Resveratrol self-emulsifying system increases the uptake by endothelial cells and improves protection against oxidative stress-mediated death.

The aim of the present study was to develop and characterize a resveratrol self-emulsifying drug delivery system (Res-SEDDS), and to compare the uptake of resveratrol by bovine aortic endothelial cells (BAECs), and the protection of these cells against hydrogen peroxide-mediated cell death, versus a control resveratrol ethanolic solution. Three Res-SEDDSs were prepared and evaluated. The in vitro self-emulsification properties of these formulations, the droplet size and the zeta potential of the nanoemulsions formed on adding them to water under mild agitation conditions were studied, together with their toxicity on BAECs. An optimal atoxic formulation (20% Miglyol® 812, 70% Montanox® 80, 10% ethanol 96% v/v) was selected and further studied. Pre-incubation of BAECs for 180 min with 25 µM resveratrol in the nanoemulsion obtained from the selected SEDDS significantly increased the membrane and intracellular concentrations of resveratrol (for example, 0.076±0.015 vs. ethanolic solution 0.041±0.016 nmol/mg of protein after 60 min incubation, p<0.05). Resveratrol intracellular localization was confirmed by fluorescence confocal microscopy. Resveratrol nanoemulsion significantly improved the endothelial cell protection from H2O2-induced injury (750, 1000 and 1500 µM H2O2) in comparison with incubation with the control resveratrol ethanolic solution (for example, 55±6% vs. 38±5% viability after 1500 µM H2O2 challenge, p<0.05). In conclusion, formulation of resveratrol as a SEDDS significantly improved its cellular uptake and potentiated its antioxidant properties on BAECs.

Best temperature for static liver graft storage is 1°C.

BACKGROUND: The best storage temperature in liver transplantation remains an unsolved question. METHODS: After storage for 24h in University of Wisconsin solution at +4°C, +1°C, or -0.5°C, rat livers were subjected, or not, to 15min of warm ischemia, rinsed with Ringer lactate, and subsequently reperfused with oxygenated Krebs-Henseleit buffer. RESULTS: In the presence of warm ischemia, for livers stored at +4°C, creatine kinase (CK) peaked at 21±5IUg(-1)h(-1), hepatic resistance at 34,700±1500dynscm(-5), bile flow reached 18±4µLg(-1)h(-1) after 10min, and oxygen consumption stabilized at about 25µmolg(-1)h(-1) after 20min. When livers were stored at +1°C, CK and hepatic resistance were lowered, bile production was 33±6µLg(-1)h(-1) (P<0.05 versus +4°C), and oxygen consumption was 105±10µmolg(-1)h(-1) (P<0.001). For livers stored at-0.5°C, results were not statistically different from those of the +1°C group except for bile flow, which was significantly lower. Without warm ischemia, the peak of CK (P=0.015) and the peak hepatic resistance (P<0.001) of the +4°C group were significantly increased compared with the +1°C or -0.5°C groups. However, no difference in bile flow or oxygen consumption was observed. The number of trypan blue-positive nonparenchymal cells (P=0.003) and the gain in liver weight during the reperfusion (P=0.015) were minimal after storage at +1°C. CONCLUSIONS: Static storage at +1°C improved liver function compared with +4°C or -0.5°C. Main beneficial effect was observed with parameters reflecting sinusoidal cells injury.

Citrulline: from metabolism to therapeutic use.

Citrulline possesses a highly specific metabolism that bypasses splanchnic extraction because it is not used by the intestine or taken up by the liver. The administration of citrulline may be used to deliver available nitrogen for protein homeostasis in peripheral tissues and as an arginine precursor synthesized de novo in the kidneys and endothelial and immune cells. Fresh research has shown that citrulline is efficiently transported across the intestinal luminal membrane by a set of transporters belonging to the B°,⁺, L, and b°,⁺ systems. Several pharmacokinetic studies have confirmed that citrulline is efficiently absorbed when administered orally. Oral citrulline could be used to deliver arginine to the systemic circulation or as a protein anabolic agent in specific clinical situations, because recent data have suggested that citrulline, although not a component of proteins, stimulates protein synthesis in skeletal muscle through the mammalian target of rapamycin signaling pathway. Hence, citrulline could play a pivotal role in maintaining protein homeostasis and is a promising pharmaconutrient in nutritional support strategies for malnourished patients, especially in aging and sarcopenia.

