapeutic approaches for the treatment of inflammatory bowel diseases, intestinal cancers or pseudo-allergic reactions.     

Combination of adsorption by porous CaCO3 microparticles and encapsulation by polyelectrolyte multilayer films for sustained drug delivery

Combination of adsorption by porous CaCO(3) microparticles and encapsulation by polyelectrolyte multilayers via the layer-by-layer (LbL) self-assembly was proposed for sustained drug release. Firstly, porous calcium carbonate microparticles with an average diameter of 5 microm were prepared for loading a model drug, ibuprofen (IBU). Adsorption of IBU into the pores was characterized by ultraviolet (UV), infrared (IR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) experiment and X-ray diffraction (XRD). The adsorbed IBU amount Gamma was 45.1mg/g for one-time adsorption and increased with increasing adsorption times. Finally, multilayer films of protamine sulfate (PRO) and sodium poly(styrene sulfonate) (PSS) were formed on the IBU-loaded CaCO(3) microparticles by the layer-by-layer self-assembly. Amorphous IBU loaded in the pores of the CaCO(3) microparticles had a rapider release in the gastric fluid and a slower release in the intestinal fluid, compared with the bare IBU crystals. Polyelectrolyte multilayers assembled on the drug-loaded particles by the LbL reduced the release rate in both fluids. In this work, polymer/inorganic hybrid core-shell microcapsules were fabricated for controlled release of poorly water-soluble drugs. The porous inorganic particles are useful to load drugs in amorphous state and the polyelectrolyte multilayer films coated on the particle assuage the initial burst release.     

Structural transformation of lignan compounds in rat gastrointestinal tract.

Structural transformation of arctiin and tracheloside, major components of seeds of Arctium lappa and Carthamus tinctorius, were investigated using rat gastric juice (pH 1.2-1.5) and rat large intestinal flora in vitro. Quantitative analysis of lignans and their metabolites was carried out by high performance liquid chromatography. Both lignans were stable in rat gastric juice and arctiin was rapidly transformed to arctigenin in rat large intestinal flora, followed by conversion to the major metabolite, 2-(3",4"-dihydroxybenzyl)-3-(3',4'-dimethoxybenzyl)-butyrolactone. On the other hand, tracheloside also decreased dependently with time and was converted to trachelogenin and its major metabolite, 2-(3",4"-dihydroxybenzyl)-3-(3',4'-dimethoxybenzyl)-2-hydroxybutyrola ctone. These experiments suggest that in the course of metabolism of lignans, firstly a cleavage of the glycosidic bond occurred and then demethylation of the phenolic methoxy group in the alimentary tract followed.     

The influence of dopamine agonists and antagonists on indomethacin lesions in stomach and small intestine in rats

Dopamine agents (saline in control groups) were coadministered with indomethacin by either single or repeated application. The ulcerogenic effect (erosions and/or ulcers) of repeated given indomethacin on gastric mucosa differed clearly from that on intestinal mucosa. The effect on intestinal mucosa was markedly greater than after a single dose. The effects of dopamine agents appeared to be more consistent. Domperidone and haloperidol, given as single or repeated doses, strongly aggravated both the gastric and intestinal lesions. Bromocriptine and amantadine had a protective effect. The adverse effects of both dopamine antagonists (increased after repeated administration) were strongly inhibited by the simultaneous administration of either bromocriptine or amantadine. The involvement of the dopamine system (central or peripheral) in the mechanisms that maintain gastric (probably related to cytoprotection also) and intestinal mucosa integrity is therefore suggested.