Development of gastro intestinal sustained release tablet formulation containing acryl-EZE and pH-dependent swelling HPMC K 15 M.

BACKGROUND: The aim of this study was to evaluate physical properties and release from matrix tablets containing different ratios of HPMC 15 M and Acryl-EZE. A further aim is to assess their suitability for pH dependent controlled release. METHODS: Matrix tablets containing HPMC 15 M and Acryl-EZE were manufactured using a fluidized bed. The release from this matrix using Sodium Diclofenac (SD) as model drug is studied in two dissolution media (0.1 N HCl or pH = 6.8 phosphate buffer solution); the release rate, mechanism, and pH dependence were characterized by fitting four kinetic models and by using a similarity factor analysis. RESULTS: The obtained results revealed that the presence of Acryl-EZE in the matrix tablets is effective in protecting the dosage forms from release in acid environments such as gastric fluid. In pH = 6.8 phosphate buffer, the drug release rate and mechanism of release from all matrices is mainly controlled by HPMC 15 M. The model of Korsmeyer-Peppas was found to fit experimental dissolution results.

Endotoxemia affects citrulline, arginine and glutamine bioavailability.

BACKGROUND: Sepsis considerably alters the intestinal barrier functions, which in turn modify the absorption and bioavailability of nutrients. However, the effects of septic shock on aminoacid (AAs) bioavailability are poorly documented. The aim of this study was to compare the bioavailability of citrulline, arginine and glutamine during endotoxemia. MATERIALS AND METHODS: Thirty-six rats were randomised into two groups: control and lipopolysaccharides (LPS). The LPS group received an intraperitoneal injection of endotoxins (7·5 mg/kg). After 12 h, each group was again randomised into three subgroups, each of which received an oral bolus of citrulline, arginine or glutamine (5·7 mmol/kg). Blood samples were collected at various times from 0 to 600 min after AA administration. The concentrations of citrulline, arginine, glutamine and their metabolites arginine and ornithine were measured to determine pharmacokinetic parameters Area Under Curve (AUC), C(max) and T(max). RESULTS: The AUC values of citrulline decreased in LPS rats [citrulline, control: 761 ± 67 and LPS: 508 ± 72 µmol min/mL (P = 0·02)]. Maximum concentrations of citrulline were also significantly decreased by endotoxemia (P = 0·01). The pharmacokinetic parameters of arginine and glutamine were not significantly modified by endotoxemia. The AUC value of arginine from citrulline conversion was diminished in endotoxemic rats. The other pharmacokinetic parameters of arginine were not significantly modified after arginine or citrulline supply in either group (control or LPS). CONCLUSION: Endotoxemia affects the bioavailability of AAs differently according to the amino acid considered. This feature may be important for nutritional strategy in ICU patients.

Altered HepG2 cell models using etomoxir versus tert-butylhydroperoxide.

Energetic failure which occurs in both ischemia/reperfusion and acute drug-induced hepatotoxicity is frequently associated with oxidative stress. This study displays the setting of a new cell culture model for hepatic energetic failure, i.e., HepG2 models modified by etomoxir [ETO] addition [0.1 mM to 1 mM] and compares the cell impact versus tert-butylhydroperoxide [TBOOH; 0.2 mM], an oxidative stress inducer. As it was observed with Minimum Essential Medium (MEM) without any interfering agent, decreasing temperature drastically lowered adenosine triphosphate (ATP) levels, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) viability test, and protein content, compared to 37 °C (p=0.02, p<0.001 and p<0.001, respectively), but to a larger extent in the presence of ETO or TBOOH. The alteration was generally highly dependent on the ETO concentration, time, and temperature. At 37 °C 24 h after (T24h), regarding ETO concentration, R² correlation ratio was 0.65 (p<0.001), 0.70 (p<0.001), and 0.89 (p<0.001) for ATP levels, protein content, and viability, respectively. The lowest ETO concentration producing a significant effect was 0.25 mM. Concerning time dependency (i.e., T24h versus after 5 h (T5h)), at 37 °C with ETO, ATP level continued to significantly decrease between T5h and T24h. In a similar way, at 37 °C, the MTT viability test decrease was accelerated only between T5h and T24h for ETO concentrations higher than 0.5 mM (p=0.016 and p=0.0001 for 0.75 and 1 mM, respectively). On the contrary, with TBOOH, comparing T24h versus T5h, cellular indicators were improved but generally remained lower than MEM without any interfering agent at T24h, suggesting that TBOOH action was time limited probably in relation with its oxidation in cell medium. This study confirms the interest of altered ETO cell model to screen agents (or formulation) prone to prevent or treat energetic depletion in relation with oxidative stress.

High plasma citrulline and arginine levels ensured by sustained-release citrulline supplementation in rats.

OBJECTIVE: Dietary-supplemented arginine has been shown to have positive effects on cardiovascular disease, but several drawbacks exist and could potentially be avoided by using L-citrulline, since it is recycled to L-arginine. However, citrulline is very rapidly metabolized. We therefore developed a sustained-release form of citrulline and evaluated its metabolic behavior in rats. METHODS: Male Sprague Dawley rats were divided into three groups: receiving "empty microcapsule" (control group), 1 g/kg/d immediate-release citrulline (IR citrulline group), or 1 g/kg/d sustained-release citrulline (SR citrulline group). Citrulline was given each day at 9 a.m. after blood samples for 9 d, and on day 10, blood samples were drawn every 4 h to study the decrease in plasma amino acid concentrations. RESULTS: SR citrulline led to a sustained increase in citrullinemia and argininemia compared to IR citrulline, and on day 6 argininemia was significantly (P < 0.01) higher with SR compared to IR citrulline. Moreover, argininemia was significantly higher in the SR citrulline group than in controls throughout the study and SR citrulline maintained high argininemia and citrullinemia, at least over 12 h. CONCLUSION: This experimental study provides a strong rationale for using this new formulation for atherosclerosis treatment.

Freeze-drying of ATP entrapped in cationic, low lipid liposomes.

Concerning the instability of ATP liposomes formulated to easily diffuse through the liver (size approximately 100 nm), this work targets the key parameters that influence the freeze-drying of a preparation that combines cholesterol, DOTAP and phosphatidylcholine (either natural soybean or egg (SPC or EPC) or hydrogenated (HSPC)). After freeze-drying blank liposomes, size increased significantly when initial lipid concentration was lowered from 20 to 5mM (p=0.0018). With low lipid concentration preparation (5mM), SPC limited size increase (SI) more efficiently compared to EPC or HSPC. With SPC and EPC, sucrose showed better size results compared to trehalose (Lyoprotectant/Lipid ratio (w/w) avoiding any SI: approximately 5 and approximately 10 (for SPC), approximately 10 and approximately 15 (for EPC), for sucrose and trehalose, respectively), but the opposite was evidenced with HSPC liposomes where a Trehalose/Lipid ratio of 25 barely prevented SI. In addition, slow versus quick cooling rate led to limiting SI for HSPC liposomes (p=0.0035). With sucrose or trehalose at both Lyoprotectant/Lipid ratios ensuring size stabilisation (10:1 and 15:1, respectively), ATP leakage ranged between 38.8+/-7.9% and 58.2+/-1.4%. In conclusion, this study emphasizes that using strict size maintenance as the primary objective does not result in drug complete retention inside the liposome core.

Metabolic response and nutritional support in traumatic brain injury: evidence for resistance to renutrition.

Abstract Traumatic brain injury (TBI) is one of the most severe injuries encountered in intensive care units. TBI patients exhibit protein wasting and gastrointestinal dysfunction, which may be risk factors for a septic state. Specific nutritional support may be required for these patients, and we hypothesize that standard nutritional support does not allow restoration of the nutritional state of TBI patients. A well-validated rat model of TBI by fluid percussion was used. Rats were randomized into three groups: healthy rats receiving standard chow diet ad libitum (AL), rats sustaining TBI and receiving standard chow diet (TBI), and rats sustaining TBI and receiving a standard enteral diet (TBI-EN) for 4 days. TBI in rats was characterized by anorexia, body weight loss (AL: +15 +/- 5 g versus TBI: -11 +/- 4 g and TBI-EN: -8 +/- 4 g; p < 0.05), decrease in nitrogen balance (AL: 2.9 +/- 0.2 g versus TBI: 1.0 +/- 0.2 g and TBI-EN: 0.2 +/- 0.2 g, p < 0.05) associated with decrease in muscular protein content (extensor digitorum longus [EDL]: AL: 36 +/- 2 mg versus TBI: 26 +/- 3 mg and TBI-EN: 28 +/- 2 mg; p < 0.05), and intestinal atrophy (ileum: AL: 673 +/- 42 mg versus TBI: 442 +/- 23 mg and TBI-EN: 377 +/- 27 mg; p < 0.05). Interestingly, standard enteral nutrition was not effective in restoring any of these parameters. This work confirms that TBI is associated with profound nutritional alterations and has a major impact on nitrogen metabolism and on intestinal trophicity. It also demonstrates that using standard enteral nutrition cannot reverse this phenomenon. Thus, developing new nutritional strategies to cover TBI patients' specific nutritional requirements appears mandatory.

Formulation and evaluation of ATP-containing liposomes including lactosylated ASGPr ligand.

An original ligand (Lac-10-Chol) designed to interact with asialoglycoprotein receptors to potentially target hepatocyte was synthesised by grafting a lactose head to a cholesteryl structure, which was then included in liposomes. Preliminary formulation tests led to the selection of conventional formulations based on soybean phosphatidylcholine/cholesterol/DOTAP (+/- DOPE) (+/- Lac-10-Chol) that present reproducible absolute entrapment value (1.45 +/- 0.10%), with a size of 109 +/- 7 nm and a slight positive charge (3.77 +/- 1.59 mV). Cell viability (via the MTT test), expressed as the percentage of nontreated cells in HepG2 cells, was very close to the control. Internalization tests evidenced an intracellular penetration of fluorescent liposomes, but no specific ligand effect was demonstrated (P > 0.05). Nevertheless, regarding the adenosine triphosphate (ATP) assay, a slight increase was obtained with liposome loaded with ATP incorporating Lac-10-chol after 24 hours (P < 0.05).

Consequences of head injury and static cold storage on hepatic function: ex vivo experiments using a model of isolated perfused rat liver.

The purpose of the study was to evaluate the effect of head injury (HI) on the metabolic and energy functions of the liver and its consequences after cold storage. In male SD rats with HI, livers were isolated 4 days after injury and perfused either immediately (HI) or after 24 hours of cold preservation. Livers isolated from healthy rats were treated identically. The hepatic functions were explored with an isolated perfused liver model. Head injury induced a liver atrophy without significant difference in the intrahepatic energy level versus healthy rats. After cold storage, hepatic adenosine triphosphate and glycogen contents in HI rats were similar to those of healthy rats. The livers of the HI group that underwent cold preservation had a lower protein catabolism. The portal flow rate at the time of reperfusion was significantly increased in the HI group. In conclusion, static cold storage of livers harvested from HI rats revealed a net protein catabolism reduction and a modification of hepatic microcirculation.

Effect of high calcium and phosphate concentrations on the physicochemical properties of two lipid emulsions used as total parenteral nutrition for neonates.

Premature infants require protein and energy for their growth and an adequate intake of calcium and phosphorus for their bone formation. However, several factors can affect the stability of intravenous lipid emulsions intended to be administered as neonatal total parenteral nutrition. This study evaluated the effect of additives and various concentrations of both calcium gluconate and glucose-1-phosphate on two intravenous lipid emulsions (Clinoleic 20% and Ivelip 20%) when using Primene 10% as source of amino acids and simulating clinical conditions (24-h storage at 37 degrees C). Two series of experiments for each lipid emulsion were carried out. One used separate ingredients (water, glucose, or amino acids) with various calcium phosphate concentrations; and the second included total parenteral nutrition admixtures with varied amino acid (1%, 2%, or 3.5%) and glucose (8% or 14%) concentrations. Evaluation was performed by visual and microscopic examination and pH, particle size, and zeta potential measurements. Calcium concentrations were determined before and after filtration by atomic absorption spectroscopy. Samples were stored 24 h at 37 degrees C. Investigations of lipid-nutrient admixtures showed a significant decrease of the pH with Primene and a visual instability when mixing with sterile water alone, while total parenteral nutrition admixtures made of Clinoleic 20% or Ivelip 20% were stable regarding pH, particle sizing, and zeta potential after storage conditions. Samples containing only calcium have their zeta potential charge reduced compared to samples containing both calcium and phosphate. Also, the evaluation of calcium phosphate solubility showed a significant decrease of the calcium concentration after filtration of the samples. Our data indicated that total parenteral nutrition admixtures could contribute to protect the lipid emulsion from its physicochemical degradation and that using organic phosphate with calcium gluconate has a less deleterious effect than using calcium alone with total parenteral nutrition. Also, the use of inline filters remains necessary for good protection from hazards of precipitates during the administration of total parenteral nutrition regimens.

Mechanisms and kinetics of citrulline uptake in a model of human intestinal epithelial cells.

BACKGROUND & AIMS: Citrulline is a major precursor of arginine by de novo synthesis in the kidneys. Oral citrulline supplementation may be beneficial in some clinical conditions. However, citrulline bioavailability depends on its intestinal absorption. Since the mechanism of citrulline transport across the intestine has not been established yet, this study was designed to characterize L-[(14)C]-citrulline uptake by Caco-2 cells. METHODS: Caco-2 cells were cultured in a bicameral insert system. Inhibition studies were conducted in the presence of neutral, cationic, acidic and non-metabolized amino acids. We performed control inhibition studies for arginine uptake. RESULTS: Citrulline uptake was pH-independent whereas the uptake rate was reduced in the absence of Na(+). Kinetic analysis indicated the involvement of Na(+)-dependent and Na(+)-independent saturable transport components. For competition studies, both the transport components were markedly inhibited by large, small neutral and cationic amino acids. It was also noticed that specific inhibitor of system lBCH inhibited uptake. The inhibition profile of arginine transport was different from that of citrulline transport as arginine uptake was insensitive to BCH. CONCLUSIONS: These characteristics suggest that system B(0,+) might be responsible for the Na(+)-dependent uptake of citrulline, whereas Na(+)-independent uptake may include systems L and b(0,+). Our results show that systems involved in citrulline transport are partly different from those involved in arginine transport.

Influence of pH conditions on the viability of Saccharomyces boulardii yeast.

Saccharomyces boulardii is a probiotic with proven health benefits. However its survival is challenged by gastrointestinal transit, and a ratio between 1 and 3% of living yeast is recovered in the feces after oral administration. The aim of the study was to determine to what extent the yeast was sensitive to gastrointestinal pH conditions. Therefore we explored the survival of different concentrations of S. boulardii in conditions mimicking the stomach pH (pH 1.1 0.1 N HCl) and the intestinal pH (pH 6.8 phosphate buffer) in vitro. The probiotic being commercialized as a freeze-dried powder obtained from an aqueous suspension, both forms were evaluated. In phosphate buffer pH 6.8, the viability remained stable for both forms of S. boulardii for 6 h. In HCl pH 1.1, viability of both forms (200 mg L(-1)) significantly decreased from 5 min. Observation under scanning/transmission electron microscopy showed morphological damages and rupture of the yeast wall. Threshold value from which S. boulardii viability was unaltered was pH 4. At the highest concentration of 200 g L(-1), the initial pH value of 1.1 rose to 3.2, exerting a protective effect. In conclusion, although the yeast in aqueous suspension was less sensitive than the freeze-dried yeast to acidic conditions, a gastric protection for improvement of oral bioavailability of viable S. boulardii appears necessary.

Effect of the intravenous lipid emulsions on the availability of calcium when using organic phosphate in TPN admixtures.

PURPOSE: The addition of high amounts of calcium remains a pharmaceutical concern due to its precipitation with phosphate in total parenteral nutrient (TPN) admixtures, compromising also the stability of the lipid emulsion. MATERIALS AND METHODS: Calcium-phosphate solubility was compared when using binary PN solutions versus all-in-one TPN (admixtures with lipid emulsions) in three formulas using organic calcium gluconate and glucose-1-phosphate. RESULTS: It was found that variation of Ca-P solubility exists between formulation with or without lipid emulsions. Concentrations of Ca decreased after filtrations of all admixtures (from 5% to 30%) and it was more significant in binary solutions. Precipitation has been observed by microscopy at high concentrations of both organic Ca-P after critical conditions of storage (24 h at 37 degrees C plus one day at ambient temperature) for admixtures containing 1% amino acids and 8% glucose with or without lipids compared to admixtures containing 2% or 3.5% amino acids and 14% glucose. CONCLUSIONS: These data demonstrated that availability of Ca using organic glucose-1-phosphate increased when lipids were present in TPN admixtures, without alteration of the lipid emulsion. Thus, high amounts of Ca (up to 30 mmol/l) and phosphates (up to 40 mmol/l) might be provided safely in parenteral nutrition admixtures.

L-cysteine encapsulation in liposomes: effect of phospholipids nature on entrapment efficiency and stability.

Liposomal entrapment of L-cysteine (L-CySH) could be a solution to enhance its oxidative stability and its intracellular bioavailability for glutathione (GSH) synthesis. This study addresses the influence of different factors (i.e. pH value (6.3 vs 7.4), antioxidant agents (EDTA or tocopherol (TO and nature of phosphatidylcholine (PC) (Soybean PC (SPC) vs hydrogenated SPC (HSPC)) to formulate and optimize Large Unilamellar Vesicles (LUVs) of L-CySH composed of PC/Cholesterol/ Phosphatidylglycerol (6:3:1). pH decrease (p = 0.0002) and substitution of SPC by HSPC (p < 0.001) reduced L-CySH oxidation. EE% (entrapment efficiency) varied from 0.98% +/- 0.54 (SPC, pH 7.4) to 6.46% +/- 1.37 (HSPC, pH 6.3) and was improved by decreasing pH (p = 0.011) and using HSPC (p < 0.0001). An immediate release of L-CySH was observed with SPC. On the contrary, with HSPC at pH 6.3, 42.0% +/- 1.2 and 73.0% +/- 1.7 remained encapsulated after 24h at 25 degrees C and 4 degrees C, respectively. In conclusion, HSPC offering both stronger rigidity and lesser propensity for peroxidation led to optimize L-CySH liposomal stability.

Evidence for impairment of hepatic energy homeostasis in head-injured rat.

Traumatic brain injury (TBI) is known to induce a metabolic adaptation characterized by a nitrogen transfer from the periphery to the liver. However, the consequences of TBI on liver energy status are poorly documented. We evaluated the consequences of TBI on liver energy homeostasis in rats. In a first set of experiments, rats were randomized into two groups: a TBI group traumatized by fluid percussion, and an ad libitum fed group (AL) of healthy rats. The rats were sacrificed at 2, 3, or 4 days (D2, D3, and D4, respectively to determine the kinetic of hepatic energy changes). Since TBI leads to a profound anorexia, in a second set of experiments TBI rats received enteral nutrition (TBI-EN group) for 4 days to specifically assess the role of anorexia in the hepatic disturbances. TBI led to a decrease in hepatic glycogen (D2: TBI 3.9 +/- 1.9 vs. AL 18.9 +/- 2.6 mg/g, p < 0.05) and ATP (D2: TBI 540 +/- 57 vs. AL 850 +/- 44 nmol/g, p < 0.05) contents. These effects were not linked to anorexia, since they were observed when rats were fed using continuous enteral nutrition. Interestingly, there was no adaptation of the mitochondrial oxidative capacity to compensate for the increase in energy requirements (cytochrome C oxidase activity: AL, 82 +/- 5; TBI, 82 +/- 4; and TBI-EN, 87 +/- 3 micromol/min/g, NS). These findings demonstrate that TBI is responsible for an impairment of liver energy homeostasis. Moreover, these alterations are related neither to anorexia nor to decreased mitochondrial oxidative capacity.

Coating of indomethacin-loaded embolic microspheres for a successful embolization therapy.

Indomethacin-loaded dietheylaminoethyl trisacryl microspheres (DEAE-MS), originally designed for therapeutic embolization, were encapsulated using two methods: coacervation and solvent evaporation/extraction. This encapsulation was achieved using a biocompatible polymer, the PLGA 50 : 50, and aimed to control the release of the anti-inflammatory non-steroidal drug (AINSD) in the occluded vessel. PLGA degradation study showed that it had an erosion half-life of approximately 35 days. Scanning electron microscopy (SEM) photographs showed that microcapsules (MC) prepared by coacervation had a wrinkled surface while those prepared using solvent-removal process showed non-porous, smooth surface, those of originally DEAE-MS showed a macro-porous, rough surface. The mean diameters were 61 microm for naked DEAE-MS vs. 71 microm and 65 microm for MC prepared by coacervation and solvent evaporation/extraction method, respectively. In vitro release study of indomethacin adsorbed onto MS indicated that drug release from MC was controlled by a diffusion process. Indomethacin diffusivity from MC was much lower than its free diffusivity from MS (mean 14.5 and 10.5 times lower for formulations prepared by coacervation and solvent evaporation/extraction method, respectively). This indicates that efficient indomethacin concentrations could be maintained over much longer time-periods in the embolized region, which is assumed to be beneficial in inhibiting normally occurring inflammatory reaction and the subsequent revascularization; responsible for treatment failure when definitive occlusion is required.

Formulations for protecting the probiotic Saccharomyces boulardii from degradation in acidic condition.

Saccharomyces boulardii is a nonpathogenic yeast with proven health benefits, some of them depending on its viability. However, the living yeast is sensitive to environmental conditions and its viability is less than 1% in the faeces after oral administration. Therefore, we assessed the survival conditions of S. boulardii in aqueous suspension and in its freeze-dried form and we formulated microspheres with the former and tablets with the latter in order to preserve the viability of the probiotic. While the viability of the yeast in aqueous suspension could be maintained for one year at -20 degrees C and +5 degrees C, increasing the temperature led to almost total mortality within 14 d at +40 degrees C and 4 d at +60 degrees C. The viability of the freeze-dried yeast was preserved for one year at +25 degrees C without moisture. With 75% relative humidity, the mortality was significant at 28 d at +25 degrees C and almost total within 1 d at +60 degrees C. In vitro, whereas less than 1% of non-encapsulated or non-tabletted S. boulardii survived after 120 min at pH 1.1, both formulations in microspheres and direct compression enabled to protect the yeast from degradation in HCl and to release it viable at pH 6.8. However, despite a similar release profile from both dosage forms, the compression led to a significant decrease in the viability of the freeze-dried yeast. In conclusion, although both formulations are efficient in protecting S. boulardii in acidic condition, microspheres provide a higher entrapment efficiency and a faster release of the viable probiotic in intestinal condition than matrix tablets.

Increased intestinal delivery of viable Saccharomyces boulardii by encapsulation in microspheres.

PURPOSE: Although probiotics are of a major potential therapeutic interest, their efficacy is usually limited by poor bioavailability of viable microorganisms on site. The aim of this study was to protect the probiotic Saccharomyces boulardii from degradation in order to ensure a greater number of viable yeast in the colon. METHODS: Alginate microspheres coated with or not with chitosan were used to encapsulate the yeast by an extrusion method. The efficiency of encapsulation was assessed both in vitro and in vivo. RESULTS: In vitro, less than 1% of the non-encapsulated probiotic survived after 120 min at pH 1.1, whereas the majority of encapsulated yeast cells remained entrapped within both types of microspheres. Further exposure to a pH 6.8 allowed the release of about 35% of viable yeasts. In vivo, the percentage of viable yeast excreted over 96 h after a single oral dose of 2 x 10(8) cfu/100 g in rats was 2.5% for nonencapsulated yeast and reached 13.3 and 9.0% of the dose administered for the uncoated and chitosan-coated microspheres, respectively. CONCLUSIONS: Given the dose-dependent efficacy of S. boulardii and the efficiency of microencapsulation in protecting the yeast from degradation, alginate microspheres could be of great interest in therapeutic applications of the yeast